Effect of pulsed electric field on pretreatment efficiency in anaerobic digestion of excess sludge

Nowadays, water pollution is one of the most important issues on which much attention has been paid. As an effective water treatment method, activated sludge process has been widely used for water purification. However, excess sludge that results from the water treatment still brings pollution to environment. Anaerobic digestion has been used in a broad range of applications in excess sludge stabilization. In order to improve the performance of anaerobic digestion, a process called sludge pretreatment is often carried out with the purpose of destructing cells of microorganism within the sludge so as to release their intracellular organic matters. In this paper, pulsed electric field (PEF) has been employed to treat excess sludge. The effects of several parameters including magnitude, frequency of PEF and ambient temperature on the efficiency of the treatment has been investigated. It was observed that the efficiency appeared to increase with the magnitude as well as the temperature, but tended to decrease with the frequency. The efficiency of treatment has been considered as a function of cell membrane electroporation occurred on microorganisms within the sludge which could be varied with the parameters discussed.