A STUDY OF CONSTRUCTION AND DEMOLITION WASTE LEACHATE FROM LABORATORY LANDFILL SIMULATORS

장용철 University of Florida 2000 해외박사

Construction and demolition (C&D) waste represents one of the larger components of solid waste from municipal activities in the United States. The waste is often disposed of in unlined C&D waste landfills. It has historically been asstuned that Ieachate produced from C&D waste landfills is innocuous relative to that of municipal solid waste landfills and hazardous waste landfills. Consequently, very little attention has been focused on leachate produced from C&D waste landfills and its characteristics. In recent years, ttte potential for adverse environmental impacts posed from C&D waste disposal has been acknowledged, and some impacts have been documented. Consequently, recent federal regulations have increased operating and monitoring for requirements at C&D waste IandFlls. However, the degree of control needed and the environmental impacts posed still remain a subject of debate. More information is needed to determine the true nature of C&D waste leachate and its potential impacts on the environment. Research was perfontted to simulate and characterize C&D waste leachate in the laboratory. Leachate samples were collected and analy2ed for a number of chemical parameters including conventional water quality parameters and heavy metals. Experiments were conducted to examine the impact of different components in the C&D waste stream, the depth of landfilled waste, changes in leachate constituents over time, and to identify problematic leachate constituents. Leachate resulting from laboratory lysimeters (landfill-simulators) containing mixed C&D waste generated a strong hydrogen sulfide odor. Sulfate reducing bacteria under anaerobic conditions utilized dissolved sulfate from gypsum drywall to produce hydrogen sulfide. A few potentially problematic contaminants in C&D waste leachate, which exceeded the drinking water standards, were identified: sulfate, total dissolved solids, arsenic, chromium, iron, and manganese. Sulfate resulting from dissolution of gypsum drywall was one of the predominant ions observed in the leachate during solids and ion balance analyses. High concentrations of sulfate, calcium and alkalinity were responsible for most of total dissolved solids concentrations in the leachate (> 90%). The most likely source of arsenic and chromium was chromated copper arsenate (CCA~treated wood. Arsenic is of particular concern due to the anticipated lowering of the drinking water limit as well as a growing prevalence of CCA-treated wood waste in the C&D waste stream. The contaminant in the leachate that exceeded the drinking water standard by the greatest magnitude was manganese, a result of wood. Copper, iron, and zinc were apparently reduced in concentration in the leachate via precipitation as insoluble metal sulfides. The concentration ranges of pollutants in leachate from the laboratory investigations were within the range of data reported in the literature for actual C&D waste landfills, suggesting that controlled laboratory scale experiments can provide valuable information regarding leachate quality and formation processes within C&D waste landfills. The information gathered suggests that while leachate form C&D waste landfills should be less harmful to the environment than other types of landfills, unlined C&D waste landfills may impart deleterious characteristics to groundwater in some hydrogeologic settings.

매립지 침출수를 이용한 미세조류 배양과 레이저 조사를 통한 지질 추출

김명균 경북대학교 대학원 2014 국내박사

In this study, the possibility of culturing microalgae in landfill leachate and elimination capacities of nutrients such as total phosphorus and total nitrogen in leachate according to growth of microalgae was identified. Because Scenedesmus sp. has several advantages such as being less contaminated by other microorganisms and having a potential of propagation in the water containing high concentration of organic materials and heavy metals, it was selected as target microalgae. For identifying the production possibility of biodiesel using biomass obtained from Scenedesmus sp. cultured in landfill leachate, lipid extraction method with laser and absorbent was developed and its optimum operation control was also sought. In addition, this study compared lipid extraction efficiency between laser extraction method under the optimum condition as derived from the experiment and existing extraction method, and also analyzed FAME content according to reaction temperature and input of catalyst for optimizing trans-esterification reaction of extracted lipid. The following results were obtained. 1. In order to test Scenedesmus sp. cultivation ability in various concentrations of landfill leachate, the microalgae's growth rate was observed. Without any alteration to the pH, the microalgae required a lag phase of about four days, and after 8∼10 days, the growth rate began to decline. When the pH was maintained at 7, the microalgae were able to grow for more than 8 days. The reason for this being, when the pH exceeded 9.3, ionized ammonia was converted into NH3, and the ammonia acts as toxic material. This showed that Scenedesmus sp. does have the potential to grow in landfill leachate, as long as the pH is maintained under 9.3. When analyzing the removal rate of TP in concentrations of landfill leachate of 10%, 30%, 50% and 100%, the results were 69.2%, 63.3%, 58.1% and 24.1% respectively. The removal rates for T-N for the same concentrations of landfill leachate were 81.7%, 71.5%, 67.3% and 26.7% respectively. 2. Scenedesmus sp. used as a target microalgae in this study showed lower total lipid content(13.2±0.73%(w/w, d.b.)) than the result(23% average lipid content of green algae) reported by literatures on the lipid content of microalgae. Research proves that lipid content in microalgae tends to increase when microalgae is faced with high stress environments such as the lack of nutrients in culture medium. Thus, it is considered that low lipid content of Scenedesmus sp. in this study is because microalgae store less fat due to an abundance of nutrient in landfill leachate. As a result of GC analysis for fatty acid composition, it showed that Scenedesmus sp. in this study has suitable composition of fatty acid(C14∼C20) which is necessary for the biodiesel production, and the order of main fatty acids was C 18:2 > C16:2 > C16:0. As unsaturated fatty acid content(68%) was higher than that of saturated fatty acid(23%), it seems that biodiesel made of lipid extracted from Scenedesmus sp. in this study has the characteristics of a good flow property at low temperature and a poor oxidation stability. 3. As a result of experiments for optimizing lipid extraction method using laser and label, 75 Wh/ℓ of consumption energy showed maximum extraction efficiency(81.8%) in the case of laser extraction method. When conducting microwave treatment for ten minutes as pre-treatment, extraction efficiency was improved up to 90.8%. In the case of laser and label extraction method, 50 Wh/ℓ of consumption energy with activated carbon showed maximum extraction efficiency (93.8%) which is higher than that of the soxhlet method (79.6%). 4. When compared to fatty acid content of extracted lipid and fatty acid extraction efficiency by each lipid extraction method to identify the possibility of transforming extracted lipid into FAME, total fatty acid contents of extracted lipid by each extraction method were respectively laser and label extraction method 853.7 mg/g oil, soxhlet extraction method 825.4 mg/g oil and laser extraction method 811.4 mg/g oil. Laser and label extraction method had also the highest value (80.1%) in extraction efficiency of fatty acid, and laser extraction method(73.7%) was more efficient than soxhlet extraction method (65.7%). It means that laser and label extraction method might have a higher production rate of biodiesel than soxhlet method as there are more unnecessary fatty acids contents(34.3%) which is not able to transform into biodiesel in lipid extracted by soxhlet extraction method. 5. In esterification reaction to reduce high acid value of lipid extracted from microalgae, optimum input of catalyst was 1.0%(w/w) which showed the highest removal rate of free fatty acid. Removal rate was lower, as input of catalyst was increased. It is likely that oil and fat content was burned because of excessive catalyst input. 6. In order to optimize trans-esterification reaction, FAME content by reaction temperature and catalytic amount was analyzed. It was identified that FAME content generally increased by increase of reaction temperature and catalytic amount. However, FAME content decreased with reaction temperature of 75℃. It indicates that transformation rate of FAME is decreased because methanol is vaporized if heating temperature is more than 65℃ in transesterification reaction when methanol reacts to extracted lipid with fixed ratio under base catalyst(KOH). In input amount of catalyst, it was identified that FAME content increases as input amount increases. Although FAME content was the highest (94.2%) at 1.5(%, w/w) of input amount, the difference when compared with 1(%, w/w) of input amount, was imperceptible.

