Experimental Study On The Trace Phosphorus Removal In Drinking Water

Coagulation sedimentation is the commonly method in drinking water treatment, through the coagulation sedimentation can remove contaminants, impurity and turbidity, filtration is the further water purification process after coagulation sedimentation,they are commonly used in drinking water treatment.This experimental research contents are:using single coagulants to remove trace phosphorus in drinking water; using coagulant combination method to remove trace phosphorus in drinking water; Application natural quartz sand to filter trace phosphorus; modified quartz sand in different mehods and research different modified quartz sand to the removal of trace phosphorus.Used Ferric trichloride, poly ferric sulfate, poly aluminium chloride, poly aluminum-ferric chloride and ferrous sulphate five different coagulants for coagulation to remove phosphorus. The results show that Ferric trichloride and poly ferric sulfate has good effect in phosphorus remove. Ferric trichloride and poly ferric sulfate dosage are15mg/L, the effluent meet drinking water biological stability limits requirement.The suitable pH range to the removal of phosphorus by ferric trichloride and poly ferric sulfate are6～7;at5～25℃conditions phosphorus removal effected by temperature is small, at35℃conditions phosphorus removal rate decreased, by increasing coagulants dosage can satisfy drinking water biological stable limit range requirements.FeCl3and PAFC combination has good phosphorus removal, FeCl3and PAFC combination can reduce coagulant total dosage, and overcome the the problem of great chromaticity by single dosage of FeCl3.Dosing FeCl3first, dosing PAFC after FeCl3, with PAFC and FeCl3dosing ratio are1:3, phosphorus removal has best effect. When coagulant total dosage are12mg/L, water phosphorus concentration can below3μg/L, meet drinking water biological stable limit range requirements.FeCl3and PAC combination to the removal of phosphorus, first dosing FeCl3, dosing PAC after, FeCl3and PAC dosing ratio are3:1has best effect.when coagulant total dosage are10mg/L, water phosphorus concentration can below3μg/L, meet the drinking water biological stable limit range requirements. FeCl3and PAC blends can reduce coagulant total dosage, and overcome the the problem of water chroma by single dosage of FeCl3Natural quartz sand has low removal rate of phosphorus. In first220min of filtering, the average removal rate of phosphorus are14.53%. Acid modified quartz sand has better effect of phosphorus removal than natural quartz sand, in the filtering at the beginning, phosphorus removal rate can reach50%, in220min of filtering by acid modified quartz sand the average removal rate of phosphorus was21.51%, is still low. Al modified quartz sand has high removal rate of phosphorus, In100mins of filtering, water meet the limits drinking water biological stability requirement, Al modified quartz sand in partial acid and neutral condition has high removal rate of trace phosphorus, the phosphorus removal rate reduced in alkaline conditions. Fe modified quartz sand filter in80mins, water meet the limits drinking water biological stability requirement, after100mins, phosphorus concentration rise fast. Fe modified quartz sand in the pH value of6phosphorus removal rate near the top, in acid and alkali conditions the phosphorus removal rate decreased.Ferric trichloride and poly ferric sulfate has good effect in trace phosphorous removal in drinking water, using PAFC and FeCl3complex or FeCl3and PAC combination can overcome the problem of water chroma by single dosage of FeCl3and reduces total coagulant dosage. When using other common coagulant difficult to meet the drinking water biological stable limit range, we can using modified filter materials to adsorption phosphorus. Al modified and Fe modified quartz sand have good effect on phosphorus removal, it is suitable for drinking water phosphorus removal.