Optimization of dredging residual water treatment by magnetic loading coagulation using response surface methodology
In this paper,the dredging residual water in the dredging mud dumping area of the project to divert water from the Yangtze River to the Huaihe River is used to carry out experiments,exploring the treatment effect of nine kinds of coagulants on dredging residual water,optimizing the process conditions of magnetic loading coagulation treatment of dredging residual water by using response surface methodology,and analy-zing the changes of colored dissolved organic matter and nitrogen and phosphorus concentrations during this process.The results of coagulant screening experiments show that aluminum sulfate is the best coagulant when the removal rate of suspended solids(SS)from dredging residual water is taken as the evaluation index.The response surface test results show that the aluminum sulfate dosage has the greatest effect on SS removal rate of dredging residual water,followed by stirring G value and magnetic powder dosage.The optimal process conditions under the experimental conditions are as follows:the magnetic powder is 260 mg/L,the a-luminum sulfate is 40 mg/L,and the stirring G value is 80 s-1.The colored dissolved organic matter in the dredging residual water is mainly fulvic acid and humic acid,which can be selectively removed by magnetic loading aluminum sulfate coagulation.Magnetic loading aluminum sulfate coagulation can achieve the standard discharge of SS,chemical oxygen demand(CODCr),ammonia nitrogen and total phosphorus in highly concen-trated dredging residual water(SS mass concentration of 1 405 mg/L),and the addition of magnetic powder significantly improves the efficiency of removal of SS by coagulation.The research can provide reference for the development and application of efficient treatment technology of dredging residual water.
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