Fate of antibiotic resistance in carcass landfill leachate : biological and physicochemical treatment

Salcedo, Dennis Espineli Korea University 2017 국내박사

This study aimed to investigate and understand the behavior of leachate and the fate of its antibiotic resistance. A synthetic leachate was formulated and monitored for more than 2 years. This is done to simulate the fate of antibiotic resistance in leachate from anaerobic carcass landfill site. Three anaerobic reactors were set-up. Initially, Escherichia coli DH5α with tetracycline resistance pB10 plasmid was inoculated in nutrient rich anaerobic reactors. The fate of tetracycline-resistant bacteria (TRB) was tracked by analysis using culture-based method, EC50 (half maximal effective concentration), and quantitative polymerase chain reaction (qPCR). Though the EC50 profile looks maintained, values during the second year shows lower standard deviation. Interestingly, pB10 plasmid has the same pattern. While the two parameters agreed with each other, the TRB time profile decreased after 300 days or almost one year. At the end of experiment, the tetracycline resistance microbial communities were investigated by 16s RNA gene-based pyro sequencing. The results of this study indicated that leachate with high organic strength in anaerobic conditions could be an antibiotic resistant point source in several year periods. To simulate the treatment of leachate, the effects of the solids retention time (SRT), using sequencing batch reactors (SBRs), was investigated. This is done to see the fate of antibiotic resistance in the leachate sample. SRTs were varied to see its influence on antibiotic resistance. Escherichia coli DH5a was used as the representative tetracycline-resistant bacteria with multiple antibiotic-resistant genes encoded in plasmid pB10. SRT contributed to an increase in antibiotic resistance in SBR C (SRT 25 days) with TRB values up to 1.25 x 107 CFU mL-1 which is one log higher than the influent. Microbial community analysis of the DNA samples from effluent of SBR C showed four major phyla: Proteobacteria, Bacteroidetes, Firmicutes, and Actinobacteria under which are ecologically-important microbial species. It was shown that antibiotic resistance genes cannot be eliminated during treatment of synthetic carcass leachate in a lab-scale sequencing batch reactor. Lastly, the fate of antibiotic resistance in an effluent after ozone disinfection was investigated by comparing the ARB and ARG removal efficiencies of ozonation using pure culture in buffer and using E. coli pB10 in wastewater samples. Based on the results, ozonation on E. coli K-12, as a representative of non-ARB, showed higher removal efficiencies than the samples inoculated with antibiotic-resistant E. coli. Another aspect of this study is monitoring the fate of antibiotic resistance in the wastewater effluent. It was found out that ARB and ARGs still perpetuated in the last stage of effluent disinfection showing that treatment in WWTPs is not effective in eliminating the antibiotic resistance.

