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Wastewater treatment, an elaborate process to protect the environment as well as human health

Wastewater treatment, stakes & objectives

Wastewater... where do they come from, where are they treated? - More

Sewage water is created by residences, institutions, hospitals, commercial and industrial establishments. It can be treated close to where it is created or collected and transported via a network of pipes and pump stations to a municipal treatment plant. As far as industrial sources of wastewater are concerned, they often require specialized treatment processes, which are frequently present on site.

Wastewater treatment... why? - More

Once water has been used by its customers, the discharged water must be released back to its natural environment. Therefore, it must be treated in order to protect the environment as well as human health. This is the aim of wastewater treatment.

Wastewater treatment... what is it exactly? - More

Wastewater treatment is the process of removing contaminants from wastewater. It includes physical, chemical and biological processes to remove physical, chemical and biological contaminants. Once treated, water can then be released back into nature.

Wastewater treatment, step by step

Sewage water treatment involves three stages, called primary, secondary and tertiary treatment.

Primary treatment - More

includes screening, clarification and flotation : the bulk is separated from the wastewater stream

Secondary treatment - More

includes biological and/or physicochemical processes. As far as biological treatments are concerned, there are two different types of treatment, aerobic and anaerobic treatment : in both cases, dissolved biological matter is progressively converted into a solid mass by using indigenous, water-borne microorganisms

Tertiary treatment - More

which, in most cases, adds a polishing step comprised of advanced oxidation, flotation or clarification: the biological solids are neutralized then disposed of or re-used, and the treated water may be disinfected chemically or physically. The final effluent can be discharged into a stream, river, bay, lagoon or wetland, or it can be re-used for irrigation. If it is sufficiently clean, it can also be used for groundwater recharge.

In industry, water is used for multiple purposes: feed boiler houses and cooling systems, constitute products, support reactions, clean facilities, rinse products, protect against fire, etc. Once they've been used, these waters contain pollutants and need to be treated, too. Sludge may also be produced through these industrial wastewater treatment processes.

Wastewater treatment allows industries to make sure their production process doesn't harm the environment. Moreover, since treatment of industrial effluents represents a cost, optimizing the production processes for the different water streams required is essential for the industry's economic performance.

For municipal plants as for industrial sites, Wastewater treatment is an elaborate process being usually performed in several phases.

Wastewater treatment flowchart

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