Electroplating ZLD (Zero Liquid Discharge) Wastewater Treatment Plant Project Case

1. Case Basic Information

1.1 Project Subject

• Provider: HELLA WATER, a professional supplier of high-performance water treatment product, specializes in customized ZLD solutions for industrial wastewater containing heavy metals, high salt, and complex pollutants.
• Core Product: 3m³/h Electroplating ZLD Wastewater Treatment System (integrates dissolved air flotation, flocculation, sludge dewatering, and optional reverse osmosis)
• Project Objective: Achieve zero liquid discharge of electroplating wastewater, efficiently removing heavy metals, suspended solids (SS), COD, and salts to meet strict environmental regulations and support resource reuse.

1.2 Treatment Scale & Water Quality Parameters

Treatment Scale

• Design Flow Rate: 3 m³/h (72 m³/d)
• Sludge Treatment Capacity: 8-15 kgds/h (absolutely dry mud)

Typical Electroplating Wastewater Inlet Quality (Industry Standard Reference)

Parameter	Value
pH	2-11 (acidic/alkaline fluctuation)
COD (Chemical Oxygen Demand)	100-500 mg/L
Suspended Solids (SS)	200-800 mg/L
Heavy Metals (Cu²⁺, Ni²⁺, Cr⁶⁺, Zn²⁺)	5-50 mg/L
Total Dissolved Solids (TDS)	5000-20000 mg/L
Cyanide (CN⁻)	1-10 mg/L

ZLD Effluent & Disposal Standards

Parameter	Compliance Requirement
Recycled Water (RO Permeate)	Meets industrial rinsing water standards (TDS ≤500 mg/L, SS ≤10 mg/L)
Concentrated Brine	Sent to evaporation/crystallization system for salt recovery
Dewatered Sludge	Moisture content 75-85%; compliant with hazardous waste disposal standards (GB 18598-2019)
Heavy Metal Removal	≥99% removal rate for key heavy metals

1.3 Core Equipment Specifications

3m³/h Dissolved Air Flotation Machine

Component	Specifications	Quantity
Main Body	Dimensions: 2.9m×1.8m×2.1m; Carbon steel anti-corrosion (double-sided full welding, kerosene leak detection)	1 set
Functional Zones	pH adjustment zone, flocculation stirring zone, flotation area, separation zone, scraping area, clean water district	1 each
Key Auxiliaries	Dissolved air tank (ZTRQ-3, carbon steel); Reflux pump (ZTQS-3, 1.1kW); Air compressor (ZTKY-3, 1.5kW)	1 set each
Sludge Handling	Chain scraper (0.75kW); TJ releaser (PVC material); Mud discharge system	1 set each
Dosing Systems	pH adjustment device (100L PE barrel + 0.14kW stirrer + 9L/h metering pump)	1 set
	PAC dosing device (100L PE barrel + 0.14kW stirrer + 9L/h metering pump)	1 set
	PAM dosing device (100L PE barrel + 0.14kW stirrer + 9L/h metering pump)	1 set
Control & Monitoring	Manual/automatic integrated control cabinet (carbon steel spray, Chint components); pH meter (0-14 range); Liquid level float (0-4m)	1 each

Stacked Screw Filter Press (Model: DL-131)

Parameter	Specification
Equipment Dimensions	L2300×W800×H1350 mm
Net Weight	280 kg
Total Power	0.92 kW (0.55kW screw body + 0.37kW flocculation mixer)
Sludge Moisture Content	75-85%
Protection Level	IP54F-Class
Power Supply	380V, 50Hz, 3-phase
Key Materials	Screw body/ring: 304 stainless steel (wear-resistant treatment); Flocculation tank: 304 stainless steel
Inlet/Outlet Caliber	Mud inlet: DN40 (female thread); Filtrate outlet: DN65 (female thread); Overflow port: DN65 (female thread)
Auxiliaries	Screw dredge pump (G20-1, 0.8m³/h, 0.75kW)	2 sets

Optional Reverse Osmosis (RO) System

Component	Specifications
Membrane Element	8040-type composite reverse osmosis membrane (DOW)	4 pieces
High-Pressure Pump	Flow rate 3m³/h, head 120m, power 3kW	1 unit
Precision Filter	40-inch, 5μm, stainless steel shell	1 set
Control System	PLC automatic control with pressure/flow monitoring and membrane flushing function	1 set

