- Email: [email protected]
Evaluation of surface water treated with lotus plant; Nelumbo nucifera
Journal of Environmental Chemical Engineering 7 (2019) 103048
Contents lists available at ScienceDirect
Journal of Environmental Chemical Engineering journal homepage: www.elsevier.com/locate/jece
Evaluation of surface water treated with lotus plant; Nelumbo nucifera a
a,⁎
b
c
N.S. Abd Rasid , M.N. Naim , H. Che Man , N.F. Abu Bakar , M.N. Mokhtar a b c
T
a
Department of Process and Food Engineering, Faculty of Engineering, Universiti Putra Malaysia, Selangor, 43400 Serdang, Malaysia Department of Biological and Agricultural Engineering, Faculty of Engineering, Universiti Putra Malaysia, 43400 Serdang, Malaysia Faculty of Chemical Engineering, Universiti Teknologi MARA, 40450 Shah Alam, Malaysia
A R T I C LE I N FO
A B S T R A C T
Keywords: Nelumbo nucifera Nymphaea Phytoremediation Surface water treatment Gas transport mechanism
The potential of Nelumbo nucifera in treating contaminated surface water was investigated in terms of biochemical oxygen demand (BOD), chemical oxygen demand (COD), turbidity, and nitrate reduction. Batch type lab-scale container cultivated with N. nucifera was exposed to the contaminated surface water for 30 days. Nitrate (NO3−) adsorption and pH level were monitored continuously to identify the plant survival and to avoid any additional contaminants into the samples such as plant decay. For comparison, water lily, Nymphaea, was prepared using the same experimental setup. After 30 days of phytoremediation, the BOD and COD values of the treated water using N. nucifera was significantly reduced to 97.1% and 55%, respectively, due to the unique gas transport mechanism that thermodynamically drive O2 gas from leaves at the water surface to the buried rhizomes located in the anoxic sediments. When treated with Nymphaea, the BOD value in water decreased by 64.5% and the COD value increased by 50.5%. The results indicate that N. nucifera was able to remove the organic contaminants from the surface water by supplying adequate amount of 0.2–2.1 mL/min O2 gas to increase the microbial activities from the control condition.
1. Introduction Rapid urbanisation has raised a new challenge in managing water as the expansion of industrial activities and increasing population stepped up the demand for more fresh water resources for survival. Furthermore, the rapid strike of industry, human population, and irrigated agricultural practice has simultaneously led to the increasing of the wastewater discharge, i.e., the run-off fertiliser into the surface water without appropriate treatment. Some of the water is flowing across the surface of the ground and some is already in the network of streams. The rivers are then conveying the water to the oceans or to closed inland seas. In a tropical region such as Malaysia which receives an average rainfall of 3000 mm annually, treated surface water is one of the major sources of drinking water which is distributed to the consumer via tap water [1] but the untreated surface water has limit its uses as a drinking water source. In addition, eutrophication, sedimentation, weed infestation, and deterioration in surface water quality severely affect the applicability of surface water for human consumption, fishery, and agricultural irrigation as it may threaten human health due to the production of cyanotoxins when the blooming algae die [2–4]. Therefore, a more natural approach of using phytoremediation process is one of the alternative techniques as an effective treatment in improving the surface water quality [5]. It can also be applied ⁎
for further alternative energy consumption processes of water resources in Malaysia as it is proven that the application of phytoremediation has the potential for cleaning metal-polluted soils in an eco-friendly and cost-effective methodology [6,7]. Phytoremediation is a process of contaminants removal in contaminated raw water using selective aquatic plants [8]. It has been successfully implemented in the removal of toxic hexavalent chromium from industrial mines wastewater [7], reducing the COD and nutrients content in palm oil mill effluent (POME) [9] and removal of heavy metal from municipal and domestic wastewater [10,11]. Study by Cho-Ruk et al. [12] highlighted that the performance of phytoremediation depended on a massive fibrous root system with long stolon and a large surface area of Alternanthera philoxeroides which contributed to the highest lead removal from leadcontaminated soils. Hadiyanto et al. [9] demonstrated that the fast absorption of nitrogen and phosphorus ions were achieved by complex root structure of water hyacinth. N. nucifera has a good characteristic in phytoremediation system due to the plant anatomy of leaves, stem, and rhizomes that provide a good habitat for bacteria to attach and grow whereby these factors contribute to 79% removal of BOD in Thailand’s domestic wastewater [11]. However, none study has been conducted on using the plant to treat fresh contaminated surface water that causes by the run-off fertilizer of an agriculture sectors. The unique feature of N. nucifera leaves
Corresponding author. E-mail address: [email protected] (M.N. Naim).
https://doi.org/10.1016/j.jece.2019.103048 Received 10 January 2019; Received in revised form 22 March 2019; Accepted 23 March 2019 Available online 01 April 2019 2213-3437/ © 2019 Elsevier Ltd. All rights reserved.
Journal of Environmental Chemical Engineering 7 (2019) 103048
N.S. Abd Rasid, et al.
that capable on produced about 10 mL/min of bubbles arising from a proximal surface of the cut in the petiole when being picked during daylight. This representing a flow of gas from the buried rhizome up the petiole and released through the cut end [13] are seen as an oxygen supply system to the hypoxic area. Previous study also demonstrates that the two-way gas transport system in N. nucifera enables each leaf to carry about 10.3 ± 4.5 mL/min of air to the rhizome buried in anaerobic sediment [14]. This condition naturally enriches the interfacial layer at the vicinity of the rhizomes region with O2 gas that is essential for microbial activities for bioremediation process to degrade the contaminants which later to be absorbed by the plant itself. The increase of microbial activities for bioremediation process in degrading the contaminants by N. nucifera is due to the unique gas canal systems inside the plant which channel the pressurised air from its petioles and rhizomes that located in the anoxic sediments, before venting the utilised gases back to the atmosphere through the large stomata in the centre of the leaves [15]. Bioremediation process that occurs simultaneously with phytoremediation process is required because the microorganism’s treatment process is the most applicable method for minimising the destruction caused by the contaminants in the contaminated soil and water [16]. After the bioremediation process, the plant root systems provide the uptake capabilities through its enormous surface area that are capable in translocating, accumulating, and degrading the contaminants or nutrients in wastewater particularly for its growth and metabolism. The uptake nutrient by the plant indicates the growing process of the plant along with the phytoremediation process. Surface water treatment by N. nucifera is still a nascent approach particularly in Malaysia due to the different geographical and climates issues. Therefore, this study was aimed to evaluate the proposed phytoremediation approach using N. nucifera in treating the surface water contaminant for the purpose of livestock and pre-processing drinking water. For comparison and to study the unique gas transportation mechanism of the plant, a similar water emergent plant, water lily or Nymphaea species was applied to the same sample batches. Nymphaea species was selected in this work because of the plant abilities to transport the oxygen gas from the leaves to the roots with a slightly lower rate compared to the N. nucifera [17]. The effectiveness of the phytoremediation treatment on the improvement of BOD5, COD, turbidity, pH and nitrate values in the surface water were systematically evaluated.
Fig. 1. The illustration of the experimental setup for measuring the gas transportation mechanism i) the needle was used to open the gas canal on the plant’s petiole, ii) then the leakage gas was collected using the water-filled syringe that attached to the opening.
mechanism of the selected plants. The gas measurement work was conducted using a syringe barrel, a needle, and a tape as shown in Fig. 1. The petiolar gas canal in the plant was opened by making a steep and downward insertion into the petiole using a 0.5 mm diameter needle at approximately 5 cm below the water surface. The syringe that connected to the needle was filled with purified water and the tape was used to seal the attached needle. The bubble that arose from the gas canal displaced the water inside the syringe and the time for the gas collection was set to 1 min. The amount of water displaced in the syringe represents the amount of gas flow rate (mL/min).
2.1.1. Phytoremediation experimental work The plants were initially acclimatised to ensure they were fully ready for phytoremediation process in 2 weeks in the Agricultural Process Engineering Laboratory, UPM. To investigate the efficiency of the phytoremediation process without any soil used, three polystyrene boxes or batch type lab-scale ponds with a dimension of 37 × 25 × 26 cm (L × W × H) were used to hold the plants under the control environment in a small open-air-room with 60% of relative humidity (RH) and temperature of 28 °C (Fig. 2). N. nucifera (lotus) and Nymphaea (water lily) species were planted in different boxes with one control sample was set up without any plant. The sunlight that penetrates through the windows act as a source of light meanwhile, the artificial light replaced the source of lights for the plants at nights. The experiment was conducted in batch containing 10 L of contaminated surface water source in each box. The sampling of the contaminated surface water samples were periodically observed and collected for every 5-day interval for 30 days. All experiments were conducted in stagnant water condition without any aeration process.
