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The basis of a policy for minimizing and recycling food waste
Environmental Science & Policy 5 (2002) 247–253
The basis of a policy for minimizing and recycling food waste M. Fehr∗ , M.D.R. Calçado, D.C. Romão Federal University, P.O. Box 811, 38400 974 Uberlˆandia, Brazil
Abstract The life cycle of basic food items was studied in order to discover the reasons for low landfill diversion rates of this material. Management failures at key points of the cycle were identified. Subjects of study were commercialization procedures of fruit and vegetables before consumption, consumption proper and after-consumption disposal procedures for food scraps in the Brazilian context. Before consumption, the rate of lost fruit and vegetables stood at 16 wt.% of the total quantity commercialized. During consumption by residents, the waste rate of food amounted to 9 wt.% of all collected household garbage. In the after-consumption sector of the cycle, biodegradables represented 72 wt.% of all household garbage collected by official means in a typical Brazilian town. The numbers produced clearly identified landfill diversion of biodegradables as a management problem. The authors experimented with original proactive administrative procedures designed to set landfill diversion targets. The occurrence of wasted fruit and vegetables at the wholesaler and retailer levels was identified. Remedies were proposed and tested to reduce this waste by at least 50%. In the after-consumption sector, the notion of divided garbage collection was developed and applied to test communities. It was shown that biodegradables may be collected separately from the rest of household waste. This resulted in a diversion potential of 100% for biodegradables alone and 77 wt.% for all collected household waste. The study produced a formal policy proposal to municipal administrations to avoid the need for tipping of biodegradable material. © 2002 Elsevier Science Ltd. All rights reserved. Keywords: Waste policy; Waste management; Food commercialization; Household waste; Divided collection; Landfill diversion
1. Introduction At first sight, landfilling biodegradable organic material may seem logical, as it would close its life cycle by returning it to nature. Necessary conditions for this procedure would be reasonable purity of the organic material at the tip and completion of the biological decomposition reactions before tipping. In present day practice, a landfill does not close any life cycles. It leaves all of them open. Landfills are accepted to be permanent depositories of mixed waste, carefully isolated from their environment by appropriate impermeable layers at the bottom and methane scavenging vegetation at the top. They perfectly fit the description of Planet Trash defined earlier by Fehr (1999a) as the sum total of untreated solid, liquid and gaseous waste. They ostensibly represent the gap in the material balance of all matter derived from earthly resources. A commendable attempt is usually made to integrate closed landfills into the landscape and thus, return the terrain to civic uses. Their contents, however, do not return to their original state in nature in the foreseeable future.
∗ Corresponding author. Tel.: +55-34-239-4291; fax: +55-34-239-4188. E-mail address: [email protected] (M. Fehr).
Consequently, seen from an ecological point of view, which advocates the closure of life cycles, landfills are undesirable solutions to the problem of waste disposal. The philosophy of landfill diversion is rapidly expanding its influence. Its basic premise is to discover and put into practice processes, technologies and management methods that help close the material balance of the environment without resorting to Planet Trash. The present study adheres to this modern diversion philosophy and experiments with specific management tools with the intention to divert biodegradables from landfills. Why is the emphasis placed on management tools and on biodegradable matter? The answer is that both offer an excellent prospect to create strong impacts on diversion rates. Existing technologies by themselves have not been able to significantly raise diversion rates of biodegradables in spite of the impressive apparent potential. Biodegradables in Brazil typically represent 70 wt.% of municipal solid waste (MSW). The available and well seasoned technologies for treating biodegradable waste components are composting (Pereira Neto, 1989; Green, 1999; DSWA, 1999), accelerated anaerobic digestion (MWPF, 1996), landfilling with methane capture for power generation (Ville de Montréal, 1992; Schoen et al., 1999; Fehr, 1999c), landfilling without methane collection (Read, 1997; Fehr, 1999b) and mixed waste incineration (Fehr, 1992; Remmen, 1998; Stöhr et al.,
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1998). The first two of these technologies produce compost and therefore, may be considered means of closing the material balance and the life cycle. For the present study, they appeared to be logical targets. It remained to bridge the gap between the waste producers, the households, and the waste consumers, the operators of composting facilities. This gap is of an administrative nature. Existing mixed waste collection and separation technologies do not deliver adequate raw material to the composting facilities to make them successful enterprises. Any company or organization specializing in composting or accelerated anaerobic digestion, of necessity, judges the success of these operations by economic criteria. As a result, an isolated biological and economic micro-system is created, which is trapped within the battery limits of the specific technology or process. The raw material of this bio-system is the mixed waste received at the tip gate. Its product is the compost sold to interested parties at going market prices. If no added value is achievable with this transformation, obviously nobody will invest in the system, and the biodegradables go to the tip. What is the challenge? Look at this micro-system as but a tiny component of an integrated bio-system, which comprises all parts of the food life cycle, and apply the economic analysis to this integrated system. Suddenly, strategic considerations, such as opportunity costs of landfill terrain and contents enter into the calculation. The economic analysis reaches beyond the battery limits of the composting plant and assumes national proportions. The authors have not encountered this type of macroscopic assessment with corresponding practical solutions in the qualified literature. All landfill facilities visited and studied through publications are trapped in the battery limits approach of management strategies for biodegradables. Landfill diversion remains low simply because it has never been a specific management priority at regional or national levels. In this context, the specific objectives of this study were the following. Observe the life cycle of basic fruit and vegetable food items in order to discover where and at what rates biodegradable waste is produced. Devise management methods for closing the waste processing gap between households and composters. Develop and test a management model acceptable to municipal administrations. The target based on previous research was a total landfill diversion of MSW in the order of 80% with all its economic implications at regional levels. The life cycle study afforded some insight into the material flow between the following specific fruit and vegetable bio-systems: soil preparation and food production, commercialization with waste generation, consumption with waste generation, waste disposal, reintegration into soil preparation, and landfill bio-systems of Planet Trash.
