국내 폐기물 매립시설은 하수슬러지(2003년) 및 음식물류 폐기물의 직매립금지(2005년)로 인하여 매립 폐기물 특성이 수분이 많은 폐기물 중심에서 소각재, 건설폐기물 등 건조한 폐기물 중심으로 바뀌었고, 또한 매립지의 최종복토층 설치기준 강화로 인해 강우 침투가 제한되어 매립지의 건조화는 급속히 진행되어 미생물 분해 활동에 제한이 생길 정도록 건조화 되고 있다. 이같은 현상이 지속되면 매립가스 발생량이 감소하며, 안정화에 장기간 소요되어 그만큼 매립지 사후관리에 오랜시간이 소요될 것이다. 이에따라 주요 선진국들에서는 일찍이 매립지내에 침출수 등을 재순환하여 매립가스 발생증대 및 안정화를 촉진시키는 제도를 도입하여 바이오리엑터 공법 기술개발에 노력을 기울이고 있으며, 국내에서는 수도권매립지관리공사를 중심으로 활발히 실증연구가 진행중에 있다. 한편, 수도권매립지 제2매립지 7단 2개 블록에 약 9개월간 일평균 408.7m³, 총 7.4만m³ 주입한 결과, 폐기물 층내 함수율 변화는 3m 깊이에서 주입 전 대비 평균 3.25%증가, 8m 깊이에서는 주입전 대비 4.68% 증가하였으며, 같은 기간 매립가스 포집량은 순메탄 기준으로 대조구역 대비 평균 29.3% 증대되었으며, 전년 동월대비 기준으로는 약 10% 증가하는 것으로 나타나 침출수 재순환으로 인한 함수율 증가로 매립지내 생물분해가 촉진되고 있는 것으로 판단된다.

본 연구에서는 교내 기숙사 식당에서 분리 수거된 음식물류 폐기물을 침출수 순환형 혐기성 소화 공정을 이용하여 신재생 에너지인 메탄가스를 최종적으로 얻기 위한 연구를 수행하였다. 침출수 순환형 혐기성 소화 공법은 혐기성 반응조에서 발생하는 침출수를 고액 분리하여 펌프(Cole-parmer Instument Co. Model No.7520-10)를 이용해 1일 1회 10mL/min의 유량으로 침출수 수집조에 수집하였다가 침출수 인발 완료 후 동일한 유량으로 반응조로 재순환 시켜 반응조 내부의 미생물의 활동을 활발하도록 하였다. 그 결과 기존의 혐기성 소화 공법에 비해 높은 메탄가스 수율을 보였다. 음식물류 폐기물을 이용한 침출수 순환형 혐기성 소화 실험은 메탄가스를 효율적으로 생산하기 위해 음식물류 폐기물/식종 혐기성 슬러지 비와 유기물 부하율을 각각 달리하여 실험을 실시하였다. 음식물류 폐기물/식종 혐기성 슬러지 비가 2:8이고 유기물 부하율이 9 gVS/L인 침출수 순환형 음식물류 혐기성 소화 반응조의 메탄가스 발생 수율이 평균 1.395 m³ Biogas/kg VS added로 가장 뛰어났고, 반응종료 시 가스 중 H2S 및 NH3의 농도는 초기값에 비해 각각 98% 및 80%정도 저감되었다. 이에 비해 음식물류 폐기물/식종 혐기성 슬러지 비가 3:7이며 유기물 부하율이 15 gVS/L인 반응조와 음식물류 폐기물/식종 혐기성 슬러지 비 8:2, 유기물 부하율 90 gVS/L인 반응조에서는 메탄가스 발생이 진행되다가 유기물 과부하로 인해 반응이 멈추는 결과를 얻었다.

경도 E129˚ 03' 40", 위도 N36˚ 51' 19"에 위치한 장군광산은 과거에 갱도채굴을 하였으며 현재에는 갱구와 광미로부터 갱내수와 침출수가 유출되고 있다. 갱내수와 침출수의 pH 값의 범위는 6.81-9.59로 중성내지 약염기성을 나타낸다. 주요 양이온과 음이온의 농도 범위는 Mg (6.70-129.80 mg/L), Ca (289.29-661.02 mg/L), Mn (4.74-14.38 mg/L), SO42- (1205.00-2448.69 mg/L) 등이다. 하천바닥에 침전된 황갈색의 침전물은 결정도가 아주 낮은 2-line 페리하이드라이트(Fe2O3˙0.5H2O로 구성되어 있다. 주사전자현미경 관찰결과 0.1μm 정도의 구형의 미세입자로 구성되어 있으며 에너지분산분광분석에 의한 반정량 결과 주 구성원소는 Fe이며 그 외 소량의 Mn, Ca, Si, As 등을 포함하고 있다.

