Earticle

실제 사업장에서 배출되는 음폐수와 축산폐수를 대상으로 혼합비율볕 HRT에 따른 산발효 진행 시 VFA 생산, 분포 및 pH 변화 등을 관찰하는 실험을 진행하였다. 음폐수의 산발효 시 AIkalinity의 주입이 요구되는데, 외부 Alkalinity의 주입량을 축산폐수와의 혼합를 통해 대체함으로써 경제성을 높이는 것이 본 연구의 목적 이다. 외부 혼합비율은 음폐수와 축산폐수의 부피기준, 9:1, 8:2, 7:3, 6:4, 5:5로 하였으며, 산발효 실험 시 별도의 약품은 주입되지 않았다. 실험결과, 음폐수의 비율이 높을수록 Lactate의 발생이 많았으며, 축산폐수의 비율이 높을수록 Lactate의 발생은 감소하고 Propionate의 발생이 증가하였다. 또한 혼합비율 5:5, HRT 2일의 조건에서 Lactate는 전혀 검출되지 않았다. VFA 생산량은 HRT 3일 기준, 혼합비율 9:1, 8:2, 7:3, 6:4, 5:5에 대해서 각각 63.3%, 122.5%, 222.7%, 371.5%, 415.0%로 증가하였으며, 생산수율은 각각 0.14, 0.22, 0.36, 0.51, 0.51로 나타났다. 축산폐수의 주입량이 증가함에 따라 pH, Alkalinity 및 Ammonia도 높게 나타났고, 산발효에 의한 pH 저하는 발생되지 않았으며, 유지되거나 약간 상승하는 경향을 보였다.

In this study, in order to increase the economic feasibility of acid production, co-digestion of food waste leachate and livestock waste water was investigated since high alkalinity content of livestock waste water enables to reduce the alkaline agent addition. The effect of mixture ratio between food waste leachate and livestock waste water on the volatile fatty acid (VFA) production and composition was investigated at different hydraulic retention time (HRT). Mixture ratio was adjusted from 9:1 to 5:5, and external alkaline agent was not added during the acid fermentation. As results, lactate production was increased with the increase of mixture ratio, while propionate was the dominant at lower mixture ratio, and lactate production was minimal under 5:5 of mixture ratio at HRT 2 days. At HRT 3 days, VFA production was increased by 63.3%, 122.5%, 222.7%, 371.5% and 415.0% from the mixture ratio of 9:1, 8:2, 7:3, 6:4 and 5:5, respectively. Successful acid fermentation was achieved without alkaline agents addition through the co-digestion with livestock waste water.

음폐수(FWL)는 퇴비화와 사료화와 같은 음식물류 자원화 시설로부터 발생된다. 본 연구의 목 적은 벤치규모의 부상분 리 및 상향류 블랭킷 여상(UBF) 연계공정을 이용한 산발효액 특성에 대해 조사 분석을 하였다 . 부상분리 공정에서 고형 물과 지방성분의 높은 제거효율을 보였다. 이는 UBF 반응조의 상부에 스컴과 머드볼의 생성 을 막을 수 있었다. 산발효 액의 휘발성 유기산(VFA)의 농도는 21,610 mg/L이었고, 조성은 acetic acid, butyric acid, propoinic acid와 같은 short chain 유기산이 약 82%를 차지하였다. 또한 산발효조에 총 미생물 중 부착미생물이 차지하는 비율은 61.2%이었다. 산 발 효한 FWL액의 특성은 N·P함량이 낮고 용존 물질이 높다. 따라서 이액은 생물학적 질소 인 제 거시 외부탄소원으로 사용 될 수 있을 것으로 사료된다.

