Study On Andvanced Treatment Of Coking Wastewater By Iron-carbon Micro-electrolysis And Coagulation

Systematic analysis of the varieties and characteristics of coking wastewater was conducted. Coking wastewater is often due to complex composition, large changes in water quality, toxic, large amounts of refractory organic matter, so is one of the intractable industrial wastewater. Currently coking wastewater is pretreatmented and biological treatmented before discharge, but water after biological treatment cann,t meet the discharge standard. Thereforethe advanced treatment of coking wastewater treatment is imperative. In this study, based on objective analysis of the advanced treatment of coking wastewater, the use of iron-carbon micro-electrolysis technology and coagulation as the respective advanced treatment of the coking wastewater treatment is studied.The results of iron-carbon micro-electrolysis used as the advanced treatment of coking wastewater show that, the react environment, the initial pH level of wastewater, the reaction time, the dosage of iron scrap and granular activated carbon are main factors affecting the treatment effect. The L9(34) orthogonal experiment is carried out to define the optimal conditions as follows: the initial pH level of wastewater is 3, the retention time is 4 hour, the dosage of cast iron and active carbon is 40 and 10g/L. Dynamic continuous experiment conduct under the best conditions, investigate the impact that reflux ratio(R) changes removal effect of CODCr and NH4+-N, the result shows that:When the reflux ratio (R) is one, the concentration of CODCr in the effluent water ranged from 96.7¹36.02mg/L, which can meet the discharge standard of wastewater polluntants for iron and steel industry (GB 13456—1992) standardâ…¡; When the reflux ratio(R) is one, the concentration of CODCr in the effluent water ranged from 58.69 to 90.19mg/L, which can meet the discharge standard of wastewater polluntants for iron and steel industry (GB 13456—1992)standardâ… . the concentration of NH4+-N in the effluent water when the reflux ratio (R) is one and two all can meet the discharge standard of wastewater polluntants for iron and steel industry (GB 13456—1992)standardâ…¡.Using coagulation as an advanced treatment of coking wastewater, three common coagulants such as PAC, PFS, PAM are used. Through experiment, the optimum pH value, optimum dosing quantity of flocculatant to this kind of wastewater, the best fit and the best quantity in best fit are determined. Results show: different flocculants have different effect on the treatment of coking wastewater. Organic flocculant is better than inorganic flocculant, ferric flocculant is better than aluminum flocculant, that is PAM>PFS>PAC. The best dosing quantity in the best fit is PFS+PAM and 60+6mg/L. The removal efficiency of COD_Cr and chroma of the treated water can reach 58.2%, 88.2%.