The Development And Application Of A High Efficient Type Of Clarification And Concentration Equipment

With the rapid development of our economy and society, the drinking water quality standard is improved gradually. In 2006, the ministry of health and the national standardization management committee issued jointly the new drinking water quality standards (GB5749-2006). The drinking water quality indexes were improved from the original 35 to 106 items. Drinking water turbidity index was also decreased from 3NTU of 1985 to 1NTU. Clarification technology always is the core process of municipal water treatment, directly influencing the treatment cost and the qualities of the production. However, many problems still exist in clarification field until now. As for the clarification equipments, which are operated in our country nowadays, are so old. Although there are a lot of advanced equipments are developed year by year, it is due to the equipments'construction difficulties, or the expensive construction and running cost, these equipments have not been widely applied. Therefore, to develop a kind of clarification equipment, which features high efficiency, low investment and operation cost and easy construction, is so necessary.Based on the above reasons, this paper compared the characteristics of the mainstream clarification equipments at home and aboard. In the end, we chose a kind of micro vortex coagulation precipitate equipment charactered with tube vortex mixing, micro vortex flocculation board and efficient compound inclined precipitation plate as the original equipment. Depending on the research and practice of clarification technology, we optimized the original equipment in the following aspects: a, widen the flocculation reaction galleries to reduce construction difficulty, b, used new flocculation reaction board to improve the efficiency of this equipment, c, added sludge concentration function, improving equipment utilization efficiency, in order to reduce the cost, d, recycled sludge, to enhance the clarification of low turbidity water, e, used new type of precipitate plate, to improve the precipitation effect.Then, this equipment was applied to clarify two different kinds of raw water (low temperature and low turbidity raw water and high turbidity raw water) from the first water plant of Changchun in order to optimize it. Experiments mainly lay in: a, in the low temperature and low turbidity case, optimizing the doses of flocculation agent (PAC) and coagulant (PAM); investigating the influence of different factors on the sludge solid content; optimizing the quantity of recycle sludge and the point where we should dose the recycle sludge, b, in the high turbidity case, optimizing the doses of flocculation agent (PAC) and coagulant (PAM); optimizing the retention time in mixed section; comparing the performance of this equipment with different series of flocculation board; optimizing the different kinds of inclined plates. The main conclusions are as follows:1, in the low temperature and low turbidity case, the removal of turbidity is very efficient and this equipment has a good adaptability of the change of the water flow. After optimizing operation parameters, the effect of sludge concentration is good. When the raw water turbidity is 7.0 ~ 9.6 NTU, the temperature is 3.5℃, water flow is 4.8 m3/h, PAC dosing for 30 mg/L, PAM dosing for 0.65 mg/L, discharging mud period for 4h, angular speed for 0.25 r/min, sludge reflux ratio for 0.03, dosing sludge points for the ninth reaction gallery; in this case, mixing time is 1s, flocculation reaction time is 12.83min, the surface load of the precipitation is 2.67mm/s, and the effluent turbidity remains below 1NTU; compared with the similar technologies at home and aboard, it has the advantages in training the low temperature and low turbidity raw water.2, in the high turbidity case, after optimizing the related components and operation parameters of this equipment, the removal of turbidity is efficient. And the effect of sludge concentration is good without the mixing of the mud scraper machine. When the raw water turbidity is 218 ~ 349NTU, the temperature is 20℃, water flow is 4.8 m~3/h, PAC dosing for 35mg/l, mixed time for 9s, PAM dosing for 2mg/l, using seriesⅡflocculation board in the reaction district, the inclined plateⅢin the precipitation section; in this case, mixing time is 9s, flocculation reaction time is 12.83min, the surface load of the precipitation is 2.67mm/s, and the effluent turbidity remains below 2.5NTU; compared with the similar technologies at home and aboard, it has the advantages in training the high turbidity raw water.3, through the economic and technical analysis of the new equipment, the original equipment and the mainstream clarification equipments both at home and abroad, we found that the new equipment achieved the goal of optimizing design with characteristics of high efficiency, sludge concentration function and easy construction. Compared to the mainstream clarification equipments at aboard, the construction cost and operation cost of the new equipmentis would be lower, and efficiency for removal the turbidity would be higher. Compared with the original equipment, the new equipment has the sludge concentration function and less difficulty in construction. Therefore, we can draw the conclusion that the new equipment has the advantages in the aspects of efficiency, low cost and easy construction, it is benefit to improve the technical level of the clarification equipment, meeting the demands of the improved"drinking water standards".