The food waste leachate (FWL) produces from food waste resource plant as a compost and feed. The objective of this study was to investigate the characteristics of acid fermentation liquid from food waste leachate by combined bench scale floating separation and upflow blanket filter (UBF) process. The constituents of solids and fat showed high removal efficiency in floating separation process. These results could prevent the generation of scum and mud balls at the top of the UBF reactor. The volatile fatty acid (VFA) of acid fermentation liquid was 21,610 mg/L, the major components were the short chain fatty acids such as acetic acid, butyric acid, and propoinic acid. These acids were about 82% in composition of VFA. Also, the ratio of attached biomass to total biomass in acid fermentation reactor was 61.2%. The characteristics of fermented FWL have a low N·P content and a high soluble matter. Therefore, this liquid could be used as an external carbon source for the biological N and P removal.

음폐수는 퇴비화와 사료화와 같은 음식물류 자원화 시설로부터 발생된다. 본연구의 목적은 음폐수의 혐기성 산발효시 VFA생성에 미치는 영향인자에 대해 조사 분석 하는데 있다. 이들 영향인자는 pH(4∼7), 온도(15, 25, 35℃), 체류시간(1∼5일), NaCl농도(0.61∼1.62%)등이다. 온도 35℃에서 VFA생성은 15℃, 25℃에 비해 각각 1.8배, 1.6배 높았다. 음폐수의 가용화 효율(ES)은 온도 35℃, 체류시간 2일에서 47.3%의 최대값을 나타냈다. 또한 이들 조건에서 VFA농도 및 생성율은 각각 25,556 mg/L, 90%로 가장 높았으며 체류시간이 길어질수록 감소하였다. 음폐수의 산발효시 생성된 VFA의 조성은 acetic acid, propoinic acid, butyric acid와 같은 short chain 유기산으로 73∼80%를 차지하였다. 염분농도 3,700 mg Cl-/L(0.61% NaCl)에서 9,800 mg Cl-/L(1.62%NaCl) 범위에서 염분농도가 증가 할수록 VFA 농도는 약 14% 감소하였다.

The food waste leachate(FWL) produces from food waste resource plant as a compost and feed. The objective of this study is to investigate the affecting factors on volatile fatty acid(VFA) production in anaerobic acid fermentation of food waste leachate. These factors were pH(4∼7), temperature(15, 25, 35℃) and HRT(1∼5days), NaCl concentration(0.61∼1.62%). The VFA production at temperature of 35℃ was 1.8, 1.6 times higher than those at temperatures of 15℃, 25℃. The solubilization efficiency(Es) of FWL showed the highest value of 47.3% at HRT of 2days, temperature of 35℃. Also the maximum concentration and production rate of VFA under these conditions were 25,556 mg/L and 90%, respectively. These values were showed to decrease as the HRT increased. The major components of VFA produced from the acidogenesis of FWL were the short chain fatty acids such as acetic acid, propoinic acid, and butyric acid. These acids were 73∼80% in composition of VFA. The VFA concentration was decreased about 14% according to the increase of the Cl-(NaCl) concentration from 3,700 mg/L(0.61% NaCl) to 9,800 mg/L(1.62% NaCl).

본 논문에서 음식물폐수의 혐기성 소화액 처리를 위해 실제 처리장 규모로 KNR 공법을 현장 적용하여 유기물 및 질소제거에 대한 연구를 수행하였다. 처리장 유입수의 평균 수질은 수온 21.7oC, pH 7.6, DO 0.1mg/L, 알 칼리도 4,835mg/L, CODCr 12,491 mg/L, CODMn 3,347mg/L, T-N 603.7mg/L, NH4 +-N 581.2mg/L, T-P 54.7mg/L이었으며, 유출수의 평균 수질은 수온 24.9oC, pH 8.7, DO 5.2 mg/L, 알칼리도 2,587mg/L, CODCr 134.5 mg/L, CODMn 47.1mg/L, T-N 11.8 mg/L, NH4 +-N 1.2 mg/L, T-P 13.5mg/L 이었다. CODCr와 CODMn 평균 제거효율은 각각 98.9%와 98.6%로 안정적으로 뛰어난 처리효 율을 보였으며, T-N 과 NH4 +-N 평균 제거효율은 각각 98.0%와 99.8%로 나타났다. UMBR 반응조에서 유기물 및 질소의 용량부하 는 각각 9.5 kgCODCr/m3·day, 0.44 kgNH4 +-N /m3·day이었고, 미생물부하는 각각 0.68 kgCODCr/kgMLVSS·day, 0.03 kgNH4 +-N/kgMLVSS·day를 유지하였으며, 대부분의 유기물(CODCr의 98%)과 질소(NH4 +-N의 95.7%)가 UMBR 반응조에서 제거되었다. 이는 UMBR 반응조가 높은 슬러지 순환비율에도 잘 견디어 NH4 +-N의 미생물에 대한 독성 및 유입수에 대한 충격부하에 대응력이 뛰어난 것을 시사하였다.

