- Email: [email protected]
Potential reuse of kitchen food waste
Journal of Environmental Chemical Engineering 5 (2017) 196–204
Contents lists available at ScienceDirect
Journal of Environmental Chemical Engineering journal homepage: www.elsevier.com/locate/jece
Potential reuse of kitchen food waste Sipra Barika , Kakoli Karar Paulb,* a b
MTech Research Scholar, Department of Civil Engineering, National Institute of Technology, Rourkela, Odisha, 769008, India Assistant Professor, Department of Civil Engineering, National Institute of Technology, Rourkela 769008, Odisha, India
A R T I C L E I N F O
Article history: Received 14 July 2016 Received in revised form 9 November 2016 Accepted 21 November 2016 Available online 27 November 2016 Keywords: Chromatography Dewater Food waste Metal Lipid
A B S T R A C T
Kitchen food waste provides serious environmental pollution including its handling and disposal problem. In this study, an initiative has been taken to chemically characterize food waste and identify possible reuse and disposal techniques. Food waste samples were collected from kitchen of girls hostel of National Institute of Technology, Rourkela, India. Collected food waste samples were dried by various methods. It is observed that oven drying method at 105 C is the optimum temperature for maximum dewatering of collected food waste. The dried samples were further used for lipid extraction. Lipid profile analysis of the food waste samples was performed by using combination of different time of contact (20, 40 and 60 min) with varying solvent to food waste volumes (1:4, 1:2, 1:1 and 2:1). Gas chromatography– mass spectrometry and gas chromatography- flame ionization detector analyses have been performed to identify and quantify the presence of organic compounds in lipid from food waste. Caproic acid (6:1), lauric acid (12:0), mystric acid (14:0), palmitic acid (16:0), stearic acid (17:0) and oleic acid (18:0) are the fatty acids that have been identified in GC–MS. Palmitic acid (60.89 mg/l), stearic acid (74.11 mg/l) and oleic acid (3.81 mg/l) dominate the lipid profile. The results obtained from lipid profile analysis suggest that the kitchen food waste can be an innovative raw material for biodiesel production. Physico-chemical characterization identify considerable amount of calcium (20.36 mg/l), iron (30.84 mg/l), magnesium (3.00 mg/l) and chromium (1.28 mg/l), suggest its reuse in pharmaceutical and agricultural industries after extracting these metals. © 2016 Published by Elsevier Ltd.
1. Introduction Solid waste generation is a worldwide problem due to urbanization and industrialization. About 1.3 billion metric tons of municipal solid waste (MSW) is generated annually in the world and this amount is expected to rise about 2.2 billion tons by 2025 [10]. As per the information collected in the year 2011–12, approximately 127,486 tons per day of waste was generated in India out of which 89,334 tons per day of waste was collected and 15,881 tons per day of waste was processed (according to CPCB). In India during 2015, average waste generation was 700 tons per day [27]. The MSW contains considerable amount of food waste. Food waste is a part of municipal solid waste obtained from kitchens of residential societies, restaurants, hostels, canteens, and food and meat processing industries. These wastes are thrown in dustbin and are no longer suitable for human consumption. According to
* Corresponding author. E-mail addresses: [email protected], [email protected] (K.K. Paul). http://dx.doi.org/10.1016/j.jece.2016.11.026 2213-3437/© 2016 Published by Elsevier Ltd.
the report released by Hong Kong Environment Bureau, 9000 tons of MSW in Hong Kong is thrown away every day at landfills containing 40% of putrescibles matters. About 90% putrescibles are food wastes [15]. The national waste report of Australia published in 2008 estimated that food waste produced approximately one-third of MSW and one-fifth of commercial and industrial waste streams. Food waste generated in Australia amount to 7.5 million tones in year 2008 [20]. Other countries like Taipei and Seoul produce 182,000 tons per year and 767,000 tons per year of food waste, respectively. In characterization of municipal solid waste, India comprises maximum of food waste (31.9%) as compared to other wastes such as plastic, textile, paper, glass, cardboard, ash, leather and metal waste [35]. The disposal of large amount of food waste is an environmental problem and its discharge into drain or sewers leads to blockages. If these wastes are dumped on landfilled, it creates air pollution problem along with water or soil. There is an urgent need for proper disposal and reuse technique for kitchen food waste.
S. Barik, K.K. Paul / Journal of Environmental Chemical Engineering 5 (2017) 196–204
Food waste contains considerable amount of lipids. The lipids are a heterogeneous group of compounds including fats, oils, steroids, waxes and related compounds. Lipids can be divided in two major classes, nonsaponifiable lipids and saponifiable lipids. A nonsaponifiable lipid cannot be broken up into smaller molecules by hydrolysis that includes triglycerides, waxes, phospholipids and sphingolipids. Nonsaponifiable lipids include steroids, prostaglandins and terpenes. Saponifiable lipid contains one or more ester groups allowing it to undergo hydrolysis in the presence of an acid, base or enzyme. Researchers used different raw materials and methods to extract lipid. Boocock et al. [2] extracted lipid from raw sewage sludge by soxhlet extraction and boiling extraction method using chloroform and toluene as solvent. Konar et al. [19] used toluene to extract lipids from dried raw sewage sludge by pyrolysis. Karmee and Lin [15] have found an alternative method of producing biodiesel from food waste instead of edible oil as it has a direct impact on food shortage. Lipid is obtained from hydrolysis of food waste with an enzyme system accumulated in the solid state fungal culture present in edible and can be used as a potential source to produce biodiesel. Worldwide petroleum consumption has increased during the past decades due to modernization. An alternative fuel to petro diesel must be technically feasible, economically competitive, environmentally acceptable and easily available. This current alternative diesel fuel can be termed as biodiesel. Usage of biodiesel will allow a balance to be sought between agriculture, economic development and environment [6]. Rudolf Diesel (1893) invented the diesel engine and ran it using peanut oil. Ali and Hanna [16] produce biodiesel from vegetable oil. Using vegetable oil for biodiesel production led to food crisis. Researchers made an effort to produce biodiesel using raw materials other than vegetable oil like rapeseed oil [30], waste cooking oil [4] and microalgae [32]. Biodiesel can be produced by various processes like microemulsion, pyrolysis, transesterification and dilution. The most common method of producing biodiesel is transesterification. In this method oil/fat produced from vegetable oil react with methanol in presence of sodium or potassium hydroxide. This reaction is base catalyzed transesterification that produces methyl ester and glycerin [23]. The worldwide increasing production of biodiesel results in accumulation of by-product crude glycerol, which accounts for approximately 10% of the weight of total biodiesel production [1]. One of the problems with biodiesel is its poor cold flow properties. Biodiesel is miscible with petroleum diesel (PD) at all levels. So, often it is used as blend component in petroleum diesel. The fuel properties of biodiesel and PD blends change with the amount of biodiesel in the fuel mixture because biodiesel has different fuel properties compared to conventional PD [31]. Biodiesel can be blended and used in many different concentrations, including B100 (pure biodiesel), B20 (20% biodiesel, 80% petro-diesel), B5 (5% biodiesel, 95% diesel) and B2 (2% biodiesel, 98% diesel). Biodiesel blends higher than B20 require special handling and engine modifications to avoid maintenance and performance problems. A number of technical standards for biodiesel fuel have been set to maintain its quality, including the European standard EN 14214, ASTM International standard D 6751 and Brazilian standard ANP 42 [18]. The aim of this study is to evaluate and identify the potential reuse techniques of kitchen food waste. This paper also identifies possible ways that would help to minimize kitchen waste disposal problem as well as energy crisis problem. Making biodiesel from food waste is one of the most productive and innovative way to utilize food waste i.e., food waste of zero value can be converted to high value added product.
197
2. Methodology 2.1. Sampling site The girls’ hostel with 1200 seated capacity of National Institute of Technology (NIT) Rourkela, India is selected as a sampling location for present study. Food waste generated from kitchen of girls’ hostels of NIT Rourkela is selected as the raw material for this research work. This study location is chosen for its huge food waste generation and their dumping problem. In each sampling about 2.5 kg of food waste is collected for experimental analysis during peak hours i.e., during lunch and dinner when food waste generation is predominant. Total of 15 samples have been collected in air tight plastic containers and brought to the laboratory for further analysis. 2.2. Food waste analysis The collected food wastes from kitchen outlet have been dried by various methods such as oven drying at 55 C for 3 days, 70 C for 3 days, 105 C for 2 days, freeze drying method for 2 days at 4 C and sun drying method for 10 days [26]. Different drying techniques have been followed to obtain the best method as dewatering is a vital stage in lipid analysis. Moisture content present in food waste may inhibit the penetration of solvent into particles. Different drying methods have been selected to obtain the optimum temperature i.e., best drying temperature that would give less moisture content. Oven drying methods were performed by hot air oven and freeze drying by Eppendorf centrifuge 5702 RH. Dried food waste sample can be used for lipid extraction and at the same time dried food waste can be used for mineral extraction. A fraction of the dried food waste sample has been used for lipid extraction. Lipids from food wastes were extracted by using magnetic stirrer (Tarson Digital, Spinot) and soxhlet extraction setup. Extraction of lipid from food waste was carried out using a combination of various times of contact (20, 40, 60, 80,100 and 120 min) with mixed solvent (methanol: chloroform as 2:1) to food waste volume ratio (1:4, 1:2, 1:1 and 2:1). The other operative conditions are maintained constant i.e., 10 g of food waste, 9 consecutive extraction stages, 330 rpm agitation speed and ambient temperature [26]. Mixed solvent is selected for lipid extraction as it has higher tendency to extract lipid than single solvent [40]. For extraction of lipid, food waste was mixed with solvent (methanol: chloroform (2:1)) according to Bleigh Dyer method. Lipid extraction continues upto nine extraction stage. The percentage of lipid yield has been calculated by Eq. (1) [25]. % lipid yield ¼
weight of lipid 100 dry weight of sample
ð1Þ
Rest part of the dried food waste has been used for physicochemical characterization. For detailed physico-chemical characterization, it is necessary to digest the food wastes samples. Nearly 0.25 g of powdered samples has been taken in a digestion tube of Milestone microwave digester (MODEL START) containing 4 ml of HNO3 (65%), 2 ml of HF (40%) and 2 ml of H2O2 (30%). The digested samples were cooled for further analysis of various physicochemical properties following IS 3025 and metallic analysis by using atomic absorption spectrophotometer (Perkin Elmer Analyst 200). 2.3. Data analysis A correlation analysis is a bivariate method that describes the degree of relationship between two variables [34]. Spearman’s
198
S. Barik, K.K. Paul / Journal of Environmental Chemical Engineering 5 (2017) 196–204
Table 1 Physico-chemical characterization of food waste at varying temperatures. S.N.
Parameter
Unit
Conductivity Total hardness Turbidity Fluoride Residual chlorine pH
1. 2. 3. 4. 5. 6.
