A dive into sanitation solutions: processing, managing and treating used water

Subject :Environment

Section: Pollution

Urban Sewer Systems:

Sewers: Underground pipe networks in densely populated urban areas transporting waste to treatment facilities.
Sewage Treatment: Conveys waste to sewage treatment plants (STPs) for purification and pollutant removal.

Sanitation System Types:

On-Site Sanitation Systems (OSS): Used in rural or spacious urban areas, including twin pits, septic tanks, bio-digester toilets, bio-tanks, and urine diversion dry toilets.
- The functionality of OSS: Collection and storage structures that passively treat used water, disposing of liquid waste into the surrounding soil. Faecal sludge or septage, mainly solids from human excreta, accumulates within pits and tanks.
Twin Pits and Septic Tanks:
- Twin Pits: Two pits are used alternately; liquid waste soaks into the ground while solids degrade at the pit’s bottom. Unused pit left for two years for safe, natural waste disposal.
- Septic Tanks: Separate solids and scum from liquid waste; require periodic removal of accumulated faecal sludge.
Other OSS Systems:
- Bio-digester Toilets, Bio-tanks, Urine Diversion Dry Toilets: Additional OSS types serving as collection and storage structures for waste treatment.

Treatment Facilities (FSTPs & STPs):

Faecal Sludge Treatment Plants (FSTPs): Use mechanical or gravity-based methods to treat faecal sludge; reuse treated solids and water for various purposes.
Sewage Treatment Plants (STPs): Employ physical, biological, and chemical processes to purify used water before discharge or reuse.
STP Variations and Functions:
- STPs can be mechanised or non-mechanised, chosen based on a city’s resources. FSTPs are smaller, often decentralised and colocated with waste management sites.
- Purpose: Removal of impurities from used water to prevent pollution and public health issues; historical shift from odour/aesthetics focus to public and environmental health.

Significance:

Effective waste management is crucial to protect water bodies and groundwater from pollution, emphasizing the importance of these sanitation systems.
These sanitation systems are essential in containing, treating, and managing used water to ensure public health safety and environmental protection from potential pollution.

Challenges:

Universal access to safe sanitation remains challenging due to poorly designed systems and inadequate operational practices.