2. Materials and methods 2.1. Preparation of the aquatic plant and gas transportation measurement Two types of aquatic plants, N. nucifera and Nymphaea were used in this study. The matured N. nucifera with the length of 40 cm was collected from a local pond in Kampar, Perak and re-cultivated in commercials plant boxes, whereas a similar age Nymphaea pants was brought from the nursery and all plants were planted in the same area. The contaminated surface water source for sampling purpose was taken from the pond that is located in agricultural land (Ladang 10), Universiti Putra Malaysia. The selection of the plants for phytoremediation is important because not all plants have the capability to absorb the degraded contaminants in water. Crump & Koch [18] described that aquatic angiosperms, Vallisneria americana, Potomogeton perfoliatus, Stuckenia pectinata and Zostera marina provide the suitable habitat for various microorganisms. For this work, the adventitious root structure of N. nucifera improved the microbial attachment compared to the tap root of Nymphaea. The factor is important because the surfaces of the rhizomes and plant roots were known to be suitable for the active sulphate-reducing and nitrogen fixing microorganism. Measurement of flow rate of gas transport in N. nucifera was performed in situ and taken from the emergent leaves of the plants or petiole. The amount of collected gas was also determined to identify the gas transportation
2.1.2. Wastewater analysis The samples of contaminated surface water were taken from the fertilizer run-off ponds and the sample were analysed for the determination of the water characteristic such as pH, BOD5, COD, nitrate (NO3−), and turbidity. Parameter such as pH, nitrate, and turbidity were measured in situ with a portable meter. A pH meter (ISFETCOM Co., Ltd., Japan) was used to measure the pH of water. Nitrate (NO3−) was measured using LAQUAtwin nitrate meter (HORIBA scientific, Japan), whereas turbidity was measured using a turbidity meter (HACH 2100AN, USA). The BOD5 test was carried out using azide modification method based on Winkler method [19], whereas according to Standard Methods for the Examination of Water and Wastewater [20] stated that the COD analysis was performed using the closed reflux titrimetric method. 2
Journal of Environmental Chemical Engineering 7 (2019) 103048
N.S. Abd Rasid, et al.
Fig. 2. Schematic diagram of the batches system that consist of cultivated (a) N. nucifera; and (b) Nymphaea during the phytoremediation process.
2.2. Determination of pollutant removal efficiency
Table 2 In situ gas transport of Nelumbo nucifera corresponding to different length of rhizome.
The percentage of pollutants removal efficiency using N. nucifera and Nymphaea in surface water treatment was determined by measuring the level of the analysed parameters at initial day and every 5-days for each sample as depicted in Eq. (1) as proposed by Akinbile et al. [10].
(Initial day − t−day) ⎞ Percentage of removal (%) = ⎜⎛ ⎟ × 100% Initial day ⎝ ⎠
(1)
Depth of water surface to soil (cm) Length of rhizome (cm)
5 15
30
40
pH of water EC of water (μS/cm) RH environment (%) Gas flow rate (mL/min)
7.4 ± 0.2 0.356 ± 0.1 69.2 ± 6.4 2.4 ± 0.3
7.1 ± 0.3 0.389 ± 0.04 58.6 ± 6.4 1.0 ± 4.8
6.9 ± 0.2 0.311 ± 0.04 57.7 ± 3.5 10.0 ± 2.1
*Obtained data are taken from an average of duplicate samples.
2.3. Statistical analysis
3.2. Plant gas transportation rate
The mean value and standard error were calculated for all of the analyses using Minitab® version 16.2.1. Two-replicate batches were done during the experimental period to obtain an average result. The data of water quality were assessed using the 1-way analysis of variance (ANOVA). The significance level of the obtained data was set at a pvalue of less than 0.05 (p < 0.05).
The gas transportation rate correlate with the surrounding parameters (pH, EC, and RH) are summarized in Table 2. The gas samplings were measured on the different length of rhizomes at the 5 cm of depth of surface water to the soil where the buried rhizome located. The different length of rhizomes represents the age of the plant. It was identified that N. nucifera had about 10 mL/min of gas flow rate in the plant system with 40 cm length of the rhizomes. However, no gas transportation rate was observed for Nymphaea although the plant was reported to have a convective gas flow of 0.143 ± 1.7 μL/min through its aerenchyma [14].
3. Results 3.1. Characteristic of influent contaminated surface water The characteristic of surface water was conducted at the beginning of the treatment. Table 1 shows the characteristics of the surface water taken from a pond located in Ladang 10, UPM which is the area of agricultural practice. In this study, the initial BOD and COD concentrations of surface water were 95 and 78.4 mg/L, respectively. It is believed there might be a usage of nitrogen fertilizer involved in the agricultural activities which lead to the surface water contamination because of the fertilizer runoff. The obtained values were compared to the national water quality standard according to the Department of Environment (DOE) Malaysia.
3.3. Effect of aquatic plant remediation in contaminated surface water Fig. 3(a) shows the changes in the BOD values after 30 days. In general, the reduction of BOD values in the water was higher when treated using N. nucifera compared to that of Nymphaea. The control sample indicated an increment of BOD value after Day 10 that may be due to the limited source of dissolved oxygen for microbial activities along the process. Fig. 3(b) shows the decrease in COD values by both N. nucifera and Nymphaea from the initial COD value of 78.4 mg/L. For the DO analysis in Fig. 3(c), there was a fluctuation trend in the water sample containing N. nucifera. Fig. 3(d) shows that the pH values of treated water using N. nucifera were 6.8 and 7 on Day 0 and Day 30, respectively. A similar trend was observed for Nymphaea and control whereby the pH values were 6.8 and 7.4 on Day 0 and Day 30, respectively. For verification of the results, an in situ NO3− value was measured along the phytoremediation process. From Fig. 3(e), the NO3− values of the treated water using Nymphaea were the highest after 30 days of treatment. The lowest NO3− values were noticed when the samples were treated by N. nucifera. The percentage of nitrate reduction in the treatment using N. nucifera was the highest of −33.3% as indicated in Table 3. The control did not show any significant changes due to minimal microbe’s activities that occur along the treatment process. A sudden increase of the NO3− value in the day 30 could be showed the sign of run-off fertilizer
Table 1 Characteristic of the contaminated surface water compared to other workers. Parameter
Surface Water (current study)
Akinbile et al. [2]
Adeleke et al. [21]
DOE [25]
DO (mg/L) BOD (mg/L) COD (mg/L) BOD/COD Turbidity (NTU) NO3− (ppm) pH EC (μS/cm)
7.5 ± 1.41 95.0 ± 14.1 78.4 ± 7.15 1.21 80.7 ± 0.6
5.77 4.66 65.52 0.07 -nd-
0.84* 228.13* 275.33* 0.83 13.3*
7 1 10 0.1 5
21.67 ± 12 6.8 ± 0.07 68.2 ± 3.8
-nd7.01 -nd-
-nd7.08* -nd-
7 6.5-8.5 1000
* The obtained numbers are from the mean values. 3
Journal of Environmental Chemical Engineering 7 (2019) 103048
N.S. Abd Rasid, et al.
Fig. 3. Profile of a) BOD5; b) COD; c) DO; d) pH; e) Nitrate; and f) turbidity of contaminated surface water after phytoremediation process in water with and without plant (○=N. nucifera; Δ=Nymphaea and ◻=Control). Table 3 Removal efficiency of the organic compound in term of selected water quality parameters. Parameter
BOD COD Turbidity NO3−
Percentage of removal (%) N. nucifera
Nymphaea
Control
97.1 ± 0.8 55.0 ± 1.6 88.3 ± 0.3 −33.3 ± 4.2
64.5 ± 0.3 50.5 ± 2.3 87.1 ± 0.6 −134.9 ± 3.4
−68.0 ± 2.8 −366.7 ± 7.4 86.8 ± 0.3 −72.1 ± 4.2
Note: The negative sign shows that the final value was increased from the initial value.
degradation that occurs naturally with or without the plants. The negative value indicates that a slight increment of nitrate amount occurred in the water from the initial value. Fig. 3(f) shows that N. nucifera was more effective in improving the clarity of the contaminated fresh water compared to Nymphaea after 30 days of phytoremediation. The turbidity reading for the treated water using N. nucifera and Nymphaea decreased gradually from the initial reading of 80.7 NTU to 9.69 and 10.35 NTU, respectively. The suspended solids in the water column were consumed by the roots of the plant for growth and respiration specifically. A complete settling of suspended solid by all samples was noticed to occur after day 20 as the turbidity of the water was almost zero as shown in Fig. 4. The water in the control experiment and treated using Nymphaea were cloudy starting from Day 20 until the end of the experiment work. The efficiency of BOD and COD removal were evaluated in terms of the percentage between the processes and the tabulated data as shown
Fig. 4. The changes in cloudiness (turbidity) of the raw surface water in N. nucifera (lotus), Nymphaea (water lily), and the control.
in Table 3. From the Table 3, the average percentages of BOD and COD removal for overall phytoremediation process by using N. nucifera were 97.1% and 56.9% respectively, which were the highest among all samples. Meanwhile, the BOD and COD removal using Nymphaea raised up to 64.5% and 50.5% respectively after the end of phytoremediation process. The negative percentages of BOD and COD removal of −68% and −366.7%, respectively, by the control system indicate that the 4
Journal of Environmental Chemical Engineering 7 (2019) 103048
N.S. Abd Rasid, et al.
were higher than the hydrilla species that do not consist of gas transportation ability.
amount of both values at the end of the experiment were higher than the initial values. 4. Discussion
4.3.2. COD value Due to the unique gas transportation system in the N. nucifera, high microorganisms’ activity is expected during the phytoremediation process. As a results, the COD removal value by N. nucifera was better than Nymphaea and the control. According to Ng, Samsudin & Chan [24], the organic suspended solids were also metabolised or consumed by the cells and converted into energy, carbon dioxide, and water which caused the reduction of the COD value in the water. According to Interim National Water Quality Standards (INWQS) requirements [25], both final COD values for the N. nucifera and Nymphaea samples were below the statutory standards and meet the requirement for the livestock drinking water of less than 50 mg/L.