2. The observed life cycle of fruits and vegetables Fruits and vegetables were chosen as a sample commodity of biodegradable food in order to study the generation of
waste during the life cycle and the possibilities for its diversion from landfills. The wording is critical in this treatment. Scraps refer to customary remains after consumption: the parts that are not eatable. An example is a banana peel. Loss refers to entire food items that do not serve their purpose: they are thrown away without being considered for consumption, for whatever reasons there might be. An example is an entire banana found in the garbage. The words waste or biodegradables are used to address the sum of scraps and losses. For convenience of analysis and data presentation, the life cycle was divided into sectors G for growing, M for marketing, C for consumption and D for disposal. Sector G runs from soil preparation to harvesting. Sector M runs from the farm gate to the retail sale. Sector C runs from the retail purchase to the garbage can, and sector D runs from the garbage can to the landfill. Data were collected at the following key points of the life cycle: commercialization procedures prior to consumption (M), consumption proper (C) and after-consumption disposal of residues (D). The study is based on the hypothesis that all fruit and vegetable items are in perfect conditions for consumption upon leaving the farm. As a consequence, no waste data were collected for Sector G. In the typical Brazilian context, farmers screen their produce at home and then transport it to a wholesale market at the outskirts of the nearest city. At this market, they may sell to wholesalers or to retailers, according to their convenience. For logistical reasons, the study is limited to this distribution model of produce, which is the only one visible. A farmer who bypasses the market and delivers the produce directly to an individual customer, or a wholesaler or retailer who imports produce without moving it through the wholesale market, are outside the physical reach of this study. Some wholesalers have reasonable infrastructure to maintain stocks for delayed commercialization, either at the wholesale market or at their private property. Others do not. For them, speed of commercialization is a critical parameter. They need a fixed net of retail customers to guarantee the continuous flow of the merchandise. Their negotiating power is limited. The retailers present at the market take their purchases directly to their respective sales outlets in town, which may be street markets, restaurants, fruit and vegetable stores, general food stores or supermarkets. In all cases, the marketing sector of the life cycle of fruits and vegetables begins at the farm gate and ends when the consumer acquires the products at the retail outlets. Specific data on commodity turnover and waste generation were collected at the wholesale market with farmers and wholesalers, and at the retailer level with fruit and vegetable stores, street market traders and supermarkets. The sector of the life cycle termed consumption (C) in this study comprises the time and the handling steps from the moment when the food is purchased at the retailer’s to the moment when the remains appear at the sidewalk for garbage collection. This sector was diagnosed by way of sorting and analysis of garbage left at the sidewalk by dwellers of apartment buildings.
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Fig. 1. Life cycle of fruits and vegetables.
Finally, the portion of the life cycle concerned with after-consumption disposal (D) begins at the sidewalk and terminates at the landfill. According to the theory of the parallel planets mentioned earlier, all tipped matter leaves Planet Earth and forms the parallel Planet Trash. The life cycle remains open. The only way to close it is to compost the biodegradable waste and return the compost to the farm. This study produced data on the rate at which biodegradable matter changes planets. The extrapolations are somewhat frightening. Fig. 1 shows the basic stops of fruit and vegetables in their life cycle for the Brazilian context under study.
3. Data collection and results at the wholesale level For the marketing sector of the life cycle, the gathered data were expected to answer question 1: What fraction of fruits and vegetables produced on the farms and offered for commercialization actually reach the final consumer? As no consumption occurs in this sector, all waste derives from losses. There are no scraps. All supply vehicles arriving at the wholesale market are weighed, such that the quantity of produce offered for commercialization is known. Table 1 shows data for the specific market subject of this study. It serves a municipality with 440,000 inhabitants and receives produce from 1283 registered farmers and importers.
Outgoing vehicles are not controlled, such that no official data exist on the destination of the produce supplied to the market. The present research produced the following original data on this topic. Quantitative information was obtained from the work with wholesalers at the market. Through daily follow-up of purchases and sales at three sample companies, and scale-up to the 58 companies engaged in wholesale, data collected from August 1998 to March 1999 showed that 4.32% of producer purchased by wholesalers deteriorates on their property and is thrown away. In addition, there exists a section, which receives donations in the form of fruits and vegetables that do not find buyers but are still eatable at a consumer’s discretion. The quantity of donations during December 1998 was measured to be 302.6 t. As no revenue is derived from them, they are accounted for as waste in this study. Table 2 summarizes the situation defined by this research for the particular market analyzed. Table 1 Turnover of fruit and vegetables, in metric tons, reported by the administration of the wholesale market studied in Brazil for the year 1998 Leave type vegetables Root type vegetables Fruit type vegetables Home grown fruits Imported fruits Total
9802 43379 55066 73215 3387 184849
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Table 2 Losses at the wholesale level relative to turnover of product in metric tons per year Turnover of produce at the market under study Measured losses extrapolated to the 58 wholesalers (4.32%) Measured donations 302.6 × 12 (1.96%)
184849 7985 3631
Total losses determined (6.28% of turnover)
11616
4. Data collection and results at the retail level Retailers take away from the wholesale market all produce not lost or donated. This amounts to 100–6.28 or 93.72% of turnover. Fig. 1 lists the handling steps involved in retailing. The types of retailers analyzed here were street market traders, fruit and vegetable stores and supermarkets. The following numbers give an idea of the size of this universe. There are in this city 160 registered street market traders, 55 listed fruit and vegetable stores, 156 supermarkets of all sizes including ordinary food stores listed as supermarkets, apart from 87 listed restaurants which did not take part in this research. One typical street market trader was picked for analysis. Some of these traders complement the purchases at the wholesale market with their own production. The main problem of the traders is to keep the produce fresh from the time of purchase or harvest to the moment of sale at one of the successive street market offerings. The trader under study did not have data either on his operational cost, or on the losses of produce. This research provided original data on this commercial sector. During the months of August and September 1998, this trader acquired 7.874 t of produce of which 0.919 t or 11.67% deteriorated during the handling steps and was discarded. All tonnage in this report refers to metric tons. The fruit and vegetable stores are businesses that specialize in retailing farm produce, which apart from fruits and vegetables may include poultry and milk derivatives. Two of these stores were chosen for analysis. Neither one of them had any data on the quantity of losses, nor on the causes of these losses. Once again, original data were generated on the effectiveness of this trade. Store B owned a cold chamber for intermediate storage of produce, store A did not. Both had suppliers other than the wholesale market to complement their purchases, but no account was kept on the exact quantities originating from each supplier. Table 3 shows the results of the measurements carried out in the two stores. Table 3 Measured losses in fruit and vegetable stores in 2 months Store
Period
Purchases (t)
Losses (t)
Losses (%)
A B
July 1998 May 1998
33.77 188.16
9.479 18.4
28.07 9.78
221.93
27.88
12.56
Total
Table 4 Measured losses in supermarket A in 2 months Period
Initial stock (t)
Purchases
Total input (t)
Losses (t)
Losses (%)
November 1998 April 1999
5.229 4.650
88.537 161.973
93.766 166.623
11.194 11.616
11.94 6.97
Total
9.879
250.510
260.389
22.810
8.76
Table 5 Losses of fruit and vegetables verified in the marketing sector of their life cycle Losses at wholesale level: 6.28% of wholesale turnover of 100 units Losses at retail level out of retail turnover of 100–6.28 = 93.72 units: street trading 11.67%; fruit and vegetable stores 12.56%; supermarkets 8.76%; average 11% Total marketing losses relative to turnover: 100 × 0.0628 + 93.72 × 0.11 = 16.59%
The last retail outlet to be studied was a supermarket of above average size. This type of business commercializes a great variety of products, of which fruits and vegetables represent only one department. Measurements were taken on two seasonally different occasions: November 1998 (rain season) and April 1999 (dry season). The result is shown on Table 4. On reaching the end of the marketing sector, a recapitulation of recorded data is in order. Due to the large and heterogeneous universe of commercial establishments in this sector, no attempt was made at closing the material balance of produce. The available data did not allow such an endeavor. The occurrence of material losses, however, may be estimated from the data collected. This was the prime objective of the study. The calculation on Table 5 crudely summarizes the losses. The answer to question 1 is 83.41%.
