Study On The Treatment And Reuse Technology Of Electric Desalting Wastewater

In this paper,the physiochemical and electrochemical methods were used to treat with the electric desalting wastewater from a refinery in the west of China,and a kind of high efficiency compound flocculant was prepared to treat with the electric desalting wastewater by air floatation and electrodialysis process,so as to solve the existing problems in the electric desalting wastewater treatment and realize the reuse goal of the electric desalting wastewater.During the compounding process of the composite flocculant,the influence of the dosage of each component on the flocculation effect was investigated.Through the single-factor experiment and the orthogonal experiment,the optimal dosage ratio of each component was determined.The optimal proportion of each component is: 12%aluminum salt LY,9% zinc salt XY,2.2% acid M,and 0.04% macromolecular compound N.The removal rate of sewage turbidity with compound flocculant can reach84.6%.The flocculation mechanism of compound flocculant was studied.Compared with other commercial flocculants,it is found that the prepared flocculant has the advantages of good flocculation effect,low dosage and low cost.In air flotation process unit,the optimal conditions of coagulation and floatation were determined,Under these conditions,the treatment effect of the air floatation process is optimal.The specific process parameters are: concentration of flocculant is 1mg/L,concentration of coagulant anion PAM is 0.6 mg/L,reflux ratio is 40%,dissolved gas pressure is 0.35 MPa,hydraulic retention time is 1.8 h.The turbidity and oil removal rates can reach to 91.3% and 42.6% respectively.Considering desalting rate and the recovery rate of freshwater,the optimal working conditions of electrodialysis process were determined,The optimal operating conditions are: working voltage is 70 V,fresh water flow is 500 L/h,concentrated water flow is100 L/h,under the experimental conditions,after dealing with twice electrodialysis processes,the conductivity of produced water was 284 ?s/cm,it can meet therequirements of the electric desalting water with the electrical conductivity of 300?s/cm or less,the total recovery and desalination rate of freshwater was achieved of69.4% and 72.5% respectively,The total energy consumption of per ton water was0.146 kw·h,Therefore the cost of using this technology dealing with electrical desalting water is low,and it has a good industrial application value.