국내 폐기물매립지 침출수의 질소제거 및 유기성폐액과의 병합처리 평가

배영신 건국대학교 대학원 2009 국내박사

Composition of wastes sent to landfill is rapidly changing due to changes in waste policies and life environment. thus it is expected that concentration ranges and fluctuations on the characteristics of leachate as a by-product of waste decomposition. This study focuses on effective methods of leachate treatment as well as on characteristic changes of leachate caused by sources of wastes. Generation and concentration range for both leachate and landfill gas composition were examined over 1,100 days using operation of a column reactor(30x120cm) filled with different types of wastes. Through this experiment, it is addressed that by-products of organic carbon decomposition can be converted into landfill gas, over 97%. This study also showed correlation of time function that enables mid-long term estimation of changes in organic pollutants in leachate. Two plans for effective leachate treatment were conducted. First, organic by-products from industrial processes were substituted for methanol as a carbon source and its feasibility was assessed. Second, co-treatment of leachate with dehydrated water of food waste(DWF) was successfully carried out. Processes which are currently used in Sudockwon-Landfill were applied to evaluate the performance of two plans. When carbon source was industrial by-products as a substitute for methanol under the load range of 0.13~0.39 ㎏COD/㎏VSS/day, 0.67~1.12 ㎏COD/㎥/day in denitrification process, there is a linear relationship between loading and removal of COD. It was shown that there is no inhibition on nitrification and removal. Organic compounds remained in the effluent of MLE, denitrification process, when the substitute replaced methanol by more than 50%. Coagulation process, however, was introduced to show better performance than the conventional process without methanol substitute. This is because a high molecular substance above a 30kD mass contained in by-products from a industrial process is not easily uptaken by microorganism. But, behaviour analysis of humic substance distribution has proven that the high molecular substance played an important role to improve the coagulation efficiency. It is extremely difficult to purify DWF, an average of its COD concentration is approximately 100 times higher than those of leachate generated from landfill, it is now subject to be treated in a facility due to execution of international agreement related to ocean dumping. In this study, merged treatment of the DWF with leachate took place in an additional anaerobic digestion tank at first, and then biological MLE followed by coagulation process in order to evaluate treatment efficiency. The anaerobic digestion tank was operated, using in the mixture ratio between the DWF & leachate, and HRT as control factor for raised inflow load of organic matters in phase. Under the circumstances, an average of over 92% removal efficiency for organic matters was sustained under 8.5 kg-SCOD/㎥/day and under 0.7 kg-SCOD/kg-VSS/day. 75% organic nitrogen in the DWF was converted into over 90% ammonium-nitrogen, thus water treatment condition for application of nitrogen removal process was created. Furthermore, coagulation, the final treatment process, was evaluated to play a significant role to effectively remove phosphorus, normal hexane, etc. as well as remove organics and color as it's primarily activity in merging application condition for the DWF. A dominant organism adopted and adjusted in each process was analyzed. Lactobacillus was dominant microorganism in the anaerobic digestion process where mixture of leachate and DWF were introduced and nitrifiers were dominant microorganism in MLE process: Paracoccus and Mesorhizobium sp. in processes with methanol and by-products, respectively. 국가폐기물관리정책과 생활환경 변화 등의 원인으로 국내 생활폐기물매립지의 매립대상 폐기물조성이 크게 달라지고 있다. 이러한 매립폐기물 조성변화는 폐기물 분해산물로 발생되는 침출수 수질특성의 변화를 예상케 하므로, 본 연구에서는 매립지침출수 원물질인 폐기물에서 기인되는 수질변화 영향을 조사하였다. 이러한 침출수 수질변화조사의 궁극적인 목적은 안전한 수준으로의 처리에 있으므로, 안전한 수준의 처리수질 확보를 기본으로 하는 효율적 처리방법을 위해 본 연구범위 내에서 두 가지 방법을 시도하였다. 질소제거공정에서 유기성폐액을 활용하여 경제성을 확보할 수 있는 방법과, 해양배출에 의존도가 높아 사회적 문제가 되고 있는 유기성폐액을 침출수와의 병합처리 시도가 그것이다. 폐기물종류에 의한 매립지침출수 수질영향 검토를 위해 ￠30㎝×H120㎝규모의 모형매립반응조에 폐기물종류별로 충전하여 1,100일 경과시간동안 침출수 및 매립가스 발생량과 조성성분 농도범위를 모니터링 하였다. 모형매립반응조에서 방출되는 탄소성분은 분해초기에는 침출수에 용해되어 높은 농도로 나타나다가 점차 메탄생성 조건이 정립되면서 매립가스형태로의 방출량이 대부분을 차지하는 것을 관찰할 수 있었다. 침출수의 유기물농도는 폐기물종류와 무관하게 분해초기 고농도를 나타내다가 급격한 농도저하현상에 이어 저농도 수준을 유지하는 비교적 단순한 변화패턴 특성을 확인하였다. 이러한 특성을 감안하여 매립경과시간과 폐기물종류별 함유도에 따른 침출수 유기오염도에 관한 상관관계식을 도출한 결과, 아래와 같은 기초모델식을 수립할 수 있었다. 매립지침출수의 효율적 처리방안 시도의 첫째는 매립지침출수에 고농도로 함유되어 있는 질소성분제거를 위해 종속영양탈질공정에 외부탄소원으로 메탄올을 대신하여 설탕제조공정에서의 유기성 제당폐액을 활용한 경제성 확보가능성을 평가하였다. 제당폐액을 탄소원으로 투입하는 0.13~0.39 kgCOD/kgVSS/d, 0.67~1.12 kg-COD/㎥/d 부하범위 조건에서 유입부하와 제거량은 선형적 비례관계를 나타내었고, 질소산화 및 제거반응에 저해영향은 없는 것으로 분석되었다. 대체비율 50%이상 투입조건에서는 질소제거공정 처리수에 탄소원투입량 증가로 인한 유기물농도의 잔류현상이 나타났다. 그러나, 후단의 응집공정을 통해 탄소원으로 메탄올을 사용한 동일경우와 비교하여 유사한 수준이거나 좀 더 개선된 수질을 나타내는 것으로 평가되었다. 이는 처리공정흐름에 따라 용존 유기물질, 휴믹물질의 분자량분포 거동분석을 통해 고분자량영역의 성분이 응집효율을 탁월하게 상승시켜 최종처리수질의 개선효과를 주는 것으로 확인하였다. 침출수의 효율적 처리방안 일환으로 진행된 두 번째 시도는 음식폐기물자원화 과정에서 발생되는 유기성폐액인 음식탈리액(음식폐기물 폐수, 일명 음폐수)을 침출수처리과정을 이용하여 침출수와의 병합처리를 유도하였다. 음식탈리액은 매립지침출수와 비교하여 COD 평균농도가 약 100배 이상 고도의 유기오염도를 함유하고 복합기질을 포함하는 특성이 있어 육상처리가 곤란하여 해양배출의존도가 높은 것으로 알려져 있으나, 점차 육상처리를 의무화 하는 방향으로 정책적 의지가 발표되고 있다. 이러한 유기성폐수의 육상처리 필요성이 강하게 요구되는 분위기에서 침출수와의 병합처리 가능성을 평가하기 위하여 질소제거공정의 대체탄소원 활용실험과 마찬가지 처리공정을 기본 모델로 하되, 선단에 혐기소화조공정을 추가 적용하여 처리성 평가를 수행하였다. 침출수와 음식탈리액의 혼합비율과 HRT를 조절인자로 유입부하를 단계적으로 상승시켜 혐기소화를 운영하였다. 그 결과 8.5 kgSCOD/㎥/d이하 및 0.7 kgSCOD/kgVSS/d이하 조건에서 유기물 제거효율이 평균 92%이상 지속 유지되었고, 음식탈리액에 포함된 75% 유기질소가 90%이상 암모니아성질소형태로 전환됨으로써 후단 질소제거공정에서 질소산화가 용이한 수질조건이 갖추어졌다. 특히, 음식탈리액 병합처리과정의 공정흐름에서 최종 응집공정은 잔류유기물질과 색도제거 외, 인(P)과 노르말헥산 성분의 완벽한 제거를 위해 중요한 의미를 갖는 것으로 평가되었다. 매립지침출수 처리효율화를 위한 상기 두 가지 내용의 검토과정에서 생물공정에 우점하고 있는 균주분석결과 침출수와 음식탈리액이 혼합·유입되는 혐기소화공정에서는 lactobacillus가 대부분을 차지하였다. 그리고, 정상적인 MLE공정이 유지되는 조건에서 탄소원으로 메탄올을 사용하였을 때 Paracoccus가, 제당폐액과 같은 복합조성의 탄소원을 투입한 경우에는 Mesorhizobium sp.과 같은 탈질세균이 우점종을 이루는 것으로 분석되었다. 이상의 실험결과를 통하여 매립대상폐기물의 종류별매립량 비율과 시간경과에 따른 침출수 유기오염도와의 상관성을 도출함으로써, 매립지침출수의 폐기물 원물질에 의한 수질영향과 중장기적 수질예측이 가능한 기틀이 마련된 데에 의미가 크다고 할 수 있다. 또한, “매립지침출수의 처리 효율화”를 위해 본 연구에서는 유기성폐액을 활용하였다. 고농도 질소성분 제거공정에 유기성폐수인 제당폐액을 외부탄소원으로 사용하였을 때 경제성 및 처리성 측면에서 효과적이었고, 고유기성폐액인 음식탈리액은 매립지침출수와의 병합처리 방법으로 많은 량을 육상처리 가능하다는 확인은 물론 ‘처리’라는 개념 그 이상의 의미를 갖는 성과를 거둘 수 있었다.