5. Data collection and results in the consumption sector In this sector, the food items acquired by the consumer at the retailer’s pragmatically divide into three destinations. Part 1 is really consumed and exits the life cycle of fruits and vegetables to enter that of human energy, a different bio-system. Part 2 comprises the scraps, the uneatable portion of the fare, which naturally and expectedly appears in the garbage. Part 3 is the loss: all items that bypass the kitchen and go from unpacking or storage straight to the wastebasket. The research on this sector pretended to answer question 2: What fraction of purchased fruits and vegetables end up in part 3 and what fraction of household waste do parts 2 and 3 represent? To obtain the pertinent data, household garbage was collected and analyzed at selected points in town. An earlier study in this city (Fehr and Castro, 1999) had determined the fraction of biodegradables in MSW as 72 wt.%. The present research was conducted
M. Fehr et al. / Environmental Science & Policy 5 (2002) 247–253 Table 6 Complete analysis of household waste
Table 7 Landfill diversion target for city under study
Two condominium buildings with 240 persons, garbage of 2 days, July 1998
50% of fruit and vegetable marketing losses (t per day) 100% of biodegradables in household waste (t per day) 100% of recyclable inerts in household waste (t per day) Absolute target Relative target 276/(276 + 84) = 77% of MSW (t per day)
Total garbage collected 264.4 kg
Biodegradable portion 176.1 kg (66.6%) Inert portion 88.3 kg (33.4%)
Biodegradable portion
Scraps 152.8 kg (86.8%) Lost food 23.3 kg (13.2%)
Lost food in biodegradables
Fruits and vegetables 9.1 kg (5.2%) Other types of food 14.2 kg (8.0%)
Lost food in garbage
Fruits and vegetables 9.1 kg (3.4%) Other types of food 14.2 kg (5.4%)
Inert portion
Recyclables 40.1 kg (45.4%) Non-recyclables 48.2 kg (54.6%)
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84 × 0.5 = 42 276 × 0.72 = 199 276 × (1 − 0.72) × 0.454 = 35 276
in two apartment buildings that represented appropriate conditions for collecting the specific data sought. Dwellers were instructed to separate their garbage into two bags: biodegradables and inerts. This procedure was termed divided collection. It not only made analysis easier, but also opened up impressive prospects for landfill diversion. Garbage was collected on various occasions until a steady state of division into the two bags had been reached, with 67% biodegradables and 33% inerts. Table 6 shows in material balance style the result of the last analysis of this series. The answer to question 2 is as follows. Lost fruits and vegetables represent 3.4% of household waste or 5.2% of biodegradables present in household waste. Biodegradable waste represents 66.6% of collected household waste from apartment buildings, which divides into 86.8% scraps and 13.2% losses. The first part of the question has no answer at this time, due to the discontinuity of measurements inside the household. To complete the data, it would be necessary to follow a family to the store and to the kitchen and weigh what they buy and what they throw away, in order to find what they consume by difference.
Table 5 indicates losses of 184,849 × 0.1659 = 30,666 t per year or 84 t per day (metric tons per day) of fruits and vegetables officially accounted for. They change planets without ever reaching the retail level. In the consumption sector, Table 6 shows that for the apartment buildings studied, 66.6% of household waste is biodegradable. According to previous research (Fehr and Castro, 1999), this number stands at 72% for the entire city. Apartment buildings represent a specific social level with above average living standard. This difference in composition is expected. In the following calculations concerning the city, the value of 72% will be used. In both sectors, the key to diversion is proper management of people and technologies. As the marketing sector is concerned with manipulation of fresh producer, the elimination of waste is an unrealistic proposition. Conservatively and somewhat arbitrarily, based on personal observations in this sector, a target of 50% loss reduction was considered achievable. The disposal sector handles only waste originating from the consumption sector. No special care is required. Consequently, a landfill diversion of 100% for biodegradables was deemed a logical target. The official MSW collection in this city stands at 276 t per day Fehr and Castro (1999). As a by-product of the waste analysis, Table 6 also gives details on inert material. The recyclable portion of this does not need to be tipped. The target for diversion is exposed in Table 7.
6. The disposal sector
8. Facing the management challenge
The city under study operates a mixed waste processing facility (MWPF) for household and commercial waste, which, according to information obtained from management, diverts an estimated 40% of collected waste from the landfill. No specific data are available to confirm this statement. The effort of collecting this type of data was beyond the scope of this research.
With the diversion target known, it remained to find answers to question 3: what has been achieved, what needs to be done and how should it be done? Obviously, this research was not expected to interfere with municipal administrations, which are perfectly autonomous decision-making bodies. The idea was to provide pertinent data for them, to develop management methods and to test their chances of success. What has been achieved is summarized in Tables 5–7. All numbers in these tables are the result of original research. None of them was known. For the first time data are now available on the losses of fruit and vegetables in the marketing and consumption sectors of their life cycle. Also for the first time, a landfill diversion target has been quantitatively set based on real data. This represents a giant step towards modern waste management practices in any city or
7. Targeting landfill diversion From the data presented in the tables of results, it was possible to set a logical target for landfill diversion in this particular city. This exercise is original in the region, and possibly in other regions as well. In the marketing sector,
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town still trapped in the era of unrestricted landfill, and there are many. What needed to be done was to find appropriate management procedures for both the marketing and the disposal sectors. Work has been initiated with the following steps. Interviews with farmers have been conducted in order to pinpoint the factors leading to losses on loading and transportation. Convenient and inconvenient packaging material and hours of the day for transportation of produce have been identified. The numbers produced by this research have alerted wholesalers about the convenience of maintaining air-conditioned storage areas and of hiring appropriate manpower. The street market trader has been induced to exercise control over his cost structure and to optimize his purchasing schedule. The fruit and vegetable stores have become conscious of the causes of losses. They are inadequate purchasing schedules and poor practices of manipulating produce in the stores. At the supermarket, the most surprising result of this research was the promotion of the material balance to a higher level of priority. Acquisitions and sales of every fruit and vegetable item are now documented and compared in order to discover and quantify losses. For the disposal sector, the model of divided waste collection has been developed and tested. Specific theories behind and experiments with divided collection have been published elsewhere (Fehr and Calçado, 1999). The steps outlined here indicate that a correct approach has been chosen to face the enormous management challenge of landfill diversion. The recent literature on this topic shows that the diversion problem is by no means local. Every country engages in finding the most appropriate method to cope with it. Examples have been found originating from Spain (GEDESMA, 1998), East Asia (Taylor, 1999) and Great Britain (Read, 1999).
