Effect Of Fe²⁺ Activated Persulfate Oxidation Combined With CPAM On Sludge Dewatering Performance

In China,with the rapid development of society, economic and urbanization,the total discharge and disposal of wastewater increased, which leads to massivesludge production. The problems of massive sludge production and immaturesludge treatment method will make the urban sludge treatment and disposalproblems quite outstanding over the next several years. And, the sludgedewatering is an indispensable part in the process of sludge treatment anddisposal.In this paper,the activated sulfate oxidation and cationicpolyacrylamide(CPAM)were used to treat sludge from the concentrated tank ofZhengyang wastewater purification Co., Ltd, in Yuci, Shanxi Province.Thefactors of drug dosage, initial pH, reaction time and reaction temperatureon themoisture content (Wc), sludge specific resistance (SRF) and viscosity of sludge were studied. On these conditions,the treatment effect at the respective optimumreaction conditions and mechanism were analyzed. The experimental results areas follows:(1) Under the optimum conditions of the activated sulfate oxidation methodof normal temperature, unadjust pH, potassium persulphate dosage at1.0mmol/gVSS,ferrous sulfate dosage at1.4mmol/gVSS and the molar ratio offerrous ions and sulfuric acid root at1.4/1,the moisture content (Wc), sludgespecific resistance (SRF) and viscosity of sludge reached the lowest,respectively,80.5%、1.01×1011m/kg and102mPa�'s, which will moderate themedium-dewatering sludge to the easy mechanical dewatering sludge.(2) Under the optimum conditions ofdosing flocculants CPAM methodofnormal temperature, mixing5min, unadjust pH, CPAM dosageat4.5kg/tDS,the moisture content and sludge specific resistanceof sludge reached90.3%,2.4×1011m/kg,respectively.(3) Combined effect of activated sulfate oxidation and CPAM at theiroptimum conditions will reduce the moisture content from82.2%to76.6%andthe sludge specific resistance from1.45×1011m/kg to0.79×1011m/kg.(4) By analyzing the contents of protein and polysaccharide in theextracellular polymer (EPS) of the sludge before and after the regulation,and theparticle size distribution, microstructure and composition of the sludge by SEMand FTIR,the results show that: a. releasing a large amount of protein andpolysaccharide due to the EPS structure of original sludge is destroyed by the activated sulfate oxidation method. b. after the regulating by CPAM alone, thesludge volume average particle size increased. However, the sludge particle sizebecome smaller, the specific surface area lager, and release part of the adsorbedwater and internal water, by activated sulfate oxidation method.And,throughcombined effectof activated sulfate oxidation and CPAM, the minified sludgeparticles flocculation will flocculate again. c. Original sludge is dense, wrappedtightly, and exists by zoogloea structure. However, the sludge flocs groupstructure appears cracks, holes, and then grows into loose layer and the wafersurface after combined effect of activated sulfate oxidation and CPAM, which ishelpful to the improvement of the dehydration properties of sludge.