Sewage Treatment
As a byproduct of human communities, sewage is produced. It is the goal of communities that the effluent (treated wastewater) is treated to an extend that it is of a similar quality to the water that it is being dumped into so as to avoid pollution and damaging ecosystems. This page will discuss the steps of sewage treatment and how we work to ensure that it is of such a quality.
Steps to Sewage Treatment
Primary Treatment involves physically removing large objects, typically by using screens, grates, and filters. The remaining solid waste will settle at the bottom of a tank as sludge.
Secondary Treatment involves the decomposition of waste. The tank is aerated to provide oxygen, increasing the rate of aerobic decomposition by bacteria. The waste is broken down into inorganic sludge and CO2 is released.
Tertiary Treatment is not always done, but it is an important step. The inorganic sludge contains various nutrients in it, which can cause eutrophication if released into water. Tertiary treatment uses chemical (and sometimes ecological) means to precipitate the nutrients out of the water.
Disinfection is the final step and is done to kill bacteria. The water is exposed to disinfectants (typically chlorine, ozone, or UV light - and sometimes more than one) in order to kill pathogens. Really fine mesh filters are sometimes used to help filter out microbes as well, in order to prevent the risk of introducing pathogens to water.