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In today's world, with increasing concerns about water scarcity and environmental pollution, residential sewage treatment plants (STPs) are becoming more popular as solutions for managing household wastewater. These systems not only ensure the safe disposal of sewage but also contribute to water conservation by treating and recycling water for non-potable uses.
What is a residential sewage treatment plant?
System designers design a residential sewage treatment plant to treat wastewater from households, ensuring the safe discharge of water for the environment. Installers fit these plants on residential properties to manage sewage and prevent pollution of nearby water sources.
The process involves physical, chemical, and biological methods to remove contaminants from sewage, breaking down organic matter and reducing harmful substances before releasing the treated water back into the environment or reusing it for non-potable purposes like irrigation or flushing toilets.
Cost of residential sewage treatment plant
The financial aspect of installing a residential STP is multifaceted, influenced by various factors such as size, capacity, technology used, and geographical location. In India, the initial investment can range from INR 1.5 lakhs to INR 80 lakhs.
The broad spectrum is indicative of the diverse options available to consumers, from basic setups for individual homes to more complex systems for larger communities. Advanced technologies like Sequential Batch Reactor (SBR), Moving Bed Biofilm Reactor (MBBR), or Membrane Bioreactor (MBR) can drive up the initial costs but offer superior efficiency and treatment quality.
Installation
Activities such as excavation, plastering, brick work, plumbing, flooring etc are included in this, along with the cost of construction material.
The construction requires different items including walls made of solid cement blocks, outside and inside plastering for water tightness, a PCC base, PVC pipes, baffle walls, gravel filter media, an RCC slab, perforated slabs, vent pipes, and plants/reeds like cana, cattails, bulrushes etc.
The cost component for construction and installation varies across different cities. Typically, an 8-10 KLD capacity plant's installation could cost around Rs. 2.5-3 lakhs.
Size and Capacity
The size and capacity of an STP are crucial determinants of its cost. A larger plant, designed to handle increased volumes of sewage, will naturally require a more substantial investment. For instance, a 10 KLD (kilo liters per day) STP suitable for larger residential complexes may cost between INR 6 lakhs to INR 10 lakhs. The capacity must align with the expected sewage output, ensuring the system’s effectiveness and longevity.
The cost of a compact sewage treatment plant (STP) with a capacity of 50 KLD (50,000 liters per day) is nearly 14.5 lakh rupees. For those unfamiliar with the term, 50 KLD stands for 50,000 liters per day or 50 kiloliters per day, which indicates the volume of sewage the plant can treat daily.
Moving to larger capacities, the cost of a compact sewage treatment plant with a capacity of 100 KLD (100,000 liters per day) is nearly INR 21 lakh. These costs are essential considerations for developers, builders, and apartment complex managers as they plan and budget for wastewater treatment facilities.
Operational and Maintenance Costs
Apart from considering the initial installation cost of sewage treatment plant, businesses or individuals must also consider the ongoing operational and maintenance expenses that come with running a residential STP. They must account for the costs related to energy consumption, chemical usage, labour, and periodic servicing to ensure optimal performance and compliance with regulations.
Decentralised wastewater treatment systems offer a low cost, on-site treatment approach, but they require continuous operation and maintenance for sustainability and to maintain the plant's desirable performance. Generally, the plant's annual operation and maintenance cost ranges from Rs. 3000-5000.
Cost summary of DWWT components for 1 KLD plant is *
| Components | Surface area requirement (sqm/KL) |
Capacity (Cum/KL) |
% of Total cost(approx) |
| Settler | 0.5 | 1 | 10 |
| Reactor | 1 | 1.73 (inner); 3 (outer) |
40 |
| Planted filter | 5 | 4 | 30 |
| Storage sump | - | 1 | 10 |
| Polishing Pond | 1 | 0.88 | 5 |
| Misc | 5 |
It is necessary to regularly de-sludge the settler and baffled reactor within 1-3 years to meet the effluent standards. When treatment efficiency goes down, replacing the filter media becomes necessary. Cleaning the gravel filter media usually occurs within 8 – 10 years.
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