Study On Treatment Of Compound Flocculant On Oil Contained Water

This article was based on the oil contained wastewater which has launched significant impact on environment and human health.The preparation of modified diatomite, cationic flocculant PDTC and modified polyaluminum chloride PASC and treatment of oil contained wastewater were illustrated by the method combinding theoretical analysis and experimental verification.Study explained these following facts: the effect of absorption of modified diatomite was better than diatomite; using both two modified agent was better than one and the best ratio was CTMAB∶TMAB=1.0∶2 .0; the dosage of modifier had effects on absorption; and the optimal conditions of absorption were pH=7～8, the best time of absorption 50min; Then the removing rate of oil from water using modified diatomite was 75.45%. And the optimal technics ready for PDTC were concluded, includes: the reaction of ethanediamine and CS2 in alkaline solution with mass ratio of 12.00:28.88:16.00, the reaction temperature of 10～15℃,20～28℃, the stirring time of 90 min with speed of 100r/min, 10ml alkali salt and little ethanol and aether. Then the removing rate of oil was 85.43% by using of PDTC with 10ml. Moreover, the optimal conditions of preparation for PASC were pH=5～6,the concentration of SiO2=2.5%,A1/Si=1.0。The operational parameters for wastewater treatment were investigated.The best operational parameters were found that dosage was 125mg/L, pH=8,stirring time was 20min,stirring temperature was 50℃. The experiment for application showed that PASC has better flocculation efficiency in wastewater treatment than PAC.Just because of the potential advantage of compound flocculant aiming at treating complicated oil contained water, to get the optimal water treatment technological process were necessary through studying different ratio of these three flocculant, that is, at ordinary temperatures, fast stirring for 3～4min(100～120r/min)and slow stirring for 14～16min(60r/min)in alkaline solution with mass ratio of modified diatomite: PDTC: modified polyaluminum chloride= 2.5g/L :0.025g/L:0.025g/L, and the removing rate of oil can get over 92%, and 91.1% when treating polluted water of refinery in Yan' an, furthermore, the removing rate of COD and turbidity were 68.3%, 98% and 70%, 85.7% accordingly when treating coal-washing wastewater and paper-making wastewater. In all, we can conclude that this kind of flocculant has good function in treating not only oil contained water, but other wastewater with high degree of turbidity.At last, mechanism of flocculant and microcosmic rules of mechanism were analyzed.