Sludge is the mixture of solids and waste collected by wastewater treatment facilities during the water treatment process. It’s the job of these facilities to take wastewater, separate materials like sludge and return treated effluent water back into the greater water system.
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Essential to the wastewater treatment process are sludge tanks. After pumping, aeration and clarification, organic material pulled from wastewater transfers to sludge tanks to await further processing.
Let’s learn more about this essential component of wastewater treatment plants.
What is a Sludge Tank?
Before 1950, it was common practice to release wastewater like sewage directly into water sources with little treatment. For example, areas in and around the Great Salt Lake in Utah saw continued raw sewage dumping until 1958.
These days, the water that makes its way into public water sources usually goes through a process that strips away harmful materials like bacteria and pathogens. Sludge tanks are essential to this process.
Situated between the clarification and sludge treatment stages, sludge tanks serve as the holding vessels for waste material. From there, sludge moves from the tanks into dewatering equipment or straight to sludge hauling.
What Does a Sludge Tank Do?
Sludge is an important product of water treatment. While it might not seem desirable, the fact of the matter is that the removal of this type of waste is one of the many steps that make up the water treatment process.
Sludge tanks are essential equipment. They act as a holding area for sludge before it receives further treatment and disposal.
Once the sludge is within the tanks, biosolids and other types of waste sink to the bottom while other organic matter like oil, soap or plastic float to the top. This top-forming material is called scum.
Tanks are only one component in the overall sludge disposal process.
These processes can vary depending on the equipment at each water treatment facility:
Thickening
Dewatering
Anaerobic digestion
Aerobic digestion
Alkaline stabilization
Composting
Regardless of how plants treat this type of waste, sludge tanks hold the biosolids material until the next stage of the process begins.
Where Do You Find Sludge Tanks?
You can find sludge tanks in wastewater treatment facilities across the world. Treatment centers usually employ them after the initial clarification stage but before dewatering and other processing equipment.
In most areas, it’s necessary to remove biosolids from wastewater to cut down on wastewater environmental problems and meet local public health regulations. Without the proper holding containers for sludge, it’s difficult to create an efficient water treatment process to meet those standards.
Sludge tanks are a universally used tool in almost every wastewater treatment facility.
Who Manages Sludge Tanks?
Who’s in charge of managing the complex wastewater treatment process? Since these practices need to meet strict standards, it requires specialized workers.
Sludge tanks are but one part of the greater wastewater treatment process. Wastewater technicians work in wastewater management plants and take care of things like managing sludge tanks and collecting lab samples. But that’s only a part of a wastewater technician’s job:
Develop maintenance programs and schedules
Locate and resolve blockages in the system
Repair leaks
Work with supervisors to manage equipment maintenance
Much more
Since wastewater technicians manage sludge, it’s their job to ensure tanks are operating properly and are free from obstructions and blockages. Even with all these tasks, most technicians spend a good part of their day doing paperwork.
Proper documentation is essential to demonstrating adherence to city, state and federal water safety guidelines.
Sludge Holding Tanks in Wastewater Treatment
After clarification, sludge tanks store the biosolids from wastewater until the next stage of the treatment process.
It is often the case that the sludge rests for a predetermined amount of time to separate naturally. We call this process sludge thickening, and it helps concentrate the biosolids even more.
The goal is to increase the solids concentration and reduce the overall sludge volume. Usually, technicians are looking for a solids concentration range of 3% to 5%. The way this usually happens is through a gravitational process that pulls the dense sludge down while leaving water and scum up top.
Using the difference between particle and fluid densities, sludge tanks can further compact the solids toward the bottom of the tank. This results in concentrated sludge and water that can enter back into the treatment process.
The advantages of the process are substantial.
Some wastewater treatment facilities use a slightly different process called flotation thickening. While this method also works using gravitational forces, the mechanics operate differently.
Flotation thickeners utilize pressurized air pumps to aerate the sludge mixture. As air mixes into the sludge solution, the air bubbles attach themselves to the biosolids. After that, they carry the sludge upwards, where a scrapper removes the waste.
Waste and Wastewater Management Services From O&M
Sludge tanks are an essential component of wastewater treatment facilities. They act as a holding area for sludge — the biosolids coming from wastewater.
Situated within the greater treatment process, sludge tanks often lightly process sludge through a process called thickening. This happens in a few different ways, but the result is the same.
The more concentrated the sludge, the easier it will be to manage down the line during further processing.
O&M Solutions serves both the public and private sectors with operations and management solutions for water and wastewater treatment. Across New Jersey, Pennsylvania and New York, we have a stellar reputation for delivering excellent results for our clients.
Get in touch today to learn more about O&M Solutions and what we can help with your water treatment needs.