This is the "Plating Wastewater Pre-Treatment & Segregation Manual".

The China Standard: In China, environmental regulations follow the Shunt/Segregation principle. You cannot mix all pipes together.

• The Risk: If you mix Cyanide Copper waste (pH 12) with Acid Copper waste (pH 1), you generate Hydrogen Cyanide Gas. This kills the operator instantly.

• The Strategy: You must pre-treat the toxic streams (Cyanide & Chrome) separately in dedicated reaction tanks before sending them to the main End-of-Pipe Sedimentation Tank.

Here is the Master’s Standard for segregation, color coding (standard Chinese industry colors), and chemical neutralization recipes using the [QLQ System].

☠️ Wastewater Segregation & Pre-Treatment Manual

Goal: Convert soluble toxic ions into insoluble sludge or harmless gas before final discharge.

Compliance: GB 21900-2008 (Electroplating Pollutant Discharge Standard).

Part I: Pipeline Color Coding & Classification

You must paint your pipes and label your tanks with these colors.

Part II: Treatment Formulas & Reaction Recipes

These processes happen in the "Reaction Tanks" (Batch Treatment) before the Clarifier.

1. 🟡 Cyanide Breaking (The "Yellow" Line)

Goal: Destroy Cyanide ($CN^-$) into Nitrogen ($N_2$) and Carbon Dioxide ($CO_2$).

Method: Two-Stage Alkaline Chlorination.

• Step A: Partial Oxidation (CN $\to$ Cyanate)

  • pH Control: Add Sodium Hydroxide (NaOH). Target pH > 11.0. (Critical! If pH < 10, Gas evolves).

  • Oxidizer: Add Sodium Hypochlorite (Bleach/NaClO) (12% solution).

  • Dosage: Approx 3-4 kg Bleach per 1 kg Cyanide.

  • Control: ORP Meter reading $\approx$ +300 mV.

  • Reaction time: 15-30 mins.

• Step B: Total Destruction (Cyanate $\to$ N2 + CO2)

  • pH Control: Add Sulfuric Acid (H2SO4). Target pH 7.5 – 8.0.

  • Oxidizer: Add Sodium Hypochlorite (Bleach).

  • Dosage: Approx 4-5 kg Bleach per 1 kg Cyanide.

  • Control: ORP Meter reading $\approx$ +650 mV.

  • Result: Safe for mixing with Blue Line.

2. 🔴 Chromium Reduction (The "Red" Line)

Goal: Turn toxic Hexavalent Chrome (Yellow/Orange $Cr^{6+}$) into Trivalent Chrome (Green $Cr^{3+}$) so it can precipitate.

• Step A: Reduction

  • pH Control: Add Sulfuric Acid (H2SO4). Target pH 2.0 – 3.0.

  • Reducer: Add Sodium Metabisulfite (Na2S2O5) or Ferrous Sulfate.

  • Visual: The water changes from Orange $\to$ Green.

  • Control: ORP Meter reading $\approx$ +250 to +300 mV.

• Step B: Precipitation

  • pH Control: Add Sodium Hydroxide (NaOH) or Lime. Target pH 8.5.

  • Result: Cr3+ turns into sludge (Chromium Hydroxide).

3. 🔵 General Heavy Metal (The "Blue" Line)

Goal: Turn dissolved Copper/Nickel into solid mud (Hydroxide Sludge).

Source: Acid Copper, Nickel, White Bronze rinses.

• Step A: Neutralization & Precipitation

  • Chemical: Sodium Hydroxide (NaOH) or Hydrated Lime (Ca(OH)2).

  • Target: Adjust pH to 9.0 – 9.5.

  • Why 9.5? This is the optimal pH where Copper and Nickel settle best.

• Step B: Coagulation (Making small particles big)

  • Chemical: PAC (Polyaluminum Chloride).

  • Dosage: 0.5 – 1.0 ml/L.

  • Function: Neutralizes the electric charge of the particles.

• Step C: Flocculation (Making big particles huge)

  • Chemical: PAM (Polyacrylamide) - Anionic.

  • Dosage: 1 – 2 ppm (Very small amount).

  • Function: Acts like a "net" to trap the sludge into large snowflakes ("Floc").

4. 🟣 Antique / "Za Se" / Complexed Waste (The "Purple" Line)

The Challenge: Antique finishes (Blackeners) and Imitation Gold contain Complexing Agents (Ammonia, Citrates) or Sulfides. These prevent metals from settling.

• Recipe: Sulfide Precipitation.

  • Chemical: Sodium Sulfide (Na2S) or specialized [QLQ] Heavy Metal Catcher.

  • Mechanism: Sulfides bond stronger than the complexing agent.

  • Warning: Creates "Rotten Egg" smell (H2S) if pH is low. Keep pH > 9.0.

  • Process: Add Sulfide $\to$ Add PAC $\to$ Add PAM $\to$ Filter Press.

Part III: Implementation Checklist (For the Boss)

1. The "Sump" Strategy:

   • Do not pipe directly to the treatment plant. Pipe to Underground Sumps (Holding Tanks) first.

   • Each color line needs its own sump.

   • Why? To equalize the flow and concentration.

2. Automation vs. Manual:

   • Manual: Operator pours buckets of Bleach. Risk: High. Accuracy: Low.

   • Auto: Install pH / ORP Controllers connected to Dosing Pumps.

   • Recommendation: For Cyanide (Yellow), Automation is Mandatory for safety.

3. Sludge Handling:

   • The "mud" at the bottom of the tank is Hazardous Waste (HW17/HW21).

   • Action: Pass through a Filter Press (Plate & Frame).

   • Disposal: Must be dried and bagged for licensed disposal companies. Do not throw in trash.

Part IV: Chemical Costing & Procurement Guide

These are the commodity chemicals you need to buy locally (not QLQ products, as they are heavy/cheap).

🌟 Featured Album: The "Green License" Series

Description for the Blog/Guide Album:

🌿 The "Green License" Album: Surviving Environmental Inspections

Wastewater treatment is the only thing that can shut your factory down overnight. This album is your safety net against the EPA.

What you will master:

• 🎨 The Color Map: A printable poster of the Yellow/Red/Blue piping standards used in Chinese plating parks.

• 📈 The ORP Secret: Understanding why pH isn't enough. How to use the ORP (Oxidation-Reduction Potential) meter to know exactly when the Cyanide is dead (+600mV).

• 🧪 The "Jar Test": A simple video showing how to mix PAC and PAM in a beaker to determine the perfect dosage for your specific Blue Line waste.

• ☠️ The Ammonia Trap: Why your Imitation Gold waste is turning your water blue (and failing inspection) and how to use Sodium Sulfide to fix it.