Researches On The Sludge Dewaterability Co-conditioned By Electrolysis And Surfactants

Sewage sludge is one of the important by-products from waste water treatment plant, and it increases greatly with the rapid urbanization process and the advanced waste water treatment process applied. The development of the cost-effective sludge treatment process is still a big challenge due to the present of the high water content and the colloid in sludge. Therefore, the improvement of the dewatering system is the prerequisite for the proper sludge disposal. Some pretreatment processes, such as polymer electrolyte, have been applied to increase the sludge dewatering ability, through the change of the physical properties of sludge flocs and chemical composition, while the high cost and the potential secondary pollution are the big barrier. In this work, electrolysis and surfactants are used as the pre-treatment process, to improve the dewatering capacity in the sludge, and the parameters, i.e. CST, SRF, Viscosity, Zeta, were choose to characterize the dewatering properties in sludge, and the results in detail were shown as follows:(1) Electro-chemical reactor was used to modify the sludge dewatering process, with Ir/RuO2 and Ti/RuO2 mesh as the anode and the cathode, respectively. The optimum operation conditions were found as follows:30v Voltage, retention time of 30min, and the mixing at 100 rpm/min, and the corresponding CST value in sludge decreased about 35.52%:The SEM image of sludge showed that the sludge structure was deformed greatly, and the sludge dewaterability was improved due to the release of the cell interstitial water from sludge. However, the dewaterability of sludge was deteriorated, when the sludge was pretreated at 50v, because the sludge was destroyed badly, and the floc size became smaller.(2) The dewatering ability of the sludge were tested by the synergy effect of the Electro-chemical and the cationic surfactants additives (CATB). It was founded that the sludge dewaterability could be improved greatly. The corresponding CST value in sludge decreased about 43.59%, and the Zeta protential in sludge decreased about 94.71%, when the dosage of CTAB was 2500 mg·L-1.Because CATB contributed to the decrease of the negative charge in the sludge flocs, and thus increased the re-aggregation process in the sludge. The extracellular polymeric substances could be also extracted from the sludge simultaneously.