| In the industrial area of synthetic and artificial leather,wastewater which contains large amount of dimethylformamide（DMF）and dimethylamid（DMA）was produced during the recycling process of DMF.This sort of effluent is volatile,irritating,high toxicity as well as carcinogenic.The yield of DMF wastewater in tanning industry is about 1 tons per year.The B/C ratio of DMF waste water is about 0.065,which is hard to be biodegraded directly.The traditional biochemical treatment method needs long treating period,and the wastewater entered into the biochemical system directly without pretreatment,which make the containment removal efficiency is bad,especially the ammonia nitrogen.To solve this problem,this study installed the pretreatment with UV ozone oxidation precipitation chemical catalyst oxidation,homogeneous catalyst was added to the system to enhance the oxidation ability of ozone,meanwhile,the biological toxicity was reduced and the biodegradability of wastewater was improved.The optimal operating conditions of oxidation which was investigated through orthogonal method were:pH=8,AlCl3 as catalyst with dosage of 4g/L and reaction time of 60 min.Using magnesium ammonium phosphate precipitation method could reduce the NH3-N concentration and improve wastewater C/N ratio,and the addition of phosphorus chemicals could supplement a sort of phosphorus nutrients which is necessary for the growth of microorganisms.Also,the efficiency of biochemical treatment was improved.Which is lack of wastewater,wastewater treatment is beneficial to improve the efficiency of biochemical systems.The optimal operating conditions of precipitation which was also investigated through orthogonal method were:pH=8.5,n（NH4+）:n(PO43-)=1:1.1,n（NH4+）:n(Mg2+)=1:1.2 and the reaction time was 20min.The ABR biochemical system was started under a condition of constant influent concentration and gradually reduce hydraulic retention time,spent 60 days to complete the start-up producer.After that,the treating result of several indexes was investigated,which was under the operating condition of pH was 7.4 and hydraulic retention time was 24h.The ABR reactor effluent did not achieve the desired target,and the NH3-N content was too high.After the sludge acclimation through the aerobic process,the quality of effluent reached the expected aim.Through above improvements,the treating results showed that the average removal rates of chemical oxygen demand（COD）,total nitrogen（TN）,ammonia nitrogen（NH3-N）,Dimethylformamide（DMF）and Dimethylacetamid（DMA）reached about 95%,98%,99%,99.5%and 99.9%,respectively.The process overcame the barriers of traditional biological treatment process which is poor biodegradability,absence of carbon source which is needed by biological nitrogen removal process.It is a creative wastewater treatment technology with huge potential. |