and lasting results may be expected. Research in a second municipality has been initiated to expand the data bank. As for the diversion target, the initial estimate was 80% of MSW. The work performed and the data collected came extremely close to confirming the prediction. The final number is 77%. As anticipated in Section 1, the research provided interesting data on the material flow in the integrated bio-system of biodegradable food components. According to Fig. 1, the system is a closed cycle except for the exits of consumption and landfilling. It has been mentioned earlier that additional research is required to quantify the exit relating to consumption. The exit relating to landfilling has been determined as the sum of waste generated in the marketing and consumption sectors of the life cycle. Numbers have been presented in Tables 5 and 6 that quantify the flow rates and permit extrapolations. The basic goal of this and related studies by the authors is to drastically reduce the rate at which biodegradables and other recyclable items change planets. For a city of 440,000 people like the one studied here, in the era of unrestricted landfill, the transfer of matter from Planet Earth to Planet Trash is 276 + 84 = 360 t per day for MSW excluding construction and hospital trash. It is left as an arithmetic exercise for interested parties to extrapolate this number to their respective contexts. As an example close to home, the Brazilian population presently stands at 158 million (IBGE, 1997). All things considered, the philosophy of landfilling will inflate the Brazilian Trash Planet at an approximate rate of 360 × (158/0.44) = 129,300 t per day. This is a fact. Any consideration on the continuous sustainability of life has to take this fact into account. If the present research succeeded in sounding the alert, it has been worthwhile.
Acknowledgements 9. Discussion and policy prospect The objectives of this research have been fulfilled. The life cycle of basic fruit and vegetable food items has been defined and observed. Waste generation in this cycle has been quantified. The management method of divided collection has been developed and successfully tested. It closes the waste processing gap between households and composting facilities by supplying biodegradable raw material of excellent quality for composting. The model is considered useful for municipal administrations and may be implemented with modest investments. In addition to separating biodegradables, it separates recyclable inerts of excellent quality, too. Composting and recycling will thus, attract the private initiative and alleviate the financial burden of the municipality. Obviously, the decision to accept and experiment with the model remains with public administrators. Admittedly, the effort to implement the model frightens administrators for the same reason it surprises engineers: it requires the ability to manage people. Once this fear of people is overcome, very rewarding
The authors thank the following Brazilian institutions for their support. The CAPES Foundation supplied a scholarship to M.D.R. Calçado. The CNPq Council supplied operational infrastructure to M. Fehr through Grant 40.0040/96-4 and a scholarship to D.C. Romão.
References DSWA 1999, Compost Recipe, Delaware Solid Waste Authority. Dover, DE. Fehr, M., 1992. A cold model analysis of solid waste incineration. Int. J. Energy Res. Coleraine 16 (4), 277–283. Fehr, M., 1999a. The dynamic nature of MSW management. J. Environ. Sys. 27 (1), 1–13. Fehr, M., 1999b. Authors’ Own Observations at Landfills in Brazil and USA. Fehr, M., 1999c. Authors’ Own Observations at Landfills in Spain. Fehr, M., Calçado, M.D.R., 1999. Divided collection of household waste passes its first test. In: Proceedings of the Fifteenth International Conference on Solid Waste Technology and Management. Philadelphia, 12–15 December, Session 7B.
M. Fehr et al. / Environmental Science & Policy 5 (2002) 247–253 Fehr, M., Castro, M.S.M.V.D., 1999. MSW analysis infers management model (in Portuguese). Saneamento Ambiental 10 (55), 38–41. GEDESMA 1998, Selective collection of used packaging material in Madrid (in Spanish), Residuos Revista Técnica 8 (43), 56–58. Green, C., 1999. Composting and greenwaste product survey. World Wastes 42 (1), 22–30. IBGE 1997, Brazil in numbers (in Portuguese), IBGE 5, 1–137. MWPF, 1996. Mixed Waste Processing Facilities Visited by the Authors in Central Brazil, Which Operate Accelerated Anaerobic Digestors. Pereira Neto, J.T., 1989. Modern concepts of composting (in Portuguese). Engenharia Sanitária 28 (2), 32–38. Read, A.D., 1997. Landfill as future waste management option in England. Resources Conservation and Recycling 20 (3), 183–205. Read, A.D., 1999. A weekly doorstep recycling collection I had no idea we could. Resources Conservation and Recycling 26 (3/4), 217–249. Remmen, T.V., 1998. Evaluation of waste incinerators. Waste Management 18 (6–8), 393–402. Schoen, M., Fine, S., Gowen, M., 1999. Controlling methane. World Wastes 42 (1), 44–48. Stöhr, J., Bechtler, R., Furrer, J., Seifert, H., 1998. Influence of disturbances in MSW incineration plants on catalytic converters. Waste Management 18 (6–8), 411–416. Taylor, D.C., 1999. Mobilizing resources to collect MSW: East Asian case studies. Waste Management and Research 17 (4), 263–274.
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Ville de Montréal 1992. The Waste Challenge (in French). City Hall, Montreal. Manfred Fehr is a chemical engineer, registered in Brazil and in Canada, with accumulated professional experience in 21 countries on five continents, speaks five languages, has to his credit more than 190 publications and appears in 31 international biographical dictionaries. His PhD is from Laval University, Canada. He founded and presided two local chapters of the Brazilian Chemical Engineering Association and the Total Environment Foundation. Presently, he is professor at the Federal University in Uberlˆandia, Brazil, where his areas of interest are environmental and energy management. [email protected] Marilda dos Reis Calçado is a chemical engineer who holds a BS (1996) and a MS (1998) degree in Chemical Engineering from the Federal University in Uberlˆandia, Brazil. She participated in the research described here and is now an environmental consultant. Daniela Cursino Romão is a biologist who holds a BS degree in Biology (1999) from the Federal University in Uberlˆandia, Brazil and is presently preparing her MS degree in Geography at the same university. She participated in the research described here and has also been active as an environmental consultant.
