Analysis of Impact of Dewatered Sludge Filtrates on UF Treatment Process for River Raw Water
A large amount of dewatered sludge filtrates is produced during the sludge treatment in water treatment plant(WTP).In order to avoid the waste of the river raw water in the South-to-North water diversion project,and actively promote the"zero discharge"construction goal of the WTP,the feasibility of recycling the sludge dewatering liquid to the raw water pool for dilution and reuse was evaluated towards the ultrafiltration(UF)using river water as the resource.The operation characteristics of the UF membrane under different sludge dewatering liquid/river raw water mixing ratio were investigated.It was found that when the sludge dewatering liquid was properly diluted,its influence on the UF effluent water qualities and membrane fouling was sharply reduced.When the dilution ratio reached to 1∶800,the effluent water quality and transmembrane pressure growth curve was close to the situation of direct UF of river raw water.In this test,transmembrane pressure growth rate of river raw water was 19.7 kPa/d,while the sludge dewatering liquid reached 25.8 kPa/d.When the two diluted at the ratio of 1∶800,the transmembrane pressure growth rate decreased to 21.3 kPa/d,which was close to river raw water were 21.3 kPa/d,which was close to river raw water.The characterization results of membrane surface showed that with the increase of dilution ratio,the thickness of cake layer,dissolved organic matter in cake layer,the infrared peak intensity of characteristic functional groups,and the relative mass fraction of fouling elements were decreased significantly,and gradually dropped to a level similar to that of direct UF of raw water.The thickness of ultrafiltration membrane cake layer in raw water group was 1.77 μm,while the thickness of cake layer in sludge dewatering liquid group was 4.00 μm,and the pollution degree was heavier.The thickness of the cake layer was reduced to 1.82 μm after the two were diluted at the ratio of 1∶800,and the pollution degree was significantly reduced.The research results can provide reference for the"zero discharge"construction of ultrafiltration WTP in cities receiving water from the South-to-North water diversion project.However,it is worth noting that the rational disposal and utilization of sludge dewatering liquidis still in the initial and exploratory stage,and it needs to be systematically evaluated from the perspective of water quality biosafety and chemical safety in the future.At the same time,pretreatment methods such as oxidation,adsorption and microfiltration separation can be considered to improve the safety of sludge dewatering liquid reuse process.
river raw waterdewatered sludge firtrateultrafiltration(UF)membrane foulingbackflow
万方数据
维普
