Multi-stage Flocculation Coupled Relationship In Water Treatment

Flocculation is one of the most significant processes for water treatments,which determine the running conditions of the following processes,quality of effluent and operation costs of water treatment eventually.Therefore flocculation process is an increasing popular concern in water treatment discipline.Discussed the the flocculation efficiency variation with G and T value changes for treating kaolin suspension and optimize the two ranges. By the Cascade of coagulation tests of coagulation to research the variation in G and GT.The experiment results showed that the efficiency of Coagulation gradually improved as the cascade coagulation reaction order increasing.effluent turbidity have a large lap between the frist and the second coagulation reaction.however,the effluent turbidity between the second and the third coagulation reaction have a relatively small lap. So the third coagulation reaction particles are substantially to form flocs,and the flocs are bigger to form sediment.The results show that,compared with the second-order reaction,the third velocity gradient under the removal rate increased by about8%,15%removal rate than the first-order ring energy will help floc cohesion grew up without crushing.In the first flocculation test,at the speed of80r/min,the residual turbidity of effluent appeared,corresponding to the minimum residual turbidity of effluent G value is67.98s-1,stirring time t is36min,GT is138679.2.In the second flocculation test, as a grade80r/min, two grade60r/min,the residual turbidity of effluent appeared,the corresponding G value is:G1=67.98s-1,G2=44.15s-1and G1:G2=1.54;stirring time t are:ti=36min, t2=18min,showed that the two step flocculation to achieve the best effect of t1/t2=2;the GT value is:GiT1=138679.2,G2T2=42384, G1T1:G2T2=3.27.Description,two step flocculation reaction,when the GT value are GiT1=138679.2,G2T2=42384, and when the optimal ratio is G1T1:G2T2=3.27,effluent quality achieve to the best.The third step flocculation test,the residual turbidity of effluent appeared:one level140r/min, two level80r/min, three level60r/min. corresponding to the G values:G1=157.37s-1, G2=67.98s-1,G3=44.15s-1.G1:G2:G3=3.56:1.54:1;the best mixing time:ti=16min,t2=14min, t;,=10min,stirring time scale at this time:1.6:1.4:1,showed that the three step flocculation in water, to achieve the best effect when t1/t2/t3=1.6:1.4:1;the corresponding optimal residual turbidity of effluent GT value is:G1Ti=151075.2,G2T2=57100.2,G3T3=26490, G1T1:G2T2:G3T3=5.70:2.16:1, description, three step flocculation reaction,when G1T1=151075.2,G2T2=57100.2, G3T3=26490,and GiT1:G2T2:G3T3=5.70:2.16:1,effluent quality to achieve the best.Through the terraced flocculation dynamics test process,the paper reaches the optimal range of composite indicator (G、t、GT) to control the flocculation effect,find the relationship between the G,t and GT in all levels of reaction,provides a scientific basis for the process design and operation,and also provides reasonable guidance for practical engineering applications.