Bhesan STP: 200 MLD with BNR & 0.3 MWe Power

Major Upgrade from CASP to IFAS + New Oxidation Ditch for Nutrient Removal & Energy Recovery
Location

Bhesan, Surat, Gujarat, India

Procedure

Upgradation of Existing Plant + New Construction (EPC/Turnkey with PMC)

Contract Type

Project Management Consultancy + EPC Execution

Capacity

200 MLD (Upgraded existing 100 MLD to IFAS + New 100 MLD Oxidation Ditch)

Bhesan STP: Transforming 100 MLD CASP to 200 MLD Advanced BNR Facility with Biogas Energy

Completed in 2021 for Surat Municipal Corporation, this transformative project upgraded the existing 100 MLD Conventional Activated Sludge Process (CASP) plant at Bhesan to IFAS technology while adding a new 100 MLD advanced Oxidation Ditch module — achieving a total capacity of 200 MLD with Biological Nutrient Removal (BNR).

The upgrade incorporates biogas-based power generation (0.3 MWe) from anaerobic digestion for renewable on-site energy, reducing costs and emissions. Executed with minimal footprint expansion through efficient retrofits and compact processes, it delivers high-quality effluent suitable for environmental discharge and supports Surat’s pioneering wastewater reuse and circular economy initiatives in the West Drainage Zone.

Capacity Doubling, Nutrient Removal Upgrade, and Sustainable Energy Integration

Main objectives:

  • Double treatment capacity from 100 MLD to 200 MLD to address growing sewage loads in Surat’s western zone.
  • Upgrade from conventional CASP to advanced IFAS and Oxidation Ditch for effective BNR (nitrogen/phosphorus removal) and superior effluent quality.
  • Minimize land use and civil modifications by retrofitting existing infrastructure and using space-efficient technologies.
  • Integrate 0.3 MWe biogas power generation for energy recovery, operational self-sufficiency, and reduced carbon footprint.
  • Enhance overall sustainability, aligning with national river pollution abatement and urban water recycling goals.

Retrofitting Legacy Systems While Minimizing Disruption and Space

Primary challenges:

  • Upgrading an operational 100 MLD CASP plant to IFAS without halting treatment or requiring major expansions.
  • Integrating a new 100 MLD Oxidation Ditch module within limited site space.
  • Achieving reliable BNR performance under variable sewage characteristics typical of municipal flows.
  • Optimizing biogas production for consistent 0.3 MWe power output from sludge digestion.
  • Coordinating phased works to maintain compliance, control costs, and avoid environmental impacts during active operations.

Hybrid IFAS + Oxidation Ditch with Biogas Optimization

Implemented a dual-train strategy: Existing 100 MLD units retrofitted with IFAS for enhanced biomass retention, nitrification, and BNR/BPR in compact form; new 100 MLD advanced Oxidation Ditch for extended aeration, denitrification, and stable nutrient removal.
Key features:

  • IFAS media addition for higher loading rates and process stability in retrofitted tanks.
  • Oxidation Ditch configuration for progressive aeration and efficient organic/nutrient breakdown.
  • Anaerobic digestion upgrades to maximize biogas yield, feeding a 0.3 MWe genset (with gas holder for storage).
  • Dual media tertiary filtration for polishing and consistent high-quality output.
  • Automation and controls to ensure minimal civil additions and energy-positive performance.

This delivered a modern, efficient, and sustainable plant aligned with Surat’s wastewater leadership.

Assessment & Feasibility

Site audit, existing plant evaluation, hydraulic/organic load analysis, and planning for IFAS retrofit + new Oxidation Ditch within footprint.

Design & Technology Integration

Detailed engineering for IFAS upgrade, Oxidation Ditch design, BNR optimization, and biogas system (0.3 MWe) sizing finalized

Phased Construction & Retrofit

Retrofit existing 100 MLD to IFAS + construct new 100 MLD Oxidation Ditch, digesters, genset — with ongoing operations preserved.

Commissioning & Tuning

Biological seeding, phased load ramp-up, BNR performance optimization, biogas-to-power synchronization, and system fine-tuning.

Validation, Handover & Monitoring

Comprehensive testing for BNR efficacy and power output, compliance certification, SMC handover, and long-term support protocols.
Stage One
Stage Two
Stage Three
Stage Four
Stage Five

Project Partners

Fostering high-impact collaborations to deliver resilient environmental infrastructure and localized engineering excellence.
Surat Municipal Corporation (SMC)
Enviro Control Pvt. Ltd.

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