S/m mg/l – mg/l mg/l mg/l
Concentration 55 C
70 C
105 C
Freeze drying
Sun drying
163.10 720.00 0.61 2.30 1.80 6.40
167.80 750.00 0.68 2.50 2.30 6.50
170.20 830.00 0.72 2.60 3.80 6.72
158.30 775.00 0.51 2.24 1.72 6.63
169.35 820.00 0.69 2.45 2.36 6.48
rank correlation coefficient as shown in Eq. (2) has been calculated using IBM SPSS 22 software for physico-chemical parameters of kitchen food waste samples. High correlation coefficient suggests a good relationship between two variables and its value near to zero shows no relationship between them [29].
r¼1
P 2 6 di : nðn2 1Þ
ð2Þ
3. Result and discussion 3.1. Physico-chemical characterization Dewatering of sample is a vital step in lipid profile analysis. It is observed that more the temperature, lesser the moisture content resulting more lipid extraction and vice versa. The average moisture content obtained for food waste samples is 0.5% at 110 C for 2 days, while 1.5% at 70 C for 3 days and 2.5% at 55 C for 3 days by oven drying methods. The moisture content obtained from centrifuge method is 7.5%. Sun drying for 10 days moisture content was found out to be 4.6%. Olkiewicz et al. [26] also found that 105 C is the optimum temperature because hydrocarbon chains may break beyond 105 C. For best yield of lipid and hence biodiesel production, it is necessary to have long hydrocarbon chains. The Table 1 summarizes that as temperature increases, conductivity, total hardness, turbidity, fluoride, residual chlorine and pH also increases. The pH affects mineral nutrient soil quality and microorganism activity. A pH range of approximately 6–7 promotes the most ready availability of plant nutrients [3]. Thus, this waste after lipid extraction can further be used for agricultural purpose. The pH in this study is found slightly acidic (6.4–6.8) for dried solid mass. Measure of conductivity gives the idea of soluble salt present in food waste sample. Excessive high salinity affects plant growth i.e., high osmotic pressure around the roots prevents efficient water absorption capacity of plants. As conductivity obtained is very high (160 S/m–170 S/m) it can affect soil as well as plant growth if used for agricultural purpose. Desalination is required prior to be used as manure. According to WHO recommendation for total hardness, it exceeds (720 mg/l–830 mg/l) the permissible limit (500 mg/l)
[12]. Therefore, the kitchen food waste should be treated to reduce hardness before disposal on land for agricultural reuse. Residual chlorine present in food waste after land disposal can be used as nutrients for plants. Plant takes up chlorine as chloride ion for photochemical reaction in photosynthesis. Chlorine uptake affects the degree of hydration of plant cell and balances the charge of positive ions in cation transport. Chlorine deficiency results in wilting of plant, lateral roots, branch and bronzing of leaves. The kitchen food waste thus, will be useful for plant growth. Soil is polluted directly or indirectly by fluoride in the form of hydrogen fluoride and silicon tetrafluoride or deposition of fluoride contaminated matter. Fluoride may get accumulated in soil causing toxicity to microorganism thereby hampering the process of organic matter decomposition or mineralization in the soil. Presence of fluoride (2.30–2.60 mg/l) in food waste also increases organic matter. High turbidity can increase temperature of water because suspended particles absorb more heat. This lead to decrease in dissolved oxygen. It can also affect aquatic life and ground water. As turbidity concentration is less (0.61-g/l) it adversely affects on aquatic plant and ground water. By analysing its nutritional characteristics it is found that kitchen food waste will be helpful for plant growth, thus minimizing disposal problem. 3.2. Correlation analysis of kitchen food waste One of the disposal techniques of kitchen food waste is to dump on land. Before disposal, detailed characteristics and their correlation data is required for its impact on soil, water and environment. Hence, Spearman’s rank correlation has been carried out using IBM SPSS 22 software as summarized in Table 2. The result shows that fluoride and conductivity (0.915) have very strong positive correlation. Also, strong positive correlations have been found between total hardness-conductivity (0.891), turbidity-conductivity (0.806), fluoride-total hardness (0.818), residual chlorine-total hardness (0.806), fluoride-turbidity (0.891), residual chlorine-turbidity (0.855), turbidity-total hardness (0.758), residual chlorine- conductivity (0.758) and residual chlorinefluoride (0.758). Similar spearman’s rank correlation has been discussed by Tahlawi et al. [36]. Moderately positive correlations are observed between pHconductivity (0.636), pH-fluoride (0.697) and pH-residual chlorine
Table 2 Spearman’s rank correlation matrix between nutritional parameters of food waste. Parameter
Conductivity
Total hardness
Turbidity
Fluoride
Residual chlorine
pH
Conductivity (C) Total hardness (TH) Turbidity (T) Fluoride (F) Residual chlorine (RC) pH
1.000 0.891a 0.806a 0.915a 0.758b 0.636b
1.000 0.758b 0.818a 0.806a 0.624
1.000 0.891a 0.855a 0.552
1.000 0.758b 0.697b
1.000 0.697b
1.000
a b
Correlation is significant at the 0.01 level (2-tailed). Correlation is significant at the 0.05 level (2-tailed).
S. Barik, K.K. Paul / Journal of Environmental Chemical Engineering 5 (2017) 196–204 Table 3 Metallic species present in food waste.
Calcium Magnesium Copper Zinc Chromium Iron Nickel
Unit
mg/l mg/l mg/l mg/l mg/l mg/l mg/l
Concentration 70 C
55 C
105 C
Freeze drying
Sun drying
20.35 3.00 0.17 3.32 1.28 30.84 0.10
18.47 0.70 1.18 2.23 0.58 29.91 0.05
22.71 2.62 0.65 2.35 0.98 30.47 0.15
19.26 1.63 1.04 2.96 1.11 26.86 0.07
21.34 2.75 1.12 2.75 0.52 28.43 0.15
(0.697). An important conclusion can be drawn by this correlation study is that no negative correlation has been obtained indicating that no particles have been absorbed. Fluoride shows strong correlations with highest number of species. This suggests that fluoride rich particles increase organic matter indicating the potential for biodiesel production. 3.3. Chemical characterization The microwave digested samples are utilized for determination of metallic species by using atomic absorption spectrophotometer (AA200, Perkin Elmer). The metallic concentrations are summarized in Table 3. Calcium (22.71 mg/l), iron (30.47 mg/l), magnesium (2.62 mg/l) and zinc 2.35 mg/l) dominate the metallic species. Pharmaceutical industry can extract iron for preparing iron tablets, while calcium and magnesium to prepare multivitamin tablets. In human nutrition, chromium is used as a nutritional supplement recommended in impaired carbohydrate metabolism characterised by reduced glucose tolerance and impaired insulin action, weight reduction, etc. Although obtained chromium (0.98 mg/l) concentration is less, still it can be used for insulin reduction as it is required in trace amount. The practical use of zinc-nickel alloy plating has become popular now days. Zinc (2.35 mg/l) and nickel (0.15 mg/l) are also obtained that can be used for alloy plating as it is more corrosion resistance than galvanised plating. Copper is an essential nutrient for plant growth but only a small amount is
3.4. Lipid profile analysis Optimisation of lipid yield has been shown in Fig. 1 and results of lipid extraction are summarized in Table 4. In all cases, the accumulated yield of lipids increased with consecutive stages of extraction reaching a constant value till stage 9. The best yield of lipid has been obtained at 120 min for the ratio 2:1 (solvent: food waste) giving 57.75% yield of lipid as compared to other ratios 1:1 (43.45%), 1:2 (36.97%) and 1:4 (16.29%). The lowest yield of lipid was obtained in 20 min for the ratio 1:1 (28.56%), 1:2 (22.56%) and 1:4 (10.76%) and 2:1 (32.97%). It can be concluded that percentage of lipid yield is dependent on amount of solvent used as well as extraction time i.e., lower the amount of solvent and extraction time, lower is the extraction efficiency and hence lower is the amount of lipid yield. The extraction time also plays an important role. The lipid yield increases as extraction time increases but up to certain extraction stages. After stage 7, lipid yield did not show any significant increase up to stage 9 indicating that no more lipids can be extracted. However, ratio 1:4 did not show any significant increase after fifth stage. Moreover, the ratio 1:2 and 1:4 did not produce any lipid yield at the beginning because almost all solvents are absorbed by the food waste sample. The ratios 1:1, 1:2, 2:1 and 1:4 do not show any significant increase of lipid yield after sixth extraction stage. After 120 min, lipid yield did not show any
%yield of lipid (cummulave)
solvent: food waste, 1:2 40
20 min
30
40 min
20
60 min
10
80 min
0 0
5
10
stage
solvent: food waste, 1:2 %yield of lipid (cummulave)
1. 2. 3. 4. 5. 6. 7.
Element
required in agriculture. The aim of metallic analysis is to provide option to reuse kitchen food waste other than biodiesel production that may help to minimize handling and disposal problems. The extracted heavy metals can be used in pharmaceutical and agricultural sectors and it may be economical also. Pharmaceutical industry can extract heavy metals by using chemical and physical technologies such as precipitation [21], solvent extraction, ion exchanger, reverse osmosis [14,39], oxidation/reduction, sedimentation, filtration, electrochemical techniques, cation surfactant, etc. Also, biosorption methods can be used for extraction of heavy metals using algae, bacteria, fungi and yeast. Electrokinetic remediation and bioleaching technology can also be used for removing heavy metals [38].
40
20 min
30
40 min
20
60 min
10
80 min
0
100 min
0
(a)
%yield of lipid (cummulave)
5
10
stage
120 min
100 min 120 min
(b)
solvent: food waste, 2:1
solvent: food waste, 1:4
80
20 20 min
60
40 min
40
60 min
20
80 min
0 0
5 stage
(c)
10
100 min 120 min
%yield of lipid (cummulave)
S.N.
199
20 min
15
40 min
10
60 min
5
80 min
0 0
5
10
stage
(d)
Fig. 1. Cumulative percentage of lipid yield vs stage with respect to time.
100 min 120 min
200
S. Barik, K.K. Paul / Journal of Environmental Chemical Engineering 5 (2017) 196–204
Table 4 Percentage of lipid yield at different solvent: food ratio and times of contact. S.N.
Solvent: food waste
Stages
Extraction time 20 min
40 min
60 min
80 min
100 min
120 min
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36
1:1
1 2 3 4 5 6 7 8 9 1 2 3 4 5 6 7 8 9 1 2 3 4 5 6 7 8 9 1 2 3 4 5 6 7 8 9
7.140 10.425 14.543 20.434 25.255 27.769 28.566 28.566 28.566 0.000 3.140 5.758 8.547 15.875 20.567 22.556 22.556 22.556 12.654 16.596 22.587 25.341 29.564 31.759 32.976 32.976 32.976 0.000 0.000 2.468 4.745 7.658 8.896 10.766 10.766 10.766
8.758 12.869 17.965 22.476 28.968 31.985 35.577 35.577 35.577 0.000 4.347 8.923 10.928 15.8932 20.289 24.723 24.723 24.723 15.478 20.648 26.959 30.644 34.823 38.713 42.815 42.815 42.815 0.000 0.000 3.856 5.579 8.876 11.987 12.857 12.857 12.857
10.457 15.785 21.857 25.748 29.874 34.874 38.313 38.313 38.313 0.000 4.392 9.370 13.938 19.721 25.912 29.120 29.120 29.120 16.578 21.328 26.126 32.213 36.856 40.832 45.287 45.287 45.287 0.000 0.000 3.579 6.796 10.786 12.877 14.568 14.568 14.568
11.465 16.536 22.846 27.785 32.658 36.986 41.755 41.755 41.755 0.000 5.213 12.120 15.913 20.237 25.928 30.299 30.299 30.299 16.217 22.792 27.283 33.3871 38.837 42.372 47.872 47.872 47.872 0.000 0.000 3.785 6.340 11.986 12.906 15.345 15.345 15.345
12.535 16.855 23.985 27.858 33.186 38.842 43.959 43.959 43.959 0.000 7.588 14.986 19.324 25.857 29.7648 35.488 35.488 35.488 18.371 25.579 32.896 36.849 43.975 49.686 55.986 55.986 55.986 0.000 0.000 4.436 6.908 11.789 12.988 15.809 15.809 15.809
13.347 16.378 25.894 27.479 34.986 38.263 43.485 43.458 43.458 0.000 8.858 14.869 21.426 26.214 30.435 36.970 36.970 36.970 19.785 27.986 34.452 37.757 46.986 50.325 57.758 57.758 57.758 0.000 0.000 4.589 7.823 12.584 13.312 16.293 16.293 16.293
1:2
2:1
1:4
significant increase concluding that the best yield can be obtained in 120 min. Hence, time of contact, amount of solvent and extraction stages plays a crucial role in optimization of lipid yield. The similar lipid extraction analysis has been performed for municipal sewage sludge for different times of contact and Table 5 Instrumentation and analytical conditions for GC–MS and GC-FID system. GC–MS Gas chromatograph Column
Oven temperature program Injector volume Column flow (N2) Pressure Inlet settlings Split flow GC-FID Inlet settings Injection volume Column
Oven temperature Column flow FID setting
Agilent 7820A Series Agilent 122-5532E: 1 DB. 5 ms 0 C–325 C (350 C): 30 m 250 mm 0.25 mm 200 C (5.6667 min), 10 C, 310 C (11.167 min) 1 mL 1 mL/min 12.537 psi 280 C, split ratio: 20:1 20 mL/min
230 C, split ratio: 20:1 1 mL Agilent 122-5532E: 1 DB-5ms 60 C–325 C (350 C) 30 m 250 mm 0.25 mm 80 C–300 C (8.4 min) at 50 C/min 1.5 mL/min Temperature: 300 C H2 flow: 30 mL/min Air flow: 300 mL/min Makeup flow (N2): 25 mL/min
extraction stages. It was found that optimum yield was obtained at 60 min and there was no significant yield after 5th stage [26]. The extracted lipids have further been analysed in GC–MS (Agilent 7820A series) to identify the presence of organic compounds. The GC–MS program details are summarized in Table 5. After identification of organic compounds, respective standards have been prepared for each compound to determine the exact concentration of the identified organic compounds in GC-FID (Agilent 7820A series). Table 5 summarizes the programme of GC–MS and GC-FID used for analysis of lipid. Fatty acids are named according to the chain length of carbon. Shortchain fatty acids, have four (C4) to ten (C10) carbons. Mediumchain fatty acids have twelve (C12) to fourteen (C14) carbons, long-chain fatty acids have sixteen (C16) to eighteen carbons (C18) and very long-chain fatty acids contain twenty (C20) or more carbon atoms. Table 6 and Fig. 2 discuss about the identified fatty acid in lipid profile analyzed in GC–MS. Saturated fatty acids identified in lipid from GC–MS include caproic acid (6:0), lauric acid (12:0), mystric acid (14:0), palmitic acid (16:0) and stearic acid (17:0). Unsaturated fatty acid identified in lipid is oleic acid (18:0). The predominant fatty acids are palmitic acid and oleic acid for ratio 1:2 and 1:1 (Table 7). Due to the presence of medium and long fatty acid, kitchen food waste has a great potential to be for biodiesel production. Similar fatty acid compositions (palmitic acid and oleic acid) have been obtained by Cheirsilp and Louhasakul [5] in plant oil indicating their potential to be used as biodiesel feedstock. Microbial oil having fatty acid composition similar to vegetable oil can be used for biodiesel production and many oleaginous microorganisms like bacteria, yeast, fungi and
S. Barik, K.K. Paul / Journal of Environmental Chemical Engineering 5 (2017) 196–204 Table 6 Free fatty acids identified in GC–MS of lipid sample.
