Study On Improvement Of Sludge Dewaterability Conditioned With Different Conditioning Methods Based On The Sulfuric Acid

Municipal wastewater treatment plant produce a large amount of excess sludge in China every year.The excess sludge without proper treatment and disposal poses a threat to ecological system and human health.The principles of sludge treatment and disposal is quantitative reduction,harmless and resources,among which,the quantitative reduction is the key step.As the high water content of excess sludge,sludge dewater is the key step to achieve the quantitative reduction.Before the process of mechanical dewater,the addition of dewatering conditioner is necessary to improve the sludge dewaterability.Therefore more efficient and economical sludge treatment technology are demanded.Meanwhile,the peculiar quality of the sludge should be considered before the selection of sludge treatment technology.In this paper,the effect of sulfuric acid treatment on the sludge dewaterability is investigated.Coal gasification residue was utilized as a novel filtration aid in combination with sulfuric acid to enhance sludge dewatering performance.The results are as follows:Sulfuric acid treatment can improve the sludge dewaterability.Sulfuric acid(5mol/L)1.5 mL,stirring time 15min,the value of SRF(Sludge resistance of filtrate)and moisture content of sludge cake decreased to 4.57×1012 m/kg and 73.79%respectively.Coal gasification residue was utilized as a novel filtration aid in combination with sulfuric acid to improve the sludge dewaterability.The results showed that the combination use of sulfuric acid and coal gasification residue can further improve the sludge dewaterability.Under the condition:sulfuric acid(5mol/L)1.5 mL,coal gasification residue 1.0 g/g DS,the SRF and moisture content of sludge cake decreased to 2.17×1012 m/kg and 53.27%respectively.According to the sludge element analysis,the sludge contained a certain amount of iron,under the condition of sulfuric acid(5mol/L)1.5 mL,stirring time 30 min,the Fe2+ content in sludge aqueous phase reached maximum.Based on the Fenton/Fentonlike mechanism,the combination use of sulfuric acid and hydrogen peroxide was utilized to the pretreatment of the sludge.The experiment results showed that under the condition:hydrogen peroxide 1.0 mL,sulfuric acid(5mol/L)1.5 mL,reaction time 5 min,the SRF and moisture content of sludge cake decreased to 0.4×1012 m/kg and 67.12%respectively.