Treatment of acidic and highly concentrated fluorine-containing photovoltaic wastewater by chemical coagulation-precipitation method
The effects of common calcium source precipitants on effluent pH and total dissolved solids(TDS)were investigated,and the optimal precipitant was identified.Based on this,the effect of chemical coagulation-precipitation method on the removal of high concentrations of F-from photovoltaic wastewater was studied.The results showed that the CaCO3 precipitant could not only effectively remove F-and reduce TDS,but also bring the pH of the treated wastewater close to neutral.FeCl3 required a lower coagulant dosage compared with polymerized aluminum chloride(PAC)and polymerized aluminum ferric chloride(PAFC).The addition of polyacrylamide(PAM)as a coagulant aid strengthened the coagulation effect and shortened the precipitation time.When the CaCO3 dosage was at 0.8 calcium-fluorine molar ratio,the mass concentration of F-reduced from 6 000 mg/L to 83 mg/L,and TDS from 9930 mg/L to 3 400 mg/L.The effluent pH of the chemically treated water after sedimentation reached 5.9.After adding 1.0 g/L FeCl3 coagulant,the F-concentration further reduced to 6.2 mg/L.Finally,with the addition of 14 mg/L PAM coagulant aid,the coagulation and precipitation time was shortened to 2 min.The F-concentration in the acidic high-concentration fluorine-containing photovoltaic wastewater treated by chemical coagulation and precipitation method met the direct discharge standards of Discharge Standard for Water Pollutants of Electronic Industry.The study provides a technical reference for the treatment of acidic high-concentration fluorine-containing photovoltaic wastewater and proposes a feasible treatment scheme for engineering applications.
fluoridephotovoltaic wastewaterchemical precipitationcoagulation and precipitationprocess parameterswastewater treatment
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