Water Decoloring Agent Case Studies for Four Wastewater Applications
Bluwat Chemicals
These laboratory cases document BWD water decoloring agent applications in textile dyeing, animal farming and coking wastewater, together with a composite decoloring agent application in papermaking wastewater. Each case presents the treatment sequence, chemical additions and measured water quality, with the original experiment photograph.
Color reduction alone does not establish overall effluent quality. These cases also show why COD, ammonia nitrogen and phosphorus need to be assessed separately when selecting a treatment process.
Textile Dyeing Wastewater
Figure 1 Original textile dyeing wastewater experiment photograph
Laboratory treatment procedure
1. Measure 80 mL of wastewater.
2. Add 1 mL (250 ppm) of diluted BWD water decoloring agent and mix thoroughly.
3. Add 1 mL (625 ppm) of diluted polyaluminium chloride (PAC) and mix thoroughly.
4. Add liquid caustic soda or hydrochloric acid to adjust the pH to 7–8, then mix thoroughly.
5. Add 1–5 mL (1–5 ppm) of aqueous polyacrylamide (PAM), mix slowly and thoroughly, then allow the flocs to settle.
6. Sludge–water separation is generally completed within 5–10 minutes.
| Parameter |
Before treatment |
After treatment |
| pH |
7.5 |
7.5 |
| COD (mg/L) |
802.0 |
200 |
| Color (dilution factor) |
2500 |
48 |
| Ammonia nitrogen (mg/L) |
10.2 |
10.3 |
The treated color value was below 50, meeting the customer’s stated color requirement. The case record also reports no residual background color. COD decreased from 802.0 to 200 mg/L; ammonia nitrogen changed from 10.2 to 10.3 mg/L.
Animal Farming Wastewater
This case evaluated BWD decoloring treatment together with changes in COD, ammonia nitrogen and total phosphorus in animal farming wastewater.
Figure 2 Original animal farming wastewater experiment photograph
Laboratory treatment procedure
1. Measure 80 mL of wastewater.
2. Add 0.5–1 mL (125–250 ppm) of diluted BWD water decoloring agent and mix thoroughly.
3. Add 1 mL (625 ppm) of diluted PAC and mix thoroughly.
4. Add liquid caustic soda or hydrochloric acid to adjust the pH to 7–8, then mix thoroughly.
5. Add 1–5 mL (1–5 ppm) of aqueous PAM, mix slowly and thoroughly, then allow the flocs to settle.
6. Sludge–water separation is generally completed within 5–10 minutes.
| Parameter |
Before treatment |
After treatment |
| pH |
7.8 |
7.5 |
| COD (mg/L) |
403.0 |
205.4 |
| Color (dilution factor) |
800 |
76 |
| Ammonia nitrogen (mg/L) |
280 |
220 |
| Total phosphorus (mg/L) |
10.3 |
1.2 |
Treatment outcome and remaining ammonia nitrogen
The treated color value was below 80 and COD was below 400 mg/L, meeting the customer’s stated requirements for these parameters. Total phosphorus decreased from 10.3 to 1.2 mg/L. Ammonia nitrogen remained elevated at 220 mg/L.
The case record identifies short retention time and poor sludge activity in the customer’s biological treatment system. It proposes BWG biological water purification agent as a way to improve treatment toward the stated irrigation reuse requirement of ammonia nitrogen below 80 mg/L. That value is a proposed downstream target; the measured post-treatment ammonia nitrogen in this test was 220 mg/L.
Coking Wastewater
The coking wastewater sample was treated with diluted BWD water decoloring agent, PAC, pH adjustment and PAM. The recorded results show color and COD reduction, while ammonia nitrogen remained essentially unchanged.
Figure 3 Original coking wastewater experiment photograph
Laboratory treatment procedure
1. Measure 80 mL of wastewater.
2. Add 0.5–1.5 mL (125–375 ppm) of diluted BWD water decoloring agent and mix thoroughly.
3. Add 0.5–1.5 mL (312–937 ppm) of diluted PAC and mix thoroughly.
4. Add liquid caustic soda or hydrochloric acid to adjust the pH to 7–8, then mix thoroughly.
5. Add 1–5 mL (1–5 ppm) of aqueous PAM, mix slowly and thoroughly, then allow the flocs to settle.
6. Sludge–water separation is generally completed within 5–10 minutes.
| Parameter |
Before treatment |
After treatment |
| pH |
7.0 |
7.5 |
| COD (mg/L) |
316.0 |
125 |
| Color (dilution factor) |
1500 |
55 |
| Ammonia nitrogen (mg/L) |
8.3 |
8.5 |
Treatment outcome
Color decreased from 1500 to 55, below the customer’s stated requirement of 80. The case record also reports no residual background color. COD decreased from 316.0 to 125 mg/L. Ammonia nitrogen changed from 8.3 to 8.5 mg/L, so this experiment does not demonstrate ammonia nitrogen removal.
