The sludge, now activated with additional billions of bacteria and other tiny organisms, can be used again by returning it to the aeration tank for mixing with air and new sewage. From the aeration tank, the partially treated sewage flows to another sedimentation tank for removal of excess bacteria.,
There are three main stages of the wastewater treatment process, aptly known as primary, secondary and tertiary water treatment.Dec 6, 2018
Sewage sludge is a mud-like residue resulting from wastewater treatment. Sewage sludge contains heavy metals and pathogens such as viruses and bacteria. It also contains valuable organic matter and nutrients such as nitrogen and phosphorus, and can therefore be very useful as a fertilizer or soil improver.
Sewage sludge not enough stabilized incorporates pathogens and can cause rapid and uncontrolled biodegradation with the release of toxic substances. However, the high organic content makes these wastes suitable for treatment by biological techniques.Jul 25, 2018
In primary treatment, sewage is stored in a basin where solids (sludge) can settle to the bottom and oil and lighter substances can rise to the top. These layers are then removed and then the remaining liquid can be sent to secondary treatment. Sewage sludge is treated in a separate process called sludge digestion.Jan 3, 2021
The incoming wastewater passes through screening equipment where objects such as rags, wood fragments, plastics, and grease are removed. The material removed is washed and pressed and disposed of in a landfill. The screened wastewater is then pumped to the next step: grit removal.
The treated wastewater is released into local waterways where it's used again for any number of purposes, such as supplying drinking water, irrigating crops, and sustaining aquatic life.
Three things can happen when raw sewage enters a body of water: It will be dissolved, it will become suspended in the water column or it will sink to the bottom and stay there. Raw sewage contains a variety of dissolved and suspended impurities. The organic materials are food and vegetable waste.Mar 15, 2018
The final destination of treated sewage sludge usually is the land. Dewatered sludge can be buried underground in a sanitary landfill. It also may be spread on agricultural land in order to make use of its value as a soil conditioner and fertilizer.