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Example ApplicationMetal Finishing

Metal Finishing Effluent with Heavy Metals

This is an illustrative scenario showing how Reynolds & Bauhm equipment can be configured for this application. Every site has unique requirements — contact us for a solution tailored to your specific wastewater characteristics.

Process Requirements & Constraints

Electroplating job shop generating 50 m3/day of mixed rinse water containing nickel 85 mg/L, chromium 45 mg/L, zinc 120 mg/L, copper 30 mg/L, and cyanide 15 mg/L from various plating lines. Must meet sewer discharge limits of total metals <2 mg/L, cyanide <0.2 mg/L, pH 6-9.

Key Performance Targets
<1
Total metals mg/L
<0.1
Cyanide mg/L
7.0
Final pH
35%
Cake solids
98%
Metals removal
100%
Compliance rate

Treatment Approach

Step-by-step process configuration from raw wastewater to compliant discharge.

01

Stream Segregation

Acidic nickel/zinc rinse, alkaline chromium rinse, and cyanide-bearing streams collected in separate batch tanks. Segregation prevents unwanted chemical reactions and enables targeted treatment for each metals group.

02

Cyanide Oxidation

Alkaline chlorination at pH 10.5 oxidises cyanide to cyanate then to nitrogen gas and carbonate. Sodium hypochlorite dosed via ORP-controlled system. Cyanide reduced from 15 to <0.1 mg/L in 45-minute reaction.

03

Metals Precipitation

Chromium reduced from Cr6+ to Cr3+ with sodium metabisulfite. All streams combined and pH adjusted to 8.5 with caustic soda. Heavy metals precipitate as hydroxides. Ferric chloride (50 mg/L) enhances coagulation.

04

Lamella Clarification

Lamella clarifier with 2-hour retention captures metal hydroxide precipitates. Effluent metals <1 mg/L. Underflow sludge at 3% solids thickened to 8% before dewatering. Overflow pH adjusted to 7.0 with CO2.

05

Filter Press & Disposal

Plate filter press dewatering metal hydroxide sludge to 35% solids. Contaminated filter cake classified as hazardous waste disposed via licensed contractor. Filter press cycle time 4 hours including automatic cloth wash.

Equipment Configuration

The specific equipment selected for this application, sized for the flow rate and contaminant load.

pH Correction System

Multi-stage pH control for precipitation at pH 8.5, acid for Cr6+ reduction, CO2 for final adjustment.

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Chemical Dosing Skid

NaOCl, NaHSO3, NaOH, FeCl3 dosing with day tanks, containment, leak detection.

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Lamella Clarifier

SS construction, 30 m2 settling area, metal hydroxide separation, sludge hopper.

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Filter Press

630x630mm plates, 30 chamber, automatic hydraulic closure, cloth wash, 35% cake solids.

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Performance Achieved

Representative performance data based on typical operating conditions for this equipment configuration.

<1
Total metals mg/L
<0.1
Cyanide mg/L
7.0
Final pH
35%
Cake solids
98%
Metals removal
100%
Compliance rate

Related Equipment

Explore the full range of equipment used in this and similar applications.

ORP Controller

ORP-based control for cyanide oxidation and chromium reduction.

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Containment Bund

Secondary containment for chemical storage tanks.

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Sludge Thickener

Thickening of metal hydroxide sludge before filter press.

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CO2 Dosing

Gentle pH reduction for final effluent adjustment.

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Related Treatment Processes

Discover how these treatment processes connect to form complete wastewater treatment solutions.

Project Approach & Engineering

Reynolds & Bauhm follows a structured engineering methodology for every project. We begin with detailed wastewater characterisation, process selection based on contaminant profiles, pilot testing where required, and full-scale design with performance guarantees. Our multidisciplinary team of chemical, mechanical, and electrical engineers ensures seamless integration of process, mechanical, and control disciplines.

Characterisation

Comprehensive influent analysis including COD, BOD, TSS, heavy metals, pH, temperature, and flow profiling.

Process Design

Process flow development with P&IDs, mass balances, and hydraulic modelling validated by CFD where appropriate.

Pilot Testing

On-site pilot trials validate performance guarantees under actual operating conditions before capital commitment.

Commissioning

FAT, SAT, performance trials, operator training, and handover documentation ensuring operational readiness.

Equipment Configuration

Pre-TreatmentScreening, grit removal, and flow equalisation
Primary TreatmentDAF or lamella clarification for solids and oil removal
Secondary TreatmentBiological oxidation (activated sludge, MBBR, or SBR)
Tertiary TreatmentFiltration, UV disinfection, or chemical polishing
Sludge ManagementThickening and dewatering via belt press or centrifuge
Control SystemPLC with HMI touchscreen and optional SCADA integration
Chemical DosingAutomated coagulant, flocculant, and pH correction
MaterialsSS316L, duplex, or rubber-lined carbon steel

Performance Outcomes

COD Removal

85 – 98% chemical oxygen demand reduction depending on process configuration and influent variability.

TSS Removal

90 – 99% suspended solids reduction through combined physical and biological treatment stages.

Water Reuse

Tertiary treatment enables up to 80% water recycling for non-potable process applications.

Apply This Configuration to Your Site

Our engineers will adapt this equipment configuration to your specific wastewater analysis, flow rate, and discharge requirements.

Industries We Serve

Our expertise spans multiple industries with sector-specific water treatment solutions.