Study On Primary Treatment Of Wastewater By Intensified Flocculation

This paper presents a study on disposing wastewater of Wuhan city by intensified flocculation in allusion to property of the wastewater. Firstly domestic sewage was treated by two flocculants, A-type nanometer-characterized water decontaminant and PAC. The operation parameters of the experiment were changed in order to optimize the operation condition of the chemical flocculation process. Then the performance of the nanometer-characterized water decontaminant was studied. It was used to treat artificial printing and dyeing wastewater. The results showed the sedimentation rate could be enhanced by B-type nanometer-characterized water decontaminant when the A-type nanometer-characterized water decontaminant was applied. At the same time, the color removal rate and COD removal rate could also be enhanced. Then dosing method of PAC was selected. The results showed the color removal rate and COD removal rate could achieve 98.6% and 98.2% as the total dosage was 650mg/L.Based on micro-vortex theory, experimental results and experiential data, vertical-piped flocculation reactor designed by our laboratory was studied a lot in this paper. The most suitable dosage of A-type nanometer-characterized water decontaminant was 400mg/L when it was used to dispose printing and dyeing wastewater in the reactor. The reactor showed good and steady disposal effect on municipal sewage when the dosage of polymeric aluminum chloride was in the range of 45-55 mg/L. And then high-charged municipal sewage at Zhuankou Developing District was treated in the intensified flocculation reactor. This municipal sewage made up of domestic sewage and industrial sewage. The reactor showed stable disposal effect when PAC, PAFC or FC was applied to this municipal sewage at dosage of 50mg/L. The three flocculants showed good phosphorus removal efficiency, especially ferrum chloride. Recurring to water level difference and hydraulics function, this reactor can run without other agitation equipments. As the reactor is small-sized and power-saving, it's of great value to be popularized. The reactor fits municipal sewage pretreatment, and it can also be used together with biochemical process to enhance phosphorus removal rate of the latter.