Effective Wastewater Treatment in Speciality Agrochemical Industry
Effective Wastewater Treatment in Speciality Agrochemical Industry
Introduction:

The agrochemical industry generates a significant volume of industrial wastewater due to continuous cleaning, washing, and multiple manufacturing processes. An Indian multinational agrochemical company faced a major challenge in handling a high organic load generated from its production operations. One of its plants, located in Gujarat GIDC, manufactures multiple agrochemical products and was struggling to maintain wastewater parameters within Pollution Control Board (PCB) discharge norms. For expert solutions on managing industrial wastewater effectively, contact Team One Biotech today.

ETP Flow Chart:

The Effluent Treatment Plant (ETP) consists of Primary, Biological, and Tertiary systems, integrated with Reverse Osmosis (RO) and Multiple Effect Evaporator (MEE). The activated sludge process (ASP) includes three aeration tanks in series and one anoxic tank positioned before the aeration units to enhance biological treatment efficiency.

Flow Parameters:

Flow: 200 m3/day
Inlet COD: 14,000 to 17,000 ppm
Inlet Ammoniacal nitrogen: 280 to 320 ppm
COD outlet after biological treatment:   9000 to 12000 ppm
Ammoniacal Nitrogen after biological treatment 220 to 270 ppm

Challenges:
 Despite maintaining high MLSS and MLVSS levels in all aeration tanks, the plant continued to record elevated COD, BOD, and Ammoniacal Nitrogen values, exceeding PCB discharge standards. The EHS department faced pressure to stabilize the biological process and meet environmental regulations. Some consultants even suggested incorporating a Membrane Bioreactor (MBR) after the ASP process, but it failed to deliver the expected COD and BOD reduction.

The Approach:
 After a detailed evaluation using Team One Biotech LLP’s WWTP evaluation form, on-site 

inspection, and extensive discussion with the EHS team, it was concluded that the main issue was the absence of an effective microbial consortium in the biological treatment system. Additionally, multiple waste streams entering the ETP from various production campaigns further disturbed microbial stability. To address this, Team One Biotech performed a Wastewater Microbiome Analysis (WMA) and Effluent Treatability Study. These scientific evaluations helped determine the adaptability and growth of microbial cultures in the effluent, confirming that bioremediation could significantly reduce COD, BOD, and TAN levels.

Performance Evaluation:
 The ETP performance was analyzed based on key parameters — Chemical Oxygen Demand (COD), Biological Oxygen Demand (BOD), Total Suspended Solids (TSS), pH, and Dissolved Oxygen (DO). Results revealed that with proper bioremediation and ETP optimization, the plant could achieve effluent quality within regulatory discharge limits.

Implementation Strategy:
 The bioremediation program spanned over 60 days, where Team One Biotech bioaugmented all biological tanks, excluding the MBR. Interestingly, the MBR was later removed from the process, as the required output was achieved without it. The implementation was structured into three focused stages:

  • Plant Optimization: The influent flow rate was stabilized to prevent biological shock. Earlier, the flow fluctuated with production, which hampered microbial activity. It was converted to a continuous flow pattern for steady biological treatment performance.
  • T1B Aerobio Dosing: A 60-day dosing plan was executed with T1B Aerobio, a proprietary microbial formulation. The first four weeks included high dosing to increase microbial population density, followed by maintenance dosing for biomass stability.
  • Flow Rate Enhancement: The treatment capacity was gradually increased from 120 m³/day to 225 m³/day by the 60th day, maintaining consistent outlet quality.
Results and Discussions:


 After 60 days, the plant achieved remarkable success: a 91% reduction in COD and 75% reduction in Total Ammoniacal Nitrogen (TAN). The COD levels decreased from ~15,000 ppm to ~500–450 ppm at the biological outlet. MLSS levels dropped from 18,000 ppm to 8,000–10,000 ppm, indicating improved biomass efficiency. The removal of the MBR system and its associated power consumption resulted in significant cost savings. Furthermore, the plant’s flow rate improved by 12%, and the RO membrane life increased due to reduced organic load. After a 3-month optimization phase, the use of RO was discontinued entirely, reflecting stable and sustainable ETP performance.

These outcomes demonstrate how Team One Biotech’s microbial bioremediation solutions effectively enhance industrial wastewater treatment efficiency and ensure compliance with PCB discharge norms. The project highlights how advanced biological treatment systems and ETP optimization strategies can reduce costs, improve environmental sustainability, and extend system life.

If you wish to improve your industrial wastewater treatment, achieve high COD and BOD reduction, and ensure sustainable ETP operations, connect with Team One Biotech LLP today. As one of the leading biotech companies in India, we provide a sustainable product range across multiple verticals, including probiotics for aquaculture, biofertilizers and plant growth promoters, eco-friendly cleaning solutions, animal probiotics, and on-site consultation for biocultures for ETP and STP.

Email:  sales@teamonebiotech.com

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blog dead zones in Aeration tank
Biological Wastewater Treatment: Uncovering Dead Zones in Aeration Tanks and Their Impact

Aeration tanks are the heart of biological wastewater treatment. Yet, even in well-run plants, unseen trouble often brews in the quiet corners- dead zones. There are under-mixed, under-related regions where sludge accumulates, oxygen struggles to penetrate, and undesirable microbial growth silently takes over. 

In this blog, we explore the causes, consequences, and countermeasures for dead zones—an issue too often overlooked until it begins to cripple performance. Contact us to get a comprehensive strategy to tackle various wastewater treatment issues arising due  to dead zones.

What Are Dead Zones?

Dead zones are localized pockets within aeration tanks where:

  • Mixing is insufficient
  • Dissolved oxygen (DO) levels drop abnormally low
  • Sludge settles or accumulates
  • Biological activity becomes suboptimal or undesirable.