폐기물 매립지의 장기침하거동에 관한 연구

조영석 동국대학교 2020 국내박사

본 연구에서는 1990년대 이후 국내 폐기물 관련 정책변화에 따른 매립지 폐기물의 조성변화를 분석하고 이를 반영하여 다단계 매립지인 수도권 제1, 2매립지 폐기물의 침하거동 및 특성을 파악하였다. 이를 위하여 제1, 2매립지에 매립된 폐기물의 수분, 매립량 및 반입비율, 물리적 조성의 변화를 분석하고, 매립지에 설치된 토압계 자료를 통하여 폐기물 단위중량을 산정하였다. 제1매립지 사면부 13개 블록, 제 2매립지 총 14개 블록에서의 폐기물 단별 침하량 자료들을 이용하여 폐기물 침하특성이 반영된 압축지수를 산정하고, 폐기물 정책변화와의 연관성을 분석한 결과 제 1매립지 생활폐기물의 1차 압축지수(Cc)는 생활폐기물 내 연탄재 함량이 감소한 반면 압축성이 큰 음식물, 종이, 플라스틱 비율이 소폭 증가함에 따라 증가하였다. 제2매립지의 1차 압축지수(Cc)는 생활폐기물을 감소시키는 정책들이 꾸준히 제정 및 시행됨에 따라 생활폐기물의 양이 꾸준히 줄어들며 감소하였다. 제1, 2매립지에 매립된 폐기물의 2차 압축지수(Cα)는 폐기물 감소정책들의 영향에 따라 감소하였다. 제1매립지 중앙부 E, H, K블록에서 약 27년간 계측된 장기침하데이터와 기존에 제안된 5가지 침하모델들을 이용하여 폐기물의 장기침하거동을 분석한 결과 Sowers 모델로 예측된 침하량은 실측침하량보다 과소평가되었고, Logarithmic function 모델과 Power creep law 모델을 이용하여 산정한 예측침하량은 실제 침하량보다 과대평가되는 것으로 나타났다. 또한, 매립완료이후에 생물학적 분해와 잔류침하를 함께 모사하는 침하모델을 포함한 복합압축모델을 제안하였다. 제안한 모델은 현장실측데이터를 이용하여 검증한 결과 실측침하량을 잘 모사하는 것으로 나타났다. 마지막으로 바이오리액터 공법연구의 일환으로 모형매립조를 이용한 실내침하실험을 수행하여 음폐수가 폐기물의 생물학적 분해촉진에 미치는 영향을 검토하였다. 그 결과 음폐수를 침출수와 함께 폐기물에 재순환하는 경우 강우조건만을 재현한 경우와 침출수만 재순환한 경우보다 폐기물 침하를 각각 약 2.9배, 약 2배 가속화할 수 있음을 확인하였다. 실험결과를 통하여 음폐수를 침출수와 함께 폐기물 매립지에 재순환하는 경우 폐기물 침하를 가속화시켜 추가 매립공간을 확보할 수 있고 매립지 조기안정화에 도움이 될 것으로 사료된다. In this study, the composition of wastes was investigated based on the changes in domestic waste-policies after the 1990s, and the settlement behavior and characteristics of wastes in Sudokwon landfills #1 were analyzed. Moisture content, amounts& content of disposal, and the change in the physical composition of wastes was collected and examined to reach the research goal. The unit weight of wastes was determined through data analysis of earth-pressure cells which are placed in landfills #1 & #2. The compression indices, which characterize the waste settlement, were determined using settlement data. They were measured at each lifts from 13 blocks of landfill #1’s slope and 14 blocks of landfill #2. The compression indices were then compared with the changes of waste policy. According to the results the primary compression indices(Cc) on MSW of landfill #1 showed a downward trend due to a reduction in reclaimed coal briquette ashes and a slight increase in the proportion of foods, papers, and plastics, which have large compressibility, in the landfill wastes. The primary compression indices on landfill #2 also presented a decreasing tendency based on enactment and enforcement of waste policies which MSW could reduce. The secondary compression indices(Cα) showed a downward trend depending on the effect of waste policy to reduce the wastes. The settlement behavior of the waste landfill was analyzed using long-term settlement data measured during 27 years at E, H, and K blocks in landfill #1’s center and the five settlement models proposed by other researchers. As a result, it showed that the settlement predicted by Sower model was underestimated and the settlement from Logarithmic function & Power creep law models was overestimated in comparison with the measured settlement. The composite compression model was also proposed in this study. This model could simulate both the biological degradation and the residual settlement of wastes. On the validation stage, the proposed model in this study was demonstrated to simulate well the field data measured at landfill #1. Subsequently, laboratory-scale settlement tests were performed as a part of the study on the bioreactor landfilling method in order to examine the acceleration of the wastes' biological degradation based on the recirculation of food waste leachate(FWL). As a result, it was confirmed that the recirculation of FWL with leachate can accelerate the waste settlement 2.9 times and 2 times when compared to distilled water injection or leachate recirculation, respectively. From the results of the experiment, it was determined that recirculation FWL with leachate could be beneficial to obtain additional reclamation spaces from the acceleration of waste settlement and would lead to early stabilization of waste landfills.