The basis of a policy for minimizing and recycling food waste M. Fehr∗ , M.D.R. Calçado, D.C. Romão Federal University, P.O. Box 811, 38400 974 Uberlˆandia, Brazil
Abstract The life cycle of basic food items was studied in order to discover the reasons for low landfill diversion rates of this material. Management failures at key points of the cycle were identified. Subjects of study were commercialization procedures of fruit and vegetables before consumption, consumption proper and after-consumption disposal procedures for food scraps in the Brazilian context. Before consumption, the rate of lost fruit and vegetables stood at 16 wt.% of the total quantity commercialized. During consumption by residents, the waste rate of food amounted to 9 wt.% of all collected household garbage. In the after-consumption sector of the cycle, biodegradables represented 72 wt.% of all household garbage collected by official means in a typical Brazilian town. The numbers produced clearly identified landfill diversion of biodegradables as a management problem. The authors experimented with original proactive administrative procedures designed to set landfill diversion targets. The occurrence of wasted fruit and vegetables at the wholesaler and retailer levels was identified. Remedies were proposed and tested to reduce this waste by at least 50%. In the after-consumption sector, the notion of divided garbage collection was developed and applied to test communities. It was shown that biodegradables may be collected separately from the rest of household waste. This resulted in a diversion potential of 100% for biodegradables alone and 77 wt.% for all collected household waste. The study produced a formal policy proposal to municipal administrations to avoid the need for tipping of biodegradable material. © 2002 Elsevier Science Ltd. All rights reserved. Keywords: Waste policy; Waste management; Food commercialization; Household waste; Divided collection; Landfill diversion
1. Introduction At first sight, landfilling biodegradable organic material may seem logical, as it would close its life cycle by returning it to nature. Necessary conditions for this procedure would be reasonable purity of the organic material at the tip and completion of the biological decomposition reactions before tipping. In present day practice, a landfill does not close any life cycles. It leaves all of them open. Landfills are accepted to be permanent depositories of mixed waste, carefully isolated from their environment by appropriate impermeable layers at the bottom and methane scavenging vegetation at the top. They perfectly fit the description of Planet Trash defined earlier by Fehr (1999a) as the sum total of untreated solid, liquid and gaseous waste. They ostensibly represent the gap in the material balance of all matter derived from earthly resources. A commendable attempt is usually made to integrate closed landfills into the landscape and thus, return the terrain to civic uses. Their contents, however, do not return to their original state in nature in the foreseeable future.
∗ Corresponding author. Tel.: +55-34-239-4291; fax: +55-34-239-4188. E-mail address: [email protected] (M. Fehr).
Consequently, seen from an ecological point of view, which advocates the closure of life cycles, landfills are undesirable solutions to the problem of waste disposal. The philosophy of landfill diversion is rapidly expanding its influence. Its basic premise is to discover and put into practice processes, technologies and management methods that help close the material balance of the environment without resorting to Planet Trash. The present study adheres to this modern diversion philosophy and experiments with specific management tools with the intention to divert biodegradables from landfills. Why is the emphasis placed on management tools and on biodegradable matter? The answer is that both offer an excellent prospect to create strong impacts on diversion rates. Existing technologies by themselves have not been able to significantly raise diversion rates of biodegradables in spite of the impressive apparent potential. Biodegradables in Brazil typically represent 70 wt.% of municipal solid waste (MSW). The available and well seasoned technologies for treating biodegradable waste components are composting (Pereira Neto, 1989; Green, 1999; DSWA, 1999), accelerated anaerobic digestion (MWPF, 1996), landfilling with methane capture for power generation (Ville de Montréal, 1992; Schoen et al., 1999; Fehr, 1999c), landfilling without methane collection (Read, 1997; Fehr, 1999b) and mixed waste incineration (Fehr, 1992; Remmen, 1998; Stöhr et al.,
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1998). The first two of these technologies produce compost and therefore, may be considered means of closing the material balance and the life cycle. For the present study, they appeared to be logical targets. It remained to bridge the gap between the waste producers, the households, and the waste consumers, the operators of composting facilities. This gap is of an administrative nature. Existing mixed waste collection and separation technologies do not deliver adequate raw material to the composting facilities to make them successful enterprises. Any company or organization specializing in composting or accelerated anaerobic digestion, of necessity, judges the success of these operations by economic criteria. As a result, an isolated biological and economic micro-system is created, which is trapped within the battery limits of the specific technology or process. The raw material of this bio-system is the mixed waste received at the tip gate. Its product is the compost sold to interested parties at going market prices. If no added value is achievable with this transformation, obviously nobody will invest in the system, and the biodegradables go to the tip. What is the challenge? Look at this micro-system as but a tiny component of an integrated bio-system, which comprises all parts of the food life cycle, and apply the economic analysis to this integrated system. Suddenly, strategic considerations, such as opportunity costs of landfill terrain and contents enter into the calculation. The economic analysis reaches beyond the battery limits of the composting plant and assumes national proportions. The authors have not encountered this type of macroscopic assessment with corresponding practical solutions in the qualified literature. All landfill facilities visited and studied through publications are trapped in the battery limits approach of management strategies for biodegradables. Landfill diversion remains low simply because it has never been a specific management priority at regional or national levels. In this context, the specific objectives of this study were the following. Observe the life cycle of basic fruit and vegetable food items in order to discover where and at what rates biodegradable waste is produced. Devise management methods for closing the waste processing gap between households and composters. Develop and test a management model acceptable to municipal administrations. The target based on previous research was a total landfill diversion of MSW in the order of 80% with all its economic implications at regional levels. The life cycle study afforded some insight into the material flow between the following specific fruit and vegetable bio-systems: soil preparation and food production, commercialization with waste generation, consumption with waste generation, waste disposal, reintegration into soil preparation, and landfill bio-systems of Planet Trash.
