Lime Drying Technology Research Of Excess Sludge From Qilihe-Anning Wastewater Treatment Plant In Lanzhou

This paper carried out the research of drying the Qilihe-Anning Wastewater TreatmentPlant excess sludge in Lanzhou by using methods of lime drying, lime and PAFC joint drying,meanwhile the effects, advantages and disadvantages of this two drying methods werecompared. In response to the phenomenon that the pH of lime drying sludge, this paperexplored the effects of amino acid on the pH of the lime drying sludge initially. Finally thispaper explored the subsequent disposal and use-patterns of drying sludge according municipalsludge treatment and disposal. The purpose of the article is to provide technical support forthe lime stabilized sludge process design, operation and management of the wastewatertreatment plant in Lanzhou and an effective and economical way for sludge treatment anddisposal of sludge in Lanzhou.The experimental study of lime drying sludge had shown that after5%,10%,15%,20%ofindustrial lime were added to the sludge, sludge temperature increased from the original23℃to32，35，44，58℃; the pH of sludge increased from7.2to12.5after lime sludge dryingprocess, with the batching time increasing, the pH of sludge almost had no change. Themoisture content of sludge was declining with the lapse of time. When the moisture content offour groups declined to60%, five days, five days, two days, one day were respectively gone,the moisture content of sludge reduced to45%, two groups with the lime addition level of15%and20%, eight days and seven days were respectively gone, the other two groups neededmore time; The organic matter content had stabilized after two days of piling．The experimental study of lime and PAFC joint drying sludge had shown that the dryingeffect is best with the lime and PAFC being added at the same time; The drying effect of thelime addition level of15%corresponded to the drying effect of joint drying of the limeaddition level of10%and the PAFC addition level of3%. After joint drying, the temperatureof joint drying is higher than the temperature of the lime drying after the dry agent was addedto the sludge; the pH was maintained at about11.9. The stacking time had little effect on thepH.When the amino acid was added to lower the pH of the lime drying sludge, the pH ofsludge corresponded to the pH of joint drying. The amino acid could not reduce the pH oflime drying sludge further.The experimental study of lime drying sludge has shown that the best addition level of lime is15%;10%lime and3%PAFC can replace15%lime to dry sludge, and the pH of jointdrying sludge is lower than the pH of lime drying sludge；The way that using amino acidreduce the pH of lime sludge drying is not feasible; The sludge of lime drying and joint dryingcannot be used for agriculture, green land and land restoration, can be filled with municipalsolid waste, can be used as the cover soil of landfill, a small amount of drying sludge can beadded to the limestone to burn construction materials.