Improvement On Sewage Sludge Dewatering By Microwave Radiation Coalition With Fly Ash

The increase in production of sewage sludge is a matter of growing concernbecause it has caused serious environmental pollution. The treatment and disposal ofsewage has been an issue related with state environmental protection and nationalecology. The bottleneck of sludge handing system is dewatering. The application ofmicrowave radiation in sewage sludge treatment has attracted most attention inrecent studies. Since dewatering was the key technology of sludge treatment,microwave and its coalition with fly ash were used in dewatering with reduction,stabilization and utilization as central tasks. The improvement of dewaterabilityunder the effect of microwave radiation and its coalition effects with fly ash wereinvestigated. The order in the coalition treatment and the control of each parameterwere analyzed， which explored new direction of sludge treatment and disposal,providing theoretical basis and practical guidance for sludge treatment.The changes in settling and vacuum filtration dewaterability of sewage sludge in3minutes of microwave radiation were investigated， influences on volatilesuspended solid（VSS）dissolving ratio, COD in supernatant and micro-morphologyof sewage sludge by microwave radiation were investigated as well. Theimprovement of dewaterability by microwave radiation, adding fly ash and thecoalition effect was mainly investigated with specific resistance and water content ofthe sludge cake as the analysis indicators. It was observed that low intensity radiationhad little effect on settling and vacuum filtration dewaterability of sewage sludgebecause it can’t transform the structure of the sludge fundamentally. The settling anddewaterability of sewage sludge could be improved dramatically by adaptablemicrowave radiation. The specific resistance decreased from2.53×10~9s~2/g ofuntreated sludge to about0.3×10~9s~2/g after adaptable microwave radiation, whichwas in the range of easy dewatering. Water content of sludge cake dewatered withfiltration reached about70%, which is lower than the85.2%of untreated sludge afterfiltration. SV declined from91.2%to44.1%. Excessive radiation damaged thestructure of cells, which caused sludge smarshed, the flood of intracellular polymer,the increase of the mixture viscosity and the dewaterability became worse.The sludge settling could be improved obviously by adding adaptable fly ash.SV were91.6%,88.2%,83%and76.8%respectively when fly ash were added0‰,2‰,4‰and6‰. When8‰fly ash was added to the sludge, the improvement of dewaterability was optimal, the specific resistance was0.36×10~9s~2/g and watercontent of sludge cake was67.2%.When coalition effect treating sewage sludge, the treatment effect ofmicrowave-fly ash was better than that of fly ash-microwave. The improvementeffect improved with the dosage of fly ash increased in microwave-fly ash treatment.While the dosage of fly ash had little to do with the improvement effect ofdewaterability in fly ash-microwave treatment. Treatment effect worsen a little withincreasing fly ash additions. The improvement effect of microwave-fly ash ondewaterability was better than that of PAM.