2. The observed life cycle of fruits and vegetables Fruits and vegetables were chosen as a sample commodity of biodegradable food in order to study the generation of
waste during the life cycle and the possibilities for its diversion from landfills. The wording is critical in this treatment. Scraps refer to customary remains after consumption: the parts that are not eatable. An example is a banana peel. Loss refers to entire food items that do not serve their purpose: they are thrown away without being considered for consumption, for whatever reasons there might be. An example is an entire banana found in the garbage. The words waste or biodegradables are used to address the sum of scraps and losses. For convenience of analysis and data presentation, the life cycle was divided into sectors G for growing, M for marketing, C for consumption and D for disposal. Sector G runs from soil preparation to harvesting. Sector M runs from the farm gate to the retail sale. Sector C runs from the retail purchase to the garbage can, and sector D runs from the garbage can to the landfill. Data were collected at the following key points of the life cycle: commercialization procedures prior to consumption (M), consumption proper (C) and after-consumption disposal of residues (D). The study is based on the hypothesis that all fruit and vegetable items are in perfect conditions for consumption upon leaving the farm. As a consequence, no waste data were collected for Sector G. In the typical Brazilian context, farmers screen their produce at home and then transport it to a wholesale market at the outskirts of the nearest city. At this market, they may sell to wholesalers or to retailers, according to their convenience. For logistical reasons, the study is limited to this distribution model of produce, which is the only one visible. A farmer who bypasses the market and delivers the produce directly to an individual customer, or a wholesaler or retailer who imports produce without moving it through the wholesale market, are outside the physical reach of this study. Some wholesalers have reasonable infrastructure to maintain stocks for delayed commercialization, either at the wholesale market or at their private property. Others do not. For them, speed of commercialization is a critical parameter. They need a fixed net of retail customers to guarantee the continuous flow of the merchandise. Their negotiating power is limited. The retailers present at the market take their purchases directly to their respective sales outlets in town, which may be street markets, restaurants, fruit and vegetable stores, general food stores or supermarkets. In all cases, the marketing sector of the life cycle of fruits and vegetables begins at the farm gate and ends when the consumer acquires the products at the retail outlets. Specific data on commodity turnover and waste generation were collected at the wholesale market with farmers and wholesalers, and at the retailer level with fruit and vegetable stores, street market traders and supermarkets. The sector of the life cycle termed consumption (C) in this study comprises the time and the handling steps from the moment when the food is purchased at the retailer’s to the moment when the remains appear at the sidewalk for garbage collection. This sector was diagnosed by way of sorting and analysis of garbage left at the sidewalk by dwellers of apartment buildings.
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Fig. 1. Life cycle of fruits and vegetables.
Finally, the portion of the life cycle concerned with after-consumption disposal (D) begins at the sidewalk and terminates at the landfill. According to the theory of the parallel planets mentioned earlier, all tipped matter leaves Planet Earth and forms the parallel Planet Trash. The life cycle remains open. The only way to close it is to compost the biodegradable waste and return the compost to the farm. This study produced data on the rate at which biodegradable matter changes planets. The extrapolations are somewhat frightening. Fig. 1 shows the basic stops of fruit and vegetables in their life cycle for the Brazilian context under study.
3. Data collection and results at the wholesale level For the marketing sector of the life cycle, the gathered data were expected to answer question 1: What fraction of fruits and vegetables produced on the farms and offered for commercialization actually reach the final consumer? As no consumption occurs in this sector, all waste derives from losses. There are no scraps. All supply vehicles arriving at the wholesale market are weighed, such that the quantity of produce offered for commercialization is known. Table 1 shows data for the specific market subject of this study. It serves a municipality with 440,000 inhabitants and receives produce from 1283 registered farmers and importers.
Outgoing vehicles are not controlled, such that no official data exist on the destination of the produce supplied to the market. The present research produced the following original data on this topic. Quantitative information was obtained from the work with wholesalers at the market. Through daily follow-up of purchases and sales at three sample companies, and scale-up to the 58 companies engaged in wholesale, data collected from August 1998 to March 1999 showed that 4.32% of producer purchased by wholesalers deteriorates on their property and is thrown away. In addition, there exists a section, which receives donations in the form of fruits and vegetables that do not find buyers but are still eatable at a consumer’s discretion. The quantity of donations during December 1998 was measured to be 302.6 t. As no revenue is derived from them, they are accounted for as waste in this study. Table 2 summarizes the situation defined by this research for the particular market analyzed. Table 1 Turnover of fruit and vegetables, in metric tons, reported by the administration of the wholesale market studied in Brazil for the year 1998 Leave type vegetables Root type vegetables Fruit type vegetables Home grown fruits Imported fruits Total
9802 43379 55066 73215 3387 184849
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Table 2 Losses at the wholesale level relative to turnover of product in metric tons per year Turnover of produce at the market under study Measured losses extrapolated to the 58 wholesalers (4.32%) Measured donations 302.6 × 12 (1.96%)
184849 7985 3631
Total losses determined (6.28% of turnover)
11616
4. Data collection and results at the retail level Retailers take away from the wholesale market all produce not lost or donated. This amounts to 100–6.28 or 93.72% of turnover. Fig. 1 lists the handling steps involved in retailing. The types of retailers analyzed here were street market traders, fruit and vegetable stores and supermarkets. The following numbers give an idea of the size of this universe. There are in this city 160 registered street market traders, 55 listed fruit and vegetable stores, 156 supermarkets of all sizes including ordinary food stores listed as supermarkets, apart from 87 listed restaurants which did not take part in this research. One typical street market trader was picked for analysis. Some of these traders complement the purchases at the wholesale market with their own production. The main problem of the traders is to keep the produce fresh from the time of purchase or harvest to the moment of sale at one of the successive street market offerings. The trader under study did not have data either on his operational cost, or on the losses of produce. This research provided original data on this commercial sector. During the months of August and September 1998, this trader acquired 7.874 t of produce of which 0.919 t or 11.67% deteriorated during the handling steps and was discarded. All tonnage in this report refers to metric tons. The fruit and vegetable stores are businesses that specialize in retailing farm produce, which apart from fruits and vegetables may include poultry and milk derivatives. Two of these stores were chosen for analysis. Neither one of them had any data on the quantity of losses, nor on the causes of these losses. Once again, original data were generated on the effectiveness of this trade. Store B owned a cold chamber for intermediate storage of produce, store A did not. Both had suppliers other than the wholesale market to complement their purchases, but no account was kept on the exact quantities originating from each supplier. Table 3 shows the results of the measurements carried out in the two stores. Table 3 Measured losses in fruit and vegetable stores in 2 months Store
Period
Purchases (t)
Losses (t)
Losses (%)
A B
July 1998 May 1998
33.77 188.16
9.479 18.4
28.07 9.78
221.93
27.88
12.56
Total
Table 4 Measured losses in supermarket A in 2 months Period
Initial stock (t)
Purchases
Total input (t)
Losses (t)
Losses (%)
November 1998 April 1999
5.229 4.650
88.537 161.973
93.766 166.623
11.194 11.616
11.94 6.97
Total
9.879
250.510
260.389
22.810
8.76
Table 5 Losses of fruit and vegetables verified in the marketing sector of their life cycle Losses at wholesale level: 6.28% of wholesale turnover of 100 units Losses at retail level out of retail turnover of 100–6.28 = 93.72 units: street trading 11.67%; fruit and vegetable stores 12.56%; supermarkets 8.76%; average 11% Total marketing losses relative to turnover: 100 × 0.0628 + 93.72 × 0.11 = 16.59%
The last retail outlet to be studied was a supermarket of above average size. This type of business commercializes a great variety of products, of which fruits and vegetables represent only one department. Measurements were taken on two seasonally different occasions: November 1998 (rain season) and April 1999 (dry season). The result is shown on Table 4. On reaching the end of the marketing sector, a recapitulation of recorded data is in order. Due to the large and heterogeneous universe of commercial establishments in this sector, no attempt was made at closing the material balance of produce. The available data did not allow such an endeavor. The occurrence of material losses, however, may be estimated from the data collected. This was the prime objective of the study. The calculation on Table 5 crudely summarizes the losses. The answer to question 1 is 83.41%.