4.1. Effect of agriculture run-off in contaminating the surface water The source of surface water obtained in this study is surrounded by the agriculture practice that used the nitrogen-based fertilizer for its daily application. However, the fertilizer tends to run-off into the surface water during the raining seasons. By referring to Table 1, in was noticed that the amount of BOD was considerably higher than that reported by Akinbile et al. [2] in Bukit Merah reservoir with the initial BOD value of 4.66 mg/L but lower than that reported by Adeleke et al. [21] in UPM Lake with the average BOD value of 228.13 mg/L. Meanwhile, the COD value in this study was lower than the average COD value of 275.33 mg/L [21]. The BOD/COD ratio is a parameter that indicates the biodegradability of the organic components in the surface water and work as an indicator for measuring the degrees of both biological and chemical decompositions [22]. Table 1 also shows that the surface water sample BOD/COD ratio was more than 0.5, which indicates that the surface water contaminants are biodegradable.
4.3.3. DO value The decreased of DO in water containing Nymphaea was caused by the senescence of the stalks and the nutrient that might be absorbed by the plant was returned into the water in the form of organic nitrogen through the broken or dead stem [26]. Therefore the more oxygen was required by the microbes to consume the degraded organic matter left by the plant. The nutrient that is originally incorporated with the biomass has the tendency to return to the water due to decomposition process [27]. The amount of DO in the water treated using N. nucifera was remarkable because the water received a consistent O2 gases along the process. In Fig. 3(c), the DO fluctuation on day 10 was regarded as a possible result of the oxygen was being used during the macrophytes breathing. In addition, Cho-Ruk et al. [12] also showed that a massive fibrous roots system with long stolon and large surface area gives a beneficial result in phytoaccumulation. Therefore, the fibrous root plants usually have a higher radial oxygen loss (ROL) [28] in which allows the excess O2 to diffuse into the rhizosphere and enriches the interfacial layer of the rhizomes region with the dissolved oxygen. The fibrous plant roots also typically provides an ideal environment for the microbial growth and enhances the degradation activity [29]. Although it was noticed that the N. nucifera has two flow pathways compared to other pressurising plants [32], only one of the pathway were used supply the O2 gases into root system. According to Colmer [30], the pathway or aerenchyma that exist in the plant gas canal system also offers a low-resistance internal pathway for gas transportation from the leaves to the roots system. The oxygen gas that transported to the rhizomes is supplied to the growing tissues where the oxygen is the most needed [31] and the excess oxygen oxygenates the rhizosphere [32]. This excess oxygen diffused out from the rhizomes through the roots and the condition acts as an aeration system which increases the amount of dissolved oxygen in the anoxic area. However, the amount of gases supplied by the plant also can be affected by the number of leaves as the oxygen from the environment diffused within the plant section through the air canal that located inside the leaf [33].
4.2. Plant evaluation for polishing the surface water quality From the obtained results indicated in Fig. 3, we agreed that the role of gas transportation mechanism is important whereby the high gas transportation rate contributes to an effective water treatment. N. nucifera plant exhibits two way gas transportation mechanisms whereas Nymphaea plant exhibits the normal diffusion on transporting oxygen to the buried roots [17]. The selectivity of the plant for treating the contaminated water samples can be evaluated by subjecting the plants with an in situ NO3− measurement. In our hypothesis, a good phytoremediator plant is not only supposed to supply an appropriate amount of O2 gas during the gas transportation mechanism but it must be able to adsorb the dissolved NO3− that converted by the microbes. Without this ability, the NO3− concentration accumulated and an imbalance Ncycle occurred in the ecosystem. This is proven in terms of the performance to remove nitrate in the water as shown in Table 3 where the percentage of nitrate removal in the water treated using Nymphaea and control were −134.9% and −72.1%, respectively. Thus, we concluded that with N. nucifera phytoremediation treatment, the nitrogen cycle in the system was active and balanced. This was due to the highly oxygenated water in N. nucifera causing the denitrification process to occur rapidly as mentioned previously with respect to Fig. 3(c). The increasing trend of NO3− in Fig. 3(e) for Nymphaea species indicates that the NO3− adsorption by the plants was lower due to the limitation of the plant to be utilised as phytoremediator. During the work, the Nymphaea plants were noticed to start wilting from day 5. A similar observation also was noticed by Ng & Chan [23] where they found out the total of nitrate removal was caused by the nitrification–denitrification process which included the plant and the microbial uptake. The increase of nitrate concentration was caused by the nitrate accumulation in bulk when the water samples was exposed to the sunlight during the experimental work.
4.3.4. pH value The pH values in this work were slightly increased from the acidic condition and reach the neutral pH upon completion of the phytoremediation process. N. Nucifera was noticed to have the lowest pH value compared to other samples. Kanabkaew & Puetpaiboon [11] also observed a similar pattern for N. nucifera whereby the plant was indicated with the lowest pH as compared to other treatment for treating the domestic wastewater in their work. Although no scientific evidence was found to explain the phenomenon, we hypothesized that the lower pH by N. nucifera could be due to the released gases from the microbe’s activities. Furthermore, it was also reported that the microbial activities has caused the optimum pH values for nitrification process varies from 6.6 to 8.0 [34].
4.3. Water quality characteristics during and after the phytoremediation process 4.3.1. BOD value During the work, we found that N. nucifera were capable to minimize the BOD value in the surface water. A similar results also was reported by Kanabkaew & Puetpaiboon [11] which obtained about 79% of BOD removal in domestic wastewater when using N. nucifera. With the existence of gas transportation mechanism in N. nucifera [14], it was postulated that the microbial activities during the phytoremediation 5
Journal of Environmental Chemical Engineering 7 (2019) 103048
N.S. Abd Rasid, et al.
4.3.5. NO3− concentration Referred to Fig. 3(e) and Table 3, the in situ measurements of NO3− concentration along the phytoremediation process were the most important characteristic for evaluating a phytoremediator plants. As mentioned earlier, good phytoremediator plant is not only supposed to supply an appropriate amount of O2 gas during the gas transportation mechanism but it must be able to adsorb the dissolved NO3− that converted by the microbes. In this work, all the NO3− values were higher compared to the initial condition. The increasing trend of NO3− indicates that the NO3− absorption by the plants was weaker due to the limitation of the plant to be utilised as phytoremediator when the plant started to wilt. A similar observation was also noticed by Ng & Chan [22] whereby the total of nitrate removal was caused by the nitrification–denitrification process which included the plant and the microbial uptake. The increase of nitrate was caused mainly by the accumulation of nitrate in bulk when the contaminated water that consisted of the run-off fertiliser and plant debris was exposed to the sunlight during the experimental work.
