Dewatering waste-activated sludge using dissolved gas-flotation followed by filtration

After the successes of flotation of waste-activated sludge (WAS), using the new technique utilizing CO₂ gas as well as using model gas (80% N₂+20% CO₂) in previous research because of the high water solubility of CO₂ gas, the aim of this study is to develop a simple method for dewatering WAS for easier reuse and safe disposal. The paper introduces a laboratory model for dewatering WAS in two stages: flotation followed by filtration. 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 compression cell for dewatering WAS. Experiments were carried out to reduce the moisture content and volume of WAS. This was executed using compression force introduced by a low value of air pressure. Using the experimental dewatering model, promising results were obtained. Furthermore, other data were obtained, such as the effect of temperature on the efficiency of dewaterability. It is hoped that the results of this study will lead to further study of collecting industrial CO₂ gas emissions from burning fossil fuels for use in wastewater treatment to decrease the resulting harmful effects of global warming.