Restart and Commissioning of ETP of a Petrochemical Industry

Introduction: 

This petrochemical industry in West Bengal has a full-fledged Activated Sludge Process (ASP) system with two aeration tanks in parallel. This Effluent Treatment Plant (ETP) experienced shock loads and frequent upsets due to multiple streams and high Polycyclic Aromatic Hydrocarbons (PAH) in the effluent. Maintenance of a good biomass in the aeration tanks along with sustainability in shock loads was a challenge as the upsets were highly shock-inducing.

ETP Details:

The industry had primary treatment, biological treatment, and then a tertiary treatment.

Previous Capacity

Flow (current) 450 KLD
Flow (design) 450 KLD
Type of process ASP (parallel tanks)
Capacity of AT-1 350 KL
Capacity of AT-2 350 KL
Retention Time 37.33 hours(combined)

Challenges: 

Parameters (PPM) Avg. Inlet parameters  Avg. Outlet parameters (MBR Outlet)
COD 4000-8000 3200-6000
BOD 2600-5800 1200-3800
TDS 7000 1000
PAH 1450 1000

Operational Challenges:

  • The primary treatment was working at 5% efficiency in terms of COD reduction.
  • The biological treatment worked at an average 20-25% efficiency in terms of COD reduction.
  • They were struggling to control the higher PAH levels, and it was inducing shock loads, as explained earlier.

The Approach:

The industry partnered with us to commission their Upflow Anaerobic Sludge Blanket (UASB) and Aeration Tank with increased capacity and restart the ETP at its full capacity in terms of hydraulic load.

We adopted a 3D approach that included:

Research/Scrutiny:

Our team visited their facility to go through the process of the new Effluent Treatment Plant (ETP) and to scrutinize the value-addition factors.

Analysis:

We analyzed the 3-month cumulative data of their ETP to see trends in the inlet-outlet parameters’ variations and the permutation combinations related to it.

Innovation:

After the research and analysis, our team curated customized products and their dosing schedules with formulation, keeping in mind the plan of action to get the desired results.

This process is called bioaugmentation.

Desired Outcomes:

  • Development of strong biology to withstand shock loads and prevent upsets.
  • Making ETP more efficient regarding COD/BOD and PAH degradation.
  • Reduction in FOG (Fats, Oils, and Grease).

Execution:

Our team selected the product:

For Aeration Tank:

  1. T1B Aerobio: consists of blends of several strains of aerobic and facultative microorganisms, usually bacteria, along with key trace elements on a complex inert media.

For Oil/Grease Trap:

     2.T1B FOG BioBloc:

  

Our plan of action included:

  • The addition of T1B Aerobio was also done every day with a reduction in the dosing every 10 days.
  • A total of 150 kgs of T1B Aerobio was used for 60 days of treatment.
  • T1B FOG BioBloc was placed at the O/G trap for FOG reduction.
  • 4 blocks of T1B FOG BioBloc were used for 60 days.

Results:

Parameters

Parameters (PPM) Avg. Inlet parameters  Avg. Outlet parameters (secondary clarifier outlet)
COD 4000-8000 1200-2300
BOD 2600-5800 500-850
TDS 7000 1000
PAH 1450 321

The implementation of the bioaugmentation program resulted in significant improvements in the performance of biological units in their Wastewater Treatment Plant (WWTP):

  • The COD/BOD degrading efficiency increased from 20% to 70% in the biological system.
  • PAH was also getting degraded up to 77%.
  • MLSS (Mixed Liquor Suspended Solids): MLVSS (Mixed Liquor Volatile Suspended Solids) ratio was optimized.
  • Biomass in the ASP system displayed great stability even during shock load situations.

This sustainable wastewater treatment approach has helped the industry optimize effluent quality, enhance microbial community stability, and ensure compliance with environmental standards.

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Effluent treatment with ammoniacal nitrogen and COD reduction
Organic Intermediates Effluent Treatment with Ammoniacal Nitrogen and COD Reduction

Introduction:

Effluent treatment in the organic intermediates industry presents significant challenges due to high levels of ammoniacal nitrogen (TAN) removal and chemical oxygen demand (COD) reduction. These industrial effluents often arise from processes such as chemical synthesis, solvent washing, and product separation, resulting in a complex mix of contaminants. High ammoniacal nitrogen wastewater levels not only hinder biological wastewater treatment but also pose serious environmental compliance and regulatory challenges.