jzus.B0710626. [5] A. Sood, P.L. Uniyal, R. Prasanna, A.S. Ahluwalia, Phytoremediation potential of aquatic macrophyte, Azolla, Ambio 41 (2012) 122–137, https://doi.org/10.1007/ s13280-011-0159-z. [6] J. Barceló, C. Poschenrieder, Phytoremediation : principles and perspectives, Contrib. Sci. 2 (2003) 333–344. [7] P. Saha, O. Shinde, S. Sarkar, Phytoremediation of industrial mines wastewater using water hyacinth, Int. J. Phytoremediation 19 (2017) 87–96, https://doi.org/ 10.1080/15226514.2016.1216078. [8] B.V. Tangahu, S.R.S. Abdullah, H. Basri, M. Idris, N. Anuar, M. Mukhlisin, A review on heavy metals (As, Pb, and Hg) uptake by plants through phytoremediation, Int. J. Chem. Eng. 1 (2011) 1–31, https://doi.org/10.1155/2011/939161. [9] M. Hadiyanto, D. Christwardana, Soetrisnanto, Phytoremediations of Palm Oil Mill Effluent (POME) by using aquatic plants and microalge for biomass production, J. Environ. Sci. Technol. 6 (2013) 79–90, https://doi.org/10.3923/jest.2013.79.90. [10] C.O. Akinbile, T.A. Ogunrinde, H.C. Man, H.A. Aziz, Phytoremediation of domestic wastewaters in free water surface constructed wetlands using Azolla pinnata, Int. J. Phytoremediation 18 (2016) 54–61, https://doi.org/10.1080/15226514.2015. 1058330. [11] T. Kanabkaew, U. Puetpaiboon, Aquatic plants for domestic wastewater treatment: Lotus (Nelumbo nucifera) and Hydrilla (Hydrilla verticillata) systems, J. Sci. Technol. 26 (2004) 749–756. [12] K. Cho-Ruk, J. Kurukote, P. Supprung, S. Vetayasuporn, Perennial plants in the phytoremediation of lead-contaminated soils, Biotechnology 5 (2006) 1–4, https:// doi.org/10.3923/biotech.2006.1.4. [13] J.W.H. Dacey, Knudsen-transitional flow and gas pressurization in leaves of Nelumbo, Plant Physiol. 85 (1987) 199–203. [14] J. Mevi-Schutz, W. Grosse, A two‐way gas transport system in Nelumbo nucifera, Plant Cell Environ. 11 (1988) 27–34, https://doi.org/10.1111/j.1365-3040.1988. tb01773.x. [15] P.G.D. Matthews, R.S. Seymour, Stomata actively regulate internal aeration of the sacred lotus Nelumbo nucifera, Plant Cell Environ. 37 (2014) 402–413, https://doi. org/10.1111/pce.12163. [16] D. Singh, A. Tiwari, R. Gupta, Phytoremediation of lead from wastewater using aquatic plants, J. Agric. Technol 8 (2012) 1–11 http://ijat-aatsea.com/pdf/ v8_n1_12_January/1_IJAT 2012_8_1__Divya Singh-accepted_review artcle_FX.pdf (Accessed 14 October 2017). [17] G. Catian, E. Scremin-Dias, Compared leaf anatomy of Nymphaea (Nymphaeaceae) species from Brazilian flood plain, Braz. J. Biol. 73 (2013) 809–817, https://doi. org/10.1590/S1519-698420130004000018. [18] B.C. Crump, E.W. Koch, Attached bacterial populations shared by four species of aquatic angiosperms, Appl. Environ. Microbiol. 74 (2008) 5948–5957, https://doi. org/10.1128/AEM.00952-08. [19] Methods for Chemical Analysis of Water and Wastes, United States Environmental Protection Agency, Washington, United States, 1983. [20] E.W. Rice, L. Bridgewater, American Public Health Association., American Water Works Association., W.E. Federation., Standard Methods for the Examination of Water and Wastewater, 22nd ed., American Public Health Association, Washington, DC, 2012 (Accessed 26 September 2017), https://books.google.com.my/books?id= dd2juAAACAAJ&dq=standard+methods+for+the+examination+of+water +and+wastewater+22nd+edition+pdf&hl=en&sa=X&redir_esc=y. [21] A.R.O. Adeleke, D.N.N. Nik, A. Ahsan, P. Biswajeet, Water quality assessment of UPM Lake and the impact of geographic information system, Int. J. Environ. Monit. Anal. 2 (2014) 158–162, https://doi.org/10.11648/j.ijema.20140203.15. [22] A.H. Lee, H. Nikraz, BOD:COD ratio as an Indicator for pollutants leaching from landfill, J. Clean Energy Technol. 2 (2014) 263–266, https://doi.org/10.7763/ JOCET.2014.V2.137. [23] Y.S. Ng, D.J.C. Chan, Wastewater phytoremediation by Salvinia molesta, J. Water Process Eng. 15 (2017) 107–115, https://doi.org/10.1016/j.jwpe.2016.08.006. [24] Y.S. Ng, N.I.S. Samsudin, D.J.C. Chan, Phytoremediation capabilities of Spirodela polyrhiza and Salvinia molesta in fish farm wastewater: a preliminary study, IOP Conf. Ser. Mater. Sci. Eng., 29th Symposium of Malaysian Chemical Engineers (SOMChE) 2016 (2017) 1–14, https://doi.org/10.1088/1757-899X/206/1/ 012084. [25] Interim National Water Quality Standards for Malaysia, Water Environ, WEPA, Partnersh. Asia, 2017 (Accessed 14 December 2017), http://www.wepa-db.net/ policies/law/malaysia/eq_surface.htm#pagetop. [26] F.A. Souza, M. Dziedzic, S.A. Cubas, L.T. Maranho, Restoration of polluted waters by phytoremediation using Myriophyllum aquaticum (Vell.) Verdc., Haloragaceae, J. Environ. Manage. 120 (2013) 5–9 (Accessed 16 November 2017), https://ac.elscdn.com/S0301479713000686/1-s2.0-S0301479713000686-main.pdf?_tid= bd9099b6-cad5-11e7-a657-00000aacb362&acdnat=1510840681_ a2c09c499e50fc76ae17927d8e121cce. [27] F. Martínez, G. Cuevas, R. Calvo, I. Walter, Ecosystem restoration biowaste effects on soil and native plants in a semiarid ecosystem, J. Environ. Qual. 32 (2003) 472–479 (Accessed 16 November 2017), https://pdfs.semanticscholar.org/45cc/ b47c81681294993296ee4c2d64dc6a80c69d.pdf?_ga=2.144793140.1815992813. 1510841359-1453132738.1510841359. [28] W.L. Lai, S.Q. Wang, C.L. Peng, Z.H. Chen, Root features related to plant growth and nutrient removal of 35 wetland plants, Water Res. 45 (2011) 3941–3950, https:// doi.org/10.1016/j.watres.2011.05.002. [29] M. Soleimani, M. Afyuni, M.A. Hajabbasi, F. Nourbakhsh, M.R. Sabzalian, J.H. Christensen, Phytoremediation of an aged petroleum contaminated soil using endophyte infected and non-infected grasses, Chemosphere 81 (2010) 1084–1090, https://doi.org/10.1016/j.chemosphere.2010.09.034. [30] T.D. Colmer, Long-distance transport of gases in plants : a perspective on internal
4.3.6. Turbidity Referred to Amr et al. [35], the reduction in turbidity was also observed in the influent and effluent water as the retention time was prolonged. This might be due to the decreased of dissolved oxygen in the water when less effective phytoremediator plants or no plants were involved during the treatment process. Referred to Fig. 3(f), Table 3 and Fig. 4, the clarity of the treated water were maintained at the lowest value after the phytoremediation process. If the turbidity value at day 5 was ignored, we will noticed that the N. nucifera samples reached the lowest value at day 10 compared to other samples. 5. Conclusions Contaminated surface water that was treated using N. nucifera showed the lowest BOD and COD removal during the phytoremediation process. Using the NO3− in situ measurement, low NO3− concentration was noticed after 30 days of treatment process. The treatment condition showed that N. nucifera plant was the best candidates for treating the run-off fertilizer in the natural environment. The thermo-osmotic gas transport mechanism that equipped in N. nucifera also provides sufficient O2 gases to the buried rhizomes, thus it improve the water quality in the ecosystems. The study also indicated that a green and low operational cost treatment was able to be performed within 30 days of treatment. Acknowledgments This work was supported by Putra Grant, GP-IPS/2016/9522800, Universiti Putra Malaysia, Serdang, Selangor, Malaysia, and 600-IRMI/ MYRA 5/3/BESTARI (021/2017), Universiti Teknologi MARA, Shah Alam, Selangor, Malaysia. References [1] N.H.A. Razak, S.M. Praveena, A.Z. Aris, Z. Hashim, Drinking water studies: a review on heavy metal, application of biomarker and health risk assessment (a special focus in Malaysia), J. Epidemiol. Glob. Health 5 (2015) 297–310, https://doi.org/ 10.1016/j.jegh.2015.04.003. [2] C.O. Akinbile, M.S. Yusoff, S.H.A. Talib, Z.A. Hasan, W.R. Ismail, U. Sansudin, Qualitative analysis and classification of surface water in Bukit Merah Reservoir in Malaysia, Water Sci. Technol. Water Supply 13 (2013) 1138–1145, https://doi.org/ 10.2166/ws.2013.104. [3] A.I. Che-Ani, N. Shaari, A. Sairi, M.F.M. Zain, M.M. Tahir, Rainwater harvesting as an alternative water supply in the future, Eur. J. Sci. Res. 34 (2009) 132–140 (Accessed 12 September 2017), https://www.researchgate.net/profile/A_Che-Ani/ publication/237821822_Rainwater_Harvesting_as_an_Alternative_Water_Supply_in_ the_Future/links/00b4952def39b1b6c4000000/Rainwater-Harvesting-as-anAlternative-Water-Supply-in-the-Future.pdf. [4] X.-E. Yang, X. Wu, H.-L. Hao, Z.-L. He, Mechanisms and assessment of water eutrophication, J. Zhejiang Univ. Sci. B 9 (2008) 197–209, https://doi.org/10.1631/
6
Journal of Environmental Chemical Engineering 7 (2019) 103048
N.S. Abd Rasid, et al.
lettuce (Pistia stratiotes) effectiveness in aquaculture wastewater treatment, Int. J. Phytoremediation 14 (2012) 201–211, https://doi.org/10.1080/15226514.2011. 587482. [35] S.S.A. Amr, H.A. Aziz, A.M. Nordin, Optimization of stabilized leachate treatment using ozone/persulfate in the advanced oxidation process, Waste Manag. 33 (2013) 1434–1441 (Accessed 17 November 2017), https://ac.els-cdn.com/ S0956053X13000731/1-s2.0-S0956053X13000731-main.pdf?_tid=ea21285ecbae-11e7-89cd-00000aacb35f&acdnat=1510933957_ dbbaf5bbea5c1c9009fb2eab9802f0e1.
