Municipal Sewage Treatment Plant in Tamil Nadu India: 2025 Guide
Engineering Solutions & Case Studies
Zhongsheng Engineering Team
Municipal Sewage Treatment Plant in Tamil Nadu India: 2025 Guide
As of 2025, Tamil Nadu has grounded 18 sewerage projects worth ₹5,670.8 crore under AMRUT, including the 10 MLD Nasapakkam tertiary STP in Chennai and the 16 million m³/year Koyambedu reuse plant. Municipal STPs in the state increasingly use ozonation, MBR, and A/O processes to meet CPCB norms and support water reuse.
Current Status of Municipal Sewage Treatment in Tamil Nadu
Tamil Nadu has grounded 18 sewerage and septage management projects worth ₹5,670.8 crore under the AMRUT scheme, signifying a major investment in urban sanitation infrastructure (MoHUA SAAP data). Chennai leads in sewage treatment capacity, with its metropolitan area housing 8 major municipal sewage treatment plants. These include long-standing facilities like the Kodungaiyur Zone-I plant, commissioned in 1991, and newer, advanced installations such as the Koyambedu and under-construction Nasapakkam STPs. The Chennai Metropolitan Water Supply and Sewerage Board (CMWSSB) reports that approximately 75% of Chennai’s sewage is collected via an extensive underground sewerage network. CMWSSB aims to achieve full sewage collection and treatment coverage across the city by 2027. Beyond Chennai, the Tamil Nadu government mandates the phased rollout of underground sewerage schemes in all urban local bodies, starting with district headquarters and major towns (IJERA Salem study). This phased approach supports statewide improvements in sanitation infrastructure, meeting urban population demands and complying with national environmental standards. For a comparative case study on STP implementation in another Indian state, refer to our guide on Municipal Sewage Treatment Plants in Rajasthan.
Key Municipal Sewage Treatment Plants in Tamil Nadu: Capacities and Technologies
municipal sewage treatment plant in tamil nadu india - Key Municipal Sewage Treatment Plants in Tamil Nadu: Capacities and Technologies
Chennai’s installed municipal sewage treatment capacity exceeds 550 MLD, with significant expansions underway and planned to meet growing urban demands. This infrastructure supports wastewater management across the region, using diverse technologies to handle variable sewage loads and meet effluent quality targets.
One of the most notable facilities is the **Koyambedu STP**, recognized as India’s largest water reuse project. It has a capacity of 16 million m³/year (approximately 44 MLD) and uses advanced processes, including ozonation for disinfection. Treated water from Koyambedu is reused in industrial applications, reducing regional demand for freshwater.
The **Nasapakkam STP** reflects a strategic shift toward water reuse. This 10 MLD tertiary treatment plant, currently under construction, is designed for advanced reuse with potential for future potable conversion. It integrates advanced technologies to produce high-purity effluent suitable for sensitive applications.
The **Kodungaiyur STP**, specifically the Zone-I plant, has operated since 1991 and remains integral to Chennai’s sewage treatment network. It treats mixed residential and commercial sewage using conventional methods refined over decades. Plans are in place to add 120 MLD to Chennai’s total STP capacity by 2026, reinforcing the city’s commitment to comprehensive wastewater management.
Below is a summary of major municipal sewage treatment plant in Tamil Nadu India:
Plant Name
City
Capacity (MLD)
Primary Technology
Status/Key Feature
Koyambedu STP
Chennai
~44 (16 million m³/year)
Conventional + Ozonation
Operational, India's largest water reuse project for industrial use
Nasapakkam STP
Chennai
10
Tertiary Treatment (Advanced)
Under construction, designed for potential potable reuse
Kodungaiyur STP (Zone-I)
Chennai
Significant, multi-phase
Conventional
Operational since 1991, treats mixed sewage
Perungudi STP
Chennai
~54
Conventional
Operational
Nesapakkam STP
Chennai
~30
Conventional
Operational
For projects requiring high-efficiency treatment and reuse-grade effluent, an MBR system offers a compact and reliable solution. Disinfection requirements, especially for reuse, can be met effectively with technologies like chlorine dioxide generation, ensuring pathogen kill without harmful residuals.
Technology Options for Modern STPs in Tamil Nadu
Anoxic/Aerobic (A/O) biological contact oxidation achieves 85–92% BOD and 80–90% COD removal, making it a robust technology for municipal sewage treatment, particularly in decentralized plants of 1 to 80 m³/h. It is valued for operational stability, simplicity, and lower capital and operational costs, which makes it suitable for smaller urban local bodies or specific city zones.
Membrane Bioreactor (MBR) systems are increasingly selected for projects requiring high effluent quality and a smaller footprint. By combining activated sludge with membrane filtration, MBR delivers effluent with turbidity typically below 1 μm, meeting or exceeding CPCB secondary standards. The technology enables up to a 60% reduction in footprint compared to conventional systems, a key advantage in land-constrained urban areas.
