Research On The Application Of Persulfate And Alkyl Glycoside In Sludge Conditioning And Dewatering Mechanism

With the increase of the number and the handling capacity of urban sewage treatmentfactories, the sludge production also grows rapidly. Due to the high hydrophilicity of thesluge, it has great significance to realize the deep dehydration of the sludge for thesubsequent sludge disposal. The thesis studies the influence rule and mechanism ofadvanced oxidation technology of the persulfate and the synergetic effect withsurface-active agent on the deep dehydration performance of the sludge, the main resultsare as follows.Taking the specific resistance as the evaluation index of the filtration performance, aseries of experiments were conducted based on response surface methodology （RSM）, toinvestigate the impact of the conditioning parameter on the dewatering of sludge. The testsfind that the factors such as the mixing speed, dosing times and reaction time in the sludgeconditioning have different influences on the sludge SRF. The interaction of factors willalso affect the resistance. Data analysis revealed that the optimal conditioning parametersare MP1=300r/min，AT=2，MP2=150r/min，RT=10min.SPS activated by Fe²⁺improves the dewatering performance and settleability ofsludge. With the single factor and optimazition experiments of RSM, it is found that, whenthe dosages of SPS is82.3mg/g DS and Fe²⁺15mg/g DS, the SRF decreased to0.2278×10¹³m/kg or91.07%reduction. The study also compared the effects of protein,polysaccharide content, size distribution and SEM analysis on dewaterability of theconditioned sludge with that of the original sludge. The test result shows that the rawsludge exists in the form of zoogloea with the dense group structure. SPS catalyzed byFe²⁺can destroy the organic matter in the sludge and make the sludge floc become theloose stratiform structure，form the fracture and holes at zoogloea, make the particle sizeof the sludge flocs decrease in the different degrees, meanwhile, dissolve the extracellularpolymeric substance（EPS） and consume the protein and polysaccharide. Besides, thechanged proportion of tightly bound EPS （TB-EPS）and loosely bound EPS （LB-EPS）promotes the dewatering performance of the sludge. Non-ionic surfactant alkyl glycoside（APG） and SPS have the synergistic effect. Thetests indicate that, based on the above conditionings, when the dosage of APG increases to0.5mg/gDS, specific resistance decrease to0.098×10¹³m/kg from2.786×10¹³m/kg of theoriginal sludge and the decline rate of SRF is96.42%. APG possesses with the function ofhydrophobic association. With dosing of APG, the sludge flocs will be polymerized againfrom the dispersed state. The diameter of particle of sludge will also gradually turn larger.The reformed aggregate is in a kind of loose form with the big porosity. Therefore, itprovides the channel for the pass of moisture and improves the dehydration performanceof the sludge and settleability. After the conditioning with the complex formula, thecontent of organics in the sludge will be less than that in the original sludge. Additionally,the organics tend to move into the filtered liquor in some degrees. However, when thedosage of SPS reduces, APG cannot greatly decrease the SPF of the sludge.