Pilot-scale Study On Modified Sludge Dewatering Properties

With the increase of urban sewage treatment facilities, sludge production volume is becoming more and more huge, the sludge moisture content is commonly 98%, its huge number, namely using filter press to reduce to 80%, still occupy a large area, coupled with complicated composition, the safety of the sludge disposal is imminent, in order to reduce the moisture content of sludge, sludge decrement, taking a hotshot of sludge dehydration equipment, studies several chemical modifier on different ratio of sludge, and then combined with the diaphragm type filter system for political dehydration to further reduce moisture content of sludge. Research shows that:in low feed pressure 0.3MPa, high-pressure 0.8MPa, maximum squeezing pressure 1.3MPa, squeeze time to 40-50 min, ferrous salt and iron salts, hydrated lime, PAC and PAM chemicals such as single or combined treatment can improve the residual activated sludge dewatering performance, the modified sludge greatly reduced the volume after diaphragm filter, This result has certain guiding significance for engineering applications.Chemical modification is an effective pretreatment technology of sludge, the experimental results show that chemical modification can drop moisture content to 50%, fully meet the subsequent sludge landfill. Using a single chemical sludge, the modification effects are poorer than drug distribution. Sludge dewatering lime role cannot be ignored, Lime alone can reduce the water content of sludge to 61%; PAM can significantly increase the alum flocs of sludge, The dosage of PAM increased from 0.2% to 0.6%, water content of cake filtration rate remained at around 64%, The specific resistance of the sludge with the increase of PAM content, decreases first and then increases slowly. Low dosing PAC bring lower contribution rate but extend the time of the total feed, promote plate and frame unit capacity.Use Design expert software for simulation, the optimum experiment is:6.5% PAC +0.25% PAM + 0.25% CaO, through comparing the F value, we can judge the effects of the drug on the target. For the different nature of the sludge, choosing the compatible chemical compound base on the sludge modification effect, also on the engineering application, using reasonable modification reagent for different sludge properties modification.After drying sludge one or two days, the moisture content of the sludge can be reduced to 50% or less, and in order to prevent odor, it should be taken away or disposed of. The sludge is suitable for land reclamation, landfill and mixing cement building materials used. The filtrate can be directly discharged into the wastewater treatment and had little effect on water quality.