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

Types of Sanitation Systems

• The type of sanitation system depends on the location.

1. Rural Areas

• In rural areas, twin pits or septic tanks are common, serving as on-site sanitation systems.
• Other on-site systems include bio-digester toilets, bio-tanks, and urine diversion dry toilets.
• These systems collect and store used water, treating it passively, with the residue known as faecal sludge.
• Twin Pits
  • Twin pits (separated by at least one metre), used alternatively, have porous walls.
  • Liquid waste soaks into the ground, while solids collect and degrade at the pit's bottom.
  • After reaching capacity, one pit is left unused for two years, ensuring safe reuse.
• Septic Tanks
  • In areas with less suitable soil, septic tanks are used.
  • These watertight tanks separate solids from liquid waste, and the cleared liquid is disposed of in the surrounding soil.
  • Regular removal of accumulated faecal sludge and scum is necessary.

2. Urban Areas

• Densely populated urban areas often use an underground network of pipes (sewers) to transport used water to treatment facilities.
• Sewage is conveyed to sewage treatment plants (STPs) through interconnected pipes, where pollutants and contaminants are removed.

Treatment Facilities

1. Faecal Sludge Treatment Plants (FSTPs)

• It uses mechanical or gravity-based systems to treat solids and liquids separately.
• Treated solids can be reused in agriculture, and treated water may be reused in landscaping.
• This process of containing, conveying and treating faecal sludge is also called faecal sludge management (FSM).
• In many small and medium towns or villages, OSS-FSM is the predominant form of the sanitation system.

2. Sewage Treatment Plants (STPs)

• STPs use a series of physical, biological, and chemical processes to remove pollutants and contaminants from used water.
• To facilitate the reuse of used water, advanced systems use additional treatment such as membrane filtration.
• STP technology can be of several types, either mechanised and non-mechanised.
• It is often chosen based on techno-managerial and the financial capacities of a city’s government.

FSTPs vs STPs

• FSTPs are generally smaller than STPs and can be colocated with municipal solid waste management sites.
• They can also be decentralised and located closer to the sources of faecal sludge.
• In contrast, STPs are much larger, centralised installations designed to serve entire communities or large urban areas.
• They require substantial infrastructure and are typically located near water bodies so they can discharge treated water.

Complexity Sanitation Systems

• The complexity of sanitation systems is necessary to remove impurities accumulated during water usage, including organic matter, pathogens, and pollutants.
• These systems aim to prevent pollution and safeguard public and environmental health.
• Universal access to well-managed sanitation services is identified as a challenge, requiring improvements in system design, construction, and maintenance practices.