Study On Enhanced Coagulation Treatment Of Low Temperature And Low Turbidity Water

With the rapid development of economy and the continuous improvement of people’s living standard, people on drinking water quality standard also will continue to in improving, which requires more effective and more advanced water treatment technology. Low temperature and low turbidity water is always a difficult problem to a feed water treatment because of its low oxygen consumption, high viscosity, low alkalinity characteristics. The traditional coagulation process is not only high cost but also the quality of the effluent cannot reach the ideal result. In this paper based on the enhanced coagulation technology of low cost and simple process, study the coagulation beaker experiment for the low temperature and low turbidity water for the optimal solution.This article mainly starts with the enhanced coagulation technology, first test of raw water for the determination of hydraulic best conditions through the orthogonal experiment method. The experiment results indicate that when the fast mixing speed to 350r/min stirring for 60 s, medium mixing speed to 120r/min stirring for 150 s, slow mixing speed to 50r/min stirring for 500 s, the water indexes of turbidity, ammonia nitrogen and CODMn are the best. On this basis, through comparison of different types of water indexes of coagulant and coagulant aid selected PAM and PAC as the best coagulant and coagulant aid and the best dosage is 40mg/L and 0.9mg/L. Enhanced Coagulation orthogonal test showed that the water indexes of turbidity and CODMn can reach targets, but ammonia nitrogen cannot reach water indicators. PAM optimal dosing time in the 60 s after PAC, PAM optimal dosing quantity is 1.0 mg/L, the PAC optimal dosing quantity is 35 mg/L, the best pH value is 7.To further remove ammonia nitrogen in the raw water, the test adopts combination method with pre-oxidation agent through comparison of different types of water indexes of pre-oxidation agent selected NaClO as the best one going on pre-oxidation enhanced coagulation technology. The test results showed that NaClO pre-oxidation enhanced coagulation can not only effective removal of ammonia nitrogen in water, but also can reduce the content of turbidity and CODMn. pre-oxidation optimum stirring speed is 200r/min, NaClO optimum dosage is 20mg/L, optimum oxidation time is 20 min, the best pH value is 7.