The ecosystem in the Gwangju Stream has taken a wide range of disturbance such as the discharging water of sewage treatment plant, the lake water and the river water from different water system over the past decade. This study was figured out some significant influence factors by analyzing the relationship between biotic and abiotic factors in the urban stream. Abiotic components included 15 water quality variables which were measured in five sampling sites along the stream from October 2014 to July 2015, whereas the benthic macroinvertebrates found in those sites were used to estimate various biotic indices representing the ecological status of the community. The results of correlation analyses indicated that abiotic factors by human activities affected on the inhabitation of benthic macroinvertebrates more than biotic factors. The results of cluster analyses and ANOVA tests also showed that biotic and abiotic characteristics were clearly different in season. The main influence factors of cluster analysis by sites were NH3-N, EPT(I) and DO. It was considered that more various statistical analyses would be necessary to find some different relationships and influence factors between biotic and abiotic variables in the urban stream.

In this research, we tried to find a solution for problem of urban sewage treatment with coal fly ash and gypsum as industrial wastes. Furthermore, we examine the feasibility of reusing coal fly ash and gypsum which increasing amount of industrial wastes as urban sewage treatment materials and the concern for urban sewage coagulation and adsorption mechanism. The result shows that when 800 mg/L of coal fly ash sintered at 700oC are injected into urban sewage, optimum removal efficiency of CODCr is 87.3%, indicating more 5% improvement than of treating with not sintered condition. The study finds that when 1000 mg/L of gypsum are injected into urban sewage without sintering, optimum removal efficiency of CODCr and turbidity indicate 87.4% and 93.7% respectively.