Advanced Bioaugmentation for Ammoniacal Nitrogen and COD Reduction at a CETP in Mumbai

Background and Problem Statement

A major Common Effluent Treatment Plant (CETP) in Mumbai was facing critical challenges in consistently meeting statutory discharge norms due to elevated ammoniacal nitrogen levels in the treated effluent, which also resulted in severe odour issues.

The CETP, designed to handle 15 million litres per day (MLD) of effluent from a cluster of industries including textiles, dye manufacturing, and pharmaceuticals, operated on conventional primary, secondary, and tertiary treatment systems.

However, with increasing wastewater complexity and variable influent composition, the system struggled to reduce ammoniacal nitrogen to below the CPCB-mandated limit of 50 mg/L.

This inefficiency was further compounded by fluctuating COD levels, putting significant stress on the biological system and threatening regulatory compliance.

The CETP managers were seeking biological solutions to address their specific challenges with ammoniacal nitrogen reduction, eliminate odour, improve treatment efficiency, and achieve environmental compliance.

As a result, the CETP team approached Organica Biotech to assess these issues and implement a targeted intervention.

Key Issues

• High Ammoniacal Nitrogen: Levels in the range of 2000 ppm at influent.
• Severe Odour Issues: Strong odour generation due to high ammoniacal nitrogen, affecting plant operations and surroundings.
• Elevated COD: Approximately 4000 ppm in incoming wastewater.

Key Objectives

• Reduce ammoniacal nitrogen to within discharge limits.
• Achieve significant COD reduction and eliminate odour for improved treatment performance.
• Restore biological health and stability of the CETP.
• Ensure long-term compliance with CPCB discharge norms.

Plan of Action

The technical team from Organica Biotech conducted a site visit to the CETP to gain a clear understanding of the existing wastewater treatment process and the characteristics of the effluent under treatment.

Following this assessment, the team recommended carrying out a treatability study, the BioSure test, to determine the suitability of customized biological solutions.

Treatability Study (BioSure Test)

A BioSure study was conducted.

The study revealed that ammonia in the effluent was being converted into nitrites and nitrates; however, it was not further reduced to nitrogen gas.

This finding highlighted that the denitrification process was not functioning effectively, resulting in an incomplete nitrogen cycle within the treatment system.

Customized Solution

Based on the BioSure analysis findings, a customized solution was formulated.

The CleanMaxx AN solution was tailored to include a higher proportion of denitrifying bacteria to address the gap in the denitrification process.

Alongside these denitrifiers, high populations of other microbial strains were incorporated into the formulation to strengthen the ammonia removal process.

This balanced microbial community ensured efficient conversion of ammonia to nitrites and nitrates, followed by their reduction to nitrogen gas.

The tailored CleanMaxx AN bioaugmentation program enabled the CETP to overcome the challenges in nitrogen removal and achieve consistent progress toward meeting regulatory discharge norms.

Results

Ammoniacal Nitrogen Reduction

• Initial AN: 2000 ppm
• Day 90: 520 ppm
• Overall Reduction: 74% within 90 days, further extended to 88% with continued treatment

Odour Reduction

Significant odour reduction was observed within 2–3 weeks.

COD Reduction

• Initial COD: 4000 ppm
• Day 90: 224 ppm
• Reduction Achieved: 94.4%

Conclusion

The introduction of a targeted microbial bioaugmentation program at the CETP enabled effective control of ammoniacal nitrogen and COD levels, achieving 88% reduction in AN, recording a value of 520 ppm, and 94.4% COD reduction, recording a value of 224 ppm within just 90 days.

The intervention also eliminated persistent odor issues, restored the biological stability of the treatment system, enhanced operational efficiency, and ensured compliance with CPCB discharge norms.

The CETP is now operating sustainably, meeting environmental regulations while handling complex, multi-industry effluents.