Population identification and functional characterization of microbiomes in biological nitrogen removal system for landfill leachate

김다정 Graduate School, Yonsei University 2023 국내석사

In the case of landfill leachate, the amount generated is also increasing along with the annual amount of landfill waste, and legal regulations are being strengthened as well. As a result, the treatment of landfill leachate containing high concentrations of ammonia nitrogen, heavy metals, and non-degradable organic matter is becoming more important, and the treatment of high concentrations of nitrogen and non-degradable organic matter should be carried out using active sludge in the biological treatment process. At this time, since nitrogen in leachate is removed by denitrification and nitrification of ammonium oxide and nitrite oxide bacteria, microbiological research is essential, and recalcitrant organic substances are known to affect the denitrification process, so research is needed to confirm the stable performance of the nitrogen removal process. Therefore, this study analyzed the relative abundace and metabolic capabilities of nitrogen removal-related microorganisms and the effect on the denitrification of humic substances whether biological nitrogen removal in the current treatment plant is being carried out stably. To this end, a microbiological study was conducted through Metagenome shotgun analysis, which can analyze the entire microbial community and functional genes in the sample by collecting raw leachate and biological process leachate from the treatment basin in the Sudokwon landfill. As a result of metabolic function analysis in all samples, metabolism was the most dominant function, and Nitrogen Metabolism analysis indicated that at least 20% of the denitrification capacity was always maintained in the denitrification basin, indicating a constant denitrification function in the biological treatment basin. Through microbial community analysis, it was also possible to identify the correlation between COD, NH4-N, and T-N removal efficiencies and the relative abundance of denitrifying and nitrifying microorganisms. Correlations between narG and nosZ relative abundance were difficult to determine, however. In the case of humic materials, there was a difference in the amount of occurrence by period due to the changing temperature and rainfall, and it increased the most in summer. Based on microbial community analysis and genetic analysis, denitrification efficiency improves with an increase in humic substances in the biological treatment basin, and even during the summer when nitrogen removal efficiency decreases most, it appears to maintain the denitrification efficiency. By examining microbiological studies, these results confirm that the biological treatment process for nitrogen removal in leachate is stable regardless of time-varying factors. 매립지에서 발생하는 침출수의 경우, 매립 폐기물의 연간 발생량 증가와 더불어 침출수 발생량 또한 함께 증가하는 추세를 보이고 있으며 법적 규제 또한 강화되고 있다. 이에 따라, 고농도의 암모니아성 질소, 중금속, 난분해성 유기물 등을 포함한 채로 처리장으로 유입되는 매립지 침출수의 처리는 더욱 중요해지고 있으며, 생물학적 처리 공정 내 활성 슬러지를 이용하여 고농도의 질소와 난분해성 유기물질 등을 처리함으로써 더욱 강화되고 있는 법적 규제를 충족시켜 방류해야 한다. 이 때, 침출수 내 질소는 암모늄 산화균과 아질산염 산화균의 탈질 및 질산화에 의해 제거되기 때문에 미생물학적 연구가 필수적이며, 난분해성 유기물질은 탈질 과정에 영향을 미치는 것으로 알려져 있어 질소 제거 공정의 안정적 수행 여부 확인을 위해 연구가 필요하다고 보았다. 따라서 본 연구에서는 질소 제거 관련 미생물의 군집 및 대사 능력 분석 그리고 난분해성 물질에 해당하는 휴믹 물질의 거동 및 탈질에 대한 영향을 분석하여 현 처리장 내 생물학적 질소 제거가 원활히 이루어지고 있는지 살펴보고자 하였다. 이를 위해 수도권매립지 침출수 처리장의 원수 및 생물학적 공정 처리수를 채취하여 시료 내 전체 미생물 군집 및 기능유전자 분석이 가능한 Metagenome shotgun analysis를 통해 분자미생물학적 연구를 수행하였다. 연구 결과, 대사 기능 분석을 통해 Metabolism은 모든 시료에서 가장 우세한 기능이였으며, 그 중 Nitrogen Metabolism을 분석한 결과 탈질-질산화조에서 탈질 능력이 항상 약 20% 이상 유지됨을 확인하여 해당 생물학적 처리조 내의 탈질 기능은 일정하게 유지되고 있음을 추정할 수 있었다. 또한, 미생물 군집 분석을 통해 얻은 탈질 및 질산화 미생물의 상대적 풍부도와 COD, NH4-N, T-N 제거 효율 간의 상관관계 분석을 통해 관련 미생물 규명이 가능하였으나 탈질유전자 narG와 nosZ의 상대적 풍부도와의 상관관계는 확인하기 어려운 것으로 밝혀졌다. 휴믹 물질의 경우, 변화하는 기온과 강우량에 의해 시기별 발생량 차이가 나타났으며 여름철에 가장 증가하였다. 미생물 군집 및 유전자 분석 결과 휴믹 물질 증가에 따라 생물학적 반응조 내 탈질 성능 또한 향상되었으며, 이에 따라 질소 제거 효율이 가장 감소하는 여름철에도 탈질 효율이 유지되는 것으로 보인다. 최종적으로 본 연구는 침출수 내 질소 제거를 위한 생물학적 처리 공정이 시기별로 변동하는 인자와 상관없이 안정적으로 수행되고 있음을 미생물학적 연구를 통해 확인하였다.