In this study, KNR process of the actual treatment plant scale was conducted on organic matter and nitrogen removal from effluent of anaerobic digester treating food waste leachate. The average influent concentration of treatment plant were temperature 21.7oC, pH 7.6, DO 0.1 mg/L, alkalinity 4,835 mg/L, CODCr 12,491 mg/L, CODMn 3,347 mg/L, T-N 603.7 mg/ L, NH4 +-N 581.2 mg/L, T-P 54.7 mg/L, respectively, and the average effluent concentration were temperature 24.9oC, pH 8.7, DO 5.2 mg/L, alkalinity 2,587 mg/L, CODCr 134.5 mg/L, CODMn 47.1 mg/L, T-N 11.8 mg/L, NH4 +-N 1.2 mg/L, T-P 13.5 mg/ L, respectively. CODCr and CODMn average removal efficiency were 98.9% and 98.6%, respectively, and T-N and NH4 +-N average removal efficiency of 98.0% and 99.8%, respectively. Very stable effluent quality was achieved during the operating period. Volumetric loading rates of organic and ammonia nitrogen in the UMBR were 9.5 kgCODCr/m3·day and 0.44 kgNH4 +- N/ m3·day, respectively, and microbial loading rates were 0.68 kgkgCODCr/kgMLVSS·day and 0.03 kgNH4 +-N/kgMLVSS· day. 98% of CODCr and 95.7% of NH4 +-N were removed from the UMBR. Prevention of shock load caused by influent fluctuation and microorganisms inhibition caused by high NH4 +-N in the UMBR was adjusted by the high recirculation rate.

본 연구에서는 단일 및 이중 다공판이 각각 설치된 중온 혐기성 소화조를 이용해서 음폐수의 바이오가스화를 수행하 였다. 기질(음폐수)의 유입은 stagnation phase 동안 반응조 내부 유체 교반을 최소화하기 위해 30분 동안 천천히 유입시 켰다. 염료 확산 실험을 통해 다공판에 의한 Plug flow를 가지는 순환 유량을 파악하였다. 혐기성 소화조 및 기질은 고온 소화를 시도한 “Trial 2”를 제외하고 39oC를 유지시켰다. 평균 메탄 발생량은 단일 다공판이 설치된 System A가 0.28 Sm3 CH4/kg VS, 이중 다공판이 설치된 System B가 0.31 Sm3 CH4/kg VS로, 이중 다공판이 설치된 반응조에서 높은 메 탄 수율을 보였는데, 이는 이중 다공판에 의한 plug flow 흐름 형성에 의해 반응이 촉진된 것에 의한 것으로 판단된다.

Biogasification of the Food-waste Leachate was carried out through the mesophilic anaerobic digesters with single and double perforated plates. The substrate which was Food-waste Leachate was slowly injected to the bottom of reactor for 30 minutes not to cause turbulence in the reactor during stagnation phase. The recirculation pumping rate to show plug flow within digester was determined by dye diffusion experiments. The anaerobic digesters and input substrate temperature were maintained at 39oC except for “Trial 2” which tried to have thermophilic digestion. The average methane productions were 0.28 Sm3 CH4/kg VS in digester with single perforated baffles (System A) and 0.31 Sm3 CH4/kg VS in digester with double perforated baffles (System B), respectively, which showed that double perforated baffles encouraged larger methane yield due to plug flow reaction by double perforated baffle.

