Flocculation Experiment On Granite Cutting Wastewater And Study Of Flocculation Kinetic

The paper is research on the granite cutting wastewater of a stone factory where in Dawu country.Base on the wastewater quality characteristics,choice the coagulation sedimentation method to handle it and get the most optimal reaction parameters and condition.Moreover,to simulating such the cutting wastewater and study on flocculation kinetics.After the purification of the wastewater,it can be discharged or to used for cooling water.Experiments selected calcium oxide and polyacrylamide coagulation for sedimentation pretreatment.Single factor experiments results show that the optimum combination conditions for the cutting wastewater is as follows: the dosage of CPAM is9mg/L,the dosage of CaO is 1500mg/L,pH value at 10 to 12,,the stirring speed is60~120 r/min and stirring time is 60~120s,total settling time is about 40 min.Under which condition the removal rate of residue is 99.52% and removal rate of suspended substants is 98.46%.Experiments results and theoretical analysis showed that the mainly mechanism is that the calcium oxide in the solution to promote the formation of calcium ions in the water to generate calcium salt precipitation.The cationic flocculant and the the negatively charged ions of solution are charge neutralized and in the whole reaction the deposition netting,sweeping,adsorption and bridging are pushing the reaction.Orthogonal experiment with simulating wastewater and find out the five factors of affect efficiency of the whole reaction are,coagulant dosage > pH > mixng rate >coagulant dosage > stirring time.The optimal condition are CPAM is 0.011g/L,the dosage of CaO is 1.1g/L,pH value at 12,the stirring speed is 60 r/min and stirring time is60 s and the removal rate of residue is 97.84% and removal rate of suspended substants is94.96%.This paper is also study on the formation kinetics of the flocculation.The regularity of particle size distribution can be divided into parts.In the first part,in the effect of flocculation and coagulant,the smaller particles were aggregated into clustersand the flocs sizes were increased.The Zeta potential of the water is turn to zero.The flocculation driving force which is dominated by the charge difference is gradually completed.In the second part,the main flocculation driving forces are the flocs differential subsidence and Brown motion.The rule of particle size distribution was studied in this paper and be tested in 60%and 140% concentrations of simulated water.The results show that the flocculation mechanism is also applicable.In addition,for this kind of water in mixing rate of 60r/min and stirring time of 60 s conditions,the G value is 4.1441 and the Fr value is 1.3322.It is consistent with expect and in the model conditions should be reduce the mixing rate and prolong the stirring time could be get better effect.