Pilot Study On Micro-flocculation-Sand-filters-UF For Treating Micro-polluted Surface Water

At present, due to surface water pollution is becoming increasingly serious, the limitations of conventional water treatment process and the increasingly stringent water quality standards, the development of efficient, and healthy drinking water treatment process has become imperative.In recent years,during the survey of the Ganjiang River,it is found that some Ganjiang water was polluted.Water quality of some reaches is III water quality standards. If water pollution is not effectively controlled, the cities located at Ganjiang River are facing water shortage. Some waterworks, due to the limitations of conventional treatment process,draw Ganjiang River and tributaries water to produce purified water, the factory's water often contain much pollutant. As a result, In view of contaminative situation of some drinking water source in Nanchang,the water prepared for experiment is collocated, and the practical use of the micro-flocculation- sand filtrating - ultrafiltration combined process is rearched in this paper.By adding the coagulant of Al₂ (SO₄)₃ and FeCl₃, it compared the micro-polluted surface water treatment effect and the impact of membrane filtration capability , and studied the long-term stability of operation of the combined process. It has found that, compared with Al₂ (SO₄)₃, FeCl₃ has the better removal effect of pollutant, but it causes more serious pollution to the ultrafiltration membrane By contraries,using Al₂(SO₄)₃ as the coagulan,it can not only remove the conta minated materials,but also keep the good running ability of the ultrafiltration film. In adding coagulant Al₂ (SO₄)₃, as the coagulant dosage increases, the re moval effect of the contaminated materials will be better, but it will also cause the decreasing of the membrane flux. By comparison,it will obtain better removal effect of pollutant and better membrane flux when the adding dosage of Al₂(SO₄)₃ is the 3 mg/l.when the coagulant dosage is 3 mg / l,and the ultrafiltration combined process is long-term running , the UV254 removal rate is over 80%,and the ammonia-nitrogen removal rate is around 60%,while the turbidity has remained below 0.5 NTU,then the outlet water quality is steady-going,so it can meet the daily water demand.it is found that during the ultrafiltration membrane running cause, if the membrane is cleaned by short-time hydraulic washing and backwashing,it can obtain higher membrane flux and meet the demand of continuous running process. When using chemical to do chemical cleaning of the membrane,it is found that,when the consistency of NaOH is 2% ,it will get the most effective cleaning.It will restore higher membrane flux by cleaning,and it is also proved that the organic matter which is micro-granule and easily dissolved in alkali is the main pollutant of the membrane.