Using aeration reactor of high efficiency pure oxygen to remove the high concentration wastewater generated by the solution separated from food waste, the results got from a pilot test are summarized as follows. 1. The process composition to remove the high concentrated organic matter and the nitrogen of wastewater is the facilities to control the primary high liquid separation and the second biological control process is composed of the anoxic tank and the high pure oxygen aeration reactor and the separation membrane tank, and the advanced control is composed of the ozone and activated carbon treatment facility. 2. As the average concentration of 200,000 mg/L is separated into high liquid to mix with excess sludge, the water separated from high liquid is able to get the average of 32,000 mg/L, and when the load of about 20 kgCODCr/m3·d removes by the reactor of the pure oxygen aeration with high efficiency, it has been removed over the 98.7% to an outflow with average 422 mg/L. 3. As the BOD flows into the raw wastewater with 90,000 mg/L, an average concentration shows 32,000 mg/L after a primary high liquid separation and is able to get the effluent water under below 10 mg/L to remove 99.9% by the aeration reactor of high efficiency pure oxygen. 4. T-N represents average 1,520 mg/L when the raw wastewater with about 3,500 mg/L is separated from high liquid, and it is removed to the efficiency of 94.1% or more when it is controlled to inflow in the aeration reactor of high efficiency pure oxygen. 5. The T-P concentration of the separated liquid is average 723 mg/L and approximately 75% are removed by high liquid separation after a primary dewatering.

본 연구에서는 음식물류 폐기물을 원료로 하여 침출수 재순환이 있는 중온 혐기성 소화 시스템을 통해 바이오 가스를 생산하였다. 실험은 동일한 구성 (생물반응조, 침출수 저장조)으로 이뤄진 System A와 System B를 통해 진행하였으며, 각 System은 투입 음식물류 폐기물의 차이만이 있었다. 생물반응조 하단 상부 30 mm 위치에 스크린을 두어 고액분리가 용이 하도록 하였으며 이를 통해 분리된 액체가 매일 30분씩 각각 침출수 저장조로 이송되고 다시 침출수 저장조 내 액 체가 생물반응조 상부로 30분 동안 유입되도록 하였다. 음식물류 폐기물은 반응조로 투입되기 전에 36oC로 가온하였다. 저해인자에 대한 파악을 하기 위해 암모니아성 질소와 염분에 대해 조사하였다. 평균 메탄발생량은 System A의 경우 0.115 L CH4/g VS로 나타났으며 System B의 경우 0.167 L CH4/g VS로 나타났다. 암모니아성 질소와 염분농도는 서서 히 증가하였는데, 이는 반응조 하단에서 음식물류 폐기물의 압밀로 침출수 재순환이 방해를 받아 미생물 활동이 저해됨 에 의해 발생된 것으로 추정된다.

Mesophilic anaerobic digestion of source-sorted food waste with leachate recirculation system was studied and its efficiency was evaluated by methane gas production comparison. Two identical systems, System A and B were fabricated equally and each system was comprised of an anaerobic bioreactor and a leachate tank. The only difference between two systems is OLR (Organic Loading Rate). Leachate in bioreactor was separated through the screen located at 30 mm above the bottom and a pump was installed to transfer collected leachate to the leachate tank. Once a day, the leachate was pumped from the bioreactor to the leachate tank for 30min and transferred leachate was pumped back to the top of the bioreactor for 30min, sequentially. Source-sorted food waste used for this experiment was water washed by cafeteria staffs before transferring to the laboratory. Transferred food waste was warmed to 36oC before being fed to bioreactors. Ammonia nitrogen and salinity were monitored to see the inhibition toward anaerobic bioreaction. Average methane productions rates were 0.115 L CH4/g VS and 0.167 L CH4/g VS for system A and B, respectively. Ammonia nitrogen and salinity were increased gradually and it is believed that compression at the lower part of bioreactor blocks leachate penetration and retards the microorganism activity within bioreactor.