What the result means for process selection
For this sample, the decoloring sequence addressed color and part of the COD load. Any separate requirement for ammonia nitrogen would need its own treatment assessment. The color result should be evaluated alongside the other measured parameters when defining the role of this step in a complete wastewater treatment system.
Papermaking Wastewater
The papermaking case used a composite decoloring agent followed by pH adjustment and PAM. A separate PAC addition is not listed in this treatment procedure.
Figure 4 Original papermaking wastewater experiment photograph
Laboratory treatment procedure
1. Measure 60 mL of wastewater.
2. Add 0.1 mL (1666 ppm) of composite decoloring agent and mix thoroughly.
3. Add liquid caustic soda or hydrochloric acid to adjust the pH to 7–8, then mix thoroughly.
4. Add 5–15 mL (5–15 ppm) of aqueous PAM, mix slowly and thoroughly, then allow the flocs to settle.
5. Sludge–water separation is generally completed within 5–10 minutes.
| Parameter |
Before treatment |
After treatment |
| pH |
6.8 |
7.5 |
| COD (mg/L) |
3000 |
800 |
| Color (dilution factor) |
10000 |
60 |
| Ammonia nitrogen (mg/L) |
– |
– |
Treatment outcome and further treatment options
Color decreased from 10000 to 60, below 80 and meeting the customer’s first-stage treatment requirement. COD decreased from 3000 to 800 mg/L. The dash in the ammonia nitrogen row indicates that no value is reported.
The case record lists combined treatment with other wastewater or activated carbon adsorption as possible follow-up routes for reuse. It does not report a final reuse water analysis after either route.
About BWD Water Decoloring Agent
BWD Water Decoloring Agent is Bluwat Chemicals’ product range for treating colored industrial wastewater. BWD-01, a water-soluble cationic polymer coagulant in this range, is developed for color removal, flocculation and associated COD reduction. Its positive charge helps destabilize negatively charged dyes and color-bearing particles, supporting the formation of flocs that can be separated from the water.
Typical applications include textile dyeing and printing, dyestuff and pigment manufacturing, printing ink, pulp and paper, and chemical processing wastewater. Depending on the wastewater and treatment objective, BWD can be evaluated as part of primary treatment or as a color removal step after biological treatment.
BWD can be used in a treatment program with PAC and PAM, with the dosage and addition sequence established by jar testing. PAC supports coagulation, while PAM helps floc growth and separation. The appropriate combination depends on the sample. The papermaking case in this article uses a composite decoloring agent and follows its own recorded addition sequence.
About Bluwat Chemicals
Yixing Bluwat Chemicals Co., Ltd. is a manufacturer and exporter of water treatment chemicals and functional polymers based in Yixing, Jiangsu, China. Our business began in 2000, the company was formally established in 2002, and the Yixing factory began operation in 2004. With three production bases, we have supplied approximately 800,000 tonnes of products to customers in around 100 countries and regions.
Our portfolio includes BWD-01 Water Decoloring Agent, BLUFLOC polyacrylamide powder and emulsions, PAC, PolyDADMAC, Polyamine, ACH, Ferric Sulphate and specialty treatment chemicals. We serve industrial wastewater treatment, municipal water treatment, pulp and paper, mining, and oilfield applications.
Bluwat supports chemical selection through sample evaluation, laboratory jar testing and application guidance. By evaluating color, COD, floc formation and separation together, we help customers select a chemical program suited to their wastewater and operating requirements.
Selecting a decoloring treatment with Bluwat Chemicals
These four cases provide practical starting points for wastewater evaluation. The reported volumes and ppm values are case-specific; dilution concentrations are not stated, so the figures should not be treated as a universal dosing recipe. Color is reported as a dilution factor, without an identified test standard.
For your project, share the wastewater source, current water analysis and target effluent requirements with Bluwat Chemicals. A jar test using a representative sample can establish the appropriate decoloring agent, dosing sequence and downstream treatment needs.
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