An organic intermediates production unit in Gujarat faced operational inefficiencies in its industrial effluent treatment plant (ETP), which used a combined anaerobic-aerobic wastewater treatment system. Persistent high TAN levels (>450 ppm) and COD levels (>20,000 ppm) hindered the plant’s ability to meet wastewater discharge standards.

Plant Details:

Flow Rate: 240 KLD
Aeration Tank Capacity:- 400 KLD
UASB Capacity:- 350 KLD
HRT:-   75 hrs (Total)

The Initial Approach:

A thorough wastewater site assessment and effluent characterization study were conducted. Key challenges identified included:

  • High ammoniacal nitrogen toxicity, impacting biological treatment efficiency.
  • Elevated COD concentration due to refractory organic pollutants.
  • Poor activated sludge quality and microbial performance in the aerobic treatment process.
  • Inadequate nitrification-denitrification process.

Effluent Treatability Study:

A laboratory-scale wastewater treatability study was performed using T1B Aerobio, a specialized microbial bioremediation solution, to evaluate its potential in addressing these challenges. The study focused on:

  • TAN reduction through enhanced microbial nitrification and denitrification.
  • COD biodegradation by targeting hard-to-degrade organic compounds.
  • Sludge management improvement for better settling properties and reduced sludge carryover.

Microscopic analysis and batch reactor trials demonstrated significant microbial adaptation to high TAN and COD levels, validating the efficacy of T1B Aerobio for industrial wastewater treatment.

T1B Aerobio: Enhancing Treatment Performance

T1B Aerobio is a bioaugmentation technology featuring a specialized microbial consortium designed for high-strength industrial effluent treatment. Its robust microbial strains include nitrifiers and denitrifiers that efficiently convert ammoniacal nitrogen to nitrogen gas, while degrading persistent organic pollutants to achieve substantial COD removal efficiency.

Execution:

Plant Optimization:

  • Adjusted aeration rates to maintain dissolved oxygen (DO) levels optimal for nitrification (2.5-3.0 mg/L).
  • Improved hydraulic retention time (HRT) to enhance microbial degradation.

Dosing Regime:

A 60-day bioaugmentation dosing schedule was implemented:

Monitoring Parameters:

  • TAN and COD concentrations.
  • Nitrate and nitrite levels during nitrification process.
  • Sludge volume index (SVI) and microbial activity.

Observations:

The addition of T1B Aerobio microbial culture resulted in substantial improvements in ETP performance. Key observations are summarized below:

Parameter Day 1 Day 15 Day 30 Day 45 Day 60
COD (ppm) 20,000 14,500 8,200 4,500 1,200
TAN (ppm) 450 350 180 90 35
Nitrate (mg/L) 0 75 150 220 240
SVI (mL/g) 180 150 100 80 50

Results:

  • TAN Removal Efficiency: Achieved a 92% reduction by Day 60, ensuring compliance with wastewater discharge limits.
  • COD Removal Efficiency: Realized a 94% reduction, meeting industrial effluent discharge standards.
  • Enhanced Nitrification Process: Consistently high nitrate formation rates indicated effective ammoniacal nitrogen removal.
  • Improved Sludge Settling Characteristics: Reduced SVI values led to better sludge compaction and settling properties.

Graphical Insights:

  • TAN and COD Reduction: Cylindrical charts illustrating the progressive decline in TAN and COD concentrations.
  • Nitrification Efficiency: A line graph depicting the steady increase in nitrate levels over time.

Conclusion:

The application of T1B Aerobio in industrial effluent treatment significantly enhanced the performance of the organic intermediates industry’s ETP. Effective TAN and COD reduction, improved nitrification efficiency, and better sludge quality management ensured compliance with wastewater discharge norms while reducing environmental impact. This sustainable wastewater treatment solution supported the client’s corporate environmental responsibility (CER) goals and contributed to an eco-friendly wastewater management approach.

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