Study On Removal Of Chroma And COD From Coking Wastewater Effluent Which Has Been Treated By Biochemical Processes

Coking wastewater was produced in the progresses that craking coal under high temperature to get coke and coal gas and reclaiming byproducts such as tar and benzene.The coking plant effluent contains high concentrations of mineral and organic compound,such as ammonia,phenols,cyanide and other aromatic organics which concluded quinoline,indole,naphthalene,indene etc.most of the substances are harmful to the environment.However,they are also hard to be disposed. The biological treatment processes deal with coking wastewater,which COD and chroma of removal rate not favorable and the effluent concentration could not attain are the wastewater drainage level,which brought severe harm to our environment.It had been demonstrated that adopting the assembled processes included flocculation,adsorption and oxidation could effectively reduce chroma and COD of coking wastewater effluent which has been treated by biochemical processes,and made it reach the wastewater drainage level two. In this research,used four flocculating agents (M180,PAC, SS-1,PAFS);two absorbing agents(activated carbon,fly ash);two oxidant(H₂O₂,ClO₂).First,used single factor analysis.SS-1,M180 and PAC were adopted in the experiments.The best reaction conditions were ascertained that SS-1:quantity of throwing was 450 mg/L,Ph value was 6,temperature was 30℃,stirring velocity was 900 r/min; M180:quantity of throwing was 350 mg/L,Ph value was 6,temperature was 30℃, quantity of throwing of PAM was 5 mg/L; PAC:quantity of throwing was 400 mg/L,Ph value was 8,temperature was 25℃, quantity of throwing of PAM was 5 mg/L.The results indicated that: SS-1,removal rate of chroma was about 30%, removal rate of COD was about 28%;M180,removal rate of chroma was about 63%, removal rate of COD was about 38%; PAC,removal rate of chroma was about 44%, removal rate of COD was about 24%.The perpendicularity experimental design was used to analysis PAFS, The best reaction conditions was ascertained that PAFS: quantity of throwing was 300 mg/L,Ph value was 9,temperature was 45℃, quantity of throwing of PAM was 5 mg/L,Al/Fe= 1:2; removal rate of chroma was about 65%, removal rate of COD was about 34%.Second,used single factor analysis. Activated carbon and fly ash were adopted in the experiments. The best reaction conditions were ascertained that activated carbon:quantity of throwing was 15g/L,Ph value was 4,temperature was 10℃, adsorbent time was 40 min; fly ash:quantity of throwing was 18g/L,Ph value was 4,temperature was 20℃, adsorbent time was 40 min; The results indicated that: activated carbon,removal rate of chroma was about 39%, removal rate of COD was about 20%; fly ash,removal rate of chroma was about 31%, removal rate of COD was about 17%.Third, fly ash was combined with M180 under the best reaction conditions. Removal rate of chroma was about 78%, removal rate of COD was about 43%.The water quality could not reach the demands as well.At last,ClO₂ and H₂O₂ was thrown into the water that had been disposed by adsorption(fly ash) and flocculation(M180).The chroma of the effluent was about 35 times;the COD of the effluent was about 85mg/L. The water quality reach the demands.