Wastewater Treatment: Turning Bad Water Into Good
Wastewater treatment involves removing contaminants from sewage that has been generated from both households and industrial facilities. At the end of the process, the contaminants will be in the form of sludge and the water will be suitable for re-use and will be returned to the environment, usually by discharging it into a river or other body of water.
Wastewater is transported to the municipal treatment plant, also known as a publicly owned treatment works (POTW) by a system of underground pipes. Normally, storm water is not channeled into this system so that the treatment plant will be overloaded. There are exceptions, however.
The first stage of the treatment process is actually referred to as pre-treatment. This involves separating material that is easily collected to prevent clogging of pipes and pumps. This typically consists of larger items like cans, plastic, etc. The pre-treatment stage also includes temporary holding tanks in order to equalize the flow into the main part of the treatment system.
Following pre-treatment, there are three phases of the actual treatment process, primary, secondary, and tertiary. Primary treatment is basically the sedimentation stage, a large part of which is the use of holding tanks in order to let the solids settle to the bottom and oils float to the top. The water actually flows through a series of tanks, also known as clarifiers.
The secondary stage removes suspended solids as well as dissolved material from the water. This is the most sensitive phase of the treatment operation because micro-organisms are used. Consequently, too much of the wrong material coming through at one time, commonly referred to as a slug, can upset the treatment system. For this reason, industrial discharges are regulated by a permit issued by the local authorities.
The final, or tertiary, treatment stage is for the purpose of raising the quality of the effluent before its final discharge back into the environment. This phase includes sand filtration in order to remove any solids not captured in the primary or secondary stage. Tertiary treatment includes the removal of nutrients, nitrogen, and phosphorus and, finally, disinfection. Methods used for disinfection include the use of chlorine, ozone, ultraviolet light, or sodium hypochlorite. At this point, the water is fit for re-use.
The sludge that is a by-product of the treatment activity must then be treated and disposed of in a safe manner. Methods include digestion, in either the presence or absence of oxygen, composting, incineration, or finding a beneficial use such as fertilization.
Tristar is an innovator in the development of wastewater treatment systems, and its leadership in the field is a distinguishing characteristic. Tristar Water’s sewage treatment plant Perth cater to large commercial plants, as well as residential developments looking to improve their water management needs.
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