抄録
Monochloramine (NH2Cl) which is a highly toxic pollutant is usually contained in chlorinated sewage effluents. Effects of NH2Cl and chlorinated sewage effluent on freshwater ecosystem were investigated by an algal growth test using a green alga Selenastrum capricornutum.
Toxicity of NH2Cl for the alga was stronger than that of free chlorine, and NH2Cl was extremely stable in freshwater. Lowest-observed-effect concentration (LOEC) of NH2Cl after 96 hours exposure was 0.01 mg-Cl2l-1. Comparison of chlorinated effluents with non-chlorinated effluents, the algal growth was inhibited significantly in chlorinated effluents. The final chlorinated effluents collected from the sewage treatment plant also affected the growth of alga, and about 80% of total residual oxidants in the effluents was detected as NH2Cl. On the contrary, the algal growth was not inhibited in dechlorinated effuents with Na2SO3 because of disappearance of the residual oxidant. Judging from these results, it was clear that NH2Cl was the most important pollutant in chlorinated wastewater effluents for aquatic organisms.
