Influences of pretreatment methods on advanced treatment of printing and dyeing wastewater by UF membrane

Taking the secondary effluent from a printing and dyeing wastewater treatment station as the experimental water,the influences of different preatment methods(sand filtration,microflocculation and microflo-cculation-direct filtration) on UF membrane performance and pollutants removal were investigated.The results showed that,along with time passing,sand filtration caused irreversible membrane fouling.The membrane fouling condition could be relieved by microflocculation,and be improved by microflocculation-direct filtration.All of the above pretreatment methods could ensure the effluent turbidity less than 0.1 NTU,the removal rate of CODCr by microflocculation direct filtration was close to 70%.Microflocculation-direct filtration could effectively relieve the membrane fouling,and had good turbidity and organic pollutants removal performance,which showed it was a good preatment process.