埋立場 浸出水의 生物學的 難分解性物質 特性 糾明에 관한 硏究

박혜숙 大田大學校 大學院 2004 국내박사

In order to determine the removal rate of non-biodegradable substances and the change of their structural properties, this study carried out an ozone-treatment experiment on leachate, benzene and parathioncollected from the landfill area of D City in Chungcheongnam-do and examined the change of the chemical properties of non-biodegradable substances. The conclusions of this study are as follows. 1. The main elements of non-biodegradable substances in landfill leachate were benzene, toluene, trichloroethane, trichloroethylene, xylene, etc. and the concentration of toluene was 15.7mg/ℓ on the average, benzene 7.2mg/ℓ. trichloroethane 1.1mg/ℓ, trichloroethylene 0.75mg/ℓ and xylene 0.5mg/ℓ. Among them, benzene, toluene and trichloroethane are included in the list of organic toxic substances announced by USEPA. In addition, benzene, toluene and xylene, which are derivatives of benzene an aromatic compound, are classified as carcinogenic substances, so require safe disposal and management. 2. When leachate was treated with ozone for 10min,30min and 60min, UV absorbance was reduced with the increase of reaction time, and the reduction rate was 38.6% at 60min. TOC was removed by 13.2% at 60min. The low reduction rate of TOC may be because TOC reacts indirectly with OH radical produced from reaction with ozone while UV absorbance usually relies on direct reaction between organic matters and ozone molecules. Color was removed by up to 97%, which suggests that ozonation is highly effective in removing coloring elements in leachate. 3. Sixteen kinds of non-biodegradable compounds were found in the leachate and most of them had the characteristic of aromatic hydrocarbon. Among them dibutyl phthalate was identical with a substance included in the list of USEPA, which is classified as a mutagen that may cause the mutation of genes and disorders in chromosomes. In addition, 2,5-Cyclohexadiene-1,4-dione, 1,2-Benzenedicarboxylic acid and butyl octyl ester were found to be similar to substances listed by USEPA. 4. According to the result of analyzing the chemical change of non-biodegradable substances after ozonation, 15 kinds of compounds were observed after 10min of ozonation, which increased to 17 after 30min and again decreased to 13 after 60min. The decrease may be because ozone oxidizes organic matters by reacting with parts of weak molecular binding such as C-C double bond of and aromatic rings and decomposes them into aldehyde, simple organic matters and CO_(2). 5. According to the result of analyzing structural changes before and after ozonation using GC-MS, cyclic compounds and aromatic compounds were observed in the original water and aliphatic compounds were newly observed after ozonation. In addition, through ozonation, humic substances of high molecular weight were oxidized and decomposed and produced tow-molecular compounds such as aldehyde, ketone and carboxyl acid and highly biodegradable aliphatic carbon, which suggests the bio-degradability of non-biodegradable substances. 6. The change of area according to the length of ozonation time proved that ozone reduces the concentration non-biodegradable substances. In 10min ozonation, benzene was removed by 58% and parathion by 62.5%, so the removal rate of benzene was slightly lower than that of parathion, but ozonation was found to be effective in removing aromatic compounds and organic phosphate in agricultural chemicals. 7. According to the result of experimenting on the material balance of parathion, after 10min reaction of 3mg/ℓ parathion solution, the residual rate of parathion was 43%, the removal rate was 31.3%, and diethyl p-nitrophenyl phosphate generated as a byproduct was 25.7%. Parathion was classified as a possible human carcinogen in the US EPA Guidelines in 1986 while diethyl p-nitrophenyl phosphate is regarded as not classifiable as to human carcinogenicity. Thus ozonation transformed a carcinogen into a non-carcinogenic substances

Management of Landfill Leachate in Light of Resource Recovery and Modern Contaminants