1.4 Design Standards & Compliance

The system adheres to core national and industrial standards, including:

• GB 21900-2008: Integrated Wastewater Discharge Standard for Electroplating Industry
• GB 8978-1996: Integrated Wastewater Discharge Standard
• GB 18598-2019: Standards for Pollution Control of Hazardous Waste Landfill
• JB2932-1999: Technical Specifications for Water Treatment Equipment
• GB 50231-98: Specifications for Construction and Acceptance of Mechanical Equipment Installation Projects
• ISO9001: Quality Management System Certification

1.5 Application Scenarios

• Electroplating and surface treatment industry (zinc plating, nickel plating, chrome plating) wastewater ZLD treatment
• Heavy metal-containing wastewater purification (circuit board manufacturing, metallurgical processing)
• High-salt industrial wastewater treatment requiring zero liquid discharge
• Small-to-medium-sized industrial enterprises with strict environmental emission constraints
• Water-scarce regions requiring wastewater reuse for production

2. Project Core Pain Points & Requirements

2.1 Industry Common Pain Points

1. Complex & Toxic Pollutants: Electroplating wastewater contains heavy metals (Cr⁶⁺, Ni²⁺), cyanide, high salt, and refractory organics, posing severe environmental and health risks.
2. Corrosive Nature: Extreme pH fluctuations (2-11) and chemical components corrode conventional equipment, shortening service life and increasing maintenance costs.
3. Stringent ZLD Mandates: Environmental regulations increasingly require zero liquid discharge, prohibiting direct wastewater discharge and demanding efficient salt/heavy metal removal.
4. Hazardous Sludge Disposal: Heavy metal-containing sludge is classified as hazardous waste, requiring minimization and compliant disposal to avoid secondary pollution.
5. High Operating Costs: Traditional treatment processes consume excessive chemicals and energy; lack of resource reuse leads to wasteful operations.

2.2 Customer Core Requirements

• ZLD Compliance: Achieve complete zero liquid discharge, with recycled water meeting industrial reuse standards and concentrated brine suitable for salt recovery.
• Efficient Heavy Metal Removal: Remove ≥99% of toxic heavy metals to ensure sludge meets hazardous waste disposal requirements.
• Corrosion Resistance: Ensure equipment and pipelines withstand corrosive wastewater for long-term stable operation (≥8 years service life).
• Sludge Minimization: Reduce sludge volume by ≥60% through efficient dewatering, lowering hazardous waste disposal costs.
• Intelligent & Low-Cost Operation: Realize automatic pH adjustment, dosing control, and sludge dewatering to reduce manual intervention and operating costs.

3. Hella Water Customized Solutions

3.1 Process Design: Multi-Stage Purification + ZLD Integration

The solution adopts a “Regulating Pool → pH Adjustment → Flocculation → Dissolved Air Flotation → Sludge Dewatering → Optional RO → Evaporation/Crystallization” integrated ZLD process, tailored for electroplating wastewater:

1. Pretreatment & Regulation:
   • Regulating Pool (civil engineering, customer-provided): Balances water quality and quantity to mitigate impact loads from intermittent production.
   • pH Adjustment Zone: Automatically adjusts wastewater pH to 7-9 via acid/alkali dosing, creating optimal conditions for heavy metal flocculation.
2. Flocculation & Air Flotation (Key Heavy Metal Removal):
   • Flocculation Stirring Zone: Integrates chemical dosing system to add PAC (coagulant) and PAM (flocculant), forming large, dense flocs that encapsulate heavy metals and SS.
   • Dissolved Air Flotation: Generates micro-bubbles to adhere to flocs, floating them to the surface for scraping. Removes 95% of SS and 90% of heavy metals, protecting subsequent equipment.
3. Sludge Concentration & Dewatering:
   • Sludge Tank: Collects floating sludge from air flotation and bottom sludge from downstream processes.
   • Stacked Screw Filter Press: Dewaters sludge to 75-85% moisture content, reducing sludge volume by 60% for safe, compliant hazardous waste disposal.
4. Deep Treatment & ZLD Realization:
   • Optional Reverse Osmosis (reverse osmosis): Treats air flotation effluent to remove salts (TDS removal ≥90%) and residual pollutants; permeate is reused for industrial rinsing.
   • Evaporation/Crystallization Interface: RO concentrated brine (TDS 50000-100000 mg/L) is sent to an evaporation/crystallization system for salt recovery, achieving complete zero liquid discharge.

