Studies On The Influence Of Coagulant On Sluge Dehydration Performance In Operating Conditions

Sludge treatment of urban sewage treatment plant(MSTP) is an indispensable and timely part,whose purpose is reducing volume,stabilifying,no-poisonus and comprehensive survey,guaranteeing the property operation and the treatment effeet of MSTP,preventing a second pollution.Sludge contains large proportion of water,up to 95%-99%,resulting in huge volume,which bring too much trouble when disposing sludge,bring a number of problems in process of treating the sludge.But due to its bad dewatering,the sludge needs for pre-treatment and improve the sludge dewater ability,then make the sludge lose a great deal liquid in the subsequent mechanical dewatering process.Based on the analysis of sludge in Chaoyang District,Nanchang City sewage treatment plant, the paper voted the chemical sludge pretreatment to improved to sludge dewatering.The paper selected two inorganic polymer coagulants(PAC,PFS) and three of organic polymer coagulants{cationic PAM(PAM⁺),anionic PAM(PAM^-),non-ionic PAM(PAM^#)} and went on experiment about activated sludge coagulation.The experimental result is as follows:(1) The sludge dehydrated performance has the improvement through Various coagulants.The effect of the organic high polymer coagulant processing sludge surpasses the inorganic high polymer coagulant.The positive ion PAM⁺ processing sludge is best,the optimum dosing is 60mg/L,the smallest resistance number is 1.97×108s2/g.(2) PAM⁺ and PAC united for sludge on conditioning,their best dosage separately is the 2.5g/L and 40mg/L,the concentration separately is 4%and 0.1%,the smallest resistance number is 1.62×10⁸s²/g.The best adition sequence that it is PAC first and PAM⁺ after.PAM⁺ and PFS united for sludge on conditioning,their best dosage separately is the 8g/L and 30mg/L,the concentration separately is 15%and 0.1%,the smallest resistance number is 1.93×10⁸s²/g,the adition sequence on sludge dewatering performance is not affected.(3) To TP regarding the filtrate,the elimination effect of PFS+PAM⁺ surpasses PAC+PAM⁺.To COD_Cr,the elimination effect of PAM⁺ surpasses other sole coagulants regarding the filtrate,the effect of PAC,PFS uinted PAM⁺ separately surpasses PAM⁺.(4) The sludge filtration pressure is controlled in the 0.04MPa,pH value is 7,the mixing time is 30s(intensity is 120r/min),the sludge dewatering effect is best.(5) the coagulant is in best dosage,the sludge resistance number is smallest, other dehydration performance index basic also achieves best.(6) In the processing cost the PAM^- processing cost is lowest,but the processing effect is relatively poor.PAC and PAM⁺ united the cost is lower than PAM⁺ slightly, the processing effect is best,PAC and PAM⁺ is more economical technology choice in the Sewage treatment plant.