© 2006 by Taylor & Francis Group, LLC 9 Food Waste Treatment Masao Ukita and Tsuyoshi Imai Yamaguchi University, Yamaguchi, Japan Yung-Tse Hung Cleveland State University, Cleveland, Ohio, U.S.A. 9.1 INTRODUCTION Food processing industries occupy an important position economically and generate large volumes of mostly biodegradable wastes. However, hazardous wastes are also occasionally generated depending on situations such as contamination by pesticides or herbicides, and pathogens. Even simply unbalanced localization may induce unsuitable accumulation or putrefaction of organic wastes. Discarded gourmet foods might also generate hazardous wastes. Wastes derived from food industries are categorized into three groups: (a) manufacturing losses, (b) food products thrown away as municipal solid waste (MSW), and (c) discarded wrappers and containers. These groups may be further divided into liquid and solid wastes. This chapter will focus on the background and issues surrounding food wastes from a structural point of view, liquid wastes and wastewater treatment systems, and solid wastes and hazardous wastes of the US and Japanese food industries. Although both countries are in developed stages, they offer contrasting pictures of food waste treatment. Additionally, several topics will be introduced regarding recent technologies relating to food wastes. These are (a) examples of fermentation factories, (b) cassava starch industries, (c) resource recovery by UASB (up-flow anaerobic sludge bed reactor) or EGSB (extended granular sludge bed reactor), (d) reduction and reuse of wastewater, (e) zero-emission of beer breweries, and (f) technology for garbage recycling. 9.2 STRUCTURAL POINT OF VIEW The recycling of food wastes should be considered as part of the long-term sustainability of agriculture. As Japan is a typical island state, the undesirable influence of oversea-dependent food production has become obvious. Although free trade systems are commonly accepted in the world today, reconsideration of them may be necessary concerning food and feed from nitrogen (N), in 10 3 tons/year. From this figure, it is obvious that the nitrogen cycles originally closed, are very open, because of the consumption of chemical fertilizer and large amount of imported food and feed. 291 environmental aspects. Figure 9.1 shows the food and feed cycle in Japan in 1998 on the basis of © 2006 by Taylor & Francis Group, LLC The rate of Japan’s self supply of domestic food was 41% in 1970, 32% in 1990, and 29% in 1998 for N, and 33% (1970), 29% (1990), and 28% (1998) for Phosphorus, excluding grass feed [1]. These facts make the recycling of food wastes difficult in various phases. We have not enough farmlands for food wastes to be recycled. The supply of composts to paddy field for rice plantation decreased from 5.07 ton/ha/year in 1965 to 1.25 ton/ha/year in 1997 [2]. Figure 9.2 shows a comparison of food balance between Japan and the United States. Figure 9.1 Nitrogen cycle relating to food in Japan. Figure 9.2 Nitrogen balance of food and feed in Japan and the United States (1992–1994). 292 Ukita et al. © 2006 by Taylor & Francis Group, LLC Based on international statistics on agriculture, forestry, and fisheries [3], the United States exports food and feed of 4.2 g N/capita/day. However Japan imports food and feed at a rate as high as 19.4 g N/capita/day. The supply of food is 15.2 g/capita/day in Japan, and 18.0 g/ capita/day in the United States. The ratio of the amount of food to be recycled to farmland vs. chemical fertilizer consumption is 15.5 : 12 ¼ 1.3 in Japan, 41.5 : 116 ¼ 0.36 in the United States. The consumption of chemical fertilizer on farmland is 121 kg N/ha and 59 kg N/ha for Japan and for the United States, respectively. Considering these situations, it easy to understand the difficulty of food waste recycling in Japan, which uses more than twice as much foreign farmland overseas as domestic farmland. These realities also profoundly affect issues of eutrophication in water, not only shortage of the demand for recycled food wastes. The principle that organic wastes should return to the land needs to be enforced. 