Faecal Sludge Treatment Plant

FSTP – The Next Indian Revolution For Its Best?

When it comes to sanitation, India is still fighting the challenges of sanitation and its management. Just constructing toilets in the areas where they never had one isn’t sufficient; we need to go beyond that. It can be observed that fecal sludge/septage can either be generated from open defecation (open fields, water bodies, etc) or on-site sanitation systems (septic tanks, bio-toilets, etc). According to Environment Impact Assessment (EAI) estimates, per day, India generates approx 0.12 million tons of fecal sludge. When we talk about 0 access to toilets in India, around 638 million people do not have it, which accounts for about 58% of open defecation. Indians leave about 100,000 tons of fecal matter in the open daily, on the river banks, in the fields, and even in the middle of the biggest cities. This has been leading to pollution of the water, land, and air. This data is according to a WHO-UNICEF report. Before understanding this further, you need to know about fecal sludge.

So What Is Fecal Sludge?

Fecal sludge, also known as septage, is the mixture of liquid and solid waste that builds up in onsite sanitation systems (OSS), such as septic tanks. The collection, storage, or treatment of mixtures of blackwater and excreta, with or without greywater, results in a raw or partially digested slurry.

Nearly all of India's 7,000 cities with populations under 1 million lack an effective underground sewerage system that is connected to a sewage treatment plant. So fecal sludge management becomes quite essential in this case.

What Is Fecal Sludge Management (FSM)?

Fecal sludge management is the safe end use or disposal of fecal sludge as well as its storage, collection, transport, and treatment. The "service chain" or "value chain" of fecal sludge management is made up of the collection, transport, treatment, and final use of fecal sludge. In the majority of cities, there are only primitive and unhygienic methods of processing waste, and there is the inadequate municipal infrastructure to manage waste. Contrary to the majority of on-site installations, only a little amount of focus has been placed on septic tank and pit latrine construction, maintenance management, and safe septage disposal.

Fecal Sludge Treatment Plant (FSTP)– The Latest & Best Way Of FSM

The Government of India launched the Swachh Bharat Mission to make India cleaner and safer. One of the things they did in the first phase was to build toilets across the small cities and villages in India. But do you think just building these toilets is enough? Exactly. This is why Fecal Sludge Management has become the central point of the second phase of this mission. This resulted in the construction of FSTP in many remote places of India for FSM of populated cities. The FSTP is beneficial for this country for the following reasons–

• FSTP is both economical and sustainable for rural and urban areas.
• The process that goes down in a FSTP is by natural means and has adopted gravity based methods.
• This mean it requires minimal energy and requires low cost of maintenance.

Working Process of FSTP

• Fecal sludge is collected from various sources in the city into tankers. The amount of fecal sludge will be some thousand liters (depending on the capacity of the FDTP).
• These tankers arrive at FSTP.
• The outlet of this tanker is connected to the inlet of the screening chamber. This helps in the prevention of big chunks of waste like plastics, bottles, and sanitary pads to go ahead.
• From there, the fecal matter goes ahead to Plant Drying Bed (PDB). PDB is usually attached to the screening chamber.
• In PDB, the solid and liquid parts of the sludge get separated. PDB has multiple layers and each layer has its functions. The topmost layer is plants that are rooted to the ground of soil (sand). As we go further down, there is a layer of small stones, then a few layers of bigger stones. The solid part of the sludge remains at the top, and the liquid part gets percolated and also gets filtered.
• From PDB, the liquid waste goes to the Integrated settler and anaerobic filter. This is a unit where there is 0 oxygen.
• This unit has two chambers separated by a baffle wall and here 90% of the pollutants are reduced. The next step is the Constructed Wetland.
• In this, odor and color are removed, and the level of oxygen is increased. Constructed Wetland is a horizontal filter media where contaminated water flows through different sizes of stones. Wetland plants like macrophytes help in increasing the oxygen level of the water and increasing the growth of friendly organisms in it.
• Finally, the treated water is repurified in the Polishing Pond. There the treated water is collected and kept open to natural air and sunlight, which helps in purification. Here the test for BOD (biochemical oxygen demand), COD (chemical oxygen demand), and pathogens is done.
• The clean water can now be obtained from the endpoint and it can be used in gardening and farming. The dried feces obtained from PDB can be used as compost or co-composted to make soil manure.

Where Does FSTP Stand Today & Where Will It Stand Tomorrow?

As per the Swachh Survekshann 2020, 400+ FSTPs are under construction, across India. As we know, two-thirds of India's population depends on agriculture. The outcome of FSTP is very profitable to the agricultural sector. The treated water can be used in the farms to water their yield and the dried matter can be used as compost or co-compost for manure.

More increment in the number of FSTPs means reaching 100% fecal sludge elimination and more aid to the agricultural sector. Because this plant is based on natural means, and almost no electricity, overall, is energy-efficient and environmentally friendly, we see no obstruction to keep adopting this in all the parts of our country.