201
Table 7 Concentrations of identified organic acids at different ratio.
S.N.
Retention time
Organic compounds
S.N.
Organic acids
1. 2. 3. 4. 5. 6.
4.070 9.191 11.181 12.595 13.741 13.853
Caproic acid (C6:0) Lauric acid (C12:0) Mystric acid (C14:0) Palmitic acid (C16:0) Stearic acid (C17:0) Oleic acid (C18:0)
1. 2. 3.
Palmitic acid (16:0) Stearic acid (18:0) Oleic acid (18:1)
microalgae have such characteristics. Yeast and microalgae have been used more frequently than fungi and bacteria for lipid and biodiesel production [11]. To reduce the cost of microbial oil production, efforts has been made for using low-cost materials as media for SCO production. Generally, two types of lipid synthesis exist in oleaginous microorganisms i.e. de novo and ex novo lipid accumulation processes. The former process is carried out on hydrophilic materials and usually requires nitrogen-limited culture conditions. Ex novo lipid production is the production of SCO through fermentation on hydrophobic materials [28]. Moreover biodiesel properties are mainly dependent on fatty acid composition. Due to the presence of high concentration of saturated fatty acid, there may be a problem for cold flow properties of biodiesel when it becomes cloudy by forming crystals but higher saturated content fatty acids will produce a better burning biodiesel. At low temperatures, higher-melting point components in the fuel lead to nucleation and growth of solid crystals due to high amount of saturated fatty acid in the fuel. Prolonged exposure of the fuel to temperatures at or below cloud point causes crystals to grow and form interlocking networks.
Solvent to food waste 2:1
1:2
1:1
4.40 mg/l 74.11 mg/l 2.02 mg/l
141.98 mg/l – 3.82 mg/l
60.89 mg/l – 2.30 mg/l
These solid crystals will cease the flow and lead to starvation of fuel in the engine and engine will not operate in that condition [9]. This problem can be overcome by the presence of branched-chain and hydroxyl fatty acid methyl esters [26]. Detailed explanations for different researchers are summarized in Table 8. Absence of polyunsaturated fatty acids is an advantage in kitchen food waste. Polyunsaturated fatty acids are liable to auto oxidation, resulting in a poor oxidation stability of biodiesel [26]. Different researchers have used different raw materials and different lipid extraction methods. Some of the researchers work and the percent of lipid yield have been compared with present study lipid analysis which is discussed in Table 9. Most of the researchers [2,8,5,37] used mixed solvent rather than single solvent to enhance the efficiency for lipid extraction. Karmee and Lin [15] extracted lipid by hydrolysis method and used lipase as enzymes for biodiesel extraction. Lipases are a class of enzymes which are known to catalyse hydrolysis. 3.5. Chemical characterization of residue left after lipid extraction The waste remained after lipid extraction (i.e., residue) has been further characterized to identify its possible reuse and disposal
Fig. 2. GC–MS of lipid for identification of fatty acids.
202
S. Barik, K.K. Paul / Journal of Environmental Chemical Engineering 5 (2017) 196–204
Table 8 Research on cold flow properties of biodiesel. S.N.
Researcher
Study on cold flow properties of biodiesel
1 2 3
Monirul et al. [22] National Biodiesel Education Program [24] Krishna et al. [41]
4 5
Robert [7] Kim et al. [17]
6
Conley [42]
7
Jon Van Gerpen [13]
Cold flow enhancers are used to improve the cold flow properties of biodiesel. Properties of biodiesel depends on the raw material (type of grease, fat or oil) from which they are produced and strong factor to determine the amount of saturated fat. To improve the cold flow properties, biodiesel should be blended with petro diesel. This will help to reduce pour point and saturated fatty acids in biodiesel. To improve cold flow problem by modifying its fatty acid profile to remove high melting components. The cold flow performance of biodiesel blends in a car and a light duty truck at 16 C and 20 C, using jatropha, soybean, palm, rapeseed, cottonseed, and waste cooking oil derived biodiesels are mixed in different fractions (B5, B10 and B20). They observed that the presence of unsaturated structures and the hydrocarbon chain length has marked effect on the low-temperature properties of biodiesel as the start-ability and drivability of the car with all B5 blends were generally good at 20 C. While the B10 and the B20 blend of palm biodiesel failed at 20 C and at 16 C respectively in the start-ability test, the B10 and B20 blends of jatropha, soybean, rapeseed and waste cooking tended to be good at 20 C in both tests. The addition of cold flow improvers coupled with blending, B1, B5, and B20 in most cases enhanced the cold flow properties of soybean and canola biodiesel. Blending improves cold flow properties of biodiesel, when he blended Tallow and soybean oil based biodiesel with diesel.
Table 9 Extraction of lipid by various researchers. S. N.
Researcher
Raw material
1.
Boocock et al. [2] Konar et al. [19] Durand et al. [8] Siddiquee and Rohani [43]
Municipal sewage sludge
2. 3. 4.
5.
6.
7. 8.
9. 10. 11.
Solvent
Lipid profile
Chloroform and toluene Toluene
79% unsaponifiable 21% glycerides fatty acids, 45% palmitic acid, 41% stearic acid 65 wt% free fatty acid, 28 wt% unsafonifiable
Chloroform-methanol
35.4% for Wissous and 11.4% for Ronchin
Hexane and methanol
–
–
Industrial waste
Acid hydrolysis method for Hexane, ether, determination of fat in foods acetone, chloroformmethanol Soxhlet extraction Chloroform-methanol
Dewatered sludge
Methane extraction
Hexane
–
Marine microalgae (tetraselmis)
–
Chloroform-methanol
Soxhlet extraction
Hexane
–
Methanol
Palmitic acid, stearic acid, oleic acid, linoleic acid, linolelaidic acid, linolenic acid, arochidic acid, behenic acid Palmitic acid (31.1 to 49.4%), oleic acid (18.3 to 32.6%), stearic acid (8.3 to 15.8%) Palmitic acid, oleic acid, linoleic acid
Boiling extraction and soxhlet extraction Raw Atlanta dried sewage sludge Boiling extraction (pyrolysed) Municipal sewage sludge Soxhlet extraction
Waste water sludge (primary, secondary, blended and stabilized) Zhu et al. [40] Municipal sewage sludge
Cheirsilp and Louhasakul [5] Pastore et al. [44] Teo et al. [37]
Methods adopted
Olkiewicz Municipal sewage sludge et al. [26] Vajpeyi and Oleaginous microorganism Chandran [33] Present study Food waste
Soxhlet extraction
Soxhlet extraction and Bligh Methanol and dyer method chloroform
techniques. The waste was acid digested in a microwave digestion system (MODEL START) and metallic species were further analyzed in atomic absorption spectrophotometer (AA200, Perkin Elmer). The characterized value has been summarized in Table 10. The availability of nutrients to plants is mainly affected by pH of soil. Nutrients are available to soil within the pH range of 6.5– 8.0 and pH (6.89) is within the permissible limit. Calcium
48.3% triglyceride, 7.8% diglycerides, 25.7% monoglycerides, 18.2% free fatty acid
Palmitic acid, stearic acid, oleic acid
(30.36 mg/kg) and magnesium (2.43 mg/kg) can be used as plant nutrients. High Ca:Mg ratio improves soil structure, balance nutrients and reduces leaching of plants. Iron (31.32 mg/kg) concentration exceeds the required plant nutrients value i.e. 20 mg/kg. Chromium and nickel were found to toxic for soil and plant growth. Lower chromium (1.20 mg/kg) and nickel (0.59 mg/ kg) concentration will not have any toxic effect on soil and plants.
Table 10 Chemical characterization of extracted residue. S.N.
