Study on optimum utilisation of water treatment plant sludge for treating domestic wastewater

The water that is treated in the water treatment plant produces sludge that contains silt, debris, and coagulants that are used for the treatment process. The sludge so produced usually is dumped into waterbodies or landfills. When doing so the chemicals percolate into the soil reaching the groundwater and polluting them. This project mainly focuses on using this water treatment plant sludge in treating domestic wastewater. An aeration tank was set up with air pumps, bottles, measuring jars and glass tanks. The sludge was directly added to the sewage water collected from the wastewater treatment plant in varying proportions with a detention time of 5 days. When tested, it was found that the levels of BOD and COD were reduced drastically as compared to the existing methods of treatment. It was found that when 30% of sludge was added to the wastewater a 67% of reduction in BOD and 6.2% of reduction in COD was observed. A combination of 15% of activated sludge and 5% of water treatment plant sludge was observed with a decrease in 68% of COD and a 38% increase in BOD. Also, it was observed that the formation of froth in the aeration tank was reduced.