This paper treats aluminum surface treatment solution wastewater and adopts coagulation-chemical precipitation method (combination of CaO, PAC and PAM) to remove F -, PO 4 3− and SO 4 2− . The study explores an approach that can remove F -, PO 4 3− and SO 4 2− in the wastewater simultaneously. Through optimization and improvement of reagent dosage and reaction conditions, the treated wastewater reaches the national discharge standards. The experimental results show that the optimal conditions for removal of F -, PO 4 3− and SO 4 2− are: 1150 mg of CaO, 110 mg of PAC, 85 mg of PAM at pH 9 and a reaction temperature of 323 K for a reaction time of 30 min. After treatment, the concentration of F -is 4.30 mg/L, which is lower than discharge standards of fluoride-containing industrial wastewater (10 mg/L). The concentration of PO 4 3− is 0.90 mg/L, lower than the second grade of discharge standard of phosphate-containing industrial wastewater (1.0 mg/L). The concentration of SO 4 2− is 125mg/L, lower than the maximum of allowable concentration of sulfate in drinking water standards (250 mg/L).
Abstract. Dyeing wastewater complex composition, color large organic pollutant concentration is very high, in the field of wastewater treatment is a kind of low biodegradability, biodegradation of industrial wastewater. Based on extensive research, printing and dyeing wastewater treatment method commonly used in the classification, and analyzes the advantages and disadvantages of each treatment and the effect of each treatment method, research has certain reference value for dyeing wastewater treatment process selection.
Removal of hexavalent chromium ions (cr 6+ ) from wastewater produced by surface treatment of aluminum was performed by ferrite precipitation. By varying the reactant concentrations and reaction conditions the optimal conditions were established for chromium removal. The following variables were tested: concentration of ferric salt (FeSo 4 ·7h 2 o), the ph during oxidation-reduction, the ph during co-precipitation, the reaction temperature and the incubation time. The results indicate that chromium removal is optimal when ferric salt is added in excess to chromium at a ratio of 14 to 1 (above the theoretical optimum), the redox reaction is performed at ph 4, precipitation is performed at ph 9, the reaction temperature is set at 75°c and the reaction duration is 20 min. under these conditions, a removal rate of 99.97% could be obtained, resulting in a residual concentration of 0.29 mg/L hexavalent chromium from with initial concentrations of 1539 mg/L. Wastewater thus treated fulfilled the maximum allowed standard of 0.5 mg/L.
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