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Basics of Wastewater Treatment

Wastewater treatment, also known as sewage treatment, is the removal of impurities from wastewater, or sewage, prior to the water being released back into nature. Nature already has ways of breaking down pollutants and removing them from the water; however, the natural process in incapable of competing with the volume of pollutants that would enter the environment due to daily human activities. Water treatment facilities apply the same natural processes on a large scale to ensure our water systems stay clean; in fact, wastewater treatment is one of the widest practiced forms of pollution control. Shanley Pump is a family pump distributor that has provided various pumps used in the wastewater treatment sector for over 40 years. Give us a call or email today to learn how was can assist your wastewater treatment plant in keeping our waterways clean.


The first step in the wastewater treatment process is collecting polluted water and then transporting it to the treatment facility. The collecting and transporting of wastewaters can be dated back to ancient cities such as the Cloaca Maxima, meaning “Great Sewer”, of ancient Rome. The Cloaca Maxima was constructed in the 6th century BC with the purpose of carrying storm water from the city to the river Tiber. Large public baths were also connected to the Cloaca Maxima making it a combined system.

Modern cities are generally composed of two separate sewerage systems, domestic and storm. Domestic systems are connected to homes and carry waste waters to treatment facilities, while storm systems are designed to carry only rainwater from the streets and transport them to a natural water source to avoid flooding within the city. Sewage systems that carry both domestic and storm waters in the same pipes are known as a combined system. Older cities, such as Atlanta, still have a combined system. Combined systems are designed to overflow directly into a nearby stream or river to prevent overloading a wastewater treatment facility. This is known as CSO, or combined sewer overflow, which is a major contributor to water pollution.

What is Removed from Sewage Water?

Once the wastewater is transported from the collection systems to the wastewater treatment facility, the process of removing impurities begins. During primary treatment, any material that will either float or readily settle out by gravity is removed. After primary treatment, the water is passed on to secondary treatment, where any soluble organic matter and suspended solids that escaped primary treatment are removed. Secondary treatment is generally completed using a biological process in which microbes consume the impurities as food, converting them into carbon dioxide, water, and energy for their growth and reproduction.

Key measurements to consider are the biochemical oxygen demand, or BOD, suspended solids, plant nutrients, and microbes within the sewage water. Biochemical oxygen demand is a measurement of the oxygen required by microbes to decompose organic substances in sewage. BOD levels are key because if waste enters a waterway with high BOD it will greatly reduce the dissolved oxygen within the water way. This can lead to the mass death of the aquatic life within the waterway. Plant nutrients such as nitrogen and phosphorus within waste can also cause issues to the aquatic life. If waste high in plant nutrients enters a waterway it can lead to the rapid growth of algae, which will also eventually lead to a lower amount of dissolved oxygen within the water. High microbial count can lead to E. coli and coliform outbreaks which can lead to illness to the human population that uses a waterway for recreation activity, such as swimming. Wastewater treatment is key to maintaining a healthy ecosystem and preserving our waterways for generations to come.

Call or email us below today to see how we can assist your wastewater treatment facility.

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*Shanley Pump Group is not affiliated with nor distributor for Seepex®, Allweiler®, Moyno®, Tarby®, Netzsch®, or Continental Inc.® all referenced product names, brands, models, or part numbers is solely for identification purposes. Seepex® is a registered trademark of Seepex®. Moyno® and Tarby® are registered trademarks of Robins and Myers® and NOV®, Netzsch® Incorporated is a registered trademark of the Netzsch® Group, Allweiler® is a registered trademark of Colfax® Corporations Continental® Pumps is a Trademark of Continental® Ultra Pumps.