9.3 LIQUID WASTES FROM FOOD INDUSTRIES 9.3.1 Wastewater Treatment Systems for Food Processing Different sources contribute to the generation of wastewater in food processing industries, including meat processing, dairy products, seafood and fish processing, fruits and vegetable processing, starch and gluten products, confectionery, sugar processing, alcoholic/nonalcoholic beverages, and bean products. Wastewaters released from these industries are turbid, with high concentrations of bio- chemical oxygen demand (BOD), Fats, oils and grease (FOG), suspended solids (SS), and usually nitrogen and phosphorus. Hazardous chemical content is generally low. Other characteri- stics of food processing wastewater are (a) large seasonal variation, (b) large hourly variation and concentration in daytime, (c) factories are often of small scale, (d) sometimes unbalanced ratio of BOD : N : P that induces the bulking of sludge, and (e) colored effluent. Usually it is desirable to group wastewater as high concentration, medium concentration, and low concentration. High-concentration wastewater may sometimes be concentrated further, treated, and recycled or disposed as solid wastes. Medium-concentration wastewater may be treated on site or discharged into public sewers. Low-concentration wastewater such as indirect cooling water may be discharged without any treatment. Decreasing the pollutant load of wastewater requires the reduction of both water consumption and pollutant, as well as reduction of the opportunity for interaction between the two. This may be accomplished by the following measures [4]: (a) reducing the amount of washing water for raw materials and reusing the water [5]; (b) mechanical separation and obtaining concentrated wastewater by saving processing water; (c) minimization of over spills during bottling processes [6] and; (d) reducing the amount of water used to wash tanks and containers after operations. Typically, the wastewater is subjected to pH adjustment and chemical/physical processes that cause the pollutants to form flocs for subsequent removal. Activated sludge processes are generally employed in food industries. Sometimes advanced treatment systems are used such as coagulation and filtration or other innovated technologies. Recent wastewater treatment Sequencing batch reactors (SBR) are often employed in small food processing factories and have been observed to improve the activated sludge process for the removal efficiency of nitrogen and phosphorus [13]. The conversion of aeration tanks to include anaerobic mixing capabilities increases the removal efficiency of phosphorus and is also effective in preventing bulking. One way to improve the nitrification or the removal efficiency of refractory organics is Food Waste Treatment 293 technologies are listed in Table 9.1 [7–12]. © 2006 by Taylor & Francis Group, LLC to use the membrane separating method of activated sludge, MF/UF bioreactors, moving-bed or fluidized-bed bioreactors, and entrapped media bioreactors. However, this is not frequently used due to its high costs. Accompanying the development of membrane technology, MF/UF bioreactors may become popular. Anaerobic treatment systems have been salvaged by adopting UASB [11] or EGSB [12] processes for saving energy. It should also be noted that the primary processing of agro- industries has shifted back to the site of production of raw materials, often in developing countries. These include sugar cane mills and sugar refineries, cassava starch factories, and alcohol fermentation using molasses. Developed countries then import processed raw materials or crude products for further refining or applications. The wastewater can be recycled after treatment, usually through oxidation ponds or stabilization ponds for irrigation on farms; biomass wastes may also be used as fuel for factory operations. Labor-intensive industries such as sea-food processing also tend to shift to developing countries where cheap labor is available. 