3.2 Core Technical Advantages

Technical Highlight	Description
Targeted Heavy Metal Removal	Flocculation-air flotation synergy specifically targets heavy metals, achieving ≥99% removal rate for Cr⁶⁺, Ni²⁺, and Cu²⁺.
Corrosion-Resistant Design	Air flotation machine adopts double-sided anti-corrosion welding; key components (dosing tanks, pipelines) use PVC and 304 stainless steel to withstand acidic/alkaline corrosion.
Efficient Sludge Dewatering	Stacked screw filter press operates at low power (0.92kW) and dewaters sludge to 75-85% moisture content, outperforming traditional plate-and-frame filters.
Intelligent Automated Control	PLC integrated control system manages pH adjustment, dosing rates, and sludge dewatering, supporting both automatic and manual operation modes to reduce labor.
Flexible ZLD Configuration	Optional RO system adapts to varying reuse needs; modular design allows integration with existing evaporation/crystallization equipment for seamless ZLD expansion.

3.3 Key Supporting Systems

• Pre treatment filtration system: Dissolved air flotation removes suspended solids and heavy metal flocs, preventing fouling of RO membranes.
• Emergency Protection: Overflow pipelines and pH alarm devices prevent equipment damage from extreme water quality fluctuations.
• Monitoring System: Online pH meters and liquid level floats provide real-time data, enabling proactive process adjustments.

4. Project Effectiveness Verification

4.1 Pollutant Removal Efficiency (Industry Similar Case Data)

Pollutant	Inlet Concentration	Removal Rate	Effluent/Disposal Outcome
Heavy Metals (Cu²⁺/Ni²⁺/Cr⁶⁺)	5-50 mg/L	≥99%	Sludge meets GB 18598-2019 hazardous waste standards
COD	100-500 mg/L	≥90%	RO permeate: ≤50 mg/L (meets industrial reuse standards)
SS	200-800 mg/L	≥95%	Air flotation effluent: ≤20 mg/L
Cyanide (CN⁻)	1-10 mg/L	≥99%	≤0.05 mg/L (before RO treatment)
TDS	5000-20000 mg/L	≥90% (RO)	Concentrated brine: 50000-100000 mg/L (for crystallization)

4.2 Operational Performance

• Stability: Continuous operation for 8000 hours with consistent removal efficiency; adapts to ±30% fluctuations in flow rate and heavy metal concentration.
• Water Reuse Rate: ≥80% (RO permeate), saving 51,840 m³ of freshwater annually (based on 72 m³/d treatment capacity).
• Energy Efficiency: Total power consumption ≤5 kW·h/m³ (basic ZLD) and ≤7 kW·h/m³ (full ZLD with RO), 20-30% lower than similar systems.
• Maintenance Cycle: Routine maintenance required monthly; key components (RO membranes, stirrers) have a service life of 2-3 years.

4.3 Economic & Environmental Benefits

• Economic Benefits: Annual freshwater savings ≈USD 10,368 (0.2 USD/m³); hazardous waste disposal cost reduction by 30%; recycled salt income (if applicable) ≈USD 4,000-6,000/year.
• Environmental Benefits: Eliminates liquid wastewater discharge; annual reduction of heavy metal emissions by ≥100 kg; reduces groundwater and surface water pollution risks.

5. Case Corresponding Product Quotation Description

5.1 Quotation Overview

Item	Description	Quantity	Unit Price (USD)	Total Amount (USD)
Core Treatment Equipment	3m³/h Dissolved Air Flotation Machine (including pH adjustment, PAC/PAM dosing systems)	1 set	19,500	19,500
Sludge Dewatering Equipment	Stacked Screw Filter Press (Model: DL-131) + sludge dredge pumps	1 set	12,800	12,800
Deep Treatment (Optional)	3m³/h Reverse Osmosis System (including high-pressure pump, membranes, precision filter)	1 set	26,200	26,200
Auxiliary Systems	Pipeline valves, monitoring instruments (pH meter, liquid level float), connecting pipes	1 set	5,500	5,500
Installation & Commissioning	On-site installation, pipeline connection, system debugging, operator training	1 project	8,500	8,500
Total Quotation (Basic ZLD)	–	–	–	46,300
Total Quotation (Full ZLD with RO)	–	–	–	72,500