aeration and radial oxygen loss from roots, Plant Cell Environ. 26 (2003) 17–36. [31] P.G.D. Matthews, R.S. Seymour, Anatomy of the gas canal system of Nelumbo nucifera, Aquat. Bot. 85 (2006) 147–154, https://doi.org/10.1016/j.aquabot.2006.03. 002. [32] W. Grosse, W. Armstrong, A history of pressurised gas-flow studies in plants, Aquat. Bot. 54 (1996) 87–100. [33] S. Vogel, Contributions to the functional anatomy and biology of Nelumbo nucifera (Nelumbonaceae). I. Pathways of air circulation, Plant Syst. Evol. (2004) 9–25, https://doi.org/10.1007/s00606-004-0201-8. [34] C.O. Akinbile, M.S. Yusoff, Assessing water hyacinth (Eichhornia crassopes) and
7
Contents lists available at ScienceDirect
Journal of Environmental Chemical Engineering journal homepage: www.elsevier.com/locate/jece
Evaluation of surface water treated with lotus plant; Nelumbo nucifera a
a,⁎
b
c
N.S. Abd Rasid , M.N. Naim , H. Che Man , N.F. Abu Bakar , M.N. Mokhtar a b c
T
a
Department of Process and Food Engineering, Faculty of Engineering, Universiti Putra Malaysia, Selangor, 43400 Serdang, Malaysia Department of Biological and Agricultural Engineering, Faculty of Engineering, Universiti Putra Malaysia, 43400 Serdang, Malaysia Faculty of Chemical Engineering, Universiti Teknologi MARA, 40450 Shah Alam, Malaysia
A R T I C LE I N FO
A B S T R A C T
Keywords: Nelumbo nucifera Nymphaea Phytoremediation Surface water treatment Gas transport mechanism
The potential of Nelumbo nucifera in treating contaminated surface water was investigated in terms of biochemical oxygen demand (BOD), chemical oxygen demand (COD), turbidity, and nitrate reduction. Batch type lab-scale container cultivated with N. nucifera was exposed to the contaminated surface water for 30 days. Nitrate (NO3−) adsorption and pH level were monitored continuously to identify the plant survival and to avoid any additional contaminants into the samples such as plant decay. For comparison, water lily, Nymphaea, was prepared using the same experimental setup. After 30 days of phytoremediation, the BOD and COD values of the treated water using N. nucifera was significantly reduced to 97.1% and 55%, respectively, due to the unique gas transport mechanism that thermodynamically drive O2 gas from leaves at the water surface to the buried rhizomes located in the anoxic sediments. When treated with Nymphaea, the BOD value in water decreased by 64.5% and the COD value increased by 50.5%. The results indicate that N. nucifera was able to remove the organic contaminants from the surface water by supplying adequate amount of 0.2–2.1 mL/min O2 gas to increase the microbial activities from the control condition.
1. Introduction Rapid urbanisation has raised a new challenge in managing water as the expansion of industrial activities and increasing population stepped up the demand for more fresh water resources for survival. Furthermore, the rapid strike of industry, human population, and irrigated agricultural practice has simultaneously led to the increasing of the wastewater discharge, i.e., the run-off fertiliser into the surface water without appropriate treatment. Some of the water is flowing across the surface of the ground and some is already in the network of streams. The rivers are then conveying the water to the oceans or to closed inland seas. In a tropical region such as Malaysia which receives an average rainfall of 3000 mm annually, treated surface water is one of the major sources of drinking water which is distributed to the consumer via tap water [1] but the untreated surface water has limit its uses as a drinking water source. In addition, eutrophication, sedimentation, weed infestation, and deterioration in surface water quality severely affect the applicability of surface water for human consumption, fishery, and agricultural irrigation as it may threaten human health due to the production of cyanotoxins when the blooming algae die [2–4]. Therefore, a more natural approach of using phytoremediation process is one of the alternative techniques as an effective treatment in improving the surface water quality [5]. It can also be applied ⁎
for further alternative energy consumption processes of water resources in Malaysia as it is proven that the application of phytoremediation has the potential for cleaning metal-polluted soils in an eco-friendly and cost-effective methodology [6,7]. Phytoremediation is a process of contaminants removal in contaminated raw water using selective aquatic plants [8]. It has been successfully implemented in the removal of toxic hexavalent chromium from industrial mines wastewater [7], reducing the COD and nutrients content in palm oil mill effluent (POME) [9] and removal of heavy metal from municipal and domestic wastewater [10,11]. Study by Cho-Ruk et al. [12] highlighted that the performance of phytoremediation depended on a massive fibrous root system with long stolon and a large surface area of Alternanthera philoxeroides which contributed to the highest lead removal from leadcontaminated soils. Hadiyanto et al. [9] demonstrated that the fast absorption of nitrogen and phosphorus ions were achieved by complex root structure of water hyacinth. N. nucifera has a good characteristic in phytoremediation system due to the plant anatomy of leaves, stem, and rhizomes that provide a good habitat for bacteria to attach and grow whereby these factors contribute to 79% removal of BOD in Thailand’s domestic wastewater [11]. However, none study has been conducted on using the plant to treat fresh contaminated surface water that causes by the run-off fertilizer of an agriculture sectors. The unique feature of N. nucifera leaves
Corresponding author. E-mail address: [email protected] (M.N. Naim).
https://doi.org/10.1016/j.jece.2019.103048 Received 10 January 2019; Received in revised form 22 March 2019; Accepted 23 March 2019 Available online 01 April 2019 2213-3437/ © 2019 Elsevier Ltd. All rights reserved.
Journal of Environmental Chemical Engineering 7 (2019) 103048
N.S. Abd Rasid, et al.
that capable on produced about 10 mL/min of bubbles arising from a proximal surface of the cut in the petiole when being picked during daylight. This representing a flow of gas from the buried rhizome up the petiole and released through the cut end [13] are seen as an oxygen supply system to the hypoxic area. Previous study also demonstrates that the two-way gas transport system in N. nucifera enables each leaf to carry about 10.3 ± 4.5 mL/min of air to the rhizome buried in anaerobic sediment [14]. This condition naturally enriches the interfacial layer at the vicinity of the rhizomes region with O2 gas that is essential for microbial activities for bioremediation process to degrade the contaminants which later to be absorbed by the plant itself. The increase of microbial activities for bioremediation process in degrading the contaminants by N. nucifera is due to the unique gas canal systems inside the plant which channel the pressurised air from its petioles and rhizomes that located in the anoxic sediments, before venting the utilised gases back to the atmosphere through the large stomata in the centre of the leaves [15]. Bioremediation process that occurs simultaneously with phytoremediation process is required because the microorganism’s treatment process is the most applicable method for minimising the destruction caused by the contaminants in the contaminated soil and water [16]. After the bioremediation process, the plant root systems provide the uptake capabilities through its enormous surface area that are capable in translocating, accumulating, and degrading the contaminants or nutrients in wastewater particularly for its growth and metabolism. The uptake nutrient by the plant indicates the growing process of the plant along with the phytoremediation process. Surface water treatment by N. nucifera is still a nascent approach particularly in Malaysia due to the different geographical and climates issues. Therefore, this study was aimed to evaluate the proposed phytoremediation approach using N. nucifera in treating the surface water contaminant for the purpose of livestock and pre-processing drinking water. For comparison and to study the unique gas transportation mechanism of the plant, a similar water emergent plant, water lily or Nymphaea species was applied to the same sample batches. Nymphaea species was selected in this work because of the plant abilities to transport the oxygen gas from the leaves to the roots with a slightly lower rate compared to the N. nucifera [17]. The effectiveness of the phytoremediation treatment on the improvement of BOD5, COD, turbidity, pH and nitrate values in the surface water were systematically evaluated.
Fig. 1. The illustration of the experimental setup for measuring the gas transportation mechanism i) the needle was used to open the gas canal on the plant’s petiole, ii) then the leakage gas was collected using the water-filled syringe that attached to the opening.
mechanism of the selected plants. The gas measurement work was conducted using a syringe barrel, a needle, and a tape as shown in Fig. 1. The petiolar gas canal in the plant was opened by making a steep and downward insertion into the petiole using a 0.5 mm diameter needle at approximately 5 cm below the water surface. The syringe that connected to the needle was filled with purified water and the tape was used to seal the attached needle. The bubble that arose from the gas canal displaced the water inside the syringe and the time for the gas collection was set to 1 min. The amount of water displaced in the syringe represents the amount of gas flow rate (mL/min).
2.1.1. Phytoremediation experimental work The plants were initially acclimatised to ensure they were fully ready for phytoremediation process in 2 weeks in the Agricultural Process Engineering Laboratory, UPM. To investigate the efficiency of the phytoremediation process without any soil used, three polystyrene boxes or batch type lab-scale ponds with a dimension of 37 × 25 × 26 cm (L × W × H) were used to hold the plants under the control environment in a small open-air-room with 60% of relative humidity (RH) and temperature of 28 °C (Fig. 2). N. nucifera (lotus) and Nymphaea (water lily) species were planted in different boxes with one control sample was set up without any plant. The sunlight that penetrates through the windows act as a source of light meanwhile, the artificial light replaced the source of lights for the plants at nights. The experiment was conducted in batch containing 10 L of contaminated surface water source in each box. The sampling of the contaminated surface water samples were periodically observed and collected for every 5-day interval for 30 days. All experiments were conducted in stagnant water condition without any aeration process.
