Research On Conditioning Echnology And Mechanism Of Municipal Excess Sludge

In recent years, With high-speed economic and social development, the capacity and efficiency of sewage treatment is increasing. Then a large amount of activated-sludge was produced. disposal and reclamation of urban sewage and sludge have become environmental concerns for the whole world. Activated-sludge has the main characteristic of high water content(>99.5%), The key is to remove the sludge of moisture, to reduce the volume of sludge. The experiment, which studied polymer flocculant and surfactant and combined both of them to improve dewatering ability of activated sludge, and achieves preferable result. The experiment contents and the results are as follows:(1) Effects of cationic polyacrylamide (CPAM) and aluminium polychlorid(PAC) and combined both of them on dewaterability of sludge were discussed, The result shows that CPAM and PAC can improve sludge dewaterability and settleability and the moisture conten of sludge filter cake.The optimal concentration of CPAM and PAC separately is0.1%and4%.The addition sequence Plays an important role in the sludge dewatering performance, the right way is to add PAC into sludge before CPAM. The above three ways of sludge conditioner keep the moisture content of sludge filter cake at80%,In the experiment, the EPS in the filtrate of sludge and particle size distribution of sludge are observed to explore the action mechanism of PAC and CPAM. Bothof them have no effect on EPS. Sludge particle size has a different degrees increase compared with original sludge. Both of them mianly make use of themselves long chemical chain structure of bridging in flocculation and adsorption and charge neutralization to improve sludge dewatering.(2) Effects of cationic surfactant (TTAB) and Polymer flocculant (PAC or CPAM) and combined both of them on dewaterability of sludge were discussed, The result shows that CTAC can improve sludge dewaterability and settleability and the moisture conten of sludge filter cake. The optimal dosage of TTAB is0.28, decreasing specific resistance to filtration to6.57×108s2/g and decreasing water content of filter cake to70.33%. In the experiment, the EPS in the filtrate of sludge and particle size distribution of sludge are observed to explore the action mechanism of TTAB. The experiment shows that TTAB make sludge particle smaller and EPS of filtrate rise.TTAB improve sludge dewaterability mainly by destroying the structure of sludge to release internal bound water and EPS. Besides,The experiment shows that CTAT improve sludge dewaterabil ity mainly by destroying the structure of sludge to release internal bound water and EPS.In addition, combined technology of surfactant and PAC or CPAM respectively showed that they used for sludge conditlonlng in conjunction could both reduce water content and improve settlement performance.