9.3.2 Effluent Guidelines and Standards for Food Processing Japan 20 years ago [14]. The flow rate shown represents the values for standard size factories. It should be noted that the oxidation efficiency of COD Mn (JIS K102) may be about one-third. regulation of BOD or COD Mn has already been enacted for a long period, therefore the values for them are converged near the range of standards without large variance. On the other hand, the regulation for TN and TP began only recently, and then only for the specified enclosed water areas such as important lakes, inner sea areas like Seto Inland Sea, Tokyo Bay, and Ise Bay. [17], which were recently revised for the specified sea areas. The Japanese guidelines are set for the specified wastewater as mentioned above. The USEPA values for effluent limits are standards for food processing industries of the Tokyo Metropolitan Government [18]. For a flow Table 9.1 Recent Progress in Biological Treatment Type of reactor Characteristic point Advantage Aerobic treatment Sequencing batch reactor Automatic sequential control Space saving, removal of nutrients Anerobic–aerobic method One sludge method Removal of P, resistant to bulking Membrane separating method 0.04–0.1 mUF hollow fiber membrane Space saving, removal of microorganisims Moving-bed reactor PP, PU, PE, Activated carbon, etc., are used Enhance nitrification Entrapped media method PEG, PEG-PPG, Calcium arginate, etc., are used Enhance nitrification Anaerobic treatment UASB Self-granulation High efficiency EGSB Higher velocity of upflow Higher efficiency for medium concentration Source: Refs. 7–12. 294 Ukita et al. Table 9.2 shows the water quality of untreated wastewater from food processing industries in Table 9.3 shows the present state of effluent quality in food processing in Japan [15]. The Table 9.4 shows the effluent guidelines by USEPA [16] together with Japanese guidelines noticeably larger than the Japanese values. As a further reference, Table 9.5 shows the effluent © 2006 by Taylor & Francis Group, LLC rate of more than 500 m 3 /day, the criteria of BOD, SS, TN, and TP are set to be 20, 40, 20, and 2–3 mg/L, respectively. 9.4 SOLID WASTES FROM FOOD PROCESSING Two groups of solid wastes are generated in food industries. One group is organic residual wastes such as sludge from wastewater treatment and food wastes or garbage accompanied with consumption. Another group is solid wastes such as vessels, containers, and wrappers. Among the wastes of this group, plastic wastes should be noted in particular. 9.4.1 Organic Residual Wastes processing industries amount to only 62,000 tons of N. This is smaller than the value shown in Table 9.2 Characterization of Raw Wastewater from Food Processing in Japan Flow rate (m 3 /day) BOD 5 (mg/L) COD Mn (mg/L) SS (mg/L) TN (mg/L) TP (mg/L) Meat processing 830 600 400 300 50 15 Dairy products 820 250 170 200 35 5 Seafood cans 530 2700 1700 450 210 75 Fish paste products 650 800 600 500 150 50 Vegetable pickles 440 2300 2500 1000 100 30 Animal feeds 1490 600 300 100 50 10 Starch and gluten 2160 2300 1300 800–1300 130 30–40 Bread and cookies 540 1300 800 900 30 15 Frozen cooked products 400 440 170 200 30 5 Beet sugar processing 4600 450 300 100 25 5 Beer 8500 1000 500 300 40 10 Spirit 1170 500 200 300 20 10 Seasoning chemicals 6500 1000 680 300 460 50 Soy source and amino acids 1090 1000 300 200 100 15 Note: After the investigation by Japanese EPA in 1979–1980, before treatment; flowrate: factories of standard scale. BOD 5 , five-day