Study On Control Technology Of Residual Dissolved Aluminum In Drinking Water

Recently,the problem of excessive residual dissolved aluminum in drinking water has aroused wide concern.Aluminum entering the body can cause a range of neurological diseases,such as Alzheimer’s Disease,Parkinson’s disease,dialysis encephalopathy,osteomalacia and anemia,as well as adversely affect the water supply network.A large number of studies have found that there is an inseparable relationship between the rise of residual aluminum and the extensive use of aluminum-based coagulants,whose mechanism involves the hydrolysis of aluminum-based coagulants and the complexation of dissolved organic matter（DOM）in natural water.Due to the lack of methods that can be used to characterize the interaction process between DOM and coagulants in the coagulation environment,the understanding of the mechanism is not clear,which affects the engineering application.In this study,the pilot process and beaker test were used to simulate the coagulation process in actual engineering;UV-visible spectroscopy and the non-ideal competitive adsorption（NICA-Donnan）model were used to quantitatively characterize the microscopic characteristics of DOM and the DOM-Al complex mechanism;Analyzed the influence of coagulant dosage,pre-oxidation method,and competing ions,coagulant and p H on residual dissolved aluminum.The main research results are as follows:（1）The residual dissolved aluminum concentration is closely related to the type of coagulant and the form of the coagulant hydrolysate.（2）Residual dissolved aluminum is closely related to the content of active functional groups of DOM in water.The number of active functional groups in the raw water is limited,affected by factors such as season and temperature.The dosage of coagulant has a significant effect on the residual aluminum in the produced water.（3）Pre-oxidation has a significant effect on the characteristics of DOM in raw water and produced water.The directional control of DOM characteristics is an effective way to control residual aluminum.（4）Ferric chloride can effectively increase the removal efficiency of phenolic functional groups,and its content is closely related to the concentration of residual dissolved aluminum.In addition,Fe³⁺can inhibit the complexation between the coagulant Al³⁺and DOM.It can compete with the complex DOM in the DOM by adding competing ions and reduce the residual aluminum concentration in the water body after coagulation.（5）Factors such as p H and coagulant are the key factors affecting the residual aluminum concentration of coagulation product water.