Relatively low efficiency in anaerobic digestion process is mainly caused by unproper mixing method. In this study, tray motion type agitator was applied in actual anaerobic digestion tank in order to improve the digestion efficiency, equalize the flow velocity distribution and energy saving. The impeller of tray motion type agitator was reciprocated vertically. Gas lift type agitator and tray motion type agitator appears almost same mixing efficiency include digestion rates. However, tray motion type agitator have shown that lower energy consumption compared to the conventional gas lift type agitator. Implementation of tray motion type agitator in the anaerobic digestion tanks contributed to the stabilization of mixing environment, efficiency and energy efficiency of the tank.

본 연구에서는 분리막을 이용하여 안정적인 혐기소화조 전처리 농축공정에 대한 적용성을 평가하는데 목적을 두었다. 실험결과 슬러지 감량율의 경우 혐기조건에서 약 47.16%, 간헐폭기 조건에서 약 41.17%으로 나타났으며, 반류수의 농도의 경우 간헐폭기 조건이 평균적으로 혐기조건보다 낮은 반류수 농도를 나타냈다. Flux 감소에 대한 영향인자로 TTF, MLSS, CODcr, 및 EPS의 상관관계 분석결과 Flux 감소에 TTF가 가장 높은 연관성을 보였으며, 이외에 MLSS, CODcr 및 EPS도 밀접한 관련이 있는 것으로 도출되었다. 이러한 결과 혐기소화조의 전처리 공정으로 관형막을 이용한 경우 막오염 및 반류수 부하를 고려한 농축조 간헐폭기 조건이 안정적 전처리공정으로 적절할 것으로 사료된다.

The purpose of this study is to estimate the applicability of a stable anaerobic digester using a separator membrane to the preprocessing thickening process. The results of the experiments showed about a 47.16% weight loss rate for the sludge under anaerobic condition, and about 41.17% under intermittent aeration condition. The concentrations of rejection water were SCODCr 25 mg/L, T-N 16.6 mg/L, and T-P 1.4 mg/L on the average under the intermittent aeration condition, which were lower than the concentrations of rejection water under an anaerobic condition. As for the factors affecting the reduction of the flux, correlation analyses of TTF, MLSS, SCODCr, and EPSProtein, EPSPolysacchride resulted in -0.97, -0.95, -0.84 and -0.86, -0.95, respectively, which showed that TTF had the highest correlation to the reduction of the flux. In addition, it was concluded that MLSS, SCODCr and EPSProtein, EPSPolysacchride also have close correlations. The results are considered to show that, in the case of the process using a tubular membrane in the preprocessing process of an anaerobic digester, an intermittent aeration condition of the thickener considering the contamination of the membrane and load of rejection water is appropriate for the stable preprocessing process.

This study was performed to measure the concentration of odorous compounds and dilution ratio values at each part of the anaerobic digester process with composting facilities using swine manure and food waste. Complex odors, ammonia, volatile fatty acids and sulfur compounds were measured at each part of the process. Complex odors measured during swine manure storage, food waste storage and in the digested liquid tank, were 35,312 Odor Unit(OU), 39,086 OU and 17,733 OU, respectively. The odor contribution index was calculated by the concentration of odorous compounds during each process divided by the threshold limit. As a result, the major odorous compound that appeared during swine manure storage, food waste storage and in the digested liquid tank was hydrogen sulfide. On the other hand, the major odorous compound in the other processes was ammonia. The overall average concentrations of ammonia were highest in the digested liquid tank(337 ppm) and the separated liquid tank(131 ppm). Wastewater treatment process(10.9 ppm) and deodorization process(11.6 ppm) revealed the lowest concentration of ammonia. The overall average concentration of total volatile fatty acids(TVFAs) was 102.8 ppb during food waste storage and among the TVFAs, the main element was propionic acid(66.1 ppb). Sulfur compounds were only detected during swine manure storage, food waste storage and in the digested liquid tank. The dominant sulfur compound was hydrogen sulfide during swine manure storage(96.3 ppm) and methyl mercaptan during food waste storage(17.7 ppm) and dimethyl sulfide during food waste storage(34.5 ppm).