2. Materials and methods 2.1. Preparation of the aquatic plant and gas transportation measurement Two types of aquatic plants, N. nucifera and Nymphaea were used in this study. The matured N. nucifera with the length of 40 cm was collected from a local pond in Kampar, Perak and re-cultivated in commercials plant boxes, whereas a similar age Nymphaea pants was brought from the nursery and all plants were planted in the same area. The contaminated surface water source for sampling purpose was taken from the pond that is located in agricultural land (Ladang 10), Universiti Putra Malaysia. The selection of the plants for phytoremediation is important because not all plants have the capability to absorb the degraded contaminants in water. Crump & Koch [18] described that aquatic angiosperms, Vallisneria americana, Potomogeton perfoliatus, Stuckenia pectinata and Zostera marina provide the suitable habitat for various microorganisms. For this work, the adventitious root structure of N. nucifera improved the microbial attachment compared to the tap root of Nymphaea. The factor is important because the surfaces of the rhizomes and plant roots were known to be suitable for the active sulphate-reducing and nitrogen fixing microorganism. Measurement of flow rate of gas transport in N. nucifera was performed in situ and taken from the emergent leaves of the plants or petiole. The amount of collected gas was also determined to identify the gas transportation
2.1.2. Wastewater analysis The samples of contaminated surface water were taken from the fertilizer run-off ponds and the sample were analysed for the determination of the water characteristic such as pH, BOD5, COD, nitrate (NO3−), and turbidity. Parameter such as pH, nitrate, and turbidity were measured in situ with a portable meter. A pH meter (ISFETCOM Co., Ltd., Japan) was used to measure the pH of water. Nitrate (NO3−) was measured using LAQUAtwin nitrate meter (HORIBA scientific, Japan), whereas turbidity was measured using a turbidity meter (HACH 2100AN, USA). The BOD5 test was carried out using azide modification method based on Winkler method [19], whereas according to Standard Methods for the Examination of Water and Wastewater [20] stated that the COD analysis was performed using the closed reflux titrimetric method. 2
Journal of Environmental Chemical Engineering 7 (2019) 103048
N.S. Abd Rasid, et al.
Fig. 2. Schematic diagram of the batches system that consist of cultivated (a) N. nucifera; and (b) Nymphaea during the phytoremediation process.
2.2. Determination of pollutant removal efficiency
Table 2 In situ gas transport of Nelumbo nucifera corresponding to different length of rhizome.
The percentage of pollutants removal efficiency using N. nucifera and Nymphaea in surface water treatment was determined by measuring the level of the analysed parameters at initial day and every 5-days for each sample as depicted in Eq. (1) as proposed by Akinbile et al. [10].
(Initial day − t−day) ⎞ Percentage of removal (%) = ⎜⎛ ⎟ × 100% Initial day ⎝ ⎠
(1)
Depth of water surface to soil (cm) Length of rhizome (cm)
5 15
30
40
pH of water EC of water (μS/cm) RH environment (%) Gas flow rate (mL/min)
7.4 ± 0.2 0.356 ± 0.1 69.2 ± 6.4 2.4 ± 0.3
7.1 ± 0.3 0.389 ± 0.04 58.6 ± 6.4 1.0 ± 4.8
6.9 ± 0.2 0.311 ± 0.04 57.7 ± 3.5 10.0 ± 2.1
*Obtained data are taken from an average of duplicate samples.
2.3. Statistical analysis
3.2. Plant gas transportation rate
The mean value and standard error were calculated for all of the analyses using Minitab® version 16.2.1. Two-replicate batches were done during the experimental period to obtain an average result. The data of water quality were assessed using the 1-way analysis of variance (ANOVA). The significance level of the obtained data was set at a pvalue of less than 0.05 (p < 0.05).
The gas transportation rate correlate with the surrounding parameters (pH, EC, and RH) are summarized in Table 2. The gas samplings were measured on the different length of rhizomes at the 5 cm of depth of surface water to the soil where the buried rhizome located. The different length of rhizomes represents the age of the plant. It was identified that N. nucifera had about 10 mL/min of gas flow rate in the plant system with 40 cm length of the rhizomes. However, no gas transportation rate was observed for Nymphaea although the plant was reported to have a convective gas flow of 0.143 ± 1.7 μL/min through its aerenchyma [14].
3. Results 3.1. Characteristic of influent contaminated surface water The characteristic of surface water was conducted at the beginning of the treatment. Table 1 shows the characteristics of the surface water taken from a pond located in Ladang 10, UPM which is the area of agricultural practice. In this study, the initial BOD and COD concentrations of surface water were 95 and 78.4 mg/L, respectively. It is believed there might be a usage of nitrogen fertilizer involved in the agricultural activities which lead to the surface water contamination because of the fertilizer runoff. The obtained values were compared to the national water quality standard according to the Department of Environment (DOE) Malaysia.
3.3. Effect of aquatic plant remediation in contaminated surface water Fig. 3(a) shows the changes in the BOD values after 30 days. In general, the reduction of BOD values in the water was higher when treated using N. nucifera compared to that of Nymphaea. The control sample indicated an increment of BOD value after Day 10 that may be due to the limited source of dissolved oxygen for microbial activities along the process. Fig. 3(b) shows the decrease in COD values by both N. nucifera and Nymphaea from the initial COD value of 78.4 mg/L. For the DO analysis in Fig. 3(c), there was a fluctuation trend in the water sample containing N. nucifera. Fig. 3(d) shows that the pH values of treated water using N. nucifera were 6.8 and 7 on Day 0 and Day 30, respectively. A similar trend was observed for Nymphaea and control whereby the pH values were 6.8 and 7.4 on Day 0 and Day 30, respectively. For verification of the results, an in situ NO3− value was measured along the phytoremediation process. From Fig. 3(e), the NO3− values of the treated water using Nymphaea were the highest after 30 days of treatment. The lowest NO3− values were noticed when the samples were treated by N. nucifera. The percentage of nitrate reduction in the treatment using N. nucifera was the highest of −33.3% as indicated in Table 3. The control did not show any significant changes due to minimal microbe’s activities that occur along the treatment process. A sudden increase of the NO3− value in the day 30 could be showed the sign of run-off fertilizer
Table 1 Characteristic of the contaminated surface water compared to other workers. Parameter
Surface Water (current study)
Akinbile et al. [2]
Adeleke et al. [21]
DOE [25]
DO (mg/L) BOD (mg/L) COD (mg/L) BOD/COD Turbidity (NTU) NO3− (ppm) pH EC (μS/cm)
7.5 ± 1.41 95.0 ± 14.1 78.4 ± 7.15 1.21 80.7 ± 0.6
5.77 4.66 65.52 0.07 -nd-
0.84* 228.13* 275.33* 0.83 13.3*
7 1 10 0.1 5
21.67 ± 12 6.8 ± 0.07 68.2 ± 3.8
-nd7.01 -nd-
-nd7.08* -nd-
7 6.5-8.5 1000
* The obtained numbers are from the mean values. 3
Journal of Environmental Chemical Engineering 7 (2019) 103048
N.S. Abd Rasid, et al.
Fig. 3. Profile of a) BOD5; b) COD; c) DO; d) pH; e) Nitrate; and f) turbidity of contaminated surface water after phytoremediation process in water with and without plant (○=N. nucifera; Δ=Nymphaea and ◻=Control). Table 3 Removal efficiency of the organic compound in term of selected water quality parameters. Parameter
BOD COD Turbidity NO3−
Percentage of removal (%) N. nucifera
Nymphaea
Control
97.1 ± 0.8 55.0 ± 1.6 88.3 ± 0.3 −33.3 ± 4.2
64.5 ± 0.3 50.5 ± 2.3 87.1 ± 0.6 −134.9 ± 3.4
−68.0 ± 2.8 −366.7 ± 7.4 86.8 ± 0.3 −72.1 ± 4.2
Note: The negative sign shows that the final value was increased from the initial value.
degradation that occurs naturally with or without the plants. The negative value indicates that a slight increment of nitrate amount occurred in the water from the initial value. Fig. 3(f) shows that N. nucifera was more effective in improving the clarity of the contaminated fresh water compared to Nymphaea after 30 days of phytoremediation. The turbidity reading for the treated water using N. nucifera and Nymphaea decreased gradually from the initial reading of 80.7 NTU to 9.69 and 10.35 NTU, respectively. The suspended solids in the water column were consumed by the roots of the plant for growth and respiration specifically. A complete settling of suspended solid by all samples was noticed to occur after day 20 as the turbidity of the water was almost zero as shown in Fig. 4. The water in the control experiment and treated using Nymphaea were cloudy starting from Day 20 until the end of the experiment work. The efficiency of BOD and COD removal were evaluated in terms of the percentage between the processes and the tabulated data as shown
Fig. 4. The changes in cloudiness (turbidity) of the raw surface water in N. nucifera (lotus), Nymphaea (water lily), and the control.
in Table 3. From the Table 3, the average percentages of BOD and COD removal for overall phytoremediation process by using N. nucifera were 97.1% and 56.9% respectively, which were the highest among all samples. Meanwhile, the BOD and COD removal using Nymphaea raised up to 64.5% and 50.5% respectively after the end of phytoremediation process. The negative percentages of BOD and COD removal of −68% and −366.7%, respectively, by the control system indicate that the 4
Journal of Environmental Chemical Engineering 7 (2019) 103048
N.S. Abd Rasid, et al.
were higher than the hydrilla species that do not consist of gas transportation ability.
amount of both values at the end of the experiment were higher than the initial values. 4. Discussion
4.3.2. COD value Due to the unique gas transportation system in the N. nucifera, high microorganisms’ activity is expected during the phytoremediation process. As a results, the COD removal value by N. nucifera was better than Nymphaea and the control. According to Ng, Samsudin & Chan [24], the organic suspended solids were also metabolised or consumed by the cells and converted into energy, carbon dioxide, and water which caused the reduction of the COD value in the water. According to Interim National Water Quality Standards (INWQS) requirements [25], both final COD values for the N. nucifera and Nymphaea samples were below the statutory standards and meet the requirement for the livestock drinking water of less than 50 mg/L.
