Final answer:
Tertiary treatment is an advanced wastewater treatment process used to further purify water, particularly before it is discharged into sensitive ecosystems. It involves additional filtration methods, such as sand filtration and enhanced biological phosphorus removal, and is more common in areas where high-quality water standards are required.
Step-by-step explanation:
Tertiary treatment is a critical part of wastewater management especially when water is discharged into a sensitive ecosystem. It involves further cleaning of water that has already undergone primary and secondary treatments. Primary treatment includes the removal of solids and oils whereas secondary treatment focuses on the bacterial decomposition of organic matter. Tertiary treatment typically includes processes such as sand filtration, enhanced biological phosphorus removal, and other methods, which result in extra filtration to reduce nutrients like nitrogen and phosphorus that can disrupt aquatic ecosystems.
It is not necessarily applied at all wastewater treatment facilities, but it is particularly common in areas where the released water impacts vulnerable or protected environments. Its usage depends on the quality standards required by the receiving waters and can vary considerably by region and the specific requirements for water quality. Technologies used in tertiary treatment are employed to meet higher standards of water quality and to protect the receiving environments.
In urban areas, wastewater treatment plants commonly handle sewage, while rural areas often use septic tank systems for wastewater management. Sludge, a byproduct of both primary and secondary treatments, is treated separately to reduce volume and potential pathogens, and may be repurposed as fertilizer or for energy production through methane gas. Advanced wastewater treatment systems, including tertiary processes, play a significant role in the resolution of the global water pollution crisis and public health protection.