Anaerobic mono- and co-digestion of sewage sludge and food waste leachate (FWL) were performed by assessing methane production and characterizing microbial communities. Anaerobic digestion (AD) of waste activated sludge (WAS) alone produced the lowest methane ($281ml\;CH_4$), but an approximately 80% increase in methane production was achieved via co-digestion of WAS and FWL ($506ml\;CH_4$). There were less differences in the diversity of bacterial communities in anaerobic digesters, while archaeal (ARC) and bacterial (BAC) amounts reflected AD performance. Compared with the total ARC and BAC amounts in the mono-digestion of WAS, the ARC and BAC amounts increased two and three times, respectively, during co-digestion of FWL and WAS. In characterized archaeal communities, the dominant ratio of hydrogenotrophic methanogens in the mono-digestion of WAS approached nearly a 1:1 ratio of the two acetoclastic and hydrogenotrophic methanogens in the co-digestion of FWL and WAS. The ARC/BAC ratio in the digesters varied in the range of 5.9% to 9.1%, indicating a positive correlation with the methane production of AD.

음식물 폐기물 침출수를 처리하는 분리막 결합 고온 혐기성소화공정(생물학적 반응조) (Anaeorobic Membrane Bioreactor, AnMBR)의 파일럿 운전에서 분리막의 교차여과 속도와 막간압력이 파울링에 미치는 영향을 관찰하였다. 연구 결과 정압여과 하에서 교차여과 속도가 증가할수록 파울링의 속도는 현격히 감소되었다. 그러나 이와 같은 영향은 낮은 막간압력에서 더욱 효과적이었다. 막간압력이 증가할수록 여과대상 물질의 압축성으로 인해 투과성이 상대적으로 낮은 파울링층(혹은 케익층)이 분리막 표면에 형성된 것에 기인된 듯하다. 여과대상 시료의 입도분석을 해 본 결과 입자크기는 약 $10{\sim}100{\mu}m$ 범위에서 분포하였고 이에 따라 브라운확산에 의한 역수송보다 분리막 표면에서 교차여과에 의해 발생하는 전단력이 입자의 역수송에 더욱 기여하고 있음을 예측할 수 있었으며 이는 AnMBR의 연속운전을 통해 재확인할 수 있었다. 운전 후 막 부검을 실시한 결과 유기 및 무기 파울링이 모두 관찰되었으나 어느 것이 지배적인 파울링 기작을 나타내는지는 앞으로 더욱 연구가 필요하다. 무기 파울링의 경우 대부분 분리막 표면에서 스케일링 형성이 지배적이었으며, 따라서 분리막의 공극 막힘에 주로 기여하는 작은 콜로이드성 유기물질의 경우 분리막 표면에서 전단력에 의한 역수송 효과는 그다지 크지 않을 것으로 사료된다.

The effect of cross-flow velocity and transmembrane pressure (TMP) on membrane fouling was observed from pilot-scale operation of thermophilic anaerobic membrane bioreactor (AnMBR) treating food waste leachate. It was found that fouling rate was reduced significantly as cross-flow velocity increased at constant TMP mode of operation while this effectiveness was more pronounced at lower TMP. Higher TMP resulted in less permeable fouling layer possibly due to compressibility of foulant material on membrane surface. Particle sizes of membrane concentrate ranged from 10 to $100{\mu}m$, implying that shear-induced diffusion enhance back transport of these particle sizes away from the membrane effectively. From the continuous operation of AnMBR, it was confirmed that shear rate played an important role in the reduction of membrane fouling. Membrane autopsy works at the end of operation of AnMBR showed clearly that both organic and inorganic fouling were significant on membrane surface. Surface shear by cross-flow velocity was expected to be less effective to remove irreversible fouling which can be mainly caused by the adsorption of organic colloidal materials into membrane pores.