Parameter
Units
Concentration
Permissible limit for plant nutrients
1. 2. 3. 4. 5. 6. 7. 8.
pH Calcium Magnesium Copper Zinc Chromium Iron Nickel
– mg/kg mg/kg mg/kg mg/kg mg/kg mg/kg mg/kg
6.89 30.36 2.43 1.45 3.57 1.20 31.32 0.59
6.5–8.0 – – 10 50 1.30 20 10
S. Barik, K.K. Paul / Journal of Environmental Chemical Engineering 5 (2017) 196–204
Copper (1.45 mg/kg), a macronutrients concentration is very less and its requirement for plant growth is also minimum. This chemical characterization of residue remained after lipid extraction will help to minimize handling and disposal problem thus providing nutrients to soil and plant. 4. Conclusion Food waste is a zero cost material and non-edible resource. This study investigated and confirmed that kitchen food waste has a great potential to be used for extraction of lipid. The selection of solvent was done according to Bligh Dyer’s method. The best extraction of lipid yield was obtained in the ratio 2:1 (solvent: food waste) at 120 min time interval. The GC analyses of the samples were performed to identify the organic compounds. The extracted lipid is found to have significant potential for biodiesel production. Other than biodiesel production, kitchen food waste can also be reused for agricultural and pharmaceutical purposes. Recycling of food waste is environment friendly that increases energy production and minimizes space requirement for landfill. It also minimizes waste disposal problem. This study can be helpful for pollution control by reducing leachate generation. It will also reduce environmental problem like foul odour and fly nuisance. Thus, this study is an innovative approach to reuse kitchen food waste for biodiesel production to overcome energy crisis problem by replacing biodiesel with petro-diesel and helps to minimize handling and disposal problem of kitchen food waste. References [1] M. Azenhaa, C. Lucasb, J.L. Granjac, I.C. Alvesc, E. Guimarãesc, Glycerol resulting from biodiesel production as an admixture for cement-based materials: an experimental study, Eur. J. Environ. Civil Eng. (2016) 1–17, doi: http://dx.doi.org/10.1080/19648189.2016.1177603. [2] D.G.B. Boocock, S.K. Konar, A. Leung, D. Lang, Fuels and chemicals from sewage sludge: the solvent extraction and composition of a lipid from a raw sewage sludge, Fuels Chem. 71 (1992) 1283–1289 0016-2361/92/l 11283-07. [3] A.D. Borkar, Studies on some physicochemical parameters of soil samples in Katol Taluka District Nagpur (MS) India, Res. J. Agric. For. Sci. 3 (2015) 16–18. [4] M. Canakci, The potential of restaurant waste lipids as biodiesel feedstocks, Bioresour. Technol. 98 (1) (2007) 183–190. [5] B. Cheirsilp, Y. Louhasakul, Industrial wastes as a promising renewable source for production of microbial lipid and direct transesterification of the lipid into biodiesel, Bioresour. Technol. 142 (2013) 329–337, doi:http://dx.doi.org/ 10.1016/j.biortech.2013.05.012. [6] A. Demirbas, Characterization of biodiesel fuels, Eur. J. Environ. Civil Eng. 31 (2009) 889–896, doi:http://dx.doi.org/10.1080/15567030801904202. [7] Dunn O. Robert, Improving the Cold Flow Properties of Biodiesel by Fractionation, Soybean—Applications and Technology, in: Tzi-Bun Ng (Ed.), InTech, 2011 ISBN: 978-953-307-207-4, Available from: http://www. intechopen.com/books/soybean-applicationandtechnology/improving-thecold-flow-properties-ofbiodieselbyfractionation. [8] C. Durand, V. Reeban, A. Ambles, J. Oudot, Characterization of the organic matter of sludge: determination of lipids, hydrocarbons and PAHs from road retention/infiltration ponds in France, Environ. Pollut. 132 (3) (2004) 375–384, doi:http://dx.doi.org/10.1016/j.envpol.2004.05.038. [9] G. Dwivedi, M.P. Sharma, Cold flow behaviour of biodiesel—a review, Int. J. Renew. Energy Res. 3 (4) (2013) 827–836. [10] D. Hoornweg, P. Bhada-Tata, What a Waste: A Global Review of Solid Waste Management, World Bank, Washington, DC, 2012. [11] C. Huang, X. Chen, L. Xiong, X. Chen, L. Ma, Y. Chen, Single cell oil production from low-cost substrates: the possibility and potential of its industrialization, Biotechnol. Adv. 31 (2) (2013) 129–139, doi:http://dx.doi.org/10.1016/j. biotechadv.2012.08.010. [12] M.R. Islam, K. Alim, A. Razi, M.R. Hasan, M.H. Hasan, S. Alam, Effect of leachate on surrounding surface water: case study in Rajbandh Sanitary Landfill Site in Khulna City, Bangladesh, Glob. J. Res. Eng. 13 (2013) 2249–4596. [13] Jon Van Gerpen, Cold Flow Properties of Blends of Tallow and Soybean OilBased Biodiesel. WHITE PAPER, Crimson Renewable Energy, LP, 2016 Retrieved 12 June 2013, from http://www.crimsonrenewable.com/UofIdaho.php (n.d.). [14] R.S. Juang, R.C. Shaiu, Metal removal from aqueous solutions using chitosan enhanced membrane filtration, J. Membr. Sci. 165 (2) (2000) 159–167, doi: http://dx.doi.org/10.1016/s0376-7388(99)00235-5. [15] S.K. Karmee, C.S. Lin, Valorisation of food waste to biofuel: current trends and technological challenges, Sustain. Chem. Processes 22 (2014) 1–4, doi:http:// dx.doi.org/10.1186/s40508-014-0022-111.
203
[16] Y. Ali, M.A. Hanna, Alternative diesel fuels from vegetable oils, Bioresource Technology 50 (2) (1994) 153–163, doi:http://dx.doi.org/10.1016/0960-8524 (94)90068-X. [17] J.K. Kim, E.S. Yim, C.H. Jeon, C.S. Jung, B.H. Han, Cold performance of various biodiesel fuel blends at low temperature, Int. J. Automot. Technol. 13 (2) (2012) 293–300, doi:http://dx.doi.org/10.1007/S12239-012-0027-2. [18] G. Knothe, Analyzing biodiesel: standards and other methods, J. Am. Oil Chem. Soc. 83 (10) (2006) 823–833. [19] S.K. Konar, D.G.B. Boocock, V. Mao, J. Liu, Fuels and chemicals from sewage sludge: hydrocarbon liquids from the catalytic pyrolysis of sewage sludge lipids over activated alumina, Fuel Chem. 73 (5) (1992) 642–646, doi:http://dx. doi.org/10.1016/0016-2361(94)90002-7. [20] L. Mason, T. Boyle, J. Fyfe, T. Smith, D. Cordell, National Food Waste Data Assessment: Final Report, Prepared for the Department of Sustainability, Environment, Water, Population and Communities, by the Institute for Sustainable Futures, University of Technology, Sydney, Sydney, 2011. [21] M. Matouq, N. Jildeh, M. Qtaishat, M. Hindiyeh, M.Q.A. Syouf, The adsorption kinetics and modeling for heavy metals removal from wastewater by Moringa pods, J. Environ. Chem. Eng. 3 (2015) 775–784, doi:http://dx.doi.org/10.1016/j. jece.2015.03.027. [22] I.M. Monirul, H.H. Masjuki, M.A. Kalam, N.W.M. Zulkifli, H.K. Rasedul, M.M. Rashed, H.K. Imdadul, M.H. Mosaraf, A comprehensive review on biodiesel cold flow properties and oxidation stability along with their improvement processes, R. Soc. Chem. Adv. 105 (3) (2015) 86631–86655, doi:http://dx.doi. org/10.1039/C5RA09555. [23] B. Nas, A. Berktay, Energy potential of biodiesel generated from waste cooking oil: an environmental approach, Energy Sources 2 (1) (2007) 63–71, doi:http:// dx.doi.org/10.1080/155672240500400903. [24] National Biodiesel Education Program, Diesel Fuel Cold Flow Properties. Biodiesel Shortcourse -Cold Flow, Biodiesel Education, (2016) Retrieved 12 June 2013, from http://web.cals.uidaho.edu/biodiesel/biodiesel-shortcoursecold-flow/ (n.d.). [25] I.I. Nkafamiya, H.M. Maina, S.A. Osemeahon, U.U. Modibbo, Percentage oil yield and physiochemical properties of different groundnut species (Arachis hypogaea), Afr. J. Food Sci. 4 (7) (2010) 418–421. [26] M. Olkiewicz, M.P. Caporgno, A. Fortuny, F. Stuber, A. Fabregeat, J. Font, C. Bengoa, Direct liquid–liquid extraction of lipid from municipal sewage sludge for biodiesel production, Fuel Process Technol. 128 (2014) 331–338, doi:http:// dx.doi.org/10.1016/j.fuproc.2014.07.041. [27] B.K. Pandey, S. Vyas, M. Pandey, A. Gaur, Characterisation of municipal solid waste generated from Bhopal, India Curr. Sci. Perspect. 2 (2016) 52–56. [28] S. Papanikolaou, G. Aggelis, Lipids of oleaginous yeasts. Part II. Technology and potential applications, Eur. J. Lipid Sci. Technol. 113 (8) (2011) 1052–1073, doi: http://dx.doi.org/10.1002/ejlt.201100015. [29] V.T. Patil, P.R. Patil, Physicochemical analysis of selected groundwater samples of Amalner Town in Jalgaon District, Maharashtra, India, J. Chem. 7 (2010) 111– 116. [30] M. Predel, W. Kaminsky, Pyrolysis of rapeseed in a fluidised bed reactor, Bioresour. Technol. 66 (1998) 113–117. [31] K. Rajagopal, R.C. Bindu, R.B.N. Prasad, A. Ahmad, The effect of fatty acid profiles of biodiesel on key fuel properties of some biodiesels and blends, Energy Resour. 38 (11) (2016) 1582–1590, doi:http://dx.doi.org/10.1080/ 15567036.2014.929758. [32] S. Rajvanshi, M. Pal, Microalgae: a potential source of biodiesel, J. Sustain. Bioenergy Syst. 2 (2012) 49–59, doi:http://dx.doi.org/10.4236/ jsbs.2012.23008. [33] S. Vajpeyi, K. Chandran, Microbial conversion of synthetic and food wastederived volatile fatty acids to lipids, Bioresour. Technol. 188 (2015) 49–55, doi: http://dx.doi.org/10.1016/j.biortech.2015.01.099. [34] R. Shyam, G.S. Kalwania, Ground water chemistry: a case study of eastern part of Sikar city (Rajasthan), India, Int. J. Appl. Eng. Res. 2 (2011) 367–378. [35] R. Srivastava, V. Krishna, I. Sonkar, Characterization and management of municipal solid waste: a case study of Vanaras city, India, Int. J. Curr. Res. Acad. Rev. 2 (2014) 10–16. [36] M.R.E. Tahlawi, M.A. Mohamed, G.Y. Boghdadi, R.E. Rabeiy, H.A. Saleem, Groundwater quality assessment to estimate its suitability for different uses in Assiut Governorate, Egypt, Int. J. Recent Technol. Eng. 3 (2014) 2277–3878. [37] C.H. Teo, H. Jamaluddin, N.A.M. Zain, A. Idris, Biodiesel production via lipase catalysed transesterification of microalgae lipids from Tetraselmis sp, Renew. Energy 68 (2014) 1–5, doi:http://dx.doi.org/10.1016/j.renene.2014.01.027. [38] Y. Xu, C. Zhang, M. Zhao, H. Rong, K. Zhang, Q. Chen, Comparison of bioleaching and electrokinetic remediation processes for removal of heavy metals from wastewater treatment sludge, Chemosphere (2016) 1–6, doi:http://dx.doi.org/ 10.1016/j.chemosphere.2016.10.086. [39] G. Yan, T. Viraraghavan, Heavy metal removal in a biosorption column by immobilized M. rouxii biomass, Bioresour. Technol. 78 (3) (2001) 243–249, doi:http://dx.doi.org/10.1016/S0960-8524(01)00020-7 11341683. [40] F. Zhu, L. Zhao, Z. Zhang, H. Jiang, Preliminary study at lipids extraction technology from municipal sludge by organic solvent, Environ. Sci. 16 (2012) 352–356, doi:http://dx.doi.org/10.1016/j.proenv.2012.10.050. [41] C.R. Krishna, B. Thomas, M. Devinder, T. Kaitlin, B. Christopher, Improving cold flow properties of biodiesel, 2008, Retrieved 12 June 2013, from http://www. aertc.org/conference/AEC_Sessions%5CCopy%20of%20Session%202%5CTrack% 20B%20Renewables%5C1.%20Climate%20Change%20Biofuels%20III%5C1.% 20Dr.%20CR%20Krishna%5CCR%20Krishna%20presentation.pdf.
204
S. Barik, K.K. Paul / Journal of Environmental Chemical Engineering 5 (2017) 196–204
[42] S.P. Conley, Biodiesel Quality: Is All Biodiesel Created equal? BioEnergy, 2012, ID-338. Purdue extension http://www.extension.purdue.edu/extmedia/ID/ID338.pdf from http://www.ces.purdue.edu/bioenergy. [43] M.N. Siddiquee, S. Rohani, Lipid extraction and biodiesel production from municipal sewage sludges: A review, Renew. Sustain. Energy Rev. 15 (2011) 1067–1072.
[44] C. Pastore, A. Lopez, V. Lotito, G. Mascolo, Biodiesel from dewatered wastewater sludge: A two-step process for a more advantageous production, Chemosphere 92 (2013) 667–673, doi:http://dx.doi.org/10.1016/j. chemosphere.2013.03.046.
