Influence of vacuum pressure, pH, and potential gradient on the vacuum electro-osmosis dewatering of drinking water treatment sludge

ABSTRACT

This paper describes research that evaluated the influence of vacuum pressure, pH, and potential gradient on the vacuum electro-osmosis dewatering (VEOD) of drinking water treatment sludge (DWTS). In the first phase of the VEOD process, a vacuum pressure of −0.05 MPa was applied alone to DWTS for 30 min, removing almost all free water and part of pore water. In phase two, electro-osmosis was applied in combination with intermittent vacuum filtration, further reducing pore water and surface adhesion water in DWTS. However, statistical analysis indicated that the optimum dewatering parameter values were vacuum pressure at −0.06 MPa, pH at 6.2, and potential gradient at 2.5 V/cm, which resulted in a relevant energy consumption of 0.35 kW.h/kg removed water.

KEYWORDS:

• Dewatering
• electro-osmosis
• sludge
• sludge moisture distribution
• vacuum filtration

Additional information

Funding

This work was supported by the National Natural Science Foundation of China (51308185), Central University business expenses (2013B32314), and A Project Funded by the Priority Academic Program Development of Jiangsu Higher Education Institutions, National major water projects (2014ZX07405002).