| With the rapid development of our industry and constantly improve-ment of people’s living standard. The generation of municipal domestic sewage and industrial wastewater increase year after year. While in the wastewater treatment process, It will produce large amounts of sludge. The water contained in sludge almost be95to99percent of the total quality. It has a complex composition, it not only needs large area but also dangerous. So, it needs further treatment to reduce its moisture content. Since sludge has its own properties, it has a poor dewatering performance. How to improve its dewatering performance has become a global research topic. The method chemical conditioning-mechanical dewatering is the most widely used.Nowadays, for the excess sludge, the method used in many sewage treatment plant is using organic polymer flocculants,for example, the conditioner such as polyacrylamide and inorganic coagulant(AlCl3). While they are more or less of low toxicity, nonbiodegradable and have potential harmful characteristics of the human living environment. Since β-cyclodextrin has a special structure and its property of thickening can change the polymer surface tension properties, what’s more, it is non-toxic, harmless to human body, without secondary pollution, it has the potential to replace the existing sludge conditioner.In this paper, the basic natures of excess sludge from the municipal sewage treatment plant are tested and conditions are conducted on the excess sludge with a variety of selected conditioners. The sludge dewatering performance is mainly represented by sludge specific resistance. This paper, with the index of sludge specific resistance and settlement effects, draws a conclusion that there is positive correlation between the specific surface and the sludge dewatering performance. Further through selecting the best single conditioner, it gets the best dozing quantities and dosing concentration of various single conditioners. Through the comparison of single conditioner tests, the sludge dewatering performance by cationic polyacrylamide (CPAM) is approved to be the best one. The test result shows that the best dosing quantities for the three items are respectively as follows:dosing700mg/L of0.10%CPAM, the sludge resistance reduces by80.5%;800mg/L of aluminum chloride, the sludge resistance lowers by72.2%; while200mg/L of β-cyclodextrin, its resistance is decreased by69.3%with the dewatering performance order being of CPAM>AlCl3>β-CD and the filtrate turbidity order being of β-CD<AlCl3<CPAM. The best technology parameter test of composite conditioner makes a comparison between the two composite configuration methods, one is of CPAM and AlC13and the other is of CPAM and β-cyclodextrin, as a result of which the composite usage of CPAM and β-cyclodextrin is approved to have the best effects with the best dosing quantities as below:150mg/L of β-CD and70mg/L of CPAM, the sludge specificresistance is of0.98×10-12m/kg, which is decreased by94.17%than its original sludge specific resistance (16.80×1012m/kg).In the sludge configuration mechanism, the single conditioner CPAM has the best effects, which partly because the CPAM can perform its functions of offsetting the electrostatic and of compressing double electrical layers, and partly because it also can realize its functions of bridge absorption and enmeshment. While in the composition conditioning, the best effects are gained by the method of dosing relatively small quantity of β-cyclodextrin first and then adding the CPAM later, which properly due to the β-cyclodextrin is capable of seizing relatively small sludge particles in advance and also contribute to the enhanced surface tension of high polymer CPAM which is dozed at a later time. |
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