• Journal of Korean Society of Water and Wastewater
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• v.24 no.5
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• pp.561-572
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• 2010

The efficiency of biological hydrolysis at $80^{\circ}C$ on municipal solid waste mixed with anaerobic digestion sludge was investigated in 100L batch reactors. The hydrolysis effect was observed within a day, when the hydrolysis reactor used for a pre-treatment reactor for methanogenesis, and the effect was observed during two days, When the reactor used for post-treatment reactor. For both configurations, methane production rate decreased, when hydrolysis was carried out more than a day. Gaseous ammonia in the hydrolysis reactors was successtully removed by the ammonia stripping system. Microbial diversity analysis on the hydrolysis reactors indicated dependency of microbial diversity on the configuration of the hydrolysis reactors. Carbohydrate and lactate degrading microbes dominated in the hydrolysis reactor, when the hydrolysis reactor used for a pre-treatment reactor for methanogenesis, while protein degrading microbes dominated in the post-treatment reactor.

• Journal of environmental and Sanitary engineering
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• v.23 no.4
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• pp.73-82
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• 2008

In this study, a dry single-phase anaerobic digestion process (Dranco system) was investigated to evaluate the optimum operational conditions. Several factors such as injection rate of organic waste, biogas production, $CH_4$ content in the biogas, pH of the sludge, $NH_3$-N and VFA concentration were investigated based on the operation of the digestion process for 2 months (short term) and 8 months (long-term). The operation results showed that a small quantity of food waste should be injected every week and that a 10% increase of the microorganism injection rate should be needed. However, normal operation was conducted after 11 weeks based on the designed quantity. The $CH_4$ content in the biogas was high at the beginning and the end of the food injection. However, it was low during week days. When the biogas production was high, the $CH_4$ concentration was low. The biogas production increased with an increase of the injection rate. $100m^3$/ton of biogas was produced from normal operation of the digestion process based on the designed quantity. The pH values of the digestion tank based on short-term operation ranged from 8 to 8.5. However, the pH values ranged from 7.45 to 8.15 after 4 weeks of long-term operation. The $NH_3$-N concentration of short-term operation ranged from 4,500 to 5,500 ppm and it gradually decreased to 2,000ppm after normal operation was commenced. For long-term operation, it was 5,000ppm initially and 3,800ppm after normal operation was commenced. The VFA concentration of sludge was less than 900ppm and 2,500ppm for short and long-term operations, respectively, after normal operation. Overall, the differences between sludge pH, $NH_3$-N and VFA concentrations may be due to the different types of microorganisms and the digestion ability of the microorganisms which exist in the accumulation of non digested organics. Moreover, it may be also caused by the type of food waste. Further investigation is needed to confirm these relationships.