Experimental Research On Backwashing Wastewater And Iron Sludge Treatment In Groundwater Works For Iron And Manganese Removal

By experiment, the coagulation effect, influence factors of the backwashing wastewater in the groundwater works for iron and manganese removal was studied, and the sludge sedimentation and dehydration performance was discussed, and their influence factors were investigated. The results showed that the CPF and PAM coagulation effect was the best, the ferric chloride was the second, the PAC was the worse, and the aluminum sulfate was the worst. When the iron content of the backwashing wastewater was about 100mg/L, the natural settling effect was not good, but if some coagulant was added into the backwashing wastewater, the backwashing wastewater had good sedimentation effect in the shorter time. In the initial 10~30min after the coagulation, the iron content of the clear supernatant lowered quickly, and with the increase of the sedimentation time, its iron content decreased slowly. When pH value was about 7.5, the coagulation mechanism of the aluminum sulfate, polychlorinated aluminum and ferric chloride may be mainly charge neutrality action and adsorption bridging action, and the PAM coagulation mechanism may be mainly adsorption bridging action, and the CPF may have some charge neutrality action besides adsorption bridging action.When the sludge solid content is decreased, the sludge sedimentation velocity increases. When the high molecule organic coagulant (CPF) is added in the sludge, the sludge sedimentation velocity grows obviously, and increases with the growth in the coagulant dose. But when pH value is increased, the sludge sedimentation effect becomes worse, and when the pH value is 9.57, the sludge sedimentation does not happen basically. The lower the temperature, the slower the sludge sedimentation velocity. Dosing the high molecule organic coagulant in the sludge, lowering the pH value, and increasing the sludge temperature all help improve the sludge dehydration performance.