The treatment of wastewater sewage sludge is an important step in the overall water treatment process where useful compounds can be separated from harmful ones before sludge is released back into the environment as fertilizer, buried in sanitary landfills or incinerated. One stage in treatment is called “dewatering” and it is useful to know the definitions and importance of this process.
The definition of sludge dewatering is straightforward, it is removing the remaining water from the organic and inorganic solid byproducts of wastewater treatments. It can be done by drying out in beds for weeks or put through a mechanical process for a faster result. This sludge is clarified out of the water in tanks where it sinks to the bottom and is sent to a different part of the plant for treatment. Before hitting the dewatering stage, the sludge is thickened for easier handling and digested by bacteria. The bacteria destroy pathogens and release methane which can be used to fuel the process if enough is retrieved.
Drying out sludge reduces its mass further than the first few stages in the treatment process and makes it easier and less expensive to handle and dispose of. The resulting dry mass can be tested for compliance levels, nitrates and toxicity to indicate proper disposal methods. When the sludge can be incinerated after drying, it is further reduced in mass and more toxicity is removed, making safer disposal easier.
Sludge dewatering is just one of many steps to the process of reclaiming wastewater and is used in industrial and residential treatment plants. This makes the sludge easier to handle and to dispose of, reducing the costs of the process. When the sludge has been treated and dried, it can be used as fertilizer, buried in sanitary landfills or incinerated depending on the chemical compounds present and local regulations.