Introduction
Sanitation systems are a critical aspect of public health and environmental preservation. Utilizing proper channels for sanitation, such as those that direct used water into the ground or open drains, can prevent harmful impacts on people and the environment. Modern sanitation systems have evolved greatly since their rudimentary introduction around 4000 BC, with the most recognizable model being developed in London in the 1800s. Government policies and interventions play a significant role in the design and implementation of these systems.
Understanding Different Types of Sanitation Systems
On-site Sanitation Systems (OSS) include twin pits, septic tanks, bio-digester toilets, bio-tanks, and urine diversion dry toilets. Typically found in rural or more spacious urban settings, these systems passively treat used water, which includes fecal sludge or septage. They are designed to cater to different spatial constraints.
The Role of Twin Pits and Septic Tanks
In twin pits, two pits are alternately used. This design allows liquid to soak into the ground while solids settle and degrade. One pit remains inactive for about two years to ensure pathogen-free content for reutilization. However, they are unsuitable for rocky soils.
Septic tanks are watertight tanks through which used water flows, allowing solids to settle at the bottom and oil or grease to float to the top. Despite gradual degradation of solids, accumulated faecal sludge and scum must be removed regularly. This process is performed by special trucks fitted with vacuum pumps that transport the sludge to treatment facilities known as Faecal Sludge Treatment Plants (FSTPs).
Urban Sewer Systems: Catering to Dense Populations
Urban areas with high population density often employ sewer systems. Comprising an underground pipe network, these systems collect and convey wastewater to treatment facilities. The sewage, i.e., used water, is then transported by sewers to Sewage Treatment Plants (STPs) for further treatment.
Treatment Facilities: FSTPs and STPs
FSTPs operate using either mechanical or gravity-based systems to manage faecal sludge. Also referred to as “Faecal Sludge Management” or FSM, these facilities treat the sludge so that it can be safely disposed of or reused. For example, treated solids from FSTPs can often be composted with organic municipal waste for agricultural use.
On the other hand, STPs utilize physical, biological, and chemical processes to remove pollutants from used water. Advanced STPs may also use methods like membrane filtration to enhance water reuse capabilities.
Choosing Between FSTPs and STPs
The choice between FSTPs and STPs depends largely on the context and resources. While FSTPs are smaller and can coexist with Solid Waste Management sites, STPs are larger, centralised facilities typically located near bodies of water to handle disposal of treated water.
The Importance of a Complex Sanitation System
As water navigates through domestic and non-domestic uses, it accumulates various impurities, including organic matter, nutrients from detergents, pathogens, and heavy metals. To ensure this used water doesn’t become a source of pollution or public health risk, it’s essential to have an effective sanitation system. Although odour and aesthetics have been traditional considerations for sanitation, it’s only recently that the more significant implications for public and environmental health have been recognized.
Challenges in Sanitation Management
Despite significant improvements in public health due to sanitation systems, universal access and safe management remain challenges. Issues such as poorly designed and built systems, and unsafe operation and maintenance practices need to be addressed to protect increasingly precious water bodies and groundwater aquifers.