Experimental Study On Treatment Of Backwashing Wastewater By Coagulation Flocculation Membrane Filtration Process

As an important source of drinking water in North China and some arid areas,the problem of high content of iron and manganese is particularly prominent.In the process of treatment will produce a large number of high concentration of iron and manganese waste water,how to use this part of wastewater is very important for water plant.According to the actual water quality of six Waterworks in Shenyang:The mass concentration of water sample was 260mg/L-280mg/L,the mass concentration of manganese was 5.2mg/L?6.3mg/L,and the pH value was about 6.8.Considering the characteristics of the combined process of coagulation flocculation and membrane filtration,the experimental design was carried out.The whole experiment was divided into three parts.Firstly,based on the results of static experiments,the coagulation flocculation membrane filtration process was used to study the influence factors of the coagulation reaction.By controlling the single variable method,the coagulant type,coagulant and coagulant dosage,stirring time,stirring speed and settling time were studied.Pellet flocculation process is mainly affected by the type of coagulant and the effect of adding amount and stirring rate,coagulant according to their characteristics of different mechanisms are different,the general compression of electric double layer,adsorption and charge neutralization and adsorption bridging mechanism of several.The influence of different stirring speed on floc is controlled and destroyed by the rising velocity and flow shear force.PAC was added to 61mg/L as coagulant and PAM as coagulant aid was added to 4.5mg/L,and the contents of iron and manganese in the effluent were reduced to 3mg/L and 1.15mg/L after 160r/min stirring of 10min and precipitation of 15min.Secondly,on the basis of the experimental results,the influence factors of membrane reactor were studied:Aeration quantity,water output and running period.In the aeration amount is 30L/min,pumping water for 3L/h,operation cycle is 12min suction backwashing of iron and manganese in the effluent 1 min operating conditions were stable and lower than that of 0.39mg/L and 0.3mg/L.Finally,the influence factors of the cleaning and recovery of contaminated membrane were studied:Soaking solution,soaking solution concentration,soaking time.The membrane flux of ceramic membrane can be effectively recovered by immersing 12h in O.lmol/L solution of contaminated membrane in HNO3 solution.The quality of effluent water treated by combined coagulation flocculation membrane filtration process is up to the standard of reclaimed water for?urban wastewater reclamation and reuse?)(GB/T25499-2010)(The concentration of iron manganese concentration is less than 0.3mg/L less than 1.5mg/L).The results show that the process is feasible for the treatment of backwashing wastewater.