COD (Chemical Oxygen Demand) is often the hardest parameter for electroplating shops to meet under CONAMA Resolution 430/2011 (issued by Brazil's National Environment Council). Tertiary treatment is required for compliance.

Boreto & Cardoso®, with 53 years of experience (since 1972), supplies specialized inputs for tertiary treatment with complete technical documentation.

What Is COD?

COD (Chemical Oxygen Demand) is the amount of oxygen needed to chemically oxidize the organic and inorganic matter present in the effluent.

Unit of measurement: mg/L (milligrams per liter)

Why it matters:

  • Indicates the organic load of the effluent
  • Environmental control parameter
  • Legal requirement under CONAMA 430/2011

CONAMA 430/2011 Legal Limit

COD Parameter:

Parameter Legal Limit Note
**COD** Up to 180 mg/L **Critical for electroplating shops**

Consequences of noncompliance:

  • Administrative fines (Law 9,605/98, Brazil's Environmental Crimes Law)
  • Shutdown orders
  • Civil and criminal liability

Why Is COD a Challenge for Electroplating Shops?

Sources of COD in Electroplating Processes:

COD is a particular challenge for electroplating shops that use:

1. Alkaline Degreasers at High Concentration

  • Organic compounds for cleaning
  • High concentration raises COD
  • Contaminated rinse waters

2. Organic Acids for Pickling

  • Organic compounds in the process
  • Residues in rinse waters

3. Brightener Additives with Organic Components

  • Organic auxiliary products
  • Improve the finish but raise COD
  • Present in process waters

4. Technical Lacquers in Finishing Processes

  • Application of protective lacquers
  • Solvents and organic components
  • Residues in effluents

Tertiary Treatment: Stage 5

Tertiary treatment is Stage 5 (the final stage) of the complete electroplating wastewater treatment system.

Objective: Reduce COD to below 180 mg/L in line with CONAMA 430/2011.

Position in the system: After segregation, neutralization, metal precipitation and coagulation/flocculation.

Tertiary Treatment Technologies

1. Activated Carbon Filtration (Most Common)

Characteristics:

  • Established, reliable technology
  • Adsorption of organic compounds
  • Proven efficiency

How it works:

  • Activated carbon adsorbs organic matter
  • Reduces COD through physical/chemical removal
  • Filter bed with periodic replacement

Advantages:

  • Mature technology
  • Relatively simple operation
  • Good cost-benefit ratio

Considerations:

  • Periodic carbon replacement
  • Regeneration or proper disposal
  • Saturation monitoring

2. Advanced Oxidation with Hydrogen Peroxide (Highest Efficiency)

Characteristics:

  • Chemical oxidation process
  • High COD reduction efficiency
  • Advanced technology

How it works:

  • Hydrogen Peroxide (H₂O₂) oxidizes organic matter
  • Breaks down complex organic compounds
  • Converts them into simpler substances

Advantages:

  • High efficiency (> 90% reduction)
  • Fast oxidizing action
  • Generates no solid waste

Application:

  • High initial COD
  • Complex organic compounds
  • When high efficiency is required

3. Sodium Hypochlorite (Oxidation)

Characteristics:

  • Readily available oxidizing agent
  • Used in specific systems

How it works:

  • Oxidation of organic compounds
  • Additional disinfection of the effluent

Considerations:

  • Precise dosage control
  • Formation of chlorinated by-products
  • Complementary application

4. Calcium Hypochlorite (Alternative)

Characteristics:

  • Alternative to sodium hypochlorite
  • Solid form
  • More stable in storage

Application:

  • Complementary oxidation
  • Specific systems

5. Biological Treatment (For Large Volumes)

Characteristics:

  • Biological degradation of organic matter
  • Used for large volumes
  • Greater operational complexity

Consideration:

  • More common in large industries
  • Requires more space and longer retention time
  • More complex operation

Boreto & Cardoso® Inputs for Tertiary Treatment

Available Oxidizers:

1. Hydrogen Peroxide (H₂O₂)

Characteristics:

  • High-efficiency oxidizer
  • Produces no chlorinated residues
  • Versatile application

Application:

  • Oxidation of organic matter
  • COD reduction
  • Tertiary wastewater treatment

Advantages:

  • High efficiency (> 90% COD reduction)
  • Decomposes into water and oxygen
  • Adds no salts to the effluent

2. Sodium Hypochlorite

Characteristics:

  • Oxidizer and disinfectant
  • Liquid form
  • Readily available

Application:

  • Oxidation of organic compounds
  • Disinfection of the final effluent
  • Complement to treatment

3. Calcium Hypochlorite

Characteristics:

  • Powdered oxidizer
  • More stable in storage
  • Gradual chlorine release

Application:

  • Alternative to sodium hypochlorite
  • Controlled oxidation

Monitoring Tertiary Treatment Efficiency

Required Analyses:

Inlet COD:

  • Analysis before tertiary treatment
  • Establishes a baseline

Outlet COD:

  • Analysis after tertiary treatment
  • Confirms compliance (< 180 mg/L)
  • Recorded for audits

Frequency:

  • Regular analyses as required by the environmental license
  • Typical: weekly or every two weeks
  • Mandatory documentation

Expected Efficiency:

Activated Carbon:

  • Typical efficiency: 80-90% COD reduction

Hydrogen Peroxide:

  • Typical efficiency: > 90% COD reduction
  • Depends on dosage and contact time

Combined Systems:

  • Higher efficiency with combined treatments
  • Example: Carbon + chemical oxidation

Why Input Quality Matters

Unsuitable Inputs Cause:

  • Incomplete oxidation - COD above 180 mg/L
  • Noncompliance - Fines and shutdowns
  • Excessive consumption - Higher operating costs
  • Unwanted by-products - Secondary problems

Quality Inputs Ensure:

  • Efficient oxidation - COD < 180 mg/L
  • Compliance - CONAMA 430 requirements met
  • Optimized consumption - Correct dosages
  • Stable process - Consistent results
  • Complete documentation - Easier audits

Technical Documentation for Oxidizers

SDS (Safety Data Sheet)

Mandatory for all oxidizers:

  • Product identification
  • Chemical composition
  • Safety measures
  • Handling and storage (hazardous products)
  • First aid
  • Exposure control

Certificates of Analysis

For each batch:

  • Batch identification
  • Verified concentration
  • Product purity
  • Manufacturing and expiry dates
  • Full traceability

Technical Specifications

Detailed documentation:

  • Exact chemical composition
  • Concentration (%)
  • Density
  • Stability
  • Recommended applications
  • Typical dosages

What Sets Boreto & Cardoso® Apart

Assured Quality:

✅ 53 years of experience (since 1972) in the chemical market ✅ Products from certified suppliers with strict control ✅ Strict technical specifications for each product ✅ Full traceability of every batch

Regulatory Compliance:

✅ Complete, up-to-date SDS (Safety Data Sheet) ✅ Certificates of analysis with specific parameters ✅ Products compliant with environmental legislation ✅ Complete documentation for audits

Specialized Logistics:

✅ Proper storage for hazardous products ✅ Safe transport with complete documentation ✅ Scheduled deliveries for continuous operation ✅ Service from São Paulo and Limeira

Tertiary Treatment Checklist

Required Inputs:

  • Activated Carbon (periodic replacement)
  • Hydrogen Peroxide (if applicable)
  • Sodium or Calcium Hypochlorite (if applicable)
  • Adequate safety stock

Operational Controls:

  • Carbon saturation check
  • Oxidizer dosage control
  • Adequate contact time
  • Regular COD measurement

Analytical Controls:

  • Inlet COD analysis
  • Outlet COD analysis
  • Compliance check (< 180 mg/L)
  • System efficiency calculation
  • Record of results

Documentation:

  • SDS for every oxidizer
  • Up-to-date certificates of analysis
  • Record of batches used
  • COD test reports
  • Dosing protocols

Integration with the Complete System

Tertiary treatment is Stage 5 (the final stage) of a complete system:

  1. Segregation at the Source - Separate the streams
  2. Neutralization - pH 5.0-9.0
  3. Metal Precipitation - pH control by metal
  4. Coagulation/Flocculation - Solid-liquid separation
  5. Tertiary Treatment - COD < 180 mg/L (this article)

Every stage is essential for full CONAMA 430/2011 compliance.

Next Steps

Request a Quote for Oxidizers:

Headquarters - Santana de Parnaíba/SP:

  • Email: boreto@boreto.com.br
  • Phone: (11) 3931-1722 | (11) 2366-6260
  • WhatsApp: (11) 99108-2229 | (11) 94541-0088 | (11) 91311-3528 | (19) 97685-0233
  • Address: R. Alagoas, 30 - Recanto Silvestre, Santana de Parnaíba - SP, 06530-245

Branch - Limeira/SP:

  • Phone: (19) 99458-6331
  • WhatsApp: (19) 99557-1693
  • Address: R. Aratibá, 759 - Centro Industrial de Limeira (CIL), Limeira - SP, 13481-208

Business Hours:

  • Monday to Friday: 8:00 a.m. to 12:00 p.m. and 1:15 p.m. to 5:30 p.m.

Information for Your Quote:

  • Type of oxidizer required (Peroxide, Hypochlorite)
  • Current COD of the effluent (if known)
  • Volume of effluent treated (m³/day)
  • Approximate quantities
  • Purchase frequency

Conclusion

Tertiary treatment is essential to meet the COD parameter (< 180 mg/L) of CONAMA Resolution 430/2011, which is often the hardest one for electroplating shops.

Benefits of proper treatment:

✅ Compliance with CONAMA 430 (COD < 180 mg/L) ✅ No fines or shutdowns ✅ A stable, reliable process ✅ High-quality final effluent ✅ Documentation for audits

Boreto & Cardoso® supplies specialized oxidizers for tertiary treatment, backed by 53 years of experience in the chemical market.

Available inputs:

  • Hydrogen Peroxide (high efficiency)
  • Sodium Hypochlorite (oxidation and disinfection)
  • Calcium Hypochlorite (stable alternative)

All with complete SDS, certificates of analysis and full traceability.

📞 Need oxidizers for tertiary treatment? Get in touch: 📞 (11) 3931-1722 | 📧 boreto@boreto.com.br

© 2025 Boreto & Cardoso® - Suppliers of Specialized Chemical Inputs since 1972

Note to the reader This article brings together technical information drawn from various sources, with the aim of broadening knowledge about the raw materials mentioned. It is for information only and does not constitute, on the part of Boreto & Cardoso, any indication of application, formulation or direct recommendation of use. Boreto & Cardoso®, with 53 years of experience, operates strictly as a supplier of chemical inputs for a wide range of applications, and each user is responsible for verifying the suitability and compliance of their own application.