Experimental Study On Compound Coagulant Suitable For High Algae And High Organic Matter Reservoir Water

Algae and organic matter in water can produce disinfection by-products in conventional water treatment,which seriously threaten safety of drinking water.The existence of a large number of algae will also affect the normal operation of the water treatment plant and improve the cost of processing.Coagulation sedimentation method can effectively reduce algae and organic matter content in water.In this study,high algae and high organic matter water was used as test water,and various coagulants were utilized to mix different combinations and proportions for coagulation tests.Coagulant and coagulation conditions suitable for high algae and high organic matter raw water quality were screened out through comparison of coagulation effects.The main research contents are reproduced below.The determination of the optimum hydraulic conditions.The optimum hydraulic conditions are given in the factors of fast stirring speed,fast stirring time,medium speed stirring speed,medium speed stirring time,slow stirring speed and slow stirring time.The optimum hydraulic condition is given in the orthogonal test of the existing chemicals and dosage of the water plant in the experiment.The optimum hydraulic condition for high algae and high untreated water is rapid stirring speed.Degree 300r/min,rapid mixing time10 s,medium speed stirring speed 190r/min,medium speed mixing time 5.5min,slow stirring speed 60r/min,slow stirring time 9.5min.The determination of the optimal dosage.In view of the characteristics of high algae and high organic water quality,7 kinds of coagulants were selected for coagulation test,and their purification effect was investigated,and the best dosage of each coagulant was obtained.The results demonstrate that the best dosage of coagulant is aluminum sulfate 100mg/L,ferric sulfate 105mg/L,poly aluminum sulfate 70mg/L,polymerized ferric sulfate 85mg/L,poly aluminum chloride 90mg/L,poly aluminosilicate 85mg/L,poly aluminum ferric chloride70mg/L.The optimum combination and proportion determination.Polyangiaceae ferric chloride and potassium ferrate were used as main agents to mix with other coagulants respectively,and the best blending scheme was obtained through coagulation test.The results show that:for high algae and high organic water,the best combination and proportion of compound agent are 3/5poly aluminum iron chloride and 2/5 polypropene chloride,1/5 potassium ferrate and 4/5polypropene chloride.The study of coagulation singles factor test.Three factors were selected : compound dosage,pH and static time.The best values of the three were produced by coagulation single factor test.The results show that:for high algae and high organic water,the best dosage of two compound medicaments is:polypropene ferric chloride 40mg/L and poly aluminum chloride34mg/L compound;potassium ferrate 2.4mg/L and polypropene chloride 72mg/L compound.The optimal pH of the two combinations was 6 and the best stationary time was20 min.Coagulation response surfaces test.The independent variables were dosage of compound medicament,pH and static time.The dependent variables were permanganate index and chlorophyll a.The coagulant response surface test was performed,and the optimal value was predicted.The results show that for high algae and high organic water,when the compound agent dosage is polysemantic ferric chloride 42.78mg/L,poly aluminum ferric chloride37.2mg/L,pH is 6.82,and the stationary time is 23.88 min,the optimal value of response surface is predicted,the permanganate index is 1.67,the chlorophyll a 3.77?g/L,and the result of the test is 1.68 of permanganate index and the chlorophyll a 3.81?g/L is basically the same.When the dosage of potassium ferrate and poly aluminum sulfate compound agent is potassium ferrate 2.66mg/L,poly aluminum ferric chloride 74.6 mg/L,pH is 6.61,and the stationary time is 24.11 min,the optimal value of the response surface is predicted,the permanganate index is1.96,and the chlorophyll a 2.86?g/L is close to the test results and the permanganate index is1.97,The chlorophyll a 2.88?g/L,indicating that the response surface test can predict and predict the optimal value very well.