有害物質・障害生物の水環境への影響と制御 Ｍｉｃｒｏｔｏｘ試験による埋立地浸出水の処理性能とその水圏生態系への影響評価

Abstract

The release of landfill leachate containing toxic substances such as heavy metals and organochlorines may cause adverse environmental effects on aquatic environment. Therefore, it is important to clarify the effects of landfill leachate on aquatic environment based on risk analysis. Chemical analysis of landfill leachate is very difficult to evaluate its potential effects accurately because landfill leachate contains a lot of unidentified substances. It is expected that bioassay procedure can compensate the deficits of chemical analysis for samples like landfill leachate. In order to evaluate treatment performance and biological effects of landfill leachate, we conducted bioassay procedure for the raw landfill leachate collected from a real landfill disposal site and the effluent treated by the biological activated carbon fluidized bed (BACFB) process and ozone treatment using Photobacterium phosphoreum, i.e., Microtox test. Microtox test showed that EC50 for raw landfill leachate was 6.7%, which means the raw landfill leachate to be severe toxic. On the other hand, the effluent treated by BACFB showed little toxicity. In addition, bioassay for the effluent sample concentrated through Sep pak column was also carried out to evaluate the effect of ozone treatment. It was found that ozone treatment of the effluent of BACFB increased toxicity. But, when the effluent of ozone treatment was treated again by BACFB, the toxicity decreased significantly compared to that of the effluent treated by ozone or by BACFB only. This result suggests that the hybrid treatment system with the combination of BACFB and ozone treatment process is efficient to remove toxic substances from landfill leachate.