4.1. Effect of agriculture run-off in contaminating the surface water The source of surface water obtained in this study is surrounded by the agriculture practice that used the nitrogen-based fertilizer for its daily application. However, the fertilizer tends to run-off into the surface water during the raining seasons. By referring to Table 1, in was noticed that the amount of BOD was considerably higher than that reported by Akinbile et al. [2] in Bukit Merah reservoir with the initial BOD value of 4.66 mg/L but lower than that reported by Adeleke et al. [21] in UPM Lake with the average BOD value of 228.13 mg/L. Meanwhile, the COD value in this study was lower than the average COD value of 275.33 mg/L [21]. The BOD/COD ratio is a parameter that indicates the biodegradability of the organic components in the surface water and work as an indicator for measuring the degrees of both biological and chemical decompositions [22]. Table 1 also shows that the surface water sample BOD/COD ratio was more than 0.5, which indicates that the surface water contaminants are biodegradable.
4.3.3. DO value The decreased of DO in water containing Nymphaea was caused by the senescence of the stalks and the nutrient that might be absorbed by the plant was returned into the water in the form of organic nitrogen through the broken or dead stem [26]. Therefore the more oxygen was required by the microbes to consume the degraded organic matter left by the plant. The nutrient that is originally incorporated with the biomass has the tendency to return to the water due to decomposition process [27]. The amount of DO in the water treated using N. nucifera was remarkable because the water received a consistent O2 gases along the process. In Fig. 3(c), the DO fluctuation on day 10 was regarded as a possible result of the oxygen was being used during the macrophytes breathing. In addition, Cho-Ruk et al. [12] also showed that a massive fibrous roots system with long stolon and large surface area gives a beneficial result in phytoaccumulation. Therefore, the fibrous root plants usually have a higher radial oxygen loss (ROL) [28] in which allows the excess O2 to diffuse into the rhizosphere and enriches the interfacial layer of the rhizomes region with the dissolved oxygen. The fibrous plant roots also typically provides an ideal environment for the microbial growth and enhances the degradation activity [29]. Although it was noticed that the N. nucifera has two flow pathways compared to other pressurising plants [32], only one of the pathway were used supply the O2 gases into root system. According to Colmer [30], the pathway or aerenchyma that exist in the plant gas canal system also offers a low-resistance internal pathway for gas transportation from the leaves to the roots system. The oxygen gas that transported to the rhizomes is supplied to the growing tissues where the oxygen is the most needed [31] and the excess oxygen oxygenates the rhizosphere [32]. This excess oxygen diffused out from the rhizomes through the roots and the condition acts as an aeration system which increases the amount of dissolved oxygen in the anoxic area. However, the amount of gases supplied by the plant also can be affected by the number of leaves as the oxygen from the environment diffused within the plant section through the air canal that located inside the leaf [33].
4.2. Plant evaluation for polishing the surface water quality From the obtained results indicated in Fig. 3, we agreed that the role of gas transportation mechanism is important whereby the high gas transportation rate contributes to an effective water treatment. N. nucifera plant exhibits two way gas transportation mechanisms whereas Nymphaea plant exhibits the normal diffusion on transporting oxygen to the buried roots [17]. The selectivity of the plant for treating the contaminated water samples can be evaluated by subjecting the plants with an in situ NO3− measurement. In our hypothesis, a good phytoremediator plant is not only supposed to supply an appropriate amount of O2 gas during the gas transportation mechanism but it must be able to adsorb the dissolved NO3− that converted by the microbes. Without this ability, the NO3− concentration accumulated and an imbalance Ncycle occurred in the ecosystem. This is proven in terms of the performance to remove nitrate in the water as shown in Table 3 where the percentage of nitrate removal in the water treated using Nymphaea and control were −134.9% and −72.1%, respectively. Thus, we concluded that with N. nucifera phytoremediation treatment, the nitrogen cycle in the system was active and balanced. This was due to the highly oxygenated water in N. nucifera causing the denitrification process to occur rapidly as mentioned previously with respect to Fig. 3(c). The increasing trend of NO3− in Fig. 3(e) for Nymphaea species indicates that the NO3− adsorption by the plants was lower due to the limitation of the plant to be utilised as phytoremediator. During the work, the Nymphaea plants were noticed to start wilting from day 5. A similar observation also was noticed by Ng & Chan [23] where they found out the total of nitrate removal was caused by the nitrification–denitrification process which included the plant and the microbial uptake. The increase of nitrate concentration was caused by the nitrate accumulation in bulk when the water samples was exposed to the sunlight during the experimental work.
4.3.4. pH value The pH values in this work were slightly increased from the acidic condition and reach the neutral pH upon completion of the phytoremediation process. N. Nucifera was noticed to have the lowest pH value compared to other samples. Kanabkaew & Puetpaiboon [11] also observed a similar pattern for N. nucifera whereby the plant was indicated with the lowest pH as compared to other treatment for treating the domestic wastewater in their work. Although no scientific evidence was found to explain the phenomenon, we hypothesized that the lower pH by N. nucifera could be due to the released gases from the microbe’s activities. Furthermore, it was also reported that the microbial activities has caused the optimum pH values for nitrification process varies from 6.6 to 8.0 [34].
4.3. Water quality characteristics during and after the phytoremediation process 4.3.1. BOD value During the work, we found that N. nucifera were capable to minimize the BOD value in the surface water. A similar results also was reported by Kanabkaew & Puetpaiboon [11] which obtained about 79% of BOD removal in domestic wastewater when using N. nucifera. With the existence of gas transportation mechanism in N. nucifera [14], it was postulated that the microbial activities during the phytoremediation 5
Journal of Environmental Chemical Engineering 7 (2019) 103048
N.S. Abd Rasid, et al.
4.3.5. NO3− concentration Referred to Fig. 3(e) and Table 3, the in situ measurements of NO3− concentration along the phytoremediation process were the most important characteristic for evaluating a phytoremediator plants. As mentioned earlier, good phytoremediator plant is not only supposed to supply an appropriate amount of O2 gas during the gas transportation mechanism but it must be able to adsorb the dissolved NO3− that converted by the microbes. In this work, all the NO3− values were higher compared to the initial condition. The increasing trend of NO3− indicates that the NO3− absorption by the plants was weaker due to the limitation of the plant to be utilised as phytoremediator when the plant started to wilt. A similar observation was also noticed by Ng & Chan [22] whereby the total of nitrate removal was caused by the nitrification–denitrification process which included the plant and the microbial uptake. The increase of nitrate was caused mainly by the accumulation of nitrate in bulk when the contaminated water that consisted of the run-off fertiliser and plant debris was exposed to the sunlight during the experimental work.
