DEMONSTRATION OF THE J-VAP. TECHNOLOGY FOR DEWATERING AND DRYING MUNICIPAL RESIDUALS
Abstract:Due to the current state of regulations governing biosolids disposal and the public perception regarding this practice, achieving dryer biosolids for disposal or reuse is becoming both economical and desirable in many biosolids management programs. It is also, however, very desirable to achieve this dryness using less energy. Biosolids quality in terms of pathogens kill and agronomic value is important when considering use and disposal options. This paper reports the results of the research program that was conducted to evaluate an a developed process for dewatering, drying and pasteurizing biosolids and other residuals, termed the “J-Vap™.” The device modifies a conventional recessed chamber filter press by applying increased temperature and vacuum during filtration to produce a high percent solids cake. The device has a proven record of many installations in industrial residuals dewatering, however, its use in municipal dewatering is not widespread. Accordingly, this research was undertaken to demonstrate the device's effectiveness in dewatering and drying municipal residuals.
Four different biosolids and residuals from different wastewater treatment plants were used in this study. The conditioning technique (i.e., chemicals and chemical dosage) was determined for each biosolids type using bench scale jar testing procedures and a specially designed pressure filtration apparatus that simulates the J-Vap. operation without the heat and vacuum. Pilot scale testing was then conducted using the optimized conditioning technique to determine the drying efficiency.
Results have shown that the dewatering and drying efficiency of the device primarily depends on the biosolids or residuals type and the selection of the right combination of conditioners. The pilot scale device achieved 85-97% solids dryness in about 5 hrs drying time for both anaerobically digested and ATAD biosolids. Typical lab dewatering performance tests such as the Capillary Suction Time (CST) are not appropriate to predict the performance of the device in pilot scale. Moreover, the laboratory pressure filtration device was not able to predict pilot scale performance. The device produces relatively uniform, dried cake solids, and there does not appear to be a substantial difference in performance between chambers.
Document Type: Research Article
Publication date: January 1, 2003
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