Contents lists available at ScienceDirect
Journal of Environmental Chemical Engineering journal homepage: www.elsevier.com/locate/jece
Potential reuse of kitchen food waste Sipra Barika , Kakoli Karar Paulb,* a b
MTech Research Scholar, Department of Civil Engineering, National Institute of Technology, Rourkela, Odisha, 769008, India Assistant Professor, Department of Civil Engineering, National Institute of Technology, Rourkela 769008, Odisha, India
A R T I C L E I N F O
Article history: Received 14 July 2016 Received in revised form 9 November 2016 Accepted 21 November 2016 Available online 27 November 2016 Keywords: Chromatography Dewater Food waste Metal Lipid
A B S T R A C T
Kitchen food waste provides serious environmental pollution including its handling and disposal problem. In this study, an initiative has been taken to chemically characterize food waste and identify possible reuse and disposal techniques. Food waste samples were collected from kitchen of girls hostel of National Institute of Technology, Rourkela, India. Collected food waste samples were dried by various methods. It is observed that oven drying method at 105 C is the optimum temperature for maximum dewatering of collected food waste. The dried samples were further used for lipid extraction. Lipid profile analysis of the food waste samples was performed by using combination of different time of contact (20, 40 and 60 min) with varying solvent to food waste volumes (1:4, 1:2, 1:1 and 2:1). Gas chromatography– mass spectrometry and gas chromatography- flame ionization detector analyses have been performed to identify and quantify the presence of organic compounds in lipid from food waste. Caproic acid (6:1), lauric acid (12:0), mystric acid (14:0), palmitic acid (16:0), stearic acid (17:0) and oleic acid (18:0) are the fatty acids that have been identified in GC–MS. Palmitic acid (60.89 mg/l), stearic acid (74.11 mg/l) and oleic acid (3.81 mg/l) dominate the lipid profile. The results obtained from lipid profile analysis suggest that the kitchen food waste can be an innovative raw material for biodiesel production. Physico-chemical characterization identify considerable amount of calcium (20.36 mg/l), iron (30.84 mg/l), magnesium (3.00 mg/l) and chromium (1.28 mg/l), suggest its reuse in pharmaceutical and agricultural industries after extracting these metals. © 2016 Published by Elsevier Ltd.
1. Introduction Solid waste generation is a worldwide problem due to urbanization and industrialization. About 1.3 billion metric tons of municipal solid waste (MSW) is generated annually in the world and this amount is expected to rise about 2.2 billion tons by 2025 [10]. As per the information collected in the year 2011–12, approximately 127,486 tons per day of waste was generated in India out of which 89,334 tons per day of waste was collected and 15,881 tons per day of waste was processed (according to CPCB). In India during 2015, average waste generation was 700 tons per day [27]. The MSW contains considerable amount of food waste. Food waste is a part of municipal solid waste obtained from kitchens of residential societies, restaurants, hostels, canteens, and food and meat processing industries. These wastes are thrown in dustbin and are no longer suitable for human consumption. According to
* Corresponding author. E-mail addresses: [email protected], [email protected] (K.K. Paul). http://dx.doi.org/10.1016/j.jece.2016.11.026 2213-3437/© 2016 Published by Elsevier Ltd.
the report released by Hong Kong Environment Bureau, 9000 tons of MSW in Hong Kong is thrown away every day at landfills containing 40% of putrescibles matters. About 90% putrescibles are food wastes [15]. The national waste report of Australia published in 2008 estimated that food waste produced approximately one-third of MSW and one-fifth of commercial and industrial waste streams. Food waste generated in Australia amount to 7.5 million tones in year 2008 [20]. Other countries like Taipei and Seoul produce 182,000 tons per year and 767,000 tons per year of food waste, respectively. In characterization of municipal solid waste, India comprises maximum of food waste (31.9%) as compared to other wastes such as plastic, textile, paper, glass, cardboard, ash, leather and metal waste [35]. The disposal of large amount of food waste is an environmental problem and its discharge into drain or sewers leads to blockages. If these wastes are dumped on landfilled, it creates air pollution problem along with water or soil. There is an urgent need for proper disposal and reuse technique for kitchen food waste.
S. Barik, K.K. Paul / Journal of Environmental Chemical Engineering 5 (2017) 196–204
Food waste contains considerable amount of lipids. The lipids are a heterogeneous group of compounds including fats, oils, steroids, waxes and related compounds. Lipids can be divided in two major classes, nonsaponifiable lipids and saponifiable lipids. A nonsaponifiable lipid cannot be broken up into smaller molecules by hydrolysis that includes triglycerides, waxes, phospholipids and sphingolipids. Nonsaponifiable lipids include steroids, prostaglandins and terpenes. Saponifiable lipid contains one or more ester groups allowing it to undergo hydrolysis in the presence of an acid, base or enzyme. Researchers used different raw materials and methods to extract lipid. Boocock et al. [2] extracted lipid from raw sewage sludge by soxhlet extraction and boiling extraction method using chloroform and toluene as solvent. Konar et al. [19] used toluene to extract lipids from dried raw sewage sludge by pyrolysis. Karmee and Lin [15] have found an alternative method of producing biodiesel from food waste instead of edible oil as it has a direct impact on food shortage. Lipid is obtained from hydrolysis of food waste with an enzyme system accumulated in the solid state fungal culture present in edible and can be used as a potential source to produce biodiesel. Worldwide petroleum consumption has increased during the past decades due to modernization. An alternative fuel to petro diesel must be technically feasible, economically competitive, environmentally acceptable and easily available. This current alternative diesel fuel can be termed as biodiesel. Usage of biodiesel will allow a balance to be sought between agriculture, economic development and environment [6]. Rudolf Diesel (1893) invented the diesel engine and ran it using peanut oil. Ali and Hanna [16] produce biodiesel from vegetable oil. Using vegetable oil for biodiesel production led to food crisis. Researchers made an effort to produce biodiesel using raw materials other than vegetable oil like rapeseed oil [30], waste cooking oil [4] and microalgae [32]. Biodiesel can be produced by various processes like microemulsion, pyrolysis, transesterification and dilution. The most common method of producing biodiesel is transesterification. In this method oil/fat produced from vegetable oil react with methanol in presence of sodium or potassium hydroxide. This reaction is base catalyzed transesterification that produces methyl ester and glycerin [23]. The worldwide increasing production of biodiesel results in accumulation of by-product crude glycerol, which accounts for approximately 10% of the weight of total biodiesel production [1]. One of the problems with biodiesel is its poor cold flow properties. Biodiesel is miscible with petroleum diesel (PD) at all levels. So, often it is used as blend component in petroleum diesel. The fuel properties of biodiesel and PD blends change with the amount of biodiesel in the fuel mixture because biodiesel has different fuel properties compared to conventional PD [31]. Biodiesel can be blended and used in many different concentrations, including B100 (pure biodiesel), B20 (20% biodiesel, 80% petro-diesel), B5 (5% biodiesel, 95% diesel) and B2 (2% biodiesel, 98% diesel). Biodiesel blends higher than B20 require special handling and engine modifications to avoid maintenance and performance problems. A number of technical standards for biodiesel fuel have been set to maintain its quality, including the European standard EN 14214, ASTM International standard D 6751 and Brazilian standard ANP 42 [18]. The aim of this study is to evaluate and identify the potential reuse techniques of kitchen food waste. This paper also identifies possible ways that would help to minimize kitchen waste disposal problem as well as energy crisis problem. Making biodiesel from food waste is one of the most productive and innovative way to utilize food waste i.e., food waste of zero value can be converted to high value added product.
197
2. Methodology 2.1. Sampling site The girls’ hostel with 1200 seated capacity of National Institute of Technology (NIT) Rourkela, India is selected as a sampling location for present study. Food waste generated from kitchen of girls’ hostels of NIT Rourkela is selected as the raw material for this research work. This study location is chosen for its huge food waste generation and their dumping problem. In each sampling about 2.5 kg of food waste is collected for experimental analysis during peak hours i.e., during lunch and dinner when food waste generation is predominant. Total of 15 samples have been collected in air tight plastic containers and brought to the laboratory for further analysis. 2.2. Food waste analysis The collected food wastes from kitchen outlet have been dried by various methods such as oven drying at 55 C for 3 days, 70 C for 3 days, 105 C for 2 days, freeze drying method for 2 days at 4 C and sun drying method for 10 days [26]. Different drying techniques have been followed to obtain the best method as dewatering is a vital stage in lipid analysis. Moisture content present in food waste may inhibit the penetration of solvent into particles. Different drying methods have been selected to obtain the optimum temperature i.e., best drying temperature that would give less moisture content. Oven drying methods were performed by hot air oven and freeze drying by Eppendorf centrifuge 5702 RH. Dried food waste sample can be used for lipid extraction and at the same time dried food waste can be used for mineral extraction. A fraction of the dried food waste sample has been used for lipid extraction. Lipids from food wastes were extracted by using magnetic stirrer (Tarson Digital, Spinot) and soxhlet extraction setup. Extraction of lipid from food waste was carried out using a combination of various times of contact (20, 40, 60, 80,100 and 120 min) with mixed solvent (methanol: chloroform as 2:1) to food waste volume ratio (1:4, 1:2, 1:1 and 2:1). The other operative conditions are maintained constant i.e., 10 g of food waste, 9 consecutive extraction stages, 330 rpm agitation speed and ambient temperature [26]. Mixed solvent is selected for lipid extraction as it has higher tendency to extract lipid than single solvent [40]. For extraction of lipid, food waste was mixed with solvent (methanol: chloroform (2:1)) according to Bleigh Dyer method. Lipid extraction continues upto nine extraction stage. The percentage of lipid yield has been calculated by Eq. (1) [25]. % lipid yield ¼
weight of lipid 100 dry weight of sample
ð1Þ
Rest part of the dried food waste has been used for physicochemical characterization. For detailed physico-chemical characterization, it is necessary to digest the food wastes samples. Nearly 0.25 g of powdered samples has been taken in a digestion tube of Milestone microwave digester (MODEL START) containing 4 ml of HNO3 (65%), 2 ml of HF (40%) and 2 ml of H2O2 (30%). The digested samples were cooled for further analysis of various physicochemical properties following IS 3025 and metallic analysis by using atomic absorption spectrophotometer (Perkin Elmer Analyst 200). 2.3. Data analysis A correlation analysis is a bivariate method that describes the degree of relationship between two variables [34]. Spearman’s
198
S. Barik, K.K. Paul / Journal of Environmental Chemical Engineering 5 (2017) 196–204
Table 1 Physico-chemical characterization of food waste at varying temperatures. S.N.
Parameter
Unit
Conductivity Total hardness Turbidity Fluoride Residual chlorine pH
1. 2. 3. 4. 5. 6.
