Effects of sodium hypochlorite on water quality in a regulating tank in a terminal pumping station of the South-to-North Water Diversion
In the operation of the South-to-North Water Diversion Project Middle Line,algae proliferation and sedimentation gradually became a problem to regulating tanks at the end of the water transmission.The regulating tank management company proposed to dose sodium hypochlo-rite to inhibit the proliferation of algae and sludge floating.However,the effects of sodium hypo-chlorite on water quality,suspended solids,and sludge are unknown.Thus the effects of dosing sodium hypochlorite on water quality at different depths and characteristics and properties of silt were investigated.Dosing sodium hypochlorite caused a temporary increase of suspended particles in the water,but at the same time increased the sedimentation rate of suspended solids.The sedi-mentation rates of suspended solids increased with the doses of sodium hypochlorite.Sodium hypo-chlorite reduced the content of organic matter in the effluent water but did not increase turbidity,leading to the improvement of effluent water quality.As sodium hypochlorite was mixed with the sludge,it slightly destroyed the attachement of organic matters,algae and microorganism on sludge particles,leading to the increase of total organic carbon.Sodium hypochlorite caused the in-crease of turbid layer depth and settling speed in sludge settling processed.Dosing sodium hypo-chlorite did not increased the turbidity of the effluent.The formation of disinfection by-products was lower than the detection limits.The particle sizes of sludge was not affected by sodium hypo-chlorite.
South-North Water DiversionAlgaeChlorinationWater supply safetySludge