Effects Of Aluminum Salts,Iron Salts And Phoslock On Overlying Water Phosphorus And Sediment Phosphorus Forms Under Different DO And PH Conditions

Reducing the phosphorus content in water bodies and preventing the release of phosphorus from sediments is one of the keys to control the lakes eutrophication.Aluminum salts,iron salts and phoslock are often used for nutrient deposition and inactivation,which can not only remove the phosphorus in overlying water but also convert the labile phosphorus into more stable phosphorus forms in sediments,thus reduced the release risk of phosphorus from sediments.In order to find the suitable environment conditions to use of aluminum salts,iron salts and phoslock and explore their response to different environmental factors,this study selected two key factors,i.e.dissolved oxygen?DO?and pH.The experiment was carried out during April 2015to October 2016.We explored the dosage of the inactivation agent first and then set the anaerobic condition and aerobic condition and pH for 5.5,7.5 and 9.5 conditions to add a certain dosage of aluminum salts,iron salts and phoslock.We analyzed the content of phosphorus in the overlying water and sediment.Results indicated that,phosphorus removal efficiency of phoslock was better than that of aluminum salts and iron salts.Phoslock and aluminum salts can remove phosphorus from the overlying water and reduce the risk of phosphorus release from sediments and the effect of DO is not significant.While the removal of phosphorus in overlying water by iron salts was significantly better under aerobic conditions than that of anaerobic condition.The phosphorus removal by the three different inactivation agents was affected by pH.Aluminum salt and phoslock is better than iron salts.The phosphorus removal effect is the best under pH condition of 5.5,followed by 7.5 and 9.5.From the effect on phosphorus forms in sediment,inactivation agents reduced the release of phosphorus from sediments by reducing NH₄Cl-P,BD-P and Bio-P contents in the sediments.The phosphorus removal efficiency of phoslock was better than that of aluminum salts and iron salts.Phosphorus release risk was reduced by phoslock which converted a part of labile phosphorus into stable mineral rhabdophane?HCl-P?in sediment and aluminum salts converted a part of labile phosphorus into metal-oxide bounded phosphorus?Al-P?while the effect was not obvious for iron salts.Therefore,when selecting an inactivation agents we need to know the environmental factors such as dissolved oxygen and pH conditions.