This study was initiated to examine the potential impacts on the environment during the management of food waste by anaerobic digestion in Daejeon Metropolitan City (DMC) that is built in 2017. The evaluation was based on both material flow analysis (MFA) and life cycle assessment (LCA). The MFA study was performed using STAN 2.5, while the LCA was conducted according to ISO standards by utilizing Total 4 LCA software with the incorporation of CML 2002 methodology. According to the LCA results, global warming potential (GWP), acidification potential (AP), eutrophication potential (EP), and photochemical ozone creation potential (POCP) were found to be approximately 166 kg CO2-eq/ton of food waste, 0.43 kg SO2-eq/ton of food waste, 0.66 kg PO4 3−eq/ton of food waste, and 0.08 kg C2H4-eq/ ton of food waste, respectively. The disposal stage showed higher impact of GWP on the environment due to the landfilling of solid sludge and screening waste. In case of eutrophication potential, the treatment phase showed the highest impact on the environment, mainly because of the consumption of electricity. Based on the results of normalization, the highest environmental impacts was found in the treatment stage related to eutrophication potential. The results of LCA would provide policy-makers to identify and reduce potential environmental impacts associated with food waste to biogas conversion in DMC by life cycle.

Food waste, a putrescible form of waste, comprised of 30% of the total municipal solid waste stream in Daejeon Metropolitan City (DMC) in 2012. Proper management of food waste is a challenging task for local government. This study was conducted to determine material flows when treated food waste in various recycling facilities. Material flows in the recycling processes were collected by site surveys, field trips and discussion with operators and governmental employees. Material flow analysis (MFA) was conducted to quantify the flow of food waste from generation to disposal for the year 2012. MFA along with its mass transfer coefficients were determined based on the inputs, outputs and waste fluxes. According to the mass transfer coefficient results, treatment efficiency for the dry and wet feed manufacturing facility was found to be higher than other treatment facilities. Water consumption was higher for the composting site, resulting in large volume of wastewater (mass transfer coefficient 1.539). While large amounts of screening materials such as plastic, chopsticks, aluminum foils, and bottle caps were generated at the composting site, mass transfer coefficients (0.312) at the dry and wet feed facility were relatively high, implying effective treatment of food waste occurring. The results of this study help to facilitate waste management policy decision-makers in developing effective food waste management techniques in DMC.

국내 음식물류폐기물은 생활폐기물 발생량의 약 30%의 비율로 매우 많은 양 발생되고 있으며, 이러한 음식물류폐기물은 우리나라의 음식문화 특성으로 인한 높은 염분농도와 수분함량으로 침출수 및 악취문제 등 여러가지 환경문제를 야기해왔다. 이에 따라 2005년 이후 직매립을 금지시킴으로써 음식물류폐기물의 재활용 정책이 도입되고 자원화 시설이 설치되었다. 현재 국내에서는 습식 및 건식 사료화, 퇴비화, 탄화, 기계적 감량화 등 다양한 방법을 통하여 음식물류폐기물을 자원화 하고 있으며 그 중 사료화와 퇴비화 시설이 가장 보편적으로 운영되고 있다. 이와 같은 음식물류폐기물 재활용 정책의 적극적인 도입과 시설 증축으로 국내에서는 95%이상의 음식물류폐기물 재활용률을 달성 하였지만 실제 처리시설에서의 낮은 공정수율, 대량의 음폐수 발생, 악취, 운송과정에서의 부패 등 여러 가지 환경 문제점이 여전히 나타나고 있다. 따라서 본 연구에서는 실제 처리공정의 효율, 공정의 특징, 문제점 등을 파악하고자 하였으며, 이를 위하여 대전광역시 음식물류폐기물 처리시설 4곳(퇴비화 1곳, 사료화 3곳)을 중심으로 시설별 일반적 사항을 비롯한 투입 및 배출 물질의 종류와 양, 시설별 공정 주요 특징과 문제점 등을 조사하였다. 또한 조사 결과를 바탕으로 처리시설별 물질흐름분석을 통하여 물질수지를 마련함으로써 대전광역시 음식물류폐기물 처리시설의 운영 실태를 파악하고 문제점의 개선방안을 마련하였다. 본 연구에서는 대전광역시에서 발생하는 음식물류폐기물을 처리하는 시설을 바탕으로 현장조사를 실시하였다. 현장조사를 통해 확보된 투입 및 배출 물질에 대한 데이터를 바탕으로 시설별 물질흐름분석을 수행하고 물질전환계수를 산정하였다. 아울러 Stan 2.5 Software를 활용하여 분석을 실시하였다. 연구결과, 대전광역시 음식물류폐기물 처리 시설 중 반입 음식물류폐기물 대비 재활용 제품의 양의 비율은 건식 및 습식사료화 시설에서 가장 높은 것으로 나타났으며, 퇴비화 시설에서 가장 낮은 것으로 나타났다. 음폐수의 경우 퇴비화시설에서 반입되는 음식물류폐기물의 1.5배를 초과하는 대량의 음폐수가 발생되는 것으로 나타났으며, 이는 처리 공정 중 물질의 이동을 위하여 대량의 공정수가 불가피하게 투입되기 때문인 것으로 분석되었다. 이러한 낮은 공정수율, 대량의 음폐수 발생 등과 같은 문제점은 대부분 처리공정의 개선을 통하여 보완 가능한 사항들이기 때문에 보다 효율적이고 친환경적 관리를 위해서 스크류, 탈수기, 선별기 등의 시설개선이 반드시 필요할 것으로 분석되었다. 또한 적정 관리 방안 마련을 위해서는 보다 정밀한 관리시스템의 분석과 다양한 측면에서의 환경평가가 필요할 것으로 판단된다.

The management of household hazardous waste (HHW), a component of municipal solid waste (MSW) has become a major of concern partly due to their potential toxicity upon disposal. Improper management of such waste can deteriorate the environment and cause serious damage to the human health. This paper discusses the current fundamental management practices, which include the generation rate, collection systems and treatment using the survey reviews of households and interviews held with experts in the Daejeon metropolitan city. Surveys of more than 378 people in Daejeon Metropolitan City were conducted to investigate the characteristics, generation rate, social behavior and awareness regarding disposal of HHW. The target items used in this study includes used lamps, used batteries, pharmaceuticals, and household pesticide chemicals. According to the survey conducted, the generation rates of HHW varied depending upon the dwelling type, collection system, and waste type. Apartment complex residents participated actively in source separation, using the established collection system with limited items (e.g., fluorescent lamps and batteries), while single family housing residents tend to store HHW at households. There is still a need for public awareness, detailed policies and legislation requiring source segregation at households, and better collection systems for HHW. The results of this study can be used for developing better management of HHW in municipal solid waste streams to prevent potential environmental impacts and human health risks.