Project Overview
The 220 MLD Sewage Treatment Plant at Kosad, Surat is a benchmark project in sustainable wastewater management. Delivered under an EPC + O&M contract for Surat Municipal Corporation, the project expanded and upgraded the existing 134 MLD facility to 220 MLD, integrating advanced treatment processes and renewable energy systems.
The upgraded plant ensures enhanced environmental performance, operational self-sufficiency, and contributes to the decarbonisation of water treatment.
Key features include:
- Upgradation of the existing UASB system to IFAS (Integrated Fixed-Film Activated Sludge), delivering enhanced biological treatment within the same footprint.
- Addition of a new SBR (Sequencing Batch Reactor) line.
- Biological Nutrient Removal (BNR) in both IFAS and SBR lines for nitrogen and phosphorus reduction.
- Advanced fine filtration for tertiary polishing.
- Final treated effluent consistently achieving BOD and TSS ≤ 5 mg/L, safely discharged upstream of the Tapi River weir, enabling reuse and recycling as a sustainable water source.
- A 0.6 MWe captive biogas power system to ensure partial energy independence and lower grid dependency.
Project Objectives
- Accommodate an additional 86 MLD hydraulic load within the existing site footprint by upgrading and optimizing existing units.
- Achieve high-quality effluent meeting stringent discharge norms, with BOD and TSS ≤ 5 mg/L.
- Integrate Biological Nutrient Removal to enhance nitrogen and phosphorus reduction.
- Discharge treated water upstream of the Tapi River weir, supporting reuse and recycling as part of a circular water economy.
- Generate renewable power onsite through a 0.6 MWe biogas plant, contributing to decarbonisation and operational self-sufficiency.
The Challenge
The project faced critical challenges during its execution phase, primarily due to the complexity of modifying and upgrading bio-process and hydraulic design of existing two-stage treatment units. Integrating an IFAS system under a limited footprint required precise planning and advanced engineering to avoid operational disruption.
The Solution
Enviro implemented an augmentation strategy that upgraded the UASB process to IFAS, added a new SBR line, and introduced advanced nutrient removal and tertiary polishing systems. Space constraints were addressed through efficient hydraulic design modifications, while biogas-to-energy integration improved energy sustainability.
The Results
- Total capacity expanded from 134 MLD to 220 MLD.
- Consistently high-quality treated effluent meeting BOD/TSS ≤ 5 mg/L.
- Nutrient removal aligned with stringent CPCB and NGT discharge standards.
- Renewable energy generation of 0.6 MWe, reducing grid reliance.
- A model of sustainable wastewater treatment and circular resource use in an urban setting.
Why It Matters
The Kosad STP demonstrates how urban sewage treatment facilities can be expanded and modernised within limited footprints while achieving nutrient removal, energy recovery, and sustainability. It sets a precedent for smart, integrated wastewater solutions in India’s growing cities.
