Experimental study on pretreatment to high sulfate and organic wastewater with method of anaerobic reverse-sulfide and precipitation

After four stages of the hydraulic loading being lifted,high sulfur and organic wastewater approached the actual water quality conditions(COD_cr concentration=9 300 mg/L, equivalent organic sulfides concentration=534 mg/L)and was anaerobic biological treated through the hydrolysis acidification reactor.Finally,COD_Cr loading rate reached 11 kg/(m³·d) and obtained the conclusions of sulfide inhibition concentration 400 mg/L,organic sulfide reverse-sulfide rate reaching 80% and COD_Cr removal rate reaching 54%.In order to remove sulfides by process of precipitation respectively the effects of the amount of precipitation agent added, stirring speed and the initial pH on the removal of sulfides were investigated. Finally, the optimum conditions were determined as initial pH=7.5, FeCl₂·4H₂O adding amount of n(Fe²⁺):n(S^2-)=1.1 and stirring speed of 80 r/min for 30 min with sulfide removal rate reached 81%.