Study On The Multi-piped Co-coagulation Flotation Water Purification Equipment

As a high-efficient separation technology,flotation has quickly developed in water supply and treatment of domestic sewage and industrial effluent since1970s. The paper introduced a comprehensive system of air flotation technology development history,status quo and development trend,and moreover some technical parameters which is influential to the flotation effect were discussed.Basic of that we design and development of a multi-piped co-coagulation flotation wastewater treatment equipment which is under the theory that bubble adhesion with floc.The reacting system, the separating system and the slag discharge device were improved primarily.And its performance and parameters is studied in experiment in which waste emulsion is used for the raw water.The equipment mainly consists of dissolved air system, dosing system, pipe mixing and reacting system and multi-piped separating system. The whole process is as follows, raw water is pumped into the pipe mixing and reacting system by sewage pump. Also, coagulator, coagulant aids and pH-conditioning agent are injected in quantitatively by the dosing system. At the same time, dissolved air water added in the mixing and reacting system's three points is made by the DAF-pump. After the contacting and impacting of raw water and dissolved air water in mixer, the mixture flow into the separating system formed by three pipes to achieve flotation. The water level regulator is shut for slag off when the scum is thick.Treatment effect is evaluated by the removal rate of COD and SS. Experiments include coagulation test to determine the optimum dosage and pH. Some sample tests exposit the relations between removal rate and some factors, which are quantity of air, pressure, flow rate, reflux ratio and run-time. This text also discusses the effect of dissolved air water on the treatment by changing quantity and add-in position. Finally, a reasonable slag-off suggestion is decided by the relation between run-time and the thickness of scum, the variation in the thickness after shutdown and the water ratio at different height of stable dross.In the experiment of sample treatment, under the conditions of pH 7~9, operating pressure 0.30~0.35MPa, flow rate 200~300 L/h and reflux ratio50%, the MCF equipment treating the waste emulsion achieves the removal rates of COD and SS up to 80% and 90%. The scum become stable after a three-hour shutdown, of which the water ratio is 70%~90%. The scum should be removed every a hour, discharging at the upper 20mm row drosses.