Pilot Research On Pelleting Flocculation Process In Treating Backwashing Wastewater From Groundwater Filter Column For Ion And Manganese Removal

In our country’s waterworks, generally, the quantity of backwashing wastewater offilter is3%-8%of the total output water amount.If this part water is directly discharged,it will not only waste energy and water resources but also pollute environment. Pelletflocculation process is a new efficient water treatment technology, which includescoagulation, reaction, sedimentation and sludge returning. This efficient treatmenttechnology has been widely used in high-turbidity water, high algae and low-turbiditywater, the high concentration wastewater of suspended solids, sludge concentration andthe reservoir of low temperature and turbidity, and so on, the water quality withdifferent properties and kinds. The technology has the characteristics of the shorthydraulic retention time, the small floor area, the high surface load, the good effect oftreatment, flexible use and wide adaptability.The static and dynamic research of Pelleting Fluidized Bed (PFB) process wascarried out to treat backwashing wastewater from filter for ion and manganese removalby Contact Oxidation Process in the northern suburbs of Xi’an. The main contentsincluded the suitable operation parameters of PFB, the ability of resisting impact load,the property and dewatering performance of sludge, the effect of water treatment, and soon.(1) The appropriate PAC and PAM dosage was concluded when the wastewaterturbidity was respective700～800NTU and2300～2400NTU by static test. The change of PAC dosage had great influence on the purification of water quality, however, PAMdosage had relatively less influence on the purification of water quality.(2) By the pilot research，we could draw the conclusion that the suitable compulsorystirring rotation speed was n=4～8r/min and upflow velocity was34cm/min。If thedosage was increased appropriately, the maximum upflow velocity was42.5cm/min.When the influent turbidity was700～2000NTU, the suitable dosage of PAC was20mg/L around and that of PAM was1.0～1.25mg/L. When the influent turbidity was2000～3000NTU, the suitable dosage of PAC was40mg/L and that of PAM was1.0～1.25mg/L. The effluent quality could meet：turbidity, Fe, Mn, CODMnwas respectivelyless than10NTU，2.0mg/L，0.5mg/L，2mg/L.(3) The PFB could adapt the condition of intermittent operation and we should havesome effective technical measures to guarantee PAC and PAM continuous dosing.(4) Sludge water content of PFB was90%～97%.The specific resistance of sludge rwas（0.1～0.2）×109s2/g, which was easy to dewater.(5) PFB was feasible to treat the wastewater, and had the characteristics of goodeffluent quality, excellent ability to resist impact load, high stability and the gooddewatering performance of sludge.