Experimental Study On The Performance Of Combination Of Coagulants (pac-pdmdaa) On Jialing River Souce Water Treatment

Jialing River is typical of "Peach Blossom Water" in spring and the high turbidity water in summer. "Peach Blossom water" is peach hearing, it means that is the complexity quality of the raw water, high content of humus organic compounds, pharmaceuticals consumed in large quantities, the poor sedimentation of the flocs by coagulation, and it is hard to deal with by conventional water treatment processes. High turbidity water means that is turbidity of the raw water, large sediment content, it mainly refers to the turbidity of the water is greater than or equal to 1000NTU. The complex coagulant coagulation technology of aluminum chloride (PAC) and poly diallyl dimethyl ammonium chloride(PDMDAAC)is researched to raise turbidity removal in the high turbidity and to raise the humus removal of toxic and some hazardous organic compounds in "Peach Blossom Water" in this article.PDMDAAC is organic polymer quaternary ammonium in the test. The test shows that the coagulant dosage is not suitable for adding separately, and with other coagulant dosing. Through complex tests with the several coagulant dosing and PDMDAAC, it demonstrates that mixed PDMDAAC and PAC is the best.Duing the "Peach Blossom water" period, the optimal mixture ratio was PDMDAAC: PAC = 1:100, the average complex coagulant dosage was 8mg/L, PAC was 14.3mg/L. The proportion of complex was lower, the size of alum was smaller. It showed that compound coagulant dosing was superior to PAC by production experiment. The average concentration of the remaining aluminum was 0.028 mg/L in the treated water by compound coagulant; the average concentration of CODMn was 1.52mg/ L, the average removal rate was 35.8%; the average concentration of ammonia nitrogen was 0.15mg / L in settling tank effluent, the average removal rate was 35.8%.Duing the high turbidity water, the optimal mixture ratio was PDMDAAC: PAC = 3:500, the coagulation effect increased with the increase of the solution concentration. When the turbidity was less than 100NTU, the complex coagulant dosage was 6~15mg /L, the PAC was 15~20 mg/L; when the turbidity was in the 100~2000NTU, the complex coagulant dosage was 15~25 mg/L, the PAC was 30~40 mg/L; when the turbidity was in the 2000 ~ 6000NTU, the complex coagulant dosage was 30~40 mg/L, the PAC was 40~60 mg/L. It showed that compound coagulant dosing compared with the single PAC, it not only could save more dosage, and coagulation effect was well. The average concentration of the remaining aluminum was 0.034 mg/L in the treated water by compound coagulant; the average concentration of CODMn was 1.37mg/ L, the average removal rate was 66.82%; the average concentration of ammonia nitrogen was 0.11mg / L in settling tank effluent, the average removal rate was 34.81%.Therefore, the complex coagulant PAC-PDMDAAC can raise the turbidity removal rate during the high turbidity water, and the removal rate of the humus or other organic matter during the "Peach Blossom water".