본 연구에서는 실험실 규모 2상 혐기성 소화를 이용하여 음식물 쓰레기 탈리액의 처리성을 평가하였다. 이를 위해 산발효조의 적정 유입 pH 및 HRT를 도출하고, 산발효조로의 메탄조 유출수 반송 효과, 메탄발효조에서 고형물 내부반송 및 온도의 영향을 파악하였다. 산발효조에서는 유입 pH 6.0, HRT 2일인 조건에서 메탄조 유출수 반송 후 산생성 및 VS 제거효율은 30% 및 40%에서 안정적으로 유지되었다. 유기물 부하 7 g COD/L/d 이하의 조건에서 고형물 내부반송에 의해 중온 및 고온메탄발효조의 유출수 SCOD는 반송 이전보다 낮거나 같은 수준으로 유지되었고 유기물 부하 증가에 따른 비메탄생성량(specific methane production, SMP)의 감소폭이 줄어들었다. 고형물 내부반송 이후 동일한 유기물 부하에서 COD 제거효율과 SMP는 중온메탄발효조가 고온보다 우수하였으며 이는 중온메탄발효조의 MLVSS 농도가 고온보다 높기 때문인 것으로 판단되었다. 따라서 고온산발효-중온메탄발효로 구성된 시스템이 고온산발효-고온메탄발효보다 COD 제거와 메탄발생면에서 우수한 것으로 나타났다.

This study was performed to evaluate the treatability of food waste leachate using lab-scale two-phase anaerobic digestion system. Effects of influent pH, hydraulic retention time (HRT), and recycle of methanogenic reactor effluent to the thermophilic acidogenic reactors were investigated. For methanogenic reactors, effects of internal solids recycle and temperature were studied. Performance of the acidogenic reactors was stable under the conditions of influent pH of 6.0 and HRT of 2 d with the recycle of methanogenic reactor effluent, and acidification and VS removal efficiency were about 30% and 40%, respectively. Up to the organic loading rate (OLR) of 7 g COD/L/d, effluent SCOD values of mesophilic and thermophilic methanogenic reactors either lower or kept the same with the internal solids recycle. Also, decreasing tendency in specific methane production (SMP) due to the organic loading increase became diminished with the internal solids recycle. Mesophilic methanogenic reactors showed higher TCOD removal efficiency and SMP than thermophilic condition under the same OLR as VSS was always higher under mesophilic condition. In sum, thermophilic acidogenesis-mesophilic methanogenesis system was found to be better than thermophilic-thermophilic system in terms of both organic removal and methane production.

Herein , the effect of changes in the organic loading rate in anaerobic digestion was evaluated. The experiment was carried out by a laboratory -scale semi-continuous stirred tank reactor, and feedstock was food-waste leached. The organic loading rate was increased by 0.5 kgVS/m3 in each phase from 1.0 kgVS/m3 to 4.0 kgVS/m3. At the end of the operation, to check the failure of the reactor, the organic loading rate was increased by 1.0 kgVS/m3 in each phase and reached 6.0 kgVS/m3. This shows that the biogas yield decreased as organic loading rate increased. Biogas production seemed to be unstable at 3.5-6.0 kgVS/m3. Moreover, biogas production dramatically fell to approximately 0 mL at 6.0 kgVS/m3, which was decided as the operation failure on the 16th day of the las tphase. The result of the reactor analysis shows that the cumulation of volatile fatty acid increased as the organic loading rate increased. This seems to occur due to the decreasein pH in the reactor and led to extinction of anaerobic bacteria, which were the biogas products. Although the buffer compound (alkalinity) could prevent the decline in pH, the concentration of alkalinity was found to be lacking at a high organic loading rate

