Studying the high chlorine and low COD biotreated effluent of certain sewage plant,this paper discusses the influence of mercury sulfate dosage,K2Cr2O7 concentration,reaction acidity and water sample volume on COD determination.Furthermore,the most simple and effective way for eliminating the Cl-interference is presented in this paper and the results show that: The ratio between mercury sulfate and chloride ion 15∶1(mass ratio),K2Cr2O7 concentration 0.18 mol/L,water sample dilution 0.75-fold and Ag2SO4-H2SO4 dosage 28 mL,chloride ion interference can be effectively reduced.Compared with chlorine correction approach,this method is simpler,more accurate and reliable as well as expands the serviceable range of potassium dichromate method.

In order to improve the wastewater treatment efficiency of Fine Chemical Industrial Park in Zhejiang Province,organic compounds in the inflow and outflow from a biological treatment system were analyzed by GC/MS.The biodegradability and toxicity of the organic compounds contained in the inflow were topologically studied,and its consistency with analytical results was evaluated.Results indicated that acids,alcohols and some volatile phenols and anilines could be removed effectively through the biological treatment system.However,chloroanilines,chloronitrobenzenes,methoxybenzenes,nitriles and some heterocyclic compounds could still be detected in the outflow.These compounds were toxic and hardly biodegradable,resulted in a unsatisfactory water discharge.Therefore,the process option for fine chemical wastewater treatment should consider the preferential control of organic compounds with low PCD or low LC50.Effective pretreatment and bioaugmentation technique might be necessary for a high-performance wastewater treatment process.

Fine Chemical wastewater is a typical industrial organic and non-biodegradable wastewater with high strength of COD,ammonia nitrogen and color.In order to improve the treatment efficiency of the wastewater from a Fine Chemical Industrial Park in Zhejiang Province,several indexes including COD,BOD,ammonia nitrogen,color,anions,cations,heavy metals and organic compounds were analyzed by ion chromatography,ICP/MS,GC/MS and other regulatory analytical methods.The pollution characteristics of the fine chemical wastewater were revealed from chemical and biological analysis results,through which the control strategies were proposed.Results indicated that COD,ammonia nitrogen,heavy metals,dyes and their decomposition substances were the main toxic pollutants in the wastewater.The organic compounds,which were determined as hardly biodegradable or toxic compounds,inhibit the micro-organisms,so that the quality of outflow couldn't satisfy the discharge criterion.Therefore,the treatment of fine chemical wastewater should prior consider the treatment of toxic compounds,the process efficiency,the appropriate water quality structure and effective policy strategies.