Ozonation provides over 99% pathogen kill and serves as an advanced disinfection method without generating harmful chlorine residuals. It is used at facilities like the Koyambedu STP for high-end reuse where microbiological safety is critical. Ozonation also oxidizes emerging contaminants and color, enhancing effluent quality for reuse.
Tertiary treatment processes are necessary to exceed CPCB secondary discharge standards and support water reuse. These typically include multi-media filtration, activated carbon adsorption, and advanced disinfection (e.g., UV or ozonation). The Nasapakkam STP, designed for potential potable reuse, relies on such comprehensive tertiary stages to ensure maximum purification.
Here is a comparison of key treatment technologies for municipal STPs:
Technology
Key Features
Typical Effluent Quality (BOD/TSS)
Footprint
Suitable Scale
Cost Factor (Relative)
A/O Biological Contact Oxidation
Robust, simple, good nutrient removal
<30 mg/L / <50 mg/L
Medium
1-80 MLD (decentralized to medium)
Low to Medium
MBR (Membrane Bioreactor)
High effluent quality, compact, pathogen removal
<5 mg/L / <5 mg/L (turbidity <1 μm)
Small (up to 60% less)
1-100+ MLD (medium to large)
Medium to High
Conventional Activated Sludge
Well-established, flexible, scalable
<30 mg/L / <50 mg/L
Large
5-500+ MLD (medium to very large)
Low
Ozonation (Disinfection)
High pathogen kill, no chlorine residual, color removal
(Post-treatment)
Small (for disinfection unit)
All scales (as tertiary step)
Medium (as an add-on)
Tertiary Filtration (Multi-media)
Removes suspended solids, pre-treatment for advanced stages
<10 mg/L / <10 mg/L
Medium
All scales (as tertiary step)
Low to Medium (as an add-on)
For urban zones requiring a compact underground sewage treatment solution, our WSZ series integrated plants are an ideal fit. Enhancing effluent quality further can be achieved with multi-media filtration systems, particularly for water reuse applications.
Cost, Compliance, and ROI for Tamil Nadu STP Projects
municipal sewage treatment plant in tamil nadu india - Cost, Compliance, and ROI for Tamil Nadu STP Projects
The average construction cost for a municipal sewage treatment plant in Tamil Nadu ranges from ₹4–6 crore per MLD for conventional systems, rising to ₹7–9 crore per MLD for advanced MBR or reuse-ready plants. These figures are essential for initial budgeting and feasibility assessments, reflecting the investment needed for higher treatment levels and effluent quality. The increased cost for MBR and reuse-ready systems is offset by a smaller footprint, better effluent, and compliance with reuse standards, often leading to long-term cost savings.
All municipal sewage treatment plant in Tamil Nadu India must comply with Central Pollution Control Board (CPCB) effluent discharge standards. Key parameters include Biochemical Oxygen Demand (BOD) ≤ 30 mg/L, Total Suspended Solids (TSS) ≤ 50 mg/L, and Fecal Coliform ≤ 1,000 MPN/100mL for surface water discharge. Stricter norms apply for land application or sensitive environments. Meeting these standards requires proper design, reliable equipment, and consistent operation and maintenance.
Government funding improves the financial feasibility of STP projects. The Atal Mission for Rejuvenation and Urban Transformation (AMRUT) provides central assistance covering up to 35% of project costs for eligible cities and towns in Tamil Nadu. This support reduces the financial burden on urban local bodies and promotes the development of essential sewerage infrastructure. Additional state-level incentives may also be available.
Investing in advanced treatment for water reuse delivers a strong return on investment (ROI). In industrial zones facing water scarcity and high freshwater costs, reuse at 70% recovery can reduce intake costs by ₹15–25/m³. This economic benefit, combined with improved water security and lower environmental impact, makes reuse-focused STPs strategic assets for urban growth in Tamil Nadu. For a detailed cost-benefit analysis of MBR systems for reuse projects, explore our MBR Effluent Quality vs Cost guide.
Category
Parameter
Value/Range
Notes
Construction Cost
Conventional STP (per MLD)
₹4–6 crore
For basic secondary treatment
Construction Cost
MBR/Reuse-ready STP (per MLD)
₹7–9 crore
For advanced treatment and high-quality reuse
CPCB Discharge Norms
BOD
≤ 30 mg/L
For discharge into surface waters
CPCB Discharge Norms
TSS
≤ 50 mg/L
Zhongsheng Engineering Team
Our team of wastewater treatment engineers has over 15 years of experience designing and manufacturing DAF systems, MBR bioreactors, and packaged treatment plants for clients in 30+ countries worldwide.