S/m mg/l – mg/l mg/l mg/l
Concentration 55 C
70 C
105 C
Freeze drying
Sun drying
163.10 720.00 0.61 2.30 1.80 6.40
167.80 750.00 0.68 2.50 2.30 6.50
170.20 830.00 0.72 2.60 3.80 6.72
158.30 775.00 0.51 2.24 1.72 6.63
169.35 820.00 0.69 2.45 2.36 6.48
rank correlation coefficient as shown in Eq. (2) has been calculated using IBM SPSS 22 software for physico-chemical parameters of kitchen food waste samples. High correlation coefficient suggests a good relationship between two variables and its value near to zero shows no relationship between them [29].
r¼1
P 2 6 di : nðn2 1Þ
ð2Þ
3. Result and discussion 3.1. Physico-chemical characterization Dewatering of sample is a vital step in lipid profile analysis. It is observed that more the temperature, lesser the moisture content resulting more lipid extraction and vice versa. The average moisture content obtained for food waste samples is 0.5% at 110 C for 2 days, while 1.5% at 70 C for 3 days and 2.5% at 55 C for 3 days by oven drying methods. The moisture content obtained from centrifuge method is 7.5%. Sun drying for 10 days moisture content was found out to be 4.6%. Olkiewicz et al. [26] also found that 105 C is the optimum temperature because hydrocarbon chains may break beyond 105 C. For best yield of lipid and hence biodiesel production, it is necessary to have long hydrocarbon chains. The Table 1 summarizes that as temperature increases, conductivity, total hardness, turbidity, fluoride, residual chlorine and pH also increases. The pH affects mineral nutrient soil quality and microorganism activity. A pH range of approximately 6–7 promotes the most ready availability of plant nutrients [3]. Thus, this waste after lipid extraction can further be used for agricultural purpose. The pH in this study is found slightly acidic (6.4–6.8) for dried solid mass. Measure of conductivity gives the idea of soluble salt present in food waste sample. Excessive high salinity affects plant growth i.e., high osmotic pressure around the roots prevents efficient water absorption capacity of plants. As conductivity obtained is very high (160 S/m–170 S/m) it can affect soil as well as plant growth if used for agricultural purpose. Desalination is required prior to be used as manure. According to WHO recommendation for total hardness, it exceeds (720 mg/l–830 mg/l) the permissible limit (500 mg/l)
[12]. Therefore, the kitchen food waste should be treated to reduce hardness before disposal on land for agricultural reuse. Residual chlorine present in food waste after land disposal can be used as nutrients for plants. Plant takes up chlorine as chloride ion for photochemical reaction in photosynthesis. Chlorine uptake affects the degree of hydration of plant cell and balances the charge of positive ions in cation transport. Chlorine deficiency results in wilting of plant, lateral roots, branch and bronzing of leaves. The kitchen food waste thus, will be useful for plant growth. Soil is polluted directly or indirectly by fluoride in the form of hydrogen fluoride and silicon tetrafluoride or deposition of fluoride contaminated matter. Fluoride may get accumulated in soil causing toxicity to microorganism thereby hampering the process of organic matter decomposition or mineralization in the soil. Presence of fluoride (2.30–2.60 mg/l) in food waste also increases organic matter. High turbidity can increase temperature of water because suspended particles absorb more heat. This lead to decrease in dissolved oxygen. It can also affect aquatic life and ground water. As turbidity concentration is less (0.61-g/l) it adversely affects on aquatic plant and ground water. By analysing its nutritional characteristics it is found that kitchen food waste will be helpful for plant growth, thus minimizing disposal problem. 3.2. Correlation analysis of kitchen food waste One of the disposal techniques of kitchen food waste is to dump on land. Before disposal, detailed characteristics and their correlation data is required for its impact on soil, water and environment. Hence, Spearman’s rank correlation has been carried out using IBM SPSS 22 software as summarized in Table 2. The result shows that fluoride and conductivity (0.915) have very strong positive correlation. Also, strong positive correlations have been found between total hardness-conductivity (0.891), turbidity-conductivity (0.806), fluoride-total hardness (0.818), residual chlorine-total hardness (0.806), fluoride-turbidity (0.891), residual chlorine-turbidity (0.855), turbidity-total hardness (0.758), residual chlorine- conductivity (0.758) and residual chlorinefluoride (0.758). Similar spearman’s rank correlation has been discussed by Tahlawi et al. [36]. Moderately positive correlations are observed between pHconductivity (0.636), pH-fluoride (0.697) and pH-residual chlorine
Table 2 Spearman’s rank correlation matrix between nutritional parameters of food waste. Parameter
Conductivity
Total hardness
Turbidity
Fluoride
Residual chlorine
pH
Conductivity (C) Total hardness (TH) Turbidity (T) Fluoride (F) Residual chlorine (RC) pH
1.000 0.891a 0.806a 0.915a 0.758b 0.636b
1.000 0.758b 0.818a 0.806a 0.624
1.000 0.891a 0.855a 0.552
1.000 0.758b 0.697b
1.000 0.697b
1.000
a b
Correlation is significant at the 0.01 level (2-tailed). Correlation is significant at the 0.05 level (2-tailed).
S. Barik, K.K. Paul / Journal of Environmental Chemical Engineering 5 (2017) 196–204 Table 3 Metallic species present in food waste.
Calcium Magnesium Copper Zinc Chromium Iron Nickel
Unit
mg/l mg/l mg/l mg/l mg/l mg/l mg/l
Concentration 70 C
55 C
105 C
Freeze drying
Sun drying
20.35 3.00 0.17 3.32 1.28 30.84 0.10
18.47 0.70 1.18 2.23 0.58 29.91 0.05
22.71 2.62 0.65 2.35 0.98 30.47 0.15
19.26 1.63 1.04 2.96 1.11 26.86 0.07
21.34 2.75 1.12 2.75 0.52 28.43 0.15
(0.697). An important conclusion can be drawn by this correlation study is that no negative correlation has been obtained indicating that no particles have been absorbed. Fluoride shows strong correlations with highest number of species. This suggests that fluoride rich particles increase organic matter indicating the potential for biodiesel production. 3.3. Chemical characterization The microwave digested samples are utilized for determination of metallic species by using atomic absorption spectrophotometer (AA200, Perkin Elmer). The metallic concentrations are summarized in Table 3. Calcium (22.71 mg/l), iron (30.47 mg/l), magnesium (2.62 mg/l) and zinc 2.35 mg/l) dominate the metallic species. Pharmaceutical industry can extract iron for preparing iron tablets, while calcium and magnesium to prepare multivitamin tablets. In human nutrition, chromium is used as a nutritional supplement recommended in impaired carbohydrate metabolism characterised by reduced glucose tolerance and impaired insulin action, weight reduction, etc. Although obtained chromium (0.98 mg/l) concentration is less, still it can be used for insulin reduction as it is required in trace amount. The practical use of zinc-nickel alloy plating has become popular now days. Zinc (2.35 mg/l) and nickel (0.15 mg/l) are also obtained that can be used for alloy plating as it is more corrosion resistance than galvanised plating. Copper is an essential nutrient for plant growth but only a small amount is
3.4. Lipid profile analysis Optimisation of lipid yield has been shown in Fig. 1 and results of lipid extraction are summarized in Table 4. In all cases, the accumulated yield of lipids increased with consecutive stages of extraction reaching a constant value till stage 9. The best yield of lipid has been obtained at 120 min for the ratio 2:1 (solvent: food waste) giving 57.75% yield of lipid as compared to other ratios 1:1 (43.45%), 1:2 (36.97%) and 1:4 (16.29%). The lowest yield of lipid was obtained in 20 min for the ratio 1:1 (28.56%), 1:2 (22.56%) and 1:4 (10.76%) and 2:1 (32.97%). It can be concluded that percentage of lipid yield is dependent on amount of solvent used as well as extraction time i.e., lower the amount of solvent and extraction time, lower is the extraction efficiency and hence lower is the amount of lipid yield. The extraction time also plays an important role. The lipid yield increases as extraction time increases but up to certain extraction stages. After stage 7, lipid yield did not show any significant increase up to stage 9 indicating that no more lipids can be extracted. However, ratio 1:4 did not show any significant increase after fifth stage. Moreover, the ratio 1:2 and 1:4 did not produce any lipid yield at the beginning because almost all solvents are absorbed by the food waste sample. The ratios 1:1, 1:2, 2:1 and 1:4 do not show any significant increase of lipid yield after sixth extraction stage. After 120 min, lipid yield did not show any
%yield of lipid (cummulave)
solvent: food waste, 1:2 40
20 min
30
40 min
20
60 min
10
80 min
0 0
5
10
stage
solvent: food waste, 1:2 %yield of lipid (cummulave)
1. 2. 3. 4. 5. 6. 7.
Element
required in agriculture. The aim of metallic analysis is to provide option to reuse kitchen food waste other than biodiesel production that may help to minimize handling and disposal problems. The extracted heavy metals can be used in pharmaceutical and agricultural sectors and it may be economical also. Pharmaceutical industry can extract heavy metals by using chemical and physical technologies such as precipitation [21], solvent extraction, ion exchanger, reverse osmosis [14,39], oxidation/reduction, sedimentation, filtration, electrochemical techniques, cation surfactant, etc. Also, biosorption methods can be used for extraction of heavy metals using algae, bacteria, fungi and yeast. Electrokinetic remediation and bioleaching technology can also be used for removing heavy metals [38].
40
20 min
30
40 min
20
60 min
10
80 min
0
100 min
0
(a)
%yield of lipid (cummulave)
5
10
stage
120 min
100 min 120 min
(b)
solvent: food waste, 2:1
solvent: food waste, 1:4
80
20 20 min
60
40 min
40
60 min
20
80 min
0 0
5 stage
(c)
10
100 min 120 min
%yield of lipid (cummulave)
S.N.
199
20 min
15
40 min
10
60 min
5
80 min
0 0
5
10
stage
(d)
Fig. 1. Cumulative percentage of lipid yield vs stage with respect to time.
100 min 120 min
200
S. Barik, K.K. Paul / Journal of Environmental Chemical Engineering 5 (2017) 196–204
Table 4 Percentage of lipid yield at different solvent: food ratio and times of contact. S.N.
Solvent: food waste
Stages
Extraction time 20 min
40 min
60 min
80 min
100 min
120 min
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36
1:1
1 2 3 4 5 6 7 8 9 1 2 3 4 5 6 7 8 9 1 2 3 4 5 6 7 8 9 1 2 3 4 5 6 7 8 9
7.140 10.425 14.543 20.434 25.255 27.769 28.566 28.566 28.566 0.000 3.140 5.758 8.547 15.875 20.567 22.556 22.556 22.556 12.654 16.596 22.587 25.341 29.564 31.759 32.976 32.976 32.976 0.000 0.000 2.468 4.745 7.658 8.896 10.766 10.766 10.766
8.758 12.869 17.965 22.476 28.968 31.985 35.577 35.577 35.577 0.000 4.347 8.923 10.928 15.8932 20.289 24.723 24.723 24.723 15.478 20.648 26.959 30.644 34.823 38.713 42.815 42.815 42.815 0.000 0.000 3.856 5.579 8.876 11.987 12.857 12.857 12.857
10.457 15.785 21.857 25.748 29.874 34.874 38.313 38.313 38.313 0.000 4.392 9.370 13.938 19.721 25.912 29.120 29.120 29.120 16.578 21.328 26.126 32.213 36.856 40.832 45.287 45.287 45.287 0.000 0.000 3.579 6.796 10.786 12.877 14.568 14.568 14.568
11.465 16.536 22.846 27.785 32.658 36.986 41.755 41.755 41.755 0.000 5.213 12.120 15.913 20.237 25.928 30.299 30.299 30.299 16.217 22.792 27.283 33.3871 38.837 42.372 47.872 47.872 47.872 0.000 0.000 3.785 6.340 11.986 12.906 15.345 15.345 15.345
12.535 16.855 23.985 27.858 33.186 38.842 43.959 43.959 43.959 0.000 7.588 14.986 19.324 25.857 29.7648 35.488 35.488 35.488 18.371 25.579 32.896 36.849 43.975 49.686 55.986 55.986 55.986 0.000 0.000 4.436 6.908 11.789 12.988 15.809 15.809 15.809
13.347 16.378 25.894 27.479 34.986 38.263 43.485 43.458 43.458 0.000 8.858 14.869 21.426 26.214 30.435 36.970 36.970 36.970 19.785 27.986 34.452 37.757 46.986 50.325 57.758 57.758 57.758 0.000 0.000 4.589 7.823 12.584 13.312 16.293 16.293 16.293
1:2
2:1
1:4
significant increase concluding that the best yield can be obtained in 120 min. Hence, time of contact, amount of solvent and extraction stages plays a crucial role in optimization of lipid yield. The similar lipid extraction analysis has been performed for municipal sewage sludge for different times of contact and Table 5 Instrumentation and analytical conditions for GC–MS and GC-FID system. GC–MS Gas chromatograph Column
Oven temperature program Injector volume Column flow (N2) Pressure Inlet settlings Split flow GC-FID Inlet settings Injection volume Column
Oven temperature Column flow FID setting
Agilent 7820A Series Agilent 122-5532E: 1 DB. 5 ms 0 C–325 C (350 C): 30 m 250 mm 0.25 mm 200 C (5.6667 min), 10 C, 310 C (11.167 min) 1 mL 1 mL/min 12.537 psi 280 C, split ratio: 20:1 20 mL/min
230 C, split ratio: 20:1 1 mL Agilent 122-5532E: 1 DB-5ms 60 C–325 C (350 C) 30 m 250 mm 0.25 mm 80 C–300 C (8.4 min) at 50 C/min 1.5 mL/min Temperature: 300 C H2 flow: 30 mL/min Air flow: 300 mL/min Makeup flow (N2): 25 mL/min
extraction stages. It was found that optimum yield was obtained at 60 min and there was no significant yield after 5th stage [26]. The extracted lipids have further been analysed in GC–MS (Agilent 7820A series) to identify the presence of organic compounds. The GC–MS program details are summarized in Table 5. After identification of organic compounds, respective standards have been prepared for each compound to determine the exact concentration of the identified organic compounds in GC-FID (Agilent 7820A series). Table 5 summarizes the programme of GC–MS and GC-FID used for analysis of lipid. Fatty acids are named according to the chain length of carbon. Shortchain fatty acids, have four (C4) to ten (C10) carbons. Mediumchain fatty acids have twelve (C12) to fourteen (C14) carbons, long-chain fatty acids have sixteen (C16) to eighteen carbons (C18) and very long-chain fatty acids contain twenty (C20) or more carbon atoms. Table 6 and Fig. 2 discuss about the identified fatty acid in lipid profile analyzed in GC–MS. Saturated fatty acids identified in lipid from GC–MS include caproic acid (6:0), lauric acid (12:0), mystric acid (14:0), palmitic acid (16:0) and stearic acid (17:0). Unsaturated fatty acid identified in lipid is oleic acid (18:0). The predominant fatty acids are palmitic acid and oleic acid for ratio 1:2 and 1:1 (Table 7). Due to the presence of medium and long fatty acid, kitchen food waste has a great potential to be for biodiesel production. Similar fatty acid compositions (palmitic acid and oleic acid) have been obtained by Cheirsilp and Louhasakul [5] in plant oil indicating their potential to be used as biodiesel feedstock. Microbial oil having fatty acid composition similar to vegetable oil can be used for biodiesel production and many oleaginous microorganisms like bacteria, yeast, fungi and
S. Barik, K.K. Paul / Journal of Environmental Chemical Engineering 5 (2017) 196–204 Table 6 Free fatty acids identified in GC–MS of lipid sample.