5. Data collection and results in the consumption sector In this sector, the food items acquired by the consumer at the retailer’s pragmatically divide into three destinations. Part 1 is really consumed and exits the life cycle of fruits and vegetables to enter that of human energy, a different bio-system. Part 2 comprises the scraps, the uneatable portion of the fare, which naturally and expectedly appears in the garbage. Part 3 is the loss: all items that bypass the kitchen and go from unpacking or storage straight to the wastebasket. The research on this sector pretended to answer question 2: What fraction of purchased fruits and vegetables end up in part 3 and what fraction of household waste do parts 2 and 3 represent? To obtain the pertinent data, household garbage was collected and analyzed at selected points in town. An earlier study in this city (Fehr and Castro, 1999) had determined the fraction of biodegradables in MSW as 72 wt.%. The present research was conducted
M. Fehr et al. / Environmental Science & Policy 5 (2002) 247–253 Table 6 Complete analysis of household waste
Table 7 Landfill diversion target for city under study
Two condominium buildings with 240 persons, garbage of 2 days, July 1998
50% of fruit and vegetable marketing losses (t per day) 100% of biodegradables in household waste (t per day) 100% of recyclable inerts in household waste (t per day) Absolute target Relative target 276/(276 + 84) = 77% of MSW (t per day)
Total garbage collected 264.4 kg
Biodegradable portion 176.1 kg (66.6%) Inert portion 88.3 kg (33.4%)
Biodegradable portion
Scraps 152.8 kg (86.8%) Lost food 23.3 kg (13.2%)
Lost food in biodegradables
Fruits and vegetables 9.1 kg (5.2%) Other types of food 14.2 kg (8.0%)
Lost food in garbage
Fruits and vegetables 9.1 kg (3.4%) Other types of food 14.2 kg (5.4%)
Inert portion
Recyclables 40.1 kg (45.4%) Non-recyclables 48.2 kg (54.6%)
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84 × 0.5 = 42 276 × 0.72 = 199 276 × (1 − 0.72) × 0.454 = 35 276
in two apartment buildings that represented appropriate conditions for collecting the specific data sought. Dwellers were instructed to separate their garbage into two bags: biodegradables and inerts. This procedure was termed divided collection. It not only made analysis easier, but also opened up impressive prospects for landfill diversion. Garbage was collected on various occasions until a steady state of division into the two bags had been reached, with 67% biodegradables and 33% inerts. Table 6 shows in material balance style the result of the last analysis of this series. The answer to question 2 is as follows. Lost fruits and vegetables represent 3.4% of household waste or 5.2% of biodegradables present in household waste. Biodegradable waste represents 66.6% of collected household waste from apartment buildings, which divides into 86.8% scraps and 13.2% losses. The first part of the question has no answer at this time, due to the discontinuity of measurements inside the household. To complete the data, it would be necessary to follow a family to the store and to the kitchen and weigh what they buy and what they throw away, in order to find what they consume by difference.
Table 5 indicates losses of 184,849 × 0.1659 = 30,666 t per year or 84 t per day (metric tons per day) of fruits and vegetables officially accounted for. They change planets without ever reaching the retail level. In the consumption sector, Table 6 shows that for the apartment buildings studied, 66.6% of household waste is biodegradable. According to previous research (Fehr and Castro, 1999), this number stands at 72% for the entire city. Apartment buildings represent a specific social level with above average living standard. This difference in composition is expected. In the following calculations concerning the city, the value of 72% will be used. In both sectors, the key to diversion is proper management of people and technologies. As the marketing sector is concerned with manipulation of fresh producer, the elimination of waste is an unrealistic proposition. Conservatively and somewhat arbitrarily, based on personal observations in this sector, a target of 50% loss reduction was considered achievable. The disposal sector handles only waste originating from the consumption sector. No special care is required. Consequently, a landfill diversion of 100% for biodegradables was deemed a logical target. The official MSW collection in this city stands at 276 t per day Fehr and Castro (1999). As a by-product of the waste analysis, Table 6 also gives details on inert material. The recyclable portion of this does not need to be tipped. The target for diversion is exposed in Table 7.
6. The disposal sector
8. Facing the management challenge
The city under study operates a mixed waste processing facility (MWPF) for household and commercial waste, which, according to information obtained from management, diverts an estimated 40% of collected waste from the landfill. No specific data are available to confirm this statement. The effort of collecting this type of data was beyond the scope of this research.
With the diversion target known, it remained to find answers to question 3: what has been achieved, what needs to be done and how should it be done? Obviously, this research was not expected to interfere with municipal administrations, which are perfectly autonomous decision-making bodies. The idea was to provide pertinent data for them, to develop management methods and to test their chances of success. What has been achieved is summarized in Tables 5–7. All numbers in these tables are the result of original research. None of them was known. For the first time data are now available on the losses of fruit and vegetables in the marketing and consumption sectors of their life cycle. Also for the first time, a landfill diversion target has been quantitatively set based on real data. This represents a giant step towards modern waste management practices in any city or
7. Targeting landfill diversion From the data presented in the tables of results, it was possible to set a logical target for landfill diversion in this particular city. This exercise is original in the region, and possibly in other regions as well. In the marketing sector,
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town still trapped in the era of unrestricted landfill, and there are many. What needed to be done was to find appropriate management procedures for both the marketing and the disposal sectors. Work has been initiated with the following steps. Interviews with farmers have been conducted in order to pinpoint the factors leading to losses on loading and transportation. Convenient and inconvenient packaging material and hours of the day for transportation of produce have been identified. The numbers produced by this research have alerted wholesalers about the convenience of maintaining air-conditioned storage areas and of hiring appropriate manpower. The street market trader has been induced to exercise control over his cost structure and to optimize his purchasing schedule. The fruit and vegetable stores have become conscious of the causes of losses. They are inadequate purchasing schedules and poor practices of manipulating produce in the stores. At the supermarket, the most surprising result of this research was the promotion of the material balance to a higher level of priority. Acquisitions and sales of every fruit and vegetable item are now documented and compared in order to discover and quantify losses. For the disposal sector, the model of divided waste collection has been developed and tested. Specific theories behind and experiments with divided collection have been published elsewhere (Fehr and Calçado, 1999). The steps outlined here indicate that a correct approach has been chosen to face the enormous management challenge of landfill diversion. The recent literature on this topic shows that the diversion problem is by no means local. Every country engages in finding the most appropriate method to cope with it. Examples have been found originating from Spain (GEDESMA, 1998), East Asia (Taylor, 1999) and Great Britain (Read, 1999).