본 연구에서는 매립가스 증대를 위한 음폐수의 원활한 주입을 위해 혐기성 산발효 전처리를 수행하였으며 이를 통해 점도 감소와 유기산 생산량을 확인하여 매립지 주입을 위한 최적조건을 확인하고자 하였다. 산발효 후 음폐수 가용화율은 약 15% 증가함을 보였고 체류시간의 변화와 반응기형태를 달리 한 결과 큰 차이를 보이지는 않았다. 반응기형태에 따라 점도변화를 확인한 결과 상향류식 반응기에서 $76.95{\pm}3.27%$로 완전혼합반응기에 비해 약 11.38% 높은 점도 저감효율을 보였으며, VFA생산에서는 체류시간을 3일에서 5일로 증가 시 2.01배(상향류식 반응기), 1.76배(완전혼합반응기) 높은 경향을 보였다. 이는 상향류식 반응기의 경우 고정층담체의 스크린 역할로 분자량이 작은 물질에 비해 큰 물질들이 상대적으로 반응기에 체류하는 시간이 길어져 효율이 높은 것으로 사료된다.

In order to increase landfill gas (LFG) production with food waste leachate, this study was confirmed to be acidogenetic conditions for landfill site injection. Thereby, it was conducted for acidogenetic treatments to determine the decrease in viscosity and VFA production. After acidogenesis treatments, solubility of food waste leachate increased approximately 15%, and as a result, UASB and CSTR were similar by reactor type using the change of retention time. Based on the result of the change in viscosity by reactor type, efficiency of UASB showed approximately 11.38% of higher decrease in viscosity as $76.95{\pm}3.27%$ vs. CSTR. Also, VFA production showed the higher increase of 2.01 times (UASB) and 1.76 times (CSTR) respectively at the point of increasing retention time from 3 to 5 days. From the above results, efficiency of UASB in a reactor was relatively higher because large molecular lead to longer retention time than small molecular due to having screen effect in the fixed media.

본 연구에서는 음식물류 폐기물 폐수(이하, 음폐수)를 이용하여 혐기성발효 시 부산물로 생성되는 메탄가스의 생산효율을 높이고자 산발효 전처리를 수행하였으며 전처리된 음폐수를 이용하여 BMP 실험을 통해 메탄생산량 증대를 위한 산발효 최적조건을 확인하고자 하였다. 산발효된 음폐수를 이용하여 BMP 실험을 진행한 결과 HRT 3일 조건에서 0.220 L/g VS의 가장 높은 메탄생산량을 확인하였으며, 초기 pH별 BMP실험에서는 pH 6에서 19,920 mg/L로 가장 높은 VFA와 Acetic acid/TVFA(76.2%)를 보였다. 이때 메탄생산은 약 10일 이내로 대부분 생산되어 일반적인 메탄발효(30일 이내)에 비해 약 1/3수준으로 단축됨을 확인하였다. 메탄생성량은 0.294 L/g VS로 대조군 대비 약 1.3배 높은 효율을 나타내었다.

This study performed acid fermentation pre-treatment to improve production efficiency of methane that is produced as a product in case of anaerobic fermentation by using food waste leachate, and attempted to confirm the acid fermentation optimum through the BMP test by using pre-treated food waste leachate to increase the yield of methane. As a result of the BMP experiment by using acid fermented food waste leachate, the highest yield of methane of 0.220 L/g VS was confirmed in the HRT three-day condition, and in the initial BMP test by pH, pH 6 was 19,920 mg/L that the highest VFA and acetic acid/TVFA(76.2%) were shown. At this time, it was confirmed that the yield of methane was mostly within 10 days that was reduced to around one-third compared to the general methane fermentation (within 30 days). As the yield of methane was 0.294 L/g VS, it showed a high efficiency of around 1.3 times compared to the control group.