Leachate generation is an inevitable consequence of waste disposal in landfills. Numerous mathematical modelshave been developed to simulate leachate occurrence and behavior. However, these models have been successful toa limited extent because of uncertainties associated with biological, chemical, and physical processes in landfills. Inorder to predict the generation of leachate in closed landfills, correlation analysis was conducted based on precipitationin this paper. Regression analysis for deriving the correlation between precipitation and leachate generation rate wasperformed in a closed landfill. As a result, we found that the amount of leachate which is generated regardless ofprecipitation should be considered as well as the percolation of precipitation. Also, it was possible to make an fairlyaccurate prediction of leachate generation only using precipitation data in this paper. It is suggested that the amountof leachate generation is 4~8% of monthly precipitation and about 25,000m3/month of base generation regardlessof precipitation. However, the predicted values of leachate generation for the high precipitation seasons were not closeto those observed.

Six lab scale reactors were designed having the height of 1/20 scale of real burial site and each reactors contained aleachate collecting system. Cattle and pigs were buried in these reactors, and leachate was collected to determine theconcentration of antibiotics. Leachate samples were collected periodically over a period of 24 weeks along with the trendof temperature and decomposition degree. Sulfachloropyridazine was detected in the initial leachate (4 and 8 weekssamples) from the cattle 1 and cattle 2 reactors, as 56µg/L and 312µg/L respectively and thereafter it was not detectedin leachate (16~24 weeks samples). Most of the antibiotics concentration were detected higher in leachate released inbetween 4~8 weeks. However, sulfadimidine was detected throughout 24 weeks in cattle 1 reactor, with the range of2.2~17.5µg/L. As a result of comparison with different aqueous environment, improper management of carcass burialsites may result in both surface water and groundwater contamination. To protect public health and to prevent/minimizethe negative impacts of contamination by antibiotics, proper environmental monitoring of leachate before and after carcassdisposal is necessary.

This paper examined reasonable operating factor for treatment of carcass burial leachate in High Temperature Thermal Desorption (HTTD) and calculated the amount of fuel used in each device using heat and mass balance under condition of 4 scenarios. As a result, we concluded that rotary kiln for dryness and thermal desorption shoud be separated dual type and mixing ratio of sawdust and soil should be restricted no more than 1 : 14. Also, operating temperature should be kept 260, 550, 850 or higher in dryer kiln, thermal desorption kiln and secondary chamber respectively and residence time should be kept 30min in each kiln. The total amount of fuel used in each device was compared under 4 scenarios on the mixing ratio. According to a study, it showed the highest value under the scenario of 1 : 1, which showed 2.5 times higher than the scenario of 1 : 14 in terms of treatment of leachate per unit of LNG.

This study analyzed concentration and characteristics of hazardous substances in treatment of leachate from carcass burial areas by using high temperature thermal desorption (HTTD). Concentrations of pollutants emitted from HTTD treatment of leachate contaminated soil of carcass burial sites satisfied the emission standards for 11 pollutants from domestic waste incineration facilities. Dioxin concentration was 0.0060 ng I-TEQ/Sm3 and 0.0061 (0.0055-0.0070) ng ITEQ/ Sm3 in the normal operation condition and the experimental condition, respectively, which are much lower than the MSWI Standard of 0.1ng I-TEQ/Sm3. As a result, it was considered that leachate from carcass burial areas could be treated by high temperature thermal desorption (HTTD).

A field research at Sudokwon landfill was carried to analyse the effect of leachate and organic waste water injection on decomposition characteristics of landfill waste. The moisture content after leachate (79,783 m3) addition into block 3A for 1 year increased from 27.4% to 34.1%. As a result of moisture increasement, Cellulose and Lignin proportions as indicators of waste degradability changed from 1.45 to 1.18. It is also illustrated that TOC as an indicator of CH4 production potential reduced from 22.0% to 19.5%. Comparison results of TOC after 4 months of each leachate, digested waste water, food waste water injection into block 4A shows reduction of 3.5%, 4.7% and 3.7%, respectively. Hence, it is indicated that injection of leachate and organic waste water into landfill enhances the rate of CH4 production as well as the speed of landfill stabilization.

Landfill gas (LFG) has received considerable attention to produce a renewable energy source from waste because LFG contains about 45 ~ 55% methane. In order to improve LFG, the concept of bioreactor landfill is applied to Sudokown Landfill site. In landfill field test, the research area 3A (300 m × 300 m) and reference area 2A (300 m × 300) are prepared to compare the effect of leachate recirculation. Using injection wells, leachate is injected into the research area in the 2nd Landfill site and the distribution of moisture content in the research area is homogeneously saturated by the injected leachate. Leachate characteristics such as Alkalinity, BOD, COD, TKN, and TOC are increased with the input of the injected leachate because wastes are decomposed by the injected leachate but pH of leachate is almost not affected by the injected leachate. The production of LFG in the reseach area is improved by about 40% comparing with that in the reference area and the content of CH4 in LFG is consistently higher than 50%. Hence, it can be summarized that the production and the quality of LFG can be improved by the injection of leachate into landfill site.