본 연구에서는 대전 관평천의 도시유역에서 2017~2018년에 발생한 강우 20건의 유출수를 연속적으로 채취하여 As, Cd, Cr, Cu, Ni, Pb 및 Zn 의 중금속 및 총고형물질(TSS) 농도와 유량을 분석하고, 강우특성과 수질 변화의 강우사상별 및 시간별 상관관계를 조사하였다. 일정 강우강도에서 오염물질의 최대농도는 강우 초기에 발생하는 경향을 나타냈으나, 강우량 및 강우강도가 작은 경우에는 일정 시간 경과 후 발생하는 것이 관찰 되었다. 강우지속시간은 중금속 농도 및 부하량과 큰 상관성을 보이지 않았다. Cu와 Zn을 제외한 중금속 질량은 강우강도(0.60~0.88) 및 총강우 유출량(0.74~0.89)과 상대적으로 높은 상관관계를 나타냈다. 강우 시 유량가중평균농도와 선행무강우일수 또한 양의 상관성(0.54~0.73)을 보 이는 반면, 30분 강우강도로 표현된 시간별 유출량과 TSS 및 중금속 농도는 전혀 상관성을 나타내지 않았다. 무강우 기간 동안 지표면에 축적된 오 염물질이 최소한의 강우 에너지에도 세척효과가 발생하여 강우특성과는 무관하기 때문인 것으로 추정된다. 중금속과 TSS 농도의 시간에 따른 변화특성은 상관계수가 0.68~0.87로 양호한 수준을 나타냈다. 이는 고형물질의 이동과 중금속 물질의 이동이 함께 발생한다는 것을 시사하며 동시에 중금속이 고형물질에 흡착되어 이동한다는 것을 의미한다. 따라서 비강우 시에 유역 표면의 고형물질을 청소 등으로 사전에 제거할 경우 하천으로 유입되는 중금속오염물질의 양을 현격하게 저감할 수 있을 것으로 판단된다.

As an alternative for energy intensive aerobic wastewater treatment system, development of sulfate reducing bacteria (SRB)-based domestic wastewater treatment system was researched. No requirement of aeration, fast substrate utilization and less sensitiveness of SRB are main factors for energy conservative wastewater treatment system. Sulfate for SRB’s synthesis could be supplied from SOx in industrial gas, thus the system also can contribute to the economical treatment of hazardous sulfur compound in the gas. With the dissolved sulfate as an electron acceptor, SRB degrade organic matters in wastewater and produce sulfide. This produced sulfide was used for electricity generation in sulfide fuel cell system connected to continuously operating UASB reactor. This study also focused on obtaining SRB dominant granule from methanogen dominant anaerobic granule in a competition between SRB and methanogens. As a strategy to increase SRB activity and to suppress methanogens, starvation was applied by not providing organic source but continuous supplying sulfate. Based on the well adopted hypothesis on the granule structure, methanogens located relatively inner core of a granule died out due to the lack of organic source, while SRB located at outer part of granule survived utilizing extracellular polymeric substance (EPS) or organic matters from died out microbes as an organic source. By eliminating the competition, the portion of organic matter degradation by SRB was increased from 19% before starvation to 93% after starvation, achieving 80% COD removal in total. In case of sulfate removal, 15% improvement was achieved compared to the control reactor. This effect of starvation on the granule characteristics were confirmed with scanning electron microscope (SEM) and transmission electron microscope (TEM). Not only wastewater treatment by SRB but also electricity generation with sulfide fuel cell system was studied. Several sets of batch tests were conducted and continuous operation was also carried out with effluent containing 80mg/L -100mg/L sulfide. Through the batch tests, hydraulic retention time (HRT) was optimized to 8 h, removing almost all of the sulfide from the effluent, having the highest power density of 0.033 mW/cm². With the optimized HRT, sulfide fuel cell connected to the UASBr was continuously operated for over 50 days. This newly developed wastewater treatment system with SRB integrated with electricity generating sulfide fuel cell system is believed to be a promising technology for more sustainable wastewater treatment system.