Podder, Aditi The University of Utah ProQuest Dissertations & Th 2020 해외박사(DDOD)

The desire to recover useful resources, especially nutrients, from waste streams is continuously increasing. Leachate and digester reject water or centrate are two of the most challenging urban waste streams that pose enormous challenges in handling. In this study, a new treatment strategy, formulated around the theme of comanagement of leachate and centrate, was developed to recover useful resources and treat the residues. Struvite precipitation process to recover/remove phosphorous (P) and nitrogen (N) was optimized and employed. Aerobic granular sludge (AGS) process to simultaneously remove carbon and nitrogen and single-stage partial nitritation/anammox (PN/A) process to remove residual nitrogen were used as biological treatment processes.At an optimum pH of 9 and optimum P: Mg ratio of 1:1.2, more than 85% recovery/removal of phosphorus (PO43--P) and 25% recovery/removal of ammonia-nitrogen (NH4+-N) were accomplished through struvite precipitation. In the AGS reactor overall, BOD5, COD and NH4+-N removal percentages were 74%, 45% and 35%, respectively. An overall 35% of total inorganic nitrogen removal was accomplished in the PN/A reactor.Nitrogen management using anammox process in the treatment of mature landfill leachate with low readily biodegradable organic carbon was also studied. Simultaneous functional gene expressions of ammonia monooxygenase (amoA), nitrite reductase (nirK and nirS), hydrazine synthase (hzsA) using mRNA, rate measurements, and the ability to quantify a biochemical marker, heme c protein, specific for anammox microorganisms, proved the consistent contribution of ammonia-oxidizers, heterotrophic denitrifiers, and anammox in an attached growth PN/A system. The 16S rRNA amplicon sequencing revealed Proteobacteria, Planctomycetes, and Bacteroidetes as dominant phyla in the reactor.A cost analysis study based on the operational data from this research was conducted at the University of Central Florida showed that leachate management using the integrated treatment approach is less expensive than the traditional treatment approaches. This research showed for the first time that indeed nutrient recovery could be coupled with simultaneous carbon and nitrogen management in landfill leachate. The comprehensive analyses of each process will provide guidelines for their full-scale installations, which will further be beneficial in overall solid waste management.

Stability analysis of bioreactor landfills considering leachate injection and installation condition

Byun, Byung-kwon Graduate School, Yonsei University 2017 국내석사

A bioreactor landfill is a method that accelerates decomposition by the direct injection of leachate into landfills to accelerate the improvement of landfill gas generation and stabilization. However, the injection of uncontrolled leachate causes an unreasonable increase in pore water pressure inside the landfill, which in turn causes slope failure. In this study, it was examined the design factors of bioreactor landfills by coupling leachate infiltration analysis and landfill slope stability analysis to describe the heterogeneous and anisotropic characteristics of the bioreactor landfill waste and the shape of the actual landfill. Numerical analysis was performed on injection design according to injection pressure and the positioning of the injection pipes. Moreover, the effects of the degree of compaction of the waste and the condition of the subgrade were examined based on the landfill’s properties. Therefore, this study selected shape and physical properties of “Sudokwon landfill”, the world’s largest sanitary landfill in Incheon. When the injection pressure is increased, the pore water pressure inside the slope rises and the wet zone is widened, which is advantageous for the generation of the landfill gas and early stabilization, but the factor of safety (FS) is drastically reduced. Also, even with the same injection pressure, as the position of the injection pipe increases, the wet zone becomes wider and the FS decreases. In this landfill model, the injection pipe is the most optimal design to be installed at the maximum height assuming that the liner is reliable, since the FS was 1.3 or higher at the maximum height. From the viewpoint of the landfill installation conditions, the size of the slip surface varies depending on the properties of the landfill, and the safety factor also varies. Therefore, if the safety factor is reduced by injecting leachate in the landfill where the strength of the subgrade is low, the slip surface including the subgrade may occur, which may cause great environmental and economic damages. Also, it is dangerous to use it as a bioreactor landfill because there is a sudden increase in pore water pressure when leachate is injected in a low compaction waste landfill. When a bioreactor type landfill is installed in a landfill with a relatively low FS, it is possible to insure the safety factor by bringing the position of the injection pipe close to the bottom. On the other hand, if there is a plan to construct a bioreactor landfill, sufficient compaction at the construction stage and elevation of the injection pipe position may be advantageous for increasing the landfill gas and stabilizing the early stage. 바이오리엑터형 매립지는 매립지 내부에 침출수를 직접 주입함으로 분해를 촉진하여 매립가스 발생 향상 및 안정화를 가속시킬 수 있는 공법이다. 하지만 통제되지 않은 침출수의 주입은 매립지 내부의 무리한 간극수압 상승을 발생시켜 사면 붕괴를 발생할 수 있다. 본 연구에서는 바이오리엑터형 매립지 폐기물 물성의 비균질하고 이방성인 특징과 실제 매립장의 형상을 묘사하여 침출수 재순환의 침투해석과 사면 안정 해석에 대한 연계 해석을 진행, 바이오리엑터형 매립지 설계인자를 연구하고자 한다. 주요 설계인자로는 주입압과 주입관의 위치, 매립장 설치에 따른 물성 변화의 관점으로 연구를 진행하였다. 연구에 사용된 매립지 모델은 인천에 위치한 세계 최대의 위생 매립지인 “수도권 매립지”의 형상과 물성을 사용하였다. 주입압이 증가할 경우 사면 내부의 간극수압이 상승해 포화하는 영역이 넓어져 매립가스 발생과 조기 안정화에 유리하지만 안전율이 급격히 감소하는 단점이 있다. 또한, 같은 주입압이라도 주입관의 위치가 상승할수록 포화영역이 넓어져 안전율의 감소를 나타낸다. 본 모델의 경우 주입관의 높이를 최대로 하여도 안전율이 1.3 이상으로 나타나기 때문에 실제의 경우 매립지의 최종 복토가 신뢰 하다는 가정하에 최대 높이에 주입관을 설치 하는 것이 유리하다. 매립지 설치 조건의 관점에서 보면, 매립지 원지반의 물성에 따라 발생하게 되는 원호 파괴면의 크기가 다르며 안전율 또한 차이를 보인다. 따라서 원지반의 강도가 낮을 매립지에서 침출수 주입을 통해 안전율 감소가 발생한다면, 원지반을 포함하는 원호 파괴가 발생 할 수 있어 큰 환경적, 경제적 피해를 발생 시킬 수 있다. 또한 약한 다짐의 폐기물 매립지에서 침출수가 주입될 경우에 급격한 간극수압의 상승이 나타나기 때문에 바이오 리엑터 매립지로써의 사용은 위험하다. 따라서, 기존에 사용되고 있는 매립지에 바이오리엑터 시설을 설치할 경우, 사면 안전율이 낮다면 주입관을 낮게 하여 안전율을 확보할 수 있다. 반면, 바이오리엑터 매립지를 조성할 계획이 있는 경우는 시공 단계에서 충분한 다짐과, 주입관의 위치를 높게 한다면, 매립가스 증대 및 조기 안정화에 유리하다.