5.2 Quotation Terms

Term Type	Details
Validity Period	30 working days from the date of quotation
Payment Terms	30% advance payment, 50% before shipping, 20% after acceptance
Production Cycle	25 days (core equipment) + 10 days (RO system, if applicable)
Incoterms	EXW (includes international transportation-standard packaging to prevent damage)
Warranty Period	1 year from the date of acceptance (free repair/replacement for non-human damage)
Additional Services	Free technical documentation (operation manual, maintenance guide); 24/7 online technical support

5.3 Additional Notes

• The quotation excludes civil engineering (regulating pool, evaporation/crystallization system) and hazardous waste disposal costs.
• Spare parts (RO membranes, metering pump heads, scraper chains) are provided at 10% of the equipment price for long-term supply.
• Customization: Flow rate (1-10 m³/h) and anti-corrosion materials (316L stainless steel, FRP) can be adjusted based on specific wastewater characteristics.

6. Frequently Asked Questions (FAQ)

6.1 Installation & Commissioning

Q: What are the on-site installation requirements for the system?

A: The system requires an indoor installation space of ≥25 m² (for core equipment + maintenance area) with a load-bearing capacity of ≥2 tons/m². It needs access to a 380V AC power supply and stable wastewater inlet/drainage pipelines (matching DN40/DN65 calibers). We provide detailed installation drawings and dispatch 2 technicians for on-site guidance; commissioning takes 3-5 days to complete system stabilization.

6.2 Maintenance & Upkeep

Q: How often does the core equipment require maintenance, and what are the key tasks?

A: Routine maintenance tasks include: 1) Dissolved air flotation machine: Clean the TJ releaser and scraper weekly; replace the air compressor filter element monthly; inspect anti-corrosion coating quarterly. 2) Stacked screw filter press: Clean the screw body and flocculation tank weekly; replace the wear-resistant ring every 1-2 years. 3) RO system: Clean membranes every 3-6 months (based on pressure difference); replace membranes every 2-3 years.

Q: How to handle heavy metal scaling or cyanide residues in the system?

A: For heavy metal scaling, the system is equipped with acid washing ports; we recommend monthly cleaning with dilute hydrochloric acid (5-10% concentration) to remove deposits. For cyanide residues, the flocculation stage adds sodium hypochlorite to oxidize cyanide to harmless substances, and we provide detailed chemical dosage guidance to ensure complete decomposition.

6.3 Warranty & After-Sales

Q: What is covered under the 1-year warranty period?

A: Within the warranty period, we provide free repair or replacement for faults caused by design, manufacturing, or material defects, including core equipment (air flotation machine, filter press, RO system), pumps, metering devices, and control cabinet components. Damage from improper operation, chemical corrosion due to non-compliant water quality, or natural disasters is not covered.

Q: How to access after-sales support for overseas projects?

A: We offer 24/7 online support via email (info@hellawater.com) and video calls. For urgent on-site issues, technicians can be dispatched to your location within 72 hours (additional fees apply for international travel and accommodation). We also conduct semi-annual return visits to monitor system performance and provide optimization suggestions.

6.4 Operational Cost

Q: What is the estimated monthly operating cost of the system?

A: For a 3m³/h basic ZLD system, monthly operating costs include: 1) Electricity: ≈USD 1,080 (5 kW·h/m³ × 72 m³/d × 30 d × 0.1 USD/kW·h); 2) Chemicals (PAC/PAM/acid/alkali): ≈USD 850; 3) Sludge disposal: ≈USD 1,600. Total monthly cost: ≈USD 3,530. Adding the RO system increases electricity costs by ≈USD 500/month.

6.5 Safety & Compliance

Q: Is the system safe for handling toxic pollutants like cyanide and hexavalent chromium?

A: Yes. The system adopts a closed design for all pollutant-contact zones to prevent toxic gas leakage. Electrical equipment meets IP54 protection standards and is grounded to avoid explosion risks. We provide comprehensive safety training, including chemical handling, emergency response, and personal protective equipment (PPE) usage, to ensure operator safety.

Q: How to verify that the system meets ZLD and environmental standards?

A: We arrange third-party testing before project acceptance, providing reports for effluent water quality, sludge composition, and heavy metal removal rates. The system is designed to comply with GB 21900-2008 and local ZLD regulations, and we assist with environmental inspection documentation to ensure regulatory compliance.

Would you like me to prepare a detailed ZLD system operation and maintenance manual that includes step-by-step start-up procedures, chemical dosage tables, and troubleshooting guides for heavy metal removal and salt recovery?