jzus.B0710626. [5] A. Sood, P.L. Uniyal, R. Prasanna, A.S. Ahluwalia, Phytoremediation potential of aquatic macrophyte, Azolla, Ambio 41 (2012) 122–137, https://doi.org/10.1007/ s13280-011-0159-z. [6] J. Barceló, C. Poschenrieder, Phytoremediation : principles and perspectives, Contrib. Sci. 2 (2003) 333–344. [7] P. Saha, O. Shinde, S. Sarkar, Phytoremediation of industrial mines wastewater using water hyacinth, Int. J. Phytoremediation 19 (2017) 87–96, https://doi.org/ 10.1080/15226514.2016.1216078. [8] B.V. Tangahu, S.R.S. Abdullah, H. Basri, M. Idris, N. Anuar, M. Mukhlisin, A review on heavy metals (As, Pb, and Hg) uptake by plants through phytoremediation, Int. J. Chem. Eng. 1 (2011) 1–31, https://doi.org/10.1155/2011/939161. [9] M. Hadiyanto, D. Christwardana, Soetrisnanto, Phytoremediations of Palm Oil Mill Effluent (POME) by using aquatic plants and microalge for biomass production, J. Environ. Sci. Technol. 6 (2013) 79–90, https://doi.org/10.3923/jest.2013.79.90. [10] C.O. Akinbile, T.A. Ogunrinde, H.C. Man, H.A. Aziz, Phytoremediation of domestic wastewaters in free water surface constructed wetlands using Azolla pinnata, Int. J. Phytoremediation 18 (2016) 54–61, https://doi.org/10.1080/15226514.2015. 1058330. [11] T. Kanabkaew, U. Puetpaiboon, Aquatic plants for domestic wastewater treatment: Lotus (Nelumbo nucifera) and Hydrilla (Hydrilla verticillata) systems, J. Sci. Technol. 26 (2004) 749–756. [12] K. Cho-Ruk, J. Kurukote, P. Supprung, S. Vetayasuporn, Perennial plants in the phytoremediation of lead-contaminated soils, Biotechnology 5 (2006) 1–4, https:// doi.org/10.3923/biotech.2006.1.4. [13] J.W.H. Dacey, Knudsen-transitional flow and gas pressurization in leaves of Nelumbo, Plant Physiol. 85 (1987) 199–203. [14] J. Mevi-Schutz, W. Grosse, A two‐way gas transport system in Nelumbo nucifera, Plant Cell Environ. 11 (1988) 27–34, https://doi.org/10.1111/j.1365-3040.1988. tb01773.x. [15] P.G.D. Matthews, R.S. Seymour, Stomata actively regulate internal aeration of the sacred lotus Nelumbo nucifera, Plant Cell Environ. 37 (2014) 402–413, https://doi. org/10.1111/pce.12163. [16] D. Singh, A. Tiwari, R. Gupta, Phytoremediation of lead from wastewater using aquatic plants, J. Agric. Technol 8 (2012) 1–11 http://ijat-aatsea.com/pdf/ v8_n1_12_January/1_IJAT 2012_8_1__Divya Singh-accepted_review artcle_FX.pdf (Accessed 14 October 2017). [17] G. Catian, E. Scremin-Dias, Compared leaf anatomy of Nymphaea (Nymphaeaceae) species from Brazilian flood plain, Braz. J. Biol. 73 (2013) 809–817, https://doi. org/10.1590/S1519-698420130004000018. [18] B.C. Crump, E.W. Koch, Attached bacterial populations shared by four species of aquatic angiosperms, Appl. Environ. Microbiol. 74 (2008) 5948–5957, https://doi. org/10.1128/AEM.00952-08. [19] Methods for Chemical Analysis of Water and Wastes, United States Environmental Protection Agency, Washington, United States, 1983. [20] E.W. Rice, L. Bridgewater, American Public Health Association., American Water Works Association., W.E. Federation., Standard Methods for the Examination of Water and Wastewater, 22nd ed., American Public Health Association, Washington, DC, 2012 (Accessed 26 September 2017), https://books.google.com.my/books?id= dd2juAAACAAJ&dq=standard+methods+for+the+examination+of+water +and+wastewater+22nd+edition+pdf&hl=en&sa=X&redir_esc=y. [21] A.R.O. Adeleke, D.N.N. Nik, A. Ahsan, P. Biswajeet, Water quality assessment of UPM Lake and the impact of geographic information system, Int. J. Environ. Monit. Anal. 2 (2014) 158–162, https://doi.org/10.11648/j.ijema.20140203.15. [22] A.H. Lee, H. Nikraz, BOD:COD ratio as an Indicator for pollutants leaching from landfill, J. Clean Energy Technol. 2 (2014) 263–266, https://doi.org/10.7763/ JOCET.2014.V2.137. [23] Y.S. Ng, D.J.C. Chan, Wastewater phytoremediation by Salvinia molesta, J. Water Process Eng. 15 (2017) 107–115, https://doi.org/10.1016/j.jwpe.2016.08.006. [24] Y.S. Ng, N.I.S. Samsudin, D.J.C. Chan, Phytoremediation capabilities of Spirodela polyrhiza and Salvinia molesta in fish farm wastewater: a preliminary study, IOP Conf. Ser. Mater. Sci. Eng., 29th Symposium of Malaysian Chemical Engineers (SOMChE) 2016 (2017) 1–14, https://doi.org/10.1088/1757-899X/206/1/ 012084. [25] Interim National Water Quality Standards for Malaysia, Water Environ, WEPA, Partnersh. Asia, 2017 (Accessed 14 December 2017), http://www.wepa-db.net/ policies/law/malaysia/eq_surface.htm#pagetop. [26] F.A. Souza, M. Dziedzic, S.A. Cubas, L.T. Maranho, Restoration of polluted waters by phytoremediation using Myriophyllum aquaticum (Vell.) Verdc., Haloragaceae, J. Environ. Manage. 120 (2013) 5–9 (Accessed 16 November 2017), https://ac.elscdn.com/S0301479713000686/1-s2.0-S0301479713000686-main.pdf?_tid= bd9099b6-cad5-11e7-a657-00000aacb362&acdnat=1510840681_ a2c09c499e50fc76ae17927d8e121cce. [27] F. Martínez, G. Cuevas, R. Calvo, I. Walter, Ecosystem restoration biowaste effects on soil and native plants in a semiarid ecosystem, J. Environ. Qual. 32 (2003) 472–479 (Accessed 16 November 2017), https://pdfs.semanticscholar.org/45cc/ b47c81681294993296ee4c2d64dc6a80c69d.pdf?_ga=2.144793140.1815992813. 1510841359-1453132738.1510841359. [28] W.L. Lai, S.Q. Wang, C.L. Peng, Z.H. Chen, Root features related to plant growth and nutrient removal of 35 wetland plants, Water Res. 45 (2011) 3941–3950, https:// doi.org/10.1016/j.watres.2011.05.002. [29] M. Soleimani, M. Afyuni, M.A. Hajabbasi, F. Nourbakhsh, M.R. Sabzalian, J.H. Christensen, Phytoremediation of an aged petroleum contaminated soil using endophyte infected and non-infected grasses, Chemosphere 81 (2010) 1084–1090, https://doi.org/10.1016/j.chemosphere.2010.09.034. [30] T.D. Colmer, Long-distance transport of gases in plants : a perspective on internal
4.3.6. Turbidity Referred to Amr et al. [35], the reduction in turbidity was also observed in the influent and effluent water as the retention time was prolonged. This might be due to the decreased of dissolved oxygen in the water when less effective phytoremediator plants or no plants were involved during the treatment process. Referred to Fig. 3(f), Table 3 and Fig. 4, the clarity of the treated water were maintained at the lowest value after the phytoremediation process. If the turbidity value at day 5 was ignored, we will noticed that the N. nucifera samples reached the lowest value at day 10 compared to other samples. 5. Conclusions Contaminated surface water that was treated using N. nucifera showed the lowest BOD and COD removal during the phytoremediation process. Using the NO3− in situ measurement, low NO3− concentration was noticed after 30 days of treatment process. The treatment condition showed that N. nucifera plant was the best candidates for treating the run-off fertilizer in the natural environment. The thermo-osmotic gas transport mechanism that equipped in N. nucifera also provides sufficient O2 gases to the buried rhizomes, thus it improve the water quality in the ecosystems. The study also indicated that a green and low operational cost treatment was able to be performed within 30 days of treatment. Acknowledgments This work was supported by Putra Grant, GP-IPS/2016/9522800, Universiti Putra Malaysia, Serdang, Selangor, Malaysia, and 600-IRMI/ MYRA 5/3/BESTARI (021/2017), Universiti Teknologi MARA, Shah Alam, Selangor, Malaysia. References [1] N.H.A. Razak, S.M. Praveena, A.Z. Aris, Z. Hashim, Drinking water studies: a review on heavy metal, application of biomarker and health risk assessment (a special focus in Malaysia), J. Epidemiol. Glob. Health 5 (2015) 297–310, https://doi.org/ 10.1016/j.jegh.2015.04.003. [2] C.O. Akinbile, M.S. Yusoff, S.H.A. Talib, Z.A. Hasan, W.R. Ismail, U. Sansudin, Qualitative analysis and classification of surface water in Bukit Merah Reservoir in Malaysia, Water Sci. Technol. Water Supply 13 (2013) 1138–1145, https://doi.org/ 10.2166/ws.2013.104. [3] A.I. Che-Ani, N. Shaari, A. Sairi, M.F.M. Zain, M.M. Tahir, Rainwater harvesting as an alternative water supply in the future, Eur. J. Sci. Res. 34 (2009) 132–140 (Accessed 12 September 2017), https://www.researchgate.net/profile/A_Che-Ani/ publication/237821822_Rainwater_Harvesting_as_an_Alternative_Water_Supply_in_ the_Future/links/00b4952def39b1b6c4000000/Rainwater-Harvesting-as-anAlternative-Water-Supply-in-the-Future.pdf. [4] X.-E. Yang, X. Wu, H.-L. Hao, Z.-L. He, Mechanisms and assessment of water eutrophication, J. Zhejiang Univ. Sci. B 9 (2008) 197–209, https://doi.org/10.1631/
6
Journal of Environmental Chemical Engineering 7 (2019) 103048
N.S. Abd Rasid, et al.
lettuce (Pistia stratiotes) effectiveness in aquaculture wastewater treatment, Int. J. Phytoremediation 14 (2012) 201–211, https://doi.org/10.1080/15226514.2011. 587482. [35] S.S.A. Amr, H.A. Aziz, A.M. Nordin, Optimization of stabilized leachate treatment using ozone/persulfate in the advanced oxidation process, Waste Manag. 33 (2013) 1434–1441 (Accessed 17 November 2017), https://ac.els-cdn.com/ S0956053X13000731/1-s2.0-S0956053X13000731-main.pdf?_tid=ea21285ecbae-11e7-89cd-00000aacb35f&acdnat=1510933957_ dbbaf5bbea5c1c9009fb2eab9802f0e1.
aeration and radial oxygen loss from roots, Plant Cell Environ. 26 (2003) 17–36. [31] P.G.D. Matthews, R.S. Seymour, Anatomy of the gas canal system of Nelumbo nucifera, Aquat. Bot. 85 (2006) 147–154, https://doi.org/10.1016/j.aquabot.2006.03. 002. [32] W. Grosse, W. Armstrong, A history of pressurised gas-flow studies in plants, Aquat. Bot. 54 (1996) 87–100. [33] S. Vogel, Contributions to the functional anatomy and biology of Nelumbo nucifera (Nelumbonaceae). I. Pathways of air circulation, Plant Syst. Evol. (2004) 9–25, https://doi.org/10.1007/s00606-004-0201-8. [34] C.O. Akinbile, M.S. Yusoff, Assessing water hyacinth (Eichhornia crassopes) and
7