Coagulation and flocculation are essential steps in treating electroplating wastewater to remove heavy metals and comply with CONAMA Resolution 430/2011 (Brazil's federal resolution on effluent discharge standards).

Boreto & Cardoso®, with 53 years of experience (since 1972), supplies specialized coagulants and flocculants with complete technical documentation for environmental compliance.

Metal Parameters in CONAMA 430/2011

The legislation sets strict limits for discharging effluents containing heavy metals:

Metal Legal Limit (CONAMA 430/2011)
**Total Copper** 1.0 mg/L
**Total Nickel** 2.0 mg/L
**Total Zinc** 5.0 mg/L
**Total Chromium** 0.5 mg/L (most restrictive)

Non-compliance results in:

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

Metal Precipitation: pH Control

Step 3: Metal Precipitation

Before coagulation/flocculation, the metals must be precipitated through precise pH control:

Optimal pH ranges by metal:

  • Copper: pH 8.5 to 9.0
  • Nickel: pH 9.5 to 10.0
  • Zinc: pH 8.0 to 8.5
  • Chromium: pH 7.5 to 8.0

Poor pH control undermines the efficiency of the entire system.

Coagulation: Step 4 of the Treatment

What Is Coagulation?

The process of destabilizing suspended particles by adding coagulating agents. Destabilized particles clump together more easily.

Main Coagulants

1. Polyaluminum Chloride (PAC)

Characteristics:

  • High-efficiency coagulant
  • Widely used in wastewater treatment
  • Rapid particle destabilization

Advantages:

  • Effective over a wide pH range
  • Less sludge generated
  • Optimized dosage

Application:

  • Primary coagulant in treatment systems
  • Heavy metal precipitation
  • Turbidity removal

2. Aluminum Sulfate

Characteristics:

  • Traditional coagulant
  • Widely available
  • Good cost-benefit

Application:

  • Coagulation in wastewater treatment
  • Alternative to PAC
  • Systems with controlled pH

Considerations:

  • Moderate sludge generation
  • Sensitivity to pH

3. Ferric Chloride

Characteristics:

  • Iron-based coagulant
  • Used in specific cases
  • Effective over varied pH ranges

Use:

  • Processes where iron in the effluent is acceptable
  • Coagulation of specific metals
  • Complement to other coagulants

4. Sodium Aluminate

Characteristics:

  • Coagulant aid
  • Alkaline pH adjustment
  • Complement to the main coagulants

Application:

  • Process fine-tuning
  • Coagulation optimization
  • High-pH systems

Flocculation: Particle Aggregation

What Is Flocculation?

The process of aggregating the particles destabilized by coagulation, forming larger flocs that settle more easily.

Flocculants

Polyelectrolytes

Characteristics:

  • High molecular weight polymers
  • Highly efficient aggregation
  • Types: cationic, anionic, non-ionic

Application:

  • Formation of robust flocs
  • Improved settling
  • Reduced residual turbidity

Selection criteria:

  • Type of metal to be removed
  • Effluent characteristics
  • System pH
  • Treatability tests recommended

Operating Parameters

Retention Time

Recommended: 45 to 60 minutes

Time needed for:

  • Complete coagulation
  • Adequate flocculation
  • Formation of settleable flocs

Dosage Control

Essential for efficiency:

  • Underdosing: Incomplete removal
  • Overdosing: Unnecessary consumption, high cost
  • Correct dosing: Maximum efficiency, optimized cost

Recommendation:

  • Calibrated dosing equipment
  • Periodic dosage tests
  • Adjustments as the load varies

Solid-Liquid Separation

Efficient settling requires:

  • Well-formed flocs
  • Adequate retention time
  • Upflow velocity < 1.0 m/h
  • Regular sludge removal

Why Chemical Quality Matters

Inadequate Chemicals Cause:

  • Incomplete precipitation: Metals above the legal limit
  • Poor coagulation: Turbidity in the final effluent
  • Weak flocs: Poor settling
  • Excessive consumption: High operating costs
  • Non-compliance: Fines and shutdowns

Quality Chemicals Ensure:

  • Efficient precipitation: Metals within CONAMA limits
  • Robust flocs: Good settling
  • Clarified effluent: Low residual turbidity
  • Optimized consumption: Correct dosages
  • Compliance: Legal parameters met

Technical Documentation for the Chemicals

SDS (Safety Data Sheet)

Mandatory for coagulants and flocculants:

  • Product identification
  • Chemical composition
  • Safety measures
  • Handling and storage
  • Exposure controls

Certificates of Analysis

For every lot supplied:

  • Lot identification
  • Parameters tested
  • Results obtained
  • Technical specifications
  • Full traceability

Technical Specifications

Detailed documentation:

  • Chemical composition
  • Concentration
  • Density
  • pH
  • Recommended applications
  • Typical dosages

Boreto & Cardoso®: Specialized Portfolio

Coagulants Available:

✅ Polyaluminum Chloride (PAC): High-efficiency coagulant ✅ Aluminum Sulfate: Traditional coagulant ✅ Ferric Chloride: For specific cases ✅ Sodium Aluminate: Coagulant aid

Flocculants Available:

✅ Polyelectrolytes: Efficient particle aggregation

What Sets Us Apart:

✅ 53 years of experience (since 1972) in the chemical market ✅ Products from certified suppliers with quality control ✅ Strict technical specifications for every product ✅ Full traceability of all lots ✅ Up-to-date SDS and certificates of analysis ✅ Complete documentation for environmental audits

Specialized Logistics:

  • Proper storage for chemicals
  • Safe transport with complete documentation
  • Scheduled deliveries for continuous operation
  • Service in São Paulo and Limeira

Coagulation/Flocculation Checklist

Chemicals Needed:

  • Polyaluminum Chloride (PAC) or Aluminum Sulfate
  • Polyelectrolytes suited to the process
  • Auxiliary products if needed
  • Dosage proportional to the volume treated

Operational Controls:

  • Check coagulant dosage
  • Control flocculant dosage
  • Visual check of clarification
  • Adequate retention time (45 to 60 min)
  • Turbidity analysis of the final effluent

Analytical Controls:

  • Metal analysis of the treated effluent
  • Verification of compliance with CONAMA 430
  • Record of dosages used
  • Monitoring of sludge generation

Documentation:

  • SDS for all products
  • Up-to-date certificates of analysis
  • Record of lots used
  • Documented dosing protocols

Integration with the Complete System

Coagulation/flocculation is Step 4 of a complete 5-step system:

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

Every step requires specific, quality chemicals for full compliance.

Next Steps

Request a Quote for Coagulants and Flocculants:

Head office, Santana de Parnaíba/SP:

  • E-mail: boreto@boreto.com.br
  • Phone numbers: (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 coagulant required (PAC, Aluminum Sulfate, etc.)
  • Flocculants needed (Polyelectrolytes)
  • Approximate quantities
  • Purchase frequency
  • Volume of effluent treated

Conclusion

Quality coagulants and flocculants are essential for efficient removal of heavy metals from electroplating wastewater and for compliance with CONAMA 430/2011.

Benefits of the right chemicals:

✅ Efficient metal precipitation (Cu, Ni, Zn, Cr) ✅ Legal limits met ✅ Robust flocs and good settling ✅ Clarified effluent ✅ Optimized consumption ✅ Documentation for audits

Boreto & Cardoso® supplies specialized coagulants and flocculants backed by 53 years of experience in the chemical market.

📞 Need coagulants and flocculants? Get in touch: 📞 (11) 3931-1722 | 📧 boreto@boreto.com.br

© 2025 Boreto & Cardoso®: Suppliers of Specialized Chemicals since 1972

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