화학응집 및 펜톤산화공법을 이용한 침출수중 유기물제거에 관한 연구

최환세 연세대학교 산업대학원 2000 국내석사

본 연구는 폐기물매립지에서 발생하는 침출수의 난분해성 유기물을 제거하기 위하여 생물학적 처리를 거친 침출수를 대상으로 물리화학적 처리의 일종인 응집침전 및 펜톤산화처리를 이용하여, 처리실험을 수행하여 침출수중의 유기물제거의 효율을 분석한 연구이다. 실험대상인 수도권매립지 침출수는 매립경과년수, 계절 및 기후에 따라 성상변화가 심하였으므로 회분식 실험을 통해 연속식 실험조건을 결정하였다. 화학응집시약의 주입농도는 1,000mg/L로 정하고 펜톤시약의 주입비율, 즉 H_(2)O_(2) 대 FeSO_(4)(Fe^(2+))의 주입비율은 회분식 실험 결과를 근거로 1 대 1로 정하였으며 펜톤시약 주입량은 3,000mg/L로 정하여 H_(2)O_(2) 대 FeSO_(4)(Fe^(2+))를 각각 1,500mg/L씩 주입하였다. 수도권매립지 침출수를 폭기식라군시설로 처리한 침출수를 연속적으로 화학적응집 및 펜톤산화 pilot 실험한 결과, 유입수의 CODc_(r)농도는 1,378 ∼ 1,523mg/L의 범위로 평균 1,464.7mg/L를 나타내었다. 화학응집 처리수는 939 ∼ 1,094mg/L의 범위로 평균 1,004.8mg/L를 나타내어 평균 31.4%의 제거율을 보였으며 펜톤 산화처리수는 CODc_(r)으로 523 ∼ 678mg/L범위로 평균 600.9mg/L를 나타내어 40.2%의 제거율을 보였다. 회분식 및 연속식 실험 결과를 볼 때 화학적응집 및 펜톤산화공정 유입수의 CODc_(r)농도가 약 1,400mg/L인 침출수일 경우에는 FeCl_(3)를 1,000mg/L 주입하여 응집처리한 후 H_(2)O_(2)와 FeSO_(4)(Fe^(2+))를 1대 1로 각각 1,500mg/L씩 주입하였을 경우가 가장 적합한 처리율을 나타내는 것으로 확인되었다. 일반적인 침출수의 성상, 즉 생물학적처리공정후 1,400mg/L 전후의 CODc_(r)농도를 가지는 침출수의 경우에는 생물학적처리공정의 후속공정으로 화학적 응집공정 및 펜톤산화공정을 적용시킨다면 신설 COD 배출허용기준을 만족시킬 수 있을 것으로 판단된다. In this study, the test is performed for leachate after treating biological treatment by using coagulation and fenton oxidation for removal nonbiodegradable organic compounds in leachate generated in solid waste landfill. Since the Sudokwon sanitary landfill leachate characteristics are changed by landfill age, seasons, and climates, the sequence test conditions are determined by batch reactor test results. The addition of coagulation reagent concentration is set by 1,000 mg/L while the addition of fenton oxidants concentration mixed H_(2)O_(2) and FeSO_(4)(Fe^(2+)), a 1:1 mixing ratio based on batch reactor test results is set by 3,000 mg/L mixed 1,500 mg/L for each. The pilot test, the sequence chemical coagulation and fenton oxidation after treating aerated lagoon in Sudokwon landfill, results show that influent CODc_(r) concentration ranged from 1,378 to 1,523 mg/L averaged 1,467 mg/L. The effluent concentrations of chemical coagulation are ranged between 939 and 1,094 mg/L averaged 1,004.8 mg/L while the effluent concentrations of fenton oxidation are ranged between 523 and 678 mg/L averaged 600.9 mg/L. The removal efficiency of chemical coagulation and fenton oxidation are about 31.4% and 40.2%, respectively. The batch reactor and sequence test results indicate that in case, the influent concentration of CODc_(r) is about 1,400 mg/L the optimal results are acquired when the chemical added 1,000 mg/L of FeCl_(3) for coagulation treatment for coagulation process, and then added 1,500 mg/L each of H_(2)O_(2) and FeSO_(4)(Fe^(2+)) for fenton oxidation process. When concentration of leachate are around 1,400 mg/L, it can be treated under the new regulation limit of CODc_(r) if chemical coagulation and fenton oxidation process are placed for post process of biological treatment.