Mass production of methane from food wastes with concomitant wastewater treatment

• Published in: Applied biochemistry and biotechnology 2002, Vol.98 (1-9), p.753-764
• Main Authors: Kim, J.K, Cho, J.H, Lee, J.S, Hahm, K.S, Park, D.H, Kim, S.W
• Format: Article
• Language: English
• Subjects: acetates; Acetic acid; Algae; Amino acids; Anaerobic processes; Bacteria; Bacteria - growth & development; Bacteria - isolation & purification; Biochemical oxygen demand; Biofiltration; Biofuel production; Biological and medical sciences; Biological treatment of waters; Bioreactors; Biotechnology; butyrates; Carbon dioxide; Carboxylic Acids - isolation & purification; Chemical oxygen demand; Denitrifying bacteria; drainage water; Energy; Environment and pollution; Fatty acids; Fermentation; filters; Fluid filters; Food; Food processing; Food waste; Fundamental and applied biological sciences. Psychology; hexanoic acid; Hydraulic retention time; Hydrolysis; Industrial applications and implications. Economical aspects; Kinetics; Landfills; Mass production; Methane; Methane - isolation & purification; methane production; Nitrogen; nitrogen content; odors; Organic wastes; Oxygen; Oxygen Consumption; Periphyton; pH effects; Propionic acid; Reactors; Retention time; Sewage - chemistry; Sludge; Soil bacteria; soil inoculation; Sugar; sugars; Temperature; Time Factors; upflow anaerobic sludge blanket reactor; Upflow anaerobic sludge blanket reactors; Volatile fatty acids; Waste disposal sites; Waste Disposal, Fluid; wastewater; Wastewater treatment; Water treatment
• ISSN: 0273-2289; 1559-0291; 0273-2289
• DOI: 10.1385/ABAB:98-100:1-9:753

We developed a process for production of methane at a pilot scale. This process consists of three stages. The first stage is a semianaerobic hydrolysis/acidogenic step in which organic wastes are converted to various sugars, amino acids, and volatile fatty acids (VFAs). Operation temperature and pH were 45 degrees C, and 5.0-5.5, respectively. Hydraulic retention time (HRT) was 2 d. To remove the putrid odor and to enhance the hydrolysis of organic wastes, a mixture of bacteria isolated from landfill soil was inoculated into the reactor. Total chemical oxygen demand (tCOD) and biological oxygen demand (BOD) were 36,000 mg/L and 40,000 mg/L, respectively. The second stage was an anaerobic acidogenic process, which can produce large amount of VFAs including acetate, propionate, butyrate, valerate, and caproate. Operation temperature and pH were 35 degrees C, and 5.0-5.5, respectively. HRT was 2 d. The third stage was a strictly anaerobic methane fermentation step producing methane and carbon dioxide from VFAs. The working volume of upflow anaerobic sludge blanket (UASB) type reactor was 1200 L, and operation temperature and pH were 41 degrees C, and 7.7-7.9, respectively. HRT was 12 d. Seventy two percent of methane at maximum was generated and the yield was 0.45-0.50 m3/kgVS of food wastes. Through the process, 88% of tCOD and 95% of BOD were removed. The wastewater was treated with the biological aerobic and anaerobic filters immobilized with heterotrophic and autotrophic nitrifying and denitrifying bacteria. Ninety percent of total nitrogen (T-N) was removed by this treatment. The residual T-N and total phosphorous (T-P) were removed by the algal periphyton treatment system. The final concentrations of nitrogen and phosphorous in the drain water were 53 and 7 mg/L, respectively.