Education » How Wastewater Is Treated

How Wastewater Is Treated

A typical wastewater treatment plant, such as the Lower Poplar and Rocky Creek facilities owned and operated by the Macon Water Authority, utilizes several (5 typically) steps to recycle wastewater.  Wastewater treatment plants are also referred to as Water Reclamation Facilities, noting that wastewater is "reclaimed" for beneficial reuse -- either directly or indirectly returning to raw water storage facilities such as reservoirs/lakes, rivers, streams, etc.  Solids that are byproducts of the wastewater treatment process are also handled according to strict environmental regulatory oversight -- provided by the U.S. EPA on the federal level and the state EPD in Georgia.

The five steps of the wastewater treatment process include: preliminary treatment, primary treatment, secondary treatment, tertiary or advanced treatment, and finally disinfection.  The steps are outlined in more detail below:

Source: Water Environment Federation

Preliminary Treatment is the first stage that involves influent (wastewater entering the treatment plant) having many of the solids removed -- with the use of screens, grit chambers, etc. -- so that they do not clog pipes and disable treatment plant pumps down the line during the treatment process.

Primary Treatment involves a more sophisticated settling tank -- also called a sedimentation tank or clarifier -- that operates to remove most of the solids that will float or settle.

Secondary Treatment is a process that features a highly controlled artificial environment that allow microscopic organisms to feed on waste still present in the wastewater, biologically converting these dissolved solids into suspended solids that can then physically settle out.

Tertiary or Advanced Treatment is used to improve the quality of the water even more, in some cases removing specific toxic substances, but in most cases removing suspended solids and nutrients.  In addition to nutrient removal, advanced treatment may utilize some form of filtration to achieve a higher level of suspended solids removal than is possible through primary and secondary screening and sedimentation.

Disinfection is the final step or stage of the wastewater treatment process before water is released back into the environment.  Disinfection significantly reduces any remaining bacteria and viruses and helps protect the public from exposure to potentially pathogenic micro-organisms.

Solids processing and handling are also necessary components of the wastewater treatment process.  Untreated solids are often referred to as sludge, while treated solids are referenced as biosolids.  The first steps in handling solids involves conditioning and thickening, since they are typically only about 3 to 6 percent solid -- a concentration that is predominantly water.  Next, stabilization processes are used to further treat the sludge by reducing odors and pathogen levels, so that the product can be beneficially used or disposed of without posing a hazard in the environment.  The last step in the solids handling process is dewatering, which is typcially achieved through mechanical means.

Macon Soils is the Authority's subsidiary that handles and disposes of treated biosolids that are the result of the wastewater treatment processes at the MWA's Lower Poplar and Rocky Creek Water Reclamation Facitities (wastewater plants).