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Overview of Wastewater Treatment Methods

The objective of wastewater treatment is to remove impurities from wastewater prior to releasing it into a waterway to again be part of the ecosystem. The amount of impurities to be removed is determined by local environmental conditions and governmental legislature, for example the United States and other developed countries typically require 85% of suspended solids and biochemical oxygen demand (also known as BOD) to be removed prior to water being released in a waterway. There are three different levels of treatment: primary, secondary, and tertiary. These treatments must be completed in order, for example you can only perform secondary level treatments once primary level treatments are performed.

Primary Treatment

The first level of processes is known as primary treatment. Primary treatment removes all material that will either float or settle out by gravity, but is limited because it cannot remove any impurities that are dissolved within the water. This is due to primary treatment utilizing only physical changes to the water. Overall primary treatment will remove about 60% of suspended solids and 35% BOD prior primary effluent transferring over to secondary treatment levels.

Secondary Treatment

Assuming local legislation requires greater than 60% of suspended solids and 35% of BOD to be removed, water is then transferred from primary treatment processes, to secondary treatment. Secondary treatment removes soluble material, as well as more suspended solids that made it past the primary treatment. Secondary treatment is able to remove soluble material because it utilizes chemical changes to the water through biological processes in which aerobic microbes consume the organic impurities as food. Secondary treatment can remove about 85% of both total solids and BOD, making it within regulation for most developed countries, but on rare occasions the secondary effluent is passed on to tertiary treatment.

Tertiary Treatment

When specific impurities need to be targeted, or if the receiving water is very vulnerable to the effects of pollution, secondary effluent is further treated by tertiary processes. Tertiary processes are capable of removing over 99% of impurities, but the processes are often double the cost of secondary treatment. This makes tertiary treatment an economical choice only in special circumstances. Tertiary treatment utilizes both physical and chemical changes.

Shanley Pump

Shanley Pump caries multiple pumps used in wastewater treatment facilities. We stock pumps, such as our SEP progressive cavity series, used to pump sludge in both primary and secondary treatments, and our Edur DAF pumps utilized in both secondary and tertiary treatments, allowing us to often ship same day. Give us a call or email us below today to let us know how Shanley Pump can meet your wastewater treatment pumping needs.

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