Abstract—The aim of this study is to develop a simple method for dewatering waste-activated sludge (WAS) for easier reuse and safer disposal of sludge. The paper builds on the success of a new flotation technique developed in previous research by the author utilizing the high water solubility of CO2 gas along with the model-gas (80%N2+20%CO2). The paper introduces a simple laboratory model for dewatering WAS in two stages, flotation followed by centrifugation. The first stage enables recycling a mixture of greenhouse gases containing 20% of CO2 and 80% of N2 gases by volume. The second stage uses a simple centrifuge model for dewatering WAS. Experiments were carried out to reduce the moisture content and volume of WAS. This was executed by generating low pressure using centrifugal force introduced by a simple centrifuge apparatus. Using the experimental dewatering model, promising results were obtained for dewatering WAS. Furthermore, additional data were obtained, such as the effect of temperature on the efficiency of dewater-ability. It is hoped that the results of this study will lead to more study for the efficient reuse of greenhouse gases. This can happen by collecting and recycling industrial emissions of fossil fuels then utilizing them in wastewater and sludge treatment, thereby decreasing the resulting harmful effects of these gases on global warming.

Index Terms—CO2-gas, centrifugation, flotation, nitrogen, waste-activated sludge.

M. El-Zahar is with Port Said University, Faculty of Engineering, Civil Engineering Department, Port Said, Egypt. Phone: +20-160799969; fax:+20663400936; e-mail: (melzahar@gmail.com).

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Cite: Medhat El-Zahar, "Dewatering Waste Activated Sludge Using Greenhouse-Gas Flotation followed by Centrifugation," International Journal of Environmental Science and Development vol. 1, no. 2, pp. 199-204, 2010.