Research On The Effect And Mechanism Of CO-Conditioning Of FeCl₃and Pam And Cao On The Sludge Dewatering

In the urban sewage plants and industrial wastewater treatment process enormous sludge was generated, its average moisture content up to99%, and was extremely difficult to treat. Prerequisite for treatment and disposal of sludge is dewatering. There need pretreatment on the sludge before the dewatering. Currently, chemical conditioning dewatering is the most commonly used. In this thesis the effects and mechanism of co-conditioning of FeCl3and PAM and CaO on the sludge dewatering were investgated.Firstly, research was based on dyeing sludge, paper mill sludge, waterworks sludge and sewage sludge, and the tipical properties of sludges, were explored. The suction and pressure filter experiments with different dosing of FeCl3and PAM were carried out. The results showed that sludge settling is positively related to sludge resistance filter (SRF), and SRF decides the speed of dewatering rate. The bound water content and mositure water content is negatively related. The water content of sewage sludge is the highest after the conditioning which indicates that pure biochemical sludge is generally difficult to dewatering. Simultaneously, the effect of FeCl3and PAM conditioning on the dewaterability of sludge and dewatering mechanism were investigated through the index which includes SRF, mositure water content in filter cake, organic content, bound water content. The results showed that SRF increases from4.06×109s2.g-1to18×109s2.g-1when the sludge were stored for two week, but the cake moisture content decreases and conducive to sludge dewatering. After placing20minute, SRF of the sludge decreases, after placing40minute, SRF increases. Therefore, the conditioned sludge should be treated quickly.Secondly, the mechanism and effect of FeCl3and PAM and CaO on the sludge dewatering were analyzied. The filter cake and filtrate case after sludge dewatering were investigated. It was indicated that the team work of FeCl3and CaO or PAM more effectively than single conditioning and SRF significantly decreases. There need more dosage of FeCl3and CaO, by comparison less dosage of FeCl3and PAM. The water content of the cake was61.25%after dosing FeCl3and PAM, and is relative lower(59.2%) after dosing FeCl3and CaO. However in the later situation the Ca2+and Mg2+and Cl-content of cake is high which lead to difficult subsequent treatment of sludge.Finally, pressure filtration dewatering conditions were studied through frame pressure filtration experiment. The results showed that polyester silk fabric is better material to sludge conditioned by PAM and take low-high pressure way is better on sludge into the frame pressure filtration device.