| With more serious organic matter pollution, the water quality questions which caused by organic matter have become attention hotpot. This would post a challenge to traditional water treatment system. Coagulation-sedimentation process, which is the main process during water treatment, has important influence on the load and cost of subsequent process. Meanwhile, it also dominates the effluent quality of water treatment system in some extent. Most water treatment system still use aluminum coagulation,which might increase the aluminum of the water, thereby endangering humin health. In this experiment, coagulation-sedimentation continuous-flow is operated with variable speed and two layer inclined plate cogulation sedimentation technology which designed by the previous researchers. The experiments is to quest the best conditons, focusing on enhanced the effect of coagulation-sedimentation and corresponding to reduce the load of subsequent process and improve effluent quality of water treatment system.In this research, the influence of various operating conditions on the humic acid water has been investigated with variable flow rate and double plate coagulation-sedimentation technology. The operating conditions include coagulant type, particle concentration of raw water. Turbidity, particle population, particle fractal dimension, UV254 and residual Al of operational process are detected and analysisded, eanwhile evaluate effluent quality. The results show that 30mg/L is the optimal dosage for all coagulants. The best turbidity removal was obtained by PACl, whereas the Al Cl3 had slight better UV254 removal and lower residual Al. Thus, PACl was the optimal coagulant to achieve better coagulation performance for variable flow rate and double plate coagulation-sedimentation technology. With increasing particle population of raw water, residual turbidity gradually increased. While UV254 removal increased first and then decreased and increased finally. Residual Al decreased first and then increased and presented fluctuation finally. It can be found that effluent quality of PACl was more stable than other coagulants.By the analysis of the data during coagulation-sedimentation process, the type of flocculant and the dosage have the great impact on the variation of UV254 removal, dissolved Al, particle population and particle fractal dimension.of coagulation-sedimentation process. Howeber, the particle concentration in the raw water has little effect on variation of its.,significantly affect the size of its’ value. The water quality indicators between the various stages of the coagulation process is constantly changing, having a direct impact on the water quality. The effect of the primary flocculatin stage and the precipitation stage have a critical influence on the effect of the operational process.In fact, there is velocity gradient area in variable flow rate and double plate sedimentation tank., which can produce dynamic particle suspension area. The dynamic particle suspension area had the ability of interception and adsorption and adsorbing organic matter and dissolved Al, thereby improving effluent quality. For variable flow rate and double plate coagulation-sedimentation technology, sludge recycle can change the characteristics of floc particls in coagulation process to strengthen the dynamic particle suspension zrea, improving the effluent quality dramatically. However, this phenomenon could be only observed in fixed recirculating ratio of sludge.In addition, the influence of varying flow was also investigated for variable flow rate and double plate coagulation-sedimentation technology. The results showed that flow had slight effect on this technology. In the flow range of this research, the effluent quality was excellent. The residual turbidity was obviously varied with increasing flow, whereas residual Al was obviously affected by decreasing flow. Certainly, the results were still in the range of National regulations. For UV254 removal, the water flow had slight influence. |
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