Removal Of Microcystis Aeruginosa-Synthetic Organic Compounds Pollution By Pre-Oxidtion And Coagulation-Precipitation

The combined pollution is a common phenomenon in water bodies, Because of joint effect or interaction effect or process coupling effect, the combined pollution could occurred between pollutants.In this study, a series of experiments for combined pollution of Microcystis aeruginosa- nitrobenzene (M.aeruginosa-NB) and Microcystis aeruginosa-polychlorinated biphenyls (M.aeruginosa -PCBs). The mutual effect between M.aeruginosa and NB or PCBs (synthetic organic compounds ,SOC); the removal effect of the combined pollution by coagulation- precipitation and Pre-oxidation- coagulation- precipitation was carried out.Results showed that M.aeruginosa presented enrichment ability and excellent degradability for NB. In a short time after M.aeruginosa and NB contacted, M.aeruginosa achieved the strongest enrichment ability for NB, the bioconcentration factors(BCF) was 103.28;however, the enrichment ability for NB declined subsequently, 7 days after M.aeruginosa and NB contacted, the BCF was 103.28. The concentration of NB that degraded by M.aeruginosa increased successively after they contacted, and the higher initial concentration of NB, the higher degradation rate by M.aeruginosa. For example, when the concentration was 314.24μg/L of NB, after 1 day and 7 days, the degradation rate was 7.23%,30.72%, respectively. Extracellular organic materials (EOM) of M.aeruginosa can increase solubility of PCBs. M.aeruginosa can enrich PCBs too, but the enrichment ability was related to the chlorinated extent of diphenyl, the higher chlorinated extent, the stronger enrichment ability. After 24 hours that M.aeruginosa and PCBs contacted, the BCF was 104.36 for PCB28, and 104.59 for PCB138.Removal effect of M.aeruginosa and turbidity by coagulation- precipitation was very well, the removal rate was morn than 98%. The removal rate of total Trihalomathanes Formation Potential (THMFP) of M.aeruginosa-NB pollution by coagulation- precipitation was about 90%, morn than M.aeruginosa pollution. Because the majority total THMFP was constituted by M.aeruginosa, so total THMFP was removed well when M.aeruginosa removed by coagulation- precipitation. Owing to the NB, M.aeruginosa generated and secreted even more soluble organic materials and caused the concentration of extracellular THMFP to increase; and the removal effect of coagulation- precipitation for soluble organic materials was weaker. So the removal rate of extracellular THMFP of M.aeruginosa-NB pollution was about 60%, lower than M.aeruginosa pollution. The removal rate of NB and PCBs by coagulation- precipitation were different. The removal rate of NB was 9.68%;and the removal rate of PCBs increased constantly with the chlorinated extent of diphenyl increased, the removal rate was between 33.83%~87.17%.Pre-oxidation could enhance coagulation effect. The removal rate of total THMFP and extracellular THMFP of M.aeruginosa-NB pollution raised 8 and 16.8 percentage points, respectively. The removal rate of NB raised 16 percentage points and that of PCBs raised 1.67~13.74 percentage points.