201
Table 7 Concentrations of identified organic acids at different ratio.
S.N.
Retention time
Organic compounds
S.N.
Organic acids
1. 2. 3. 4. 5. 6.
4.070 9.191 11.181 12.595 13.741 13.853
Caproic acid (C6:0) Lauric acid (C12:0) Mystric acid (C14:0) Palmitic acid (C16:0) Stearic acid (C17:0) Oleic acid (C18:0)
1. 2. 3.
Palmitic acid (16:0) Stearic acid (18:0) Oleic acid (18:1)
microalgae have such characteristics. Yeast and microalgae have been used more frequently than fungi and bacteria for lipid and biodiesel production [11]. To reduce the cost of microbial oil production, efforts has been made for using low-cost materials as media for SCO production. Generally, two types of lipid synthesis exist in oleaginous microorganisms i.e. de novo and ex novo lipid accumulation processes. The former process is carried out on hydrophilic materials and usually requires nitrogen-limited culture conditions. Ex novo lipid production is the production of SCO through fermentation on hydrophobic materials [28]. Moreover biodiesel properties are mainly dependent on fatty acid composition. Due to the presence of high concentration of saturated fatty acid, there may be a problem for cold flow properties of biodiesel when it becomes cloudy by forming crystals but higher saturated content fatty acids will produce a better burning biodiesel. At low temperatures, higher-melting point components in the fuel lead to nucleation and growth of solid crystals due to high amount of saturated fatty acid in the fuel. Prolonged exposure of the fuel to temperatures at or below cloud point causes crystals to grow and form interlocking networks.
Solvent to food waste 2:1
1:2
1:1
4.40 mg/l 74.11 mg/l 2.02 mg/l
141.98 mg/l – 3.82 mg/l
60.89 mg/l – 2.30 mg/l
These solid crystals will cease the flow and lead to starvation of fuel in the engine and engine will not operate in that condition [9]. This problem can be overcome by the presence of branched-chain and hydroxyl fatty acid methyl esters [26]. Detailed explanations for different researchers are summarized in Table 8. Absence of polyunsaturated fatty acids is an advantage in kitchen food waste. Polyunsaturated fatty acids are liable to auto oxidation, resulting in a poor oxidation stability of biodiesel [26]. Different researchers have used different raw materials and different lipid extraction methods. Some of the researchers work and the percent of lipid yield have been compared with present study lipid analysis which is discussed in Table 9. Most of the researchers [2,8,5,37] used mixed solvent rather than single solvent to enhance the efficiency for lipid extraction. Karmee and Lin [15] extracted lipid by hydrolysis method and used lipase as enzymes for biodiesel extraction. Lipases are a class of enzymes which are known to catalyse hydrolysis. 3.5. Chemical characterization of residue left after lipid extraction The waste remained after lipid extraction (i.e., residue) has been further characterized to identify its possible reuse and disposal
Fig. 2. GC–MS of lipid for identification of fatty acids.
202
S. Barik, K.K. Paul / Journal of Environmental Chemical Engineering 5 (2017) 196–204
Table 8 Research on cold flow properties of biodiesel. S.N.
Researcher
Study on cold flow properties of biodiesel
1 2 3
Monirul et al. [22] National Biodiesel Education Program [24] Krishna et al. [41]
4 5
Robert [7] Kim et al. [17]
6
Conley [42]
7
Jon Van Gerpen [13]
Cold flow enhancers are used to improve the cold flow properties of biodiesel. Properties of biodiesel depends on the raw material (type of grease, fat or oil) from which they are produced and strong factor to determine the amount of saturated fat. To improve the cold flow properties, biodiesel should be blended with petro diesel. This will help to reduce pour point and saturated fatty acids in biodiesel. To improve cold flow problem by modifying its fatty acid profile to remove high melting components. The cold flow performance of biodiesel blends in a car and a light duty truck at 16 C and 20 C, using jatropha, soybean, palm, rapeseed, cottonseed, and waste cooking oil derived biodiesels are mixed in different fractions (B5, B10 and B20). They observed that the presence of unsaturated structures and the hydrocarbon chain length has marked effect on the low-temperature properties of biodiesel as the start-ability and drivability of the car with all B5 blends were generally good at 20 C. While the B10 and the B20 blend of palm biodiesel failed at 20 C and at 16 C respectively in the start-ability test, the B10 and B20 blends of jatropha, soybean, rapeseed and waste cooking tended to be good at 20 C in both tests. The addition of cold flow improvers coupled with blending, B1, B5, and B20 in most cases enhanced the cold flow properties of soybean and canola biodiesel. Blending improves cold flow properties of biodiesel, when he blended Tallow and soybean oil based biodiesel with diesel.
Table 9 Extraction of lipid by various researchers. S. N.
Researcher
Raw material
1.
Boocock et al. [2] Konar et al. [19] Durand et al. [8] Siddiquee and Rohani [43]
Municipal sewage sludge
2. 3. 4.
5.
6.
7. 8.
9. 10. 11.
Solvent
Lipid profile
Chloroform and toluene Toluene
79% unsaponifiable 21% glycerides fatty acids, 45% palmitic acid, 41% stearic acid 65 wt% free fatty acid, 28 wt% unsafonifiable
Chloroform-methanol
35.4% for Wissous and 11.4% for Ronchin
Hexane and methanol
–
–
Industrial waste
Acid hydrolysis method for Hexane, ether, determination of fat in foods acetone, chloroformmethanol Soxhlet extraction Chloroform-methanol
Dewatered sludge
Methane extraction
Hexane
–
Marine microalgae (tetraselmis)
–
Chloroform-methanol
Soxhlet extraction
Hexane
–
Methanol
Palmitic acid, stearic acid, oleic acid, linoleic acid, linolelaidic acid, linolenic acid, arochidic acid, behenic acid Palmitic acid (31.1 to 49.4%), oleic acid (18.3 to 32.6%), stearic acid (8.3 to 15.8%) Palmitic acid, oleic acid, linoleic acid
Boiling extraction and soxhlet extraction Raw Atlanta dried sewage sludge Boiling extraction (pyrolysed) Municipal sewage sludge Soxhlet extraction
Waste water sludge (primary, secondary, blended and stabilized) Zhu et al. [40] Municipal sewage sludge
Cheirsilp and Louhasakul [5] Pastore et al. [44] Teo et al. [37]
Methods adopted
Olkiewicz Municipal sewage sludge et al. [26] Vajpeyi and Oleaginous microorganism Chandran [33] Present study Food waste
Soxhlet extraction
Soxhlet extraction and Bligh Methanol and dyer method chloroform
techniques. The waste was acid digested in a microwave digestion system (MODEL START) and metallic species were further analyzed in atomic absorption spectrophotometer (AA200, Perkin Elmer). The characterized value has been summarized in Table 10. The availability of nutrients to plants is mainly affected by pH of soil. Nutrients are available to soil within the pH range of 6.5– 8.0 and pH (6.89) is within the permissible limit. Calcium
48.3% triglyceride, 7.8% diglycerides, 25.7% monoglycerides, 18.2% free fatty acid
Palmitic acid, stearic acid, oleic acid
(30.36 mg/kg) and magnesium (2.43 mg/kg) can be used as plant nutrients. High Ca:Mg ratio improves soil structure, balance nutrients and reduces leaching of plants. Iron (31.32 mg/kg) concentration exceeds the required plant nutrients value i.e. 20 mg/kg. Chromium and nickel were found to toxic for soil and plant growth. Lower chromium (1.20 mg/kg) and nickel (0.59 mg/ kg) concentration will not have any toxic effect on soil and plants.
Table 10 Chemical characterization of extracted residue. S.N.
Parameter
Units
Concentration
Permissible limit for plant nutrients
1. 2. 3. 4. 5. 6. 7. 8.
