Research On The Water Conservation And Wastewater Treatment Technology Of Flue Gas Wet Desulfurization In The Coal-fired Power Plant

Taking water system of limestone-gypsum Wet Flue Gas Desulfurization (WFGD) device as object of study, First, this paper carries on the analysis and computation to the used water and the consumed water of WFGD system, and carries on the analysis to the water balance test of WFGD, further proposes the saving water measures. Then in view of the water quality characteristic of desulfurization wastewater the paper proposes the materialized-biological treatment method, and conducts the experimental study. In the materialized method selecting polymerization sulfuric acid ferro-aluminum (PAFS) as the coagulant, the suspension's elimination efficiency by PAFS is above 99%. Then using the orthogonal experiments determine PAFS best text condition under remove of the sulfide, the fluoride and the COD by PAFS: the pH value 8⁹, PAFS throwing content 7.5ml/l, PAM throwing content 1ml/l, coagulation mixing time 20min, settling time 20min. Under the best test condition the treatment effect : after coagulation processing, sulfide content 0.845 mgl/1, elimination rate 95.88%; Fluoride content 8.74 mgl/1, elimination rate 93.87%; COD content 115.19 mgl/1, elimination rate 62.93%. In the biochemistry method the desulfurization wastewater throwed the domestic sewage in power plant is enable to biochemical ability. Controlling the proportional of throwed adds in the 40%⁴5%, Cl- density about 6000 mg/l. Using the orthogonal experiments determine the best operational paramenters of SBR reactor treatmented the desulfurization wastewater after chemical treatment: anaerobic time 0.5h, the aeration time is 8h, oxygen deficit time 4h, sedimentation time 1h, aeration quantity 0.2 m³/h, MLSS 2000 mg/L. Under optimum condition the elimination rate of COD,NH⁴⁺-N, NO₃^- N from SBR respectively achieves 91.60%,89.23% and 63.90%, the effluent density of wastewater respectively is 73.41 mg/L, 7.19 mg/L and 9.34mg/L. And the results achieve requests of GB8978-1998 " integrated wastewater discharge standard ".