biochemical oxygen demand; COD, chemical oxygen demand; SS, suspended solids; TN, total nitrogen; TP, total phosphorus. Source: Ref. 14. Food Waste Treatment 295 Table 9.6 shows the estimated amount of bio-organic wastes in Japan [19]. Wastes from food Figure 9.1 because the statistics of food wastes are not sufficiently arranged. © 2006 by Taylor & Francis Group, LLC Table 9.3 Present State of Effluent Quality in Food Processing in Japan Categories of specified plants Number of samples Flow rate (m 3 /day) Relative varience BOD 5 (mg/L) Relative varience COD Mn (mg/L) SS (mg/L) n-hex. extract (mg/L) TN (mg/L) TP (mg/L) Meat and dairy products 528 649 1.1 12 0.2 16 13 2.0 10.9 2.77 Fishery products 443 317 2.1 19 0.3 25 28 3.8 21.7 4.01 Vegetables and fruits products 404 451 1.5 29 3.1 27 15 1.3 7.4 1.41 Soy source and amino acids 133 2,144 5.5 10 0.1 23 14 2.0 11.2 2.42 Sugar processing 36 21,850 0.8 28 0.4 19 15 0.0 4.2 0.19 Bread and cookies 53 465 2.5 7 0.1 14 11 0.9 8.3 2.43 Rice cake and kouji 46 312 0.9 17 0.2 21 21 1.8 5.2 5.26 Beverage 399 1,068 1.9 12 0.2 14 11 0.9 5.2 1.45 Animal feeds and organic fertilizer 61 952 1.6 18 0.2 20 17 1.3 36.5 0.91 Animal oil processing 56 3,852 2.3 51 2.2 20 17 7.1 11.4 2.29 Yeast 3 6,762 1.1 16 0.2 3 14 – 1.4 0.01 Starch and gluten 43 4,785 1.4 49 0.4 47 53 0.6 6.4 2.65 Glucose and maltose 12 7,239 1.3 22 0.2 16 16 0.6 3.3 1.21 Noodle products 98 305 0.9 5 0.1 9 8 1.3 4.7 1.31 Bean curd and processing 187 429 1.9 10 0.1 15 12 1.3 12.3 2.24 Instant coffee 4 2,170 0.5 7 0.0 12 3 0.8 5.8 0.64 Frozen cooked products 94 275 0.9 11 0.1 16 12 1.8 8.4 2.00 Note: Number of samples for some items is less than that for flow rate. Source: Ref. 15. 296 Ukita et al. © 2006 by Taylor & Francis Group, LLC For organic food wastes, the options of feedstuff use, composting, biogas then composting, and heat recovery are adopted for treatment and recycling. Feedstuff Use Industrial wastes from food processing are still recycled as feed or organic fertilizer to a fair Table 9.4 Effluent Guidelines for Food Processing in the United States and Japan Category of Japanese guidelines for effluent a USEPA guidelines (BPT) b USEPA guidelines (SPN) c industries COD Mn TN TP BOD 5 TSS BOD 5 TSS Meat processing 30–80 10–60 1–16 370–740 450–900 370–740 450–900 Seafood products Tuna processing 30–120 10–55 3–12 3300–8300 Fish meal processing 3900–7000 1500–3700 3800–6700 1500–3700 Dairy Products Fluid products 20–50 10–30 1–16 1350 –3375 2025 –5506 370 –740 463–925 Dry milk 650–1625 975–2438 18–36 225–450 Canned vegetables and fruits 30–80 10–30 3–12 140–420 80–240 Cereal processing Flour and other grain mill products 30–70 10–30 1.5–7.5 Animal feeds 20–90 10–30 1–3.5 Starch and gluten 40–80 10–30 1.5–10 2000–6000 2000–6000 100–3000 1000–3000 Bread and cookies 40–70 10–30 1.5–7.5 Sugar processing Beet sugar 30–80 10–30 1.5–7.5 2200–3300 Raw cane sugar processing 630–1140 470–1410 Cane sugar refining 30–80 10–30 1.5–7.5 430–1190 90–270 90 –180 35 –110 Oil mill and processing 30–80 10–30 1–7.5 Wines and beverage Beer 30 –70 10 –30 1.5 –4 Spirit 20–50 10–30 1.5–4 Yeast 90–130 10–30 1.5–7.5 Seasoning 20–100 10–145 1.5–9 a Effluent limitations guidelines for specified wastewater from specified plants. Local governments select a value in the range from lower values and higher values. b Effluent limitations guidelines for existing point sources attainable by the application of the best practicable control technology currently available. Lower values: maximum for any 1 day; higher values: average for concecutive 30 days. c Standards of performance for new sources of effluent discharged into navigable waters. Source: Refs. 16 and 17. Food Waste Treatment 297 extent. As shown in Table 9.7, 5.5 million tons of food processing byproducts are used for Table 9.5 Effluent Standards for Food Processing Industries by Tokyo Metropolitan Government Flow