pH Calcium Magnesium Copper Zinc Chromium Iron Nickel
– mg/kg mg/kg mg/kg mg/kg mg/kg mg/kg mg/kg
6.89 30.36 2.43 1.45 3.57 1.20 31.32 0.59
6.5–8.0 – – 10 50 1.30 20 10
S. Barik, K.K. Paul / Journal of Environmental Chemical Engineering 5 (2017) 196–204
Copper (1.45 mg/kg), a macronutrients concentration is very less and its requirement for plant growth is also minimum. This chemical characterization of residue remained after lipid extraction will help to minimize handling and disposal problem thus providing nutrients to soil and plant. 4. Conclusion Food waste is a zero cost material and non-edible resource. This study investigated and confirmed that kitchen food waste has a great potential to be used for extraction of lipid. The selection of solvent was done according to Bligh Dyer’s method. The best extraction of lipid yield was obtained in the ratio 2:1 (solvent: food waste) at 120 min time interval. The GC analyses of the samples were performed to identify the organic compounds. The extracted lipid is found to have significant potential for biodiesel production. Other than biodiesel production, kitchen food waste can also be reused for agricultural and pharmaceutical purposes. Recycling of food waste is environment friendly that increases energy production and minimizes space requirement for landfill. It also minimizes waste disposal problem. This study can be helpful for pollution control by reducing leachate generation. It will also reduce environmental problem like foul odour and fly nuisance. Thus, this study is an innovative approach to reuse kitchen food waste for biodiesel production to overcome energy crisis problem by replacing biodiesel with petro-diesel and helps to minimize handling and disposal problem of kitchen food waste. References [1] M. Azenhaa, C. Lucasb, J.L. Granjac, I.C. Alvesc, E. Guimarãesc, Glycerol resulting from biodiesel production as an admixture for cement-based materials: an experimental study, Eur. J. Environ. Civil Eng. (2016) 1–17, doi: http://dx.doi.org/10.1080/19648189.2016.1177603. [2] D.G.B. Boocock, S.K. Konar, A. Leung, D. Lang, Fuels and chemicals from sewage sludge: the solvent extraction and composition of a lipid from a raw sewage sludge, Fuels Chem. 71 (1992) 1283–1289 0016-2361/92/l 11283-07. [3] A.D. Borkar, Studies on some physicochemical parameters of soil samples in Katol Taluka District Nagpur (MS) India, Res. J. Agric. For. Sci. 3 (2015) 16–18. [4] M. Canakci, The potential of restaurant waste lipids as biodiesel feedstocks, Bioresour. Technol. 98 (1) (2007) 183–190. [5] B. Cheirsilp, Y. Louhasakul, Industrial wastes as a promising renewable source for production of microbial lipid and direct transesterification of the lipid into biodiesel, Bioresour. Technol. 142 (2013) 329–337, doi:http://dx.doi.org/ 10.1016/j.biortech.2013.05.012. [6] A. Demirbas, Characterization of biodiesel fuels, Eur. J. Environ. Civil Eng. 31 (2009) 889–896, doi:http://dx.doi.org/10.1080/15567030801904202. [7] Dunn O. Robert, Improving the Cold Flow Properties of Biodiesel by Fractionation, Soybean—Applications and Technology, in: Tzi-Bun Ng (Ed.), InTech, 2011 ISBN: 978-953-307-207-4, Available from: http://www. intechopen.com/books/soybean-applicationandtechnology/improving-thecold-flow-properties-ofbiodieselbyfractionation. [8] C. Durand, V. Reeban, A. Ambles, J. Oudot, Characterization of the organic matter of sludge: determination of lipids, hydrocarbons and PAHs from road retention/infiltration ponds in France, Environ. Pollut. 132 (3) (2004) 375–384, doi:http://dx.doi.org/10.1016/j.envpol.2004.05.038. [9] G. Dwivedi, M.P. Sharma, Cold flow behaviour of biodiesel—a review, Int. J. Renew. Energy Res. 3 (4) (2013) 827–836. [10] D. Hoornweg, P. Bhada-Tata, What a Waste: A Global Review of Solid Waste Management, World Bank, Washington, DC, 2012. [11] C. Huang, X. Chen, L. Xiong, X. Chen, L. Ma, Y. Chen, Single cell oil production from low-cost substrates: the possibility and potential of its industrialization, Biotechnol. Adv. 31 (2) (2013) 129–139, doi:http://dx.doi.org/10.1016/j. biotechadv.2012.08.010. [12] M.R. Islam, K. Alim, A. Razi, M.R. Hasan, M.H. Hasan, S. Alam, Effect of leachate on surrounding surface water: case study in Rajbandh Sanitary Landfill Site in Khulna City, Bangladesh, Glob. J. Res. Eng. 13 (2013) 2249–4596. [13] Jon Van Gerpen, Cold Flow Properties of Blends of Tallow and Soybean OilBased Biodiesel. WHITE PAPER, Crimson Renewable Energy, LP, 2016 Retrieved 12 June 2013, from http://www.crimsonrenewable.com/UofIdaho.php (n.d.). [14] R.S. Juang, R.C. Shaiu, Metal removal from aqueous solutions using chitosan enhanced membrane filtration, J. Membr. Sci. 165 (2) (2000) 159–167, doi: http://dx.doi.org/10.1016/s0376-7388(99)00235-5. [15] S.K. Karmee, C.S. Lin, Valorisation of food waste to biofuel: current trends and technological challenges, Sustain. Chem. Processes 22 (2014) 1–4, doi:http:// dx.doi.org/10.1186/s40508-014-0022-111.
203
[16] Y. Ali, M.A. Hanna, Alternative diesel fuels from vegetable oils, Bioresource Technology 50 (2) (1994) 153–163, doi:http://dx.doi.org/10.1016/0960-8524 (94)90068-X. [17] J.K. Kim, E.S. Yim, C.H. Jeon, C.S. Jung, B.H. Han, Cold performance of various biodiesel fuel blends at low temperature, Int. J. Automot. Technol. 13 (2) (2012) 293–300, doi:http://dx.doi.org/10.1007/S12239-012-0027-2. [18] G. Knothe, Analyzing biodiesel: standards and other methods, J. Am. Oil Chem. Soc. 83 (10) (2006) 823–833. [19] S.K. Konar, D.G.B. Boocock, V. Mao, J. Liu, Fuels and chemicals from sewage sludge: hydrocarbon liquids from the catalytic pyrolysis of sewage sludge lipids over activated alumina, Fuel Chem. 73 (5) (1992) 642–646, doi:http://dx. doi.org/10.1016/0016-2361(94)90002-7. [20] L. Mason, T. Boyle, J. Fyfe, T. Smith, D. Cordell, National Food Waste Data Assessment: Final Report, Prepared for the Department of Sustainability, Environment, Water, Population and Communities, by the Institute for Sustainable Futures, University of Technology, Sydney, Sydney, 2011. [21] M. Matouq, N. Jildeh, M. Qtaishat, M. Hindiyeh, M.Q.A. Syouf, The adsorption kinetics and modeling for heavy metals removal from wastewater by Moringa pods, J. Environ. Chem. Eng. 3 (2015) 775–784, doi:http://dx.doi.org/10.1016/j. jece.2015.03.027. [22] I.M. Monirul, H.H. Masjuki, M.A. Kalam, N.W.M. Zulkifli, H.K. Rasedul, M.M. Rashed, H.K. Imdadul, M.H. Mosaraf, A comprehensive review on biodiesel cold flow properties and oxidation stability along with their improvement processes, R. Soc. Chem. Adv. 105 (3) (2015) 86631–86655, doi:http://dx.doi. org/10.1039/C5RA09555. [23] B. Nas, A. Berktay, Energy potential of biodiesel generated from waste cooking oil: an environmental approach, Energy Sources 2 (1) (2007) 63–71, doi:http:// dx.doi.org/10.1080/155672240500400903. [24] National Biodiesel Education Program, Diesel Fuel Cold Flow Properties. Biodiesel Shortcourse -Cold Flow, Biodiesel Education, (2016) Retrieved 12 June 2013, from http://web.cals.uidaho.edu/biodiesel/biodiesel-shortcoursecold-flow/ (n.d.). [25] I.I. Nkafamiya, H.M. Maina, S.A. Osemeahon, U.U. Modibbo, Percentage oil yield and physiochemical properties of different groundnut species (Arachis hypogaea), Afr. J. Food Sci. 4 (7) (2010) 418–421. [26] M. Olkiewicz, M.P. Caporgno, A. Fortuny, F. Stuber, A. Fabregeat, J. Font, C. Bengoa, Direct liquid–liquid extraction of lipid from municipal sewage sludge for biodiesel production, Fuel Process Technol. 128 (2014) 331–338, doi:http:// dx.doi.org/10.1016/j.fuproc.2014.07.041. [27] B.K. Pandey, S. Vyas, M. Pandey, A. Gaur, Characterisation of municipal solid waste generated from Bhopal, India Curr. Sci. Perspect. 2 (2016) 52–56. [28] S. Papanikolaou, G. Aggelis, Lipids of oleaginous yeasts. Part II. Technology and potential applications, Eur. J. Lipid Sci. Technol. 113 (8) (2011) 1052–1073, doi: http://dx.doi.org/10.1002/ejlt.201100015. [29] V.T. Patil, P.R. Patil, Physicochemical analysis of selected groundwater samples of Amalner Town in Jalgaon District, Maharashtra, India, J. Chem. 7 (2010) 111– 116. [30] M. Predel, W. Kaminsky, Pyrolysis of rapeseed in a fluidised bed reactor, Bioresour. Technol. 66 (1998) 113–117. [31] K. Rajagopal, R.C. Bindu, R.B.N. Prasad, A. Ahmad, The effect of fatty acid profiles of biodiesel on key fuel properties of some biodiesels and blends, Energy Resour. 38 (11) (2016) 1582–1590, doi:http://dx.doi.org/10.1080/ 15567036.2014.929758. [32] S. Rajvanshi, M. Pal, Microalgae: a potential source of biodiesel, J. Sustain. Bioenergy Syst. 2 (2012) 49–59, doi:http://dx.doi.org/10.4236/ jsbs.2012.23008. [33] S. Vajpeyi, K. Chandran, Microbial conversion of synthetic and food wastederived volatile fatty acids to lipids, Bioresour. Technol. 188 (2015) 49–55, doi: http://dx.doi.org/10.1016/j.biortech.2015.01.099. [34] R. Shyam, G.S. Kalwania, Ground water chemistry: a case study of eastern part of Sikar city (Rajasthan), India, Int. J. Appl. Eng. Res. 2 (2011) 367–378. [35] R. Srivastava, V. Krishna, I. Sonkar, Characterization and management of municipal solid waste: a case study of Vanaras city, India, Int. J. Curr. Res. Acad. Rev. 2 (2014) 10–16. [36] M.R.E. Tahlawi, M.A. Mohamed, G.Y. Boghdadi, R.E. Rabeiy, H.A. Saleem, Groundwater quality assessment to estimate its suitability for different uses in Assiut Governorate, Egypt, Int. J. Recent Technol. Eng. 3 (2014) 2277–3878. [37] C.H. Teo, H. Jamaluddin, N.A.M. Zain, A. Idris, Biodiesel production via lipase catalysed transesterification of microalgae lipids from Tetraselmis sp, Renew. Energy 68 (2014) 1–5, doi:http://dx.doi.org/10.1016/j.renene.2014.01.027. [38] Y. Xu, C. Zhang, M. Zhao, H. Rong, K. Zhang, Q. Chen, Comparison of bioleaching and electrokinetic remediation processes for removal of heavy metals from wastewater treatment sludge, Chemosphere (2016) 1–6, doi:http://dx.doi.org/ 10.1016/j.chemosphere.2016.10.086. [39] G. Yan, T. Viraraghavan, Heavy metal removal in a biosorption column by immobilized M. rouxii biomass, Bioresour. Technol. 78 (3) (2001) 243–249, doi:http://dx.doi.org/10.1016/S0960-8524(01)00020-7 11341683. [40] F. Zhu, L. Zhao, Z. Zhang, H. Jiang, Preliminary study at lipids extraction technology from municipal sludge by organic solvent, Environ. Sci. 16 (2012) 352–356, doi:http://dx.doi.org/10.1016/j.proenv.2012.10.050. [41] C.R. Krishna, B. Thomas, M. Devinder, T. Kaitlin, B. Christopher, Improving cold flow properties of biodiesel, 2008, Retrieved 12 June 2013, from http://www. aertc.org/conference/AEC_Sessions%5CCopy%20of%20Session%202%5CTrack% 20B%20Renewables%5C1.%20Climate%20Change%20Biofuels%20III%5C1.% 20Dr.%20CR%20Krishna%5CCR%20Krishna%20presentation.pdf.
204
S. Barik, K.K. Paul / Journal of Environmental Chemical Engineering 5 (2017) 196–204
[42] S.P. Conley, Biodiesel Quality: Is All Biodiesel Created equal? BioEnergy, 2012, ID-338. Purdue extension http://www.extension.purdue.edu/extmedia/ID/ID338.pdf from http://www.ces.purdue.edu/bioenergy. [43] M.N. Siddiquee, S. Rohani, Lipid extraction and biodiesel production from municipal sewage sludges: A review, Renew. Sustain. Energy Rev. 15 (2011) 1067–1072.
[44] C. Pastore, A. Lopez, V. Lotito, G. Mascolo, Biodiesel from dewatered wastewater sludge: A two-step process for a more advantageous production, Chemosphere 92 (2013) 667–673, doi:http://dx.doi.org/10.1016/j. chemosphere.2013.03.046.