Pilot Study On The Treatment Of Qiantang River Source Water By Uf-Nf Membrane Process

Due to its difficulty to be degraded and biological inhibition, the antibiotics were hard to remove effectively by conventional drinking water plant and finally resided in the water, which was hazardous to human health. The paper studied the removal efficiency of the combination of UF and NF process to sulfamethazine by pilot tests, and the effects of water matrices and operating conditions on the combination process to remove sulfamethazine were studied as well. The stability and performance of physical cleaning and chemical cleaning on membrane fouling control by the hybrid system were analyzed. The unit cost of water was calculated based on the optimization of the hybrid system, and meanwhile the combined process capacity of emerging pollution was investigated.Water matrix had a great influence on the removal of sulfamethazine in the combined process. When the dosage was 8 mg/L humic acid and 5mg/L kaolin, the removal rate of sulfamethazine increased 14.4% and 9.4% respectively, however, the UF membrane fouling was exacerbated; when the ionic strength increased from 200 s/cm to 400 s/cm, the removal rate of sulfamethazine increased by 3.4% through the combined process, and the greater ion intensity was, the higher the removal rate would; the p H value affected the process of sulfamethazine hydrolysis, when the p H=9 the removal rate of sulfamethazine could reach 99.9% of the combined process, and alkaline environment was more conducive to the removal sulfamethazine; polyvalent ion changed the charge density in the membrane surface, enhanced charge repulsion, and improved the removal rate of sulfamethazine in the combination process, in addition, 2.5 m M Ca²⁺, Mg²⁺, CO₃^2- and SO₄^2- could make the removal rate increase to more than 99.8%.Operating pressure, running time, cross-flow velocity and recovery of the system had a significant effect on the change of membrane flux, but lower effect on sulfamethazine removal of the combined process; membrane pore size exerted a significant influence on sulfamethazine removal, when the pore size changed from 0.55 nm to 0.85 nm sulfamethazine removal rate decreased by 11.9%, which indicated that the smaller pore size was, the higher the removal rate was. Ultrafiltration had better removal efficiency on turbidity, particle number and microbial removal, while the dissolved organic matter removal effect was poorer. Increasing flux, extending running time, and enhancing concentrated water discharge cycle could improve the removal efficiency of organic matter and turbidity of ultrafiltration to some degree, due to the cake layer’s adsorption and intercept action, while the membrane fouling rate would increase; raising operating pressure, recovery and cross-flow velocity not only improved the desalination performance of nanofiltration membrane, but also accelerated NF membrane fouling rate. Through adding high concentration of pollutants into the influent and detecting the water quality of the effluent, it could be found that the combination process had a good treatment effect on emerging pollution, such as organic matter, inorganic salt ions and heavy metal ions. So it could be used as an emergency technology in water treatment plant.