Effect of Low-Temperature Treatment on Sludge Dewatering Characteristics
Jill Ruhsing Pan
|關鍵字:||低溫處理;污泥調理;高分子聚合物;流變;黏度;加藥量;Low-Temperature conditioing;sludge conditoning;polyelectrolytes;rheology;viscosity;polymer dosing|
Currently, approximately one hundred and seventy thousand tons of sludge is produced annually from the water treatment plants in Taiwan. This amount is expected to increase astronomically due to the increasing demand for more quality water and the more stringent regulations regarding wastewater treatments implemented by the Government. How to minimize the sludge volume and optimize the sludge condition for final disposal in an efficient way has become the focus of many studies. Traditionally, sludge is conditioned chemically by using polymers. The current law forbids the discharge of wastewater containing certain types of polymers into water bodies, which limits the use of polymers. Other disadvantages of using polyelectrolytes include their significant cost and safety concerns. Therefore, it is necessary to search for other options for sludge conditioning. In this study, the feasibility of low-temperature treatment was evaluated. Cationic polyelectrolyte was also applied with the low-temperature treatment. Experimental conditions such as temperature, duration of cold storage, and the rate of lowering the temperature of the sludge are manipulated to find the most efficient conditioning. Experimental results indicate that the success of low-temperature treatment relies on the degree of freezing. After the freezing/thawing stage, the dewaterability, filterability and settling properties were all improved greatly. Better performance was observed at slower freezing rates, lower temperatures and longer period of freezing time. If the temperature was not low enough to freeze the sludge, no significant change in dewatering characteristics was observed. When low-temperature treatment was combined with polyelectrolyte conditioning, the improvement in dewatering rate was better than chemical conditioning alone, suggesting that low-temperature treatment may replace the use of polymer to some extent.
|Appears in Collections:||Thesis|