and lasting results may be expected. Research in a second municipality has been initiated to expand the data bank. As for the diversion target, the initial estimate was 80% of MSW. The work performed and the data collected came extremely close to confirming the prediction. The final number is 77%. As anticipated in Section 1, the research provided interesting data on the material flow in the integrated bio-system of biodegradable food components. According to Fig. 1, the system is a closed cycle except for the exits of consumption and landfilling. It has been mentioned earlier that additional research is required to quantify the exit relating to consumption. The exit relating to landfilling has been determined as the sum of waste generated in the marketing and consumption sectors of the life cycle. Numbers have been presented in Tables 5 and 6 that quantify the flow rates and permit extrapolations. The basic goal of this and related studies by the authors is to drastically reduce the rate at which biodegradables and other recyclable items change planets. For a city of 440,000 people like the one studied here, in the era of unrestricted landfill, the transfer of matter from Planet Earth to Planet Trash is 276 + 84 = 360 t per day for MSW excluding construction and hospital trash. It is left as an arithmetic exercise for interested parties to extrapolate this number to their respective contexts. As an example close to home, the Brazilian population presently stands at 158 million (IBGE, 1997). All things considered, the philosophy of landfilling will inflate the Brazilian Trash Planet at an approximate rate of 360 × (158/0.44) = 129,300 t per day. This is a fact. Any consideration on the continuous sustainability of life has to take this fact into account. If the present research succeeded in sounding the alert, it has been worthwhile.
Acknowledgements 9. Discussion and policy prospect The objectives of this research have been fulfilled. The life cycle of basic fruit and vegetable food items has been defined and observed. Waste generation in this cycle has been quantified. The management method of divided collection has been developed and successfully tested. It closes the waste processing gap between households and composting facilities by supplying biodegradable raw material of excellent quality for composting. The model is considered useful for municipal administrations and may be implemented with modest investments. In addition to separating biodegradables, it separates recyclable inerts of excellent quality, too. Composting and recycling will thus, attract the private initiative and alleviate the financial burden of the municipality. Obviously, the decision to accept and experiment with the model remains with public administrators. Admittedly, the effort to implement the model frightens administrators for the same reason it surprises engineers: it requires the ability to manage people. Once this fear of people is overcome, very rewarding
The authors thank the following Brazilian institutions for their support. The CAPES Foundation supplied a scholarship to M.D.R. Calçado. The CNPq Council supplied operational infrastructure to M. Fehr through Grant 40.0040/96-4 and a scholarship to D.C. Romão.
References DSWA 1999, Compost Recipe, Delaware Solid Waste Authority. Dover, DE. Fehr, M., 1992. A cold model analysis of solid waste incineration. Int. J. Energy Res. Coleraine 16 (4), 277–283. Fehr, M., 1999a. The dynamic nature of MSW management. J. Environ. Sys. 27 (1), 1–13. Fehr, M., 1999b. Authors’ Own Observations at Landfills in Brazil and USA. Fehr, M., 1999c. Authors’ Own Observations at Landfills in Spain. Fehr, M., Calçado, M.D.R., 1999. Divided collection of household waste passes its first test. In: Proceedings of the Fifteenth International Conference on Solid Waste Technology and Management. Philadelphia, 12–15 December, Session 7B.
M. Fehr et al. / Environmental Science & Policy 5 (2002) 247–253 Fehr, M., Castro, M.S.M.V.D., 1999. MSW analysis infers management model (in Portuguese). Saneamento Ambiental 10 (55), 38–41. GEDESMA 1998, Selective collection of used packaging material in Madrid (in Spanish), Residuos Revista Técnica 8 (43), 56–58. Green, C., 1999. Composting and greenwaste product survey. World Wastes 42 (1), 22–30. IBGE 1997, Brazil in numbers (in Portuguese), IBGE 5, 1–137. MWPF, 1996. Mixed Waste Processing Facilities Visited by the Authors in Central Brazil, Which Operate Accelerated Anaerobic Digestors. Pereira Neto, J.T., 1989. Modern concepts of composting (in Portuguese). Engenharia Sanitária 28 (2), 32–38. Read, A.D., 1997. Landfill as future waste management option in England. Resources Conservation and Recycling 20 (3), 183–205. Read, A.D., 1999. A weekly doorstep recycling collection I had no idea we could. Resources Conservation and Recycling 26 (3/4), 217–249. Remmen, T.V., 1998. Evaluation of waste incinerators. Waste Management 18 (6–8), 393–402. Schoen, M., Fine, S., Gowen, M., 1999. Controlling methane. World Wastes 42 (1), 44–48. Stöhr, J., Bechtler, R., Furrer, J., Seifert, H., 1998. Influence of disturbances in MSW incineration plants on catalytic converters. Waste Management 18 (6–8), 411–416. Taylor, D.C., 1999. Mobilizing resources to collect MSW: East Asian case studies. Waste Management and Research 17 (4), 263–274.
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Ville de Montréal 1992. The Waste Challenge (in French). City Hall, Montreal. Manfred Fehr is a chemical engineer, registered in Brazil and in Canada, with accumulated professional experience in 21 countries on five continents, speaks five languages, has to his credit more than 190 publications and appears in 31 international biographical dictionaries. His PhD is from Laval University, Canada. He founded and presided two local chapters of the Brazilian Chemical Engineering Association and the Total Environment Foundation. Presently, he is professor at the Federal University in Uberlˆandia, Brazil, where his areas of interest are environmental and energy management. [email protected] Marilda dos Reis Calçado is a chemical engineer who holds a BS (1996) and a MS (1998) degree in Chemical Engineering from the Federal University in Uberlˆandia, Brazil. She participated in the research described here and is now an environmental consultant. Daniela Cursino Romão is a biologist who holds a BS degree in Biology (1999) from the Federal University in Uberlˆandia, Brazil and is presently preparing her MS degree in Geography at the same university. She participated in the research described here and has also been active as an environmental consultant.