Seven bench-scale trials