This study investigated microbial communities and their diversity in a full-scale mesophilic anaerobic digester treating sewage sludge. Influent sewage sludge and anaerobic digester samples collected from a wastewater treatment plant in Busan were analyzed using high-throughput sequencing. It was found that the microbial community structure and diversity in the anaerobic digester could be affected by inoculation effect with influent sewage sludge. Nevertheless, distinct microbial communities were identified as the dominant microbial communities in the anaerobic digester. Twelve genera were identified as abundant bacterial communities, which included several groups of syntrophic bacteria communities, such as Candidatus Cloacimonas, Cloacimonadaceae W5, Smithella, which are (potential) syntrophic-propionate-oxidizing bacteria and Mesotoga and Thermovigra, which are (potential) syntrophic-acetate-oxidizing bacteria. Lentimicrobium, the most abundant genus in the anaerobic digester, may contribute to the decomposition of carbohydrates and the production of volatile fatty acids during the anaerobic digestion of sewage sludge. Of the methanogens identified, Methanollinea, Candidatus Methanofastidiosum, Methanospirillum, and Methanoculleus were the dominant hydrogenotrophic methanogens, and Methanosaeta was the dominant aceticlastic methanogens. The findings may be used as a reference for developing microbial indicators to evaluate the process stability and process efficiency of the anaerobic digestion of sewage sludge.

하수에는 유기물, 질소, 인, 중금속 등 다양한 종류의 오염물질이 함유되어 있으며, 수계로 미처리하여 방류되게 되면 수계 수질을 악화시키게 된다. 그 중 질소(Nitrogen)와 인(Phosphorus)은 영양염류(Nutrient)로 분류되며 수계 부영양화(Eutrophication)의 주요한 원인으로 알려져 있다. 생물학적 영양소 제거 방법은 화학적 처리 방법에 비해 경제적, 환경적 및 운영적 장점을 가지고 있어 대부분의 하수처리에 적용되고 있다. 하지만, 현재 적용되는 기술에서는 암모니아성 질소를 질산성 질소 상태로 산화시킨 후 탈질 반응을 거치는 완전질산화(Nitrification)반응이 적용되고 있다. 만약 아질산성 질소 상태에서 탈질을 유도하는 아질산화 반응(Nitritation)을 적용하게 된다면, 완전질산화에 비해 이론적으로 약 25%의 산소를 절감할 수 있는 효과를 기대할 수 있다. 본 연구에서는 하수처리장에서 슬러지 처리 공정 중 혐기 소화단계에서 발생하는 고농도 질소를 함유한 혐기 소화 상징액을 대상으로 하여, SRT가 암모니아성 질소 제거율(Ammonium nitrogen removal rate)와 아질산화율(NItrite conversion rate)에 미치는 영향에 대한 연구를 수행하였다. 서울 A 하수처리장의 혐기 소화 상징액을 대상으로 한 실험실 규모 아질산화 반응조 운전 결과 안정적인 암모니아성 질소 제거율을 기대하기 위해서는 SRT 0.5d 이상, 고효율의 아질산화율을 기대하기 위해서는 SRT 1d를 유지해야 하는 것으로 나타났다. 이는 암모니아성 질소 제거율의 경우 일정한 SRT 이상 유지시켜 주면, 안정적인 효율을 기대 할 수 있는 반면, 아질산화율의 경우에는 일정한 SRT를 유지시켜 주어야만 안정적인 효율을 얻을 수 있는 것으로 해석 할 수 있다. 따라서 암모니아성 질소 제거 및 아질산화 반응에 서 SRT는 그 효율 및 유도에 있어 매우 중요한 인자로 작용하는 것을 확인 할 수 있다.

The main objective of this experimental investigation was CH4 recovery from biogas generated in municipal and wastewater treatment plant. The polysulfone hollow fiber membrane was prepared in order to investigate the permeation properties of CH4 and CO2. Permeability of CO2 in Polysulfone membrane was 11-fold higher than of CH4 gas. A membrane pilot plant for upgrading biogas was constructed and operated at a municipal wastewater treatment plant. The raw biogas contained 66 ~ 68 Vol % CH4, the balance being mainly CO2. The effect of the operating pressure of feed and permeate side and feed flowrate on CH4 recovery concentration and efficiency were investigated with double stage membrane pilot plant. The CH4 concentration in the retentate stream was raised in these tests to 93 Vol % CH4.

Methane production from grain dust was studied using a 3 L laboratory-scale anaerobic plug flow digester. The digester was operated at; temperature of 35, 45, and 55℃ hydraulic retention time(HRT) of 6 and 12 days; and influent concentration(S_0) of 7.8 and 9.0 % total solids(%TS). With ten different operation conditions, this study showed the significant effects of temperature, hydraulic retention time, and influent concentration on methane production, The highest methane-production rate achieved was 1.903 (L methane) /(L digester)(day) at 55℃, 6 days HRT, and S_0 of 7.8 %TS. A total of 3.767 L of biogas per day with a methane content of 50.57% was obtained from this condition. The ultimate methane yield(B_0 was found to be a function of temperature and influent concentration, and was described as : B_0= 0.02907T-0.1263-0.00297(T-10)(%TS), where TS is the total solids in the liquid effluent, and T is temperature(℃). Our results showed that thermophilic condition is better than mesophilic for grain dust stabilization in an anaerobic plug flow digester.