Think of them as “black holes” in your biological reactor zones where the intended plug-flow or completely mixed flow behaviour is interrupted. Instead of aiding treatment, these zones become hotspots for filamentous bacteria, sludge bulking, septic conditions, or even toxic compound buildup.

The Hidden Causes: Poor Hydraulic and Tank Design

Dead zones are often not caused by process failure, but rather by physical design flaws or hydraulic inefficiencies. Here’s a closer look:

  1. Suboptimal Tank Geometry
  • Corners, Blind spots, or irregular shapes (e.g., square tanks without proper baffle orientation) create areas where flow velocity drops significantly.
  • Depth variations can lead to low-velocity pockets at tank bottoms, encouraging sludge accumulation.

2. Improper Diffuser Layout

  • Aeration systems that don’t cover the entire tank floor uniformly may leave some regions without adequate oxygen or turbulence.
  • Inadequate back pressure balancing between diffusers can create unequal air distributions, especially in older or retrofitted systems.

3. Overloaded Inlets or Wrong Entry Points

  • High-velocity influent entering from a single point without directional control can short-circuit across the tank, leaving side areas untouched.
  • Multiple inlets without a mixing plan can cause flow imbalances.

4. Mixer Failures or Poor Mixing Strategy

  • Absence of mechanical mixers in tanks where air mixing alone isn’t enough can allow MLSS to settle.
  • Mixing energy per unit volume (measured in W/m3 ) may fall below the minimum needed for homogeneity.
Why Dead Zones Matter: The Domino Effect 

Ignoring dead zones can result in a cascade of problems across your ETP

  1. Localized Sludge Accumulation
  • In these regions, MLSS settles and compacts, especially during low load periods or during blower shutdowns.
  • Accumulated sludge may go anaerobic, producing foul odors, sulfides, or toxic intermediates that disturb the biology when re-entrained.

2. Low DO Conditions

  • Lack of oxygen allows facultative or anaerobic organisms to dominate. This compromises nitrification, COD removal, and pathogen reduction.
  • Ammonia and organic acids can spike downstream.

3. Filamentous Growth

  • Type o21N, Thiothrix, and other filamentous bacteria thrive in low DO, Low shear environments.
  • This causes sludge bulking, poor settling in the secondary clarifier, and high TSS in treated water.

4. Short-circuiting of Hydraulic Retention Time (HRT)

  • The presence of dead zones leads to non-ideal mixing, reducing actual HRT, which directly affects COD/BOD reduction and biomass contact time.
Real-World Red Flags That Indicate Dead Zones
  • Uneven MLSS distribution across tank sections during grab sampling
  • Sudden drop in DO in specific parts of the tank despite adequate blower output.
  • Filamentous bulking despite controlled F/M and good nutrient levels
  • Odor generation from aeration zones (not just from sludge handling units)
  • Frequent need for desludging or unexpected sludge layer observations
How to Diagnose and Map Dead Zones
  1. DO profiling

Perform multi-point dissolved oxygen monitoring using portable probes across the tank length, width, and depth. Dead zones typically register <0.5 mg/L even when others are above 2 mg/L.

2. Tracer Tests

Use salt or dye tracer studies to evaluate hydraulic flow paths and identify stagnant pockets.

3. MLSS Distribution Sampling

Draw sludge samples from different depths and locations. Higher settled solids in specific zones indicate poor mixing.

4. CFD Modelling

Use Computational Fluid Dynamics to simulate flow patterns in tank designs- extremely useful during retrofit planning or new design validation.

Engineering Solutions: Eliminate the Trouble at Its Source

A. Improve Diffuser Coverage

  • Ensure uniform grid layout of fine or coarse bubble diffusers.
  • For retrofit, use drop-tube aeration or supplemental spot aerators for trouble zones.

B. Add or Reposition Mixers

  • Mechanical mixers (submersible or side-entry) can prevent MLSS settlement where airflow alone is inadequate.
  • Install in corners or far ends of tanks where air-induced mixing doesn’t reach.

C. Re-evaluate Inlet & Outlet Design

  • Use directional baffles or flow splitters to achieve even distribution across tank cross-sectional velocities.
  • Consider multi-point inlets instead of single-point discharge, especially in large tanks.

D. Tank Shape Optimization

  • In new designs, favor circular or plug-flow channels with controlled cross-sectional velocities.
  • Avoid dead-end zones or large side bays that aren’t actively aerated.

Microbial Recovery After Corrective Action

Once Dead Zones are eliminated or minimized:

  • Expect a reduction in filamentous load within 7-10 days.
  • DO profile across the tank becomes more uniform, improving nitrification and COD removal.
  • Clarifier performance improves due to better sludge settling and compaction.
  • Bioculture effectiveness increases as MLSS is more uniformly exposed to substrate and oxygen.
Final Thoughts: Dead Zones Are Silent Killers

Dead zones in aeration tanks are not just hydraulic nuisances — they can stealthily derail your entire biological treatment process. Whether you operate a 100 KLD plant or a 10 MLD facility, regular physical inspections, DO mapping, and hydraulic reviews should be part of your preventive operations strategy.

By addressing these silent trouble spots proactively, you not only stabilize ETP performance but also prolong equipment life, reduce energy wastage, and ensure consistent compliance.

Team One bIotech is one of the top biotech companies in India, addressing multiple issues related to industrial wastewater treatment with its innovative microbial culture solutions. Reach out now to enhance your wastewater treatment efficiency.

Email: sales@teamonebiotech.com

Visit: www.teamonebiotech.com

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Connect with Us on LinkedIn – Stay updated with expert content & trends!

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