본 연구에서는 음폐수를 이용 낮은 유기물 부하율에서 소화조 내부 pH 조절 유무에 따른 소화조 운전의 바이오가스 발생량 및 미생물 군집도 변화에 대한 비교 분석했다. 그 결과, 내부 pH를 조절하지 않은 반응조는 pH, Free ammonia, Volatile fatty acid의 증가에 의한 반응조 안정성이 떨어짐에도 불구하고 내부 pH 조절 반응조와 비슷한 바이오가스 전환율을 보였다. 이는 미생물 군집도 분석 결과에 따르면 외부환경에 대한 내성이 강한 Methanosarcina sp.의 우점에 의해 반응조의 안정성을 유지할 수 있었던 것으로 나타났다.

In this study, the performance and microbial community of anaerobic digestion fed by food waste leachate at low organic loading rate were investigated with and without internal pH control. Experimental results show that similar biogas yield was achieved in both reactors regardless of increase in pH, the concentrations of free ammonia and volatile fatty acids in case of without internal pH controlled one. The results of a methanogenic community analysis by Polymerase Chain Reaction and Denaturing Gradient Gel Electrophoresis revealed that the apparent preponderance of Methanosarcina sp. could be one of reasons for the maintenance of reactor stability.

본 연구는 음식물류폐기물의 직매립 금지가 매립지가스, 악취 및 침출수 발생에 미치는 영향을 평가하고 현행 제도의 타당성을 평가하기 위하여 실시하였다. 음식물류폐기물을 각각 약 45% (Exp.45)와 약 15% (Exp.15)를 충전한 2개의 매립모형조를 비교하였다. 570일 동안 매립지가스 발생량은 Exp.45가 1400 L로 Exp.15의 906 L보다 많았다. 매립가스 조성은 두 반응기 모두 메탄과 이산화탄소가 1 : 1 정도로 발생되어 큰 차이는 없었다. 황화수소는 Exp.15와 Exp.45에서 각각 2~7 ppmv과 2~30 ppmv가 발생하였다. 침출수량에는 큰 차이가 없었으나 $BOD_5$가 Exp.45는 37000 mg/L, Exp.15는 25630 mg/L를 나타내었고 $COD_{Cr}$도 각각 45480 mg/L와 30294 mg/L를 나타내었다. TOC의 농도도 운전기간 동안 Exp.45가 Exp.15보다 2~3배 정도 높았다. 음식물류폐기물 함량이 높은 폐기물 매립은 가스발생량을 증가시켰지만 악취발생 및 침출수 수질 악화 등 환경적 악영향을 더 많이 유발하였기 때문에 현행 음식물류폐기물의 분리배출 및 직매립 금지조치는 적절한 것으로 평가되었다.

This research was performed to evaluate the effect of 'Food Wastes (FW) Direct Landfilling Prohibition' on characteristics of landfill gas (LFG) and leachate and the appropriateness of current legislation. Approximately 45% (Exp.45) and 15% (Exp.15) of FW were filled in two lysimeters. During 570 days, 1400 L of LFG was generated from Exp.45%, which was much more than 906 L of Exp.15. There was no significant difference of LFG composition between Exp.15 and Exp.45. 2~30 ppmv of odorous hydrogen sulfide was detected in Exp.45, while 2~7 ppmv was in Exp.15. There was also no significant difference in the leachate generation between the two. On day 570, $BOD_5$ of Exp.45 and Exp.15 were 37000 mg/Land 25630 mg/L and $COD_{Cr}$ of Exp.45 and Exp.15 were 45480 mg/L, 30294 mg/L. TOC of Exp.45 was 2~3 times higher than Exp.15. Higher portion of FW in landfilling increased LFG generation. However, it generated more odor and made the quality of leachate. Therefore, 'FW direct Landfilling Prohibition' was evaluated as an appropriate legislation.