rate (m 3 /day) BOD (mg/L) COD Mn (mg/L) SS (mg/L) TN (mg/L) TP (mg/L) Odor intensity Existing 50–500 25 25 50 30 6 4 .500 20 20 40 20 3 4 New sources 50–500 20 20 40 25 3 4 .500 20 20 40 20 2 4 Source: Ref. 18. Table 9.6 Amount of Bio-organic Wastes in Japan Generation Dry matter Contents Generation of N, P (10 4 tons) (parts) (10 4 tons) Nitrogen P 2 O 5 NP Agriculture Rice stems 1094 0.60 0.20 6.6 0.96 Straw 78 0.40 0.20 0.3 0.07 Rice husks 232 0.60 0.20 1.4 0.20 Stockbreeding Manure 9430 0.79 0.13 74.9 11.96 Residues 167 5.01 7.13 8.4 5.20 Forestry Bark 95 0.53 0.08 0.5 0.03 Sawdust 50 0.15 0.03 0.1 0.01 Wood waste 402 0.15 0.03 0.6 0.05 Food processing Animal/plant residues 248 0.28 69 1.41 0.53 1.0 0.16 Sludge 1504 0.05 75 7.01 4.02 5.3 1.32 Construction waste Wood waste 632 0.15 0.03 0.9 0.08 Municipal solid waste Garbage 2028 0.29 588 1.41 0.53 8.3 1.36 Wood and bamboo 247 0.76 0.19 1.9 0.20 Others Sewage sludge 8550 0.02 171 5.18 5.37 8.9 4.01 Nightsoil sludge 1995 0.6 0.10 12.0 0.87 Joukasou septage 1359 0.02 27 5.18 5.37 1.4 0.63 Farm sewage sludge 32 0.02 0.6 5.18 5.37 0.0 0.01 Total 28,143 132.3 27.13 Source: Ref. 19. 298 Ukita et al. © 2006 by Taylor & Francis Group, LLC © 2006 by Taylor & Francis Group, LLC feeding [20]. The rate of use is 77%. Other than that, rice bran, wheat bran, and plant oil residues and BMP, and others are used for general feedstuff products. Feeding use of residual food for pigs has drastically decreased from 206 kg/head/year in 1965 to 6 kg/head/year in 1997 in Japan [2]. Although this system is a good option for recycling, it is a general tendency that pig farms has gradually shifted far from residential areas and have changed to modernized farms. Composting and Biogas Production Composting is a traditional, reliable method of recycling food wastes. This will be discussed later together with biogas production. Incineration with Energy Recovery Utilization of biomass as it relates to CO 2 reduction against global warming has been focused on recently. For this purpose, woody biomass is more suitable, and organic wastes including various minerals may not be appropriate for incineration. 9.4.2 Vessels, Containers, and Wrapping Wastes Another type of waste relating to food industries is the waste originating from containers, vessels, bottles, and wrapping materials. These wastes occupy a large portion of municipal solid waste (MSW). Among these wastes, plastic wastes in particular should be focused on from an environmental standpoint. One company, FP Co. Ltd., has developed a good recycling system for polystylene paper (PSP) trays in Japan. They employ a whole network of transportation systems from factories through markets and back to factories again. The recycling is a tray-to-tray system. However, the rate of recycling is restricted one-third, because the efficiency of transportation for wastes of PSP tray is one-third of that for the products that can be packed compactly. Polyethylene terephtalate (PET) bottles are the most suitable wastes for material recycling. They can be recycled as polyester fiber products through PET flake and to raw chemicals through chemical recycling. However, the amount of incinerated PET bottles has still been increasing because the rate of consumption continues to exceed the recycling effort. Chemical recycling to obtain the monomer of dimethyl terephtalate (DMT) has been conducted successfully using recycled PET bottles collected by municipalities [21]. The company Teijin Co. Ltd. plans to transport PET bottles amounting to 60,000 t/year to its factory in the Yamaguchi Prefecture. Table 9.7 Feedstuff Use of Byproducts from Food Processing Byproducts of: Generation, a (10 3 t/year) Use for feed, b (10 3 t/year) b/a (%) Fruit juice 116 98 84 Vegetable can 80 72 90 Wine 3030 2707 89 Starch processing 1162 80 7 Bean processing 795 411 52 Sugar 1858 1350 73 Fish processing 58 24 41 Bread and malt 29 16 55 Total 7128 5487 77 Source: Ref. 20. Food Waste Treatment 299 © 2006 by Taylor & Francis Group, LLC Recently, other plastic wastes used for wrapping and vessels have been recycled by means of gasification, liquifaction to oil, or heat recovery in the blast furnaces of steel industries (substituting cokes) and cement kilns (substituting coal). However, there are complicated arguments as to whether the direct incineration for heat recovery is more environmentally friendly than options through gas and oil as mentioned above. 9.5 HAZARDOUS WASTES FROM FOOD PROCESSING 9.5.1 Management of Chemicals Based on EPCRA or PRTR Chemicals commonly encountered in food processing are listed in Table 9.8, relating to the Emergency Planning and Community Right-to-Know Act (EPCRA) in the United States [22]. The Pollutant Release and Transfer Register (PRTR) system was also enacted in Japan from the applicable for other materials included in the food itself. Food that has been accidentally contaminated by pesticides, herbicides, or fumigants may also be treated as hazardous waste. Chlorine is frequently used for sanitary cleaning in food processing at the end of daily operations. Therefore chlorinated organic compounds should be noted in the wastewater treatment plants of food industries. It is very possible that wastewater contains certain levels of trihalomethane and related compounds. 9.5.2 Accidentally Contaminated Food Wastes Food products contaminated with pathogenic microbes or food poisoning sometimes result in hazardous wastes. The incident of Kanemi rice oil contaminated by PCB in 1968 is still discussed with regards to dioxins (DXNs) as the possible cause of the Kanemi Yusho disease. Two recent examples discussed below include the treatment of contaminated milk products and the issues relating to the issues of BSE. Table 9.8 Chemicals Commonly Encountered in Food Processing Purposes Chemicals used Water treatment Chlorine, chlorine dioxide Refrigerant uses Ammonia, ethylene glycol, freon gas Food ingredients Phosphoric acid, various food dyes, various metals, peracetic acid Reactants Ammonia, benzoyl peroxide, Cl 2 , ClO 2 , ethylene oxide, propylene oxide, phosphoric acid Catalysts Nickel and nickel compounds Extraction/carrier solvents n-Butyl alcohol, dichloromethane, n-hexane, phosphoric acid, cyclohexane, tert-butyl alcohol Cleaning/disinfectant uses Chlorine, chlorine dioxide, formaldehyde, nitric acid, phosphoric acid, 1,1,1-trichloroethane Wastewater treatment Ammonia, hydrochloric acid, sulfuric acid Fumigants Bromomethane, ethylene oxide, propylene oxide, bromine Pesticides/herbicides Various pesticides and herbicides Byproducts Ammonia, chloroform, methanol, hydrogen fluoride, nitrate compounds Can making/coating Various ink and coating solvents, various listed metals, various metal pigment compounds Source: Ref. 22. 300 Ukita et al. 2001 fiscal year. Figure 9.3 describes the chemicals used in food processing [22]. Similarly, it is [...]... discussed, incineration of food wastes together with other miscellaneous wastes is not a suitable solution because of the generation of hazardous ash containing DXNs and heavy metals; doing so also threatens food recycling efforts A recommended option would be composting followed by the combination of biogas production and composting of the sludge During the past 30 years, wastewater from food processing in. .. Wastes (in Japanese); Research Group for Biological Organic Works, 199 9 Japan Livestock Industry Association Report on Promoting Feed Use of Un-utilized Resources (in Japanese); Japan Livestock Industry Association, 199 6 Teijin Ltd Technical Report on PET recycling; Teijin Ltd., 2000 USEPA EPCRA Section 313 Reporting Guidance for Food Processors; USEPA: Washington, DC, 199 8 The final report of the investigation... consumption and wastewater quantities in the food industry by water recycling using membrane processes Desalination 2000, 131, 75 – 86 Ridgway; Henthorn; Hull Controlling of overfilling in food processing J Mater Process Technol., 199 9, 93 , 360– 367 Norcross, K.L Sequencing batch reactors – An overview Water Sci Technol 199 2, 26 (9 – 11), 2523– 2526 Wentzel, M.C.; Ekama, G.A.; Marais, G.V.R Kinetic of nitrification... alternative for the treatment of high-strength, hot wastewater The thermophilic process, compared to the mesophilic anaerobic process, has the advantages of increased loading rate and the elimination of cooling before treatment Furthermore, the heat content of the wastewater would be available for post -treatment Loading rates up to 80 kgCOD/m3/day and more have been reached in laboratory-scale thermophilic... management change in sludge characteristics in the start-up procedure using mesophilic granular sludge In Proceedings of 7th International Symposium on Anaerobic Digestion, 199 4; 348 Daoming, S.; Forster, C.F An examination of the start-up of a thermophilic upflow sludge blanket reactor treating a synthetic coffee waste Environ Technol., 199 4, 14, 96 5 Lepisto, S.S.; Rintala, J The removal of chlorinated phenolic... becomes higher, then incineration with power generation becomes advantageous [50] 9. 7 CONCLUSION This chapter discussed the structural point of view and the characterization of food processing relating to liquid, solid, and hazardous wastes Focusing on case studies mainly in Japan the details of food waste generation and treatment have been presented, sometimes in comparison with cases in the United States... when wastewater enriched with VSS is treated The combination of membrane with UASB was also studied However, the results are not feasible for practical use [45] 9. 6.4 Zero-Emission in Beer Breweries Waste recycling systems in beer breweries are very complete Kirin Beer Co Ltd has achieved zero-emission for its industrial wastes since 199 8 Table 9. 22 shows the amounts for each of the wastes and their... 199 9 199 9 199 9 240 16 22.3 2000 2000 2001 2002 2002 2002 2002 80 35 90 15 20 105 69 a: power generation with cogeneration; b: heat use only Source: Ref 49 © 2006 by Taylor & Francis Group, LLC Technology 8.0 8.0 3.5 a a b Thermophilic Thermophilic Mesophilic 1.3 0 .9 3.0 16.0 8.0 1.0 3.0 a b b a b b b Thermophilic Mesophilic Mesophilic Thermophilic Thermophilic Thermophilic Thermophilic Food Waste Treatment. .. various minor nutrients like Ca, Mg, Fe, Mn, Cu, Zn, Mo, and B This means mineral resources derived from food are contaminated by heavy metals through incinaration of garbage together with various other wastes Figure 9. 4 Ash recycling for Portland cement feedstock © 2006 by Taylor & Francis Group, LLC Food Waste Treatment 9. 6 9. 6.1 303 RECENT TECHNOLOGIES ON FOOD WASTES TREATMENT Waste Management in Fermentation... used The wastewater comes from (a) the mother liquid after harvesting the products, (b) cleaning water of cells or reactors, (c) condensates from the evaporator, (d) spent eluting solution in purifying processes, and (e) ammonium sulfate, used in salt crystallization of enzymes, and others The following information is cited mainly from a thesis [25] published in 198 3 While details may have changed since . 41% in 197 0, 32% in 199 0, and 29% in 199 8 for N, and 33% ( 197 0), 29% ( 199 0), and 28% ( 199 8) for Phosphorus, excluding grass feed [1]. These facts make the recycling of food wastes difficult in. organic wastes including various minerals may not be appropriate for incineration. 9. 4.2 Vessels, Containers, and Wrapping Wastes Another type of waste relating to food industries is the waste originating. INDUSTRIES 9. 3.1 Wastewater Treatment Systems for Food Processing Different sources contribute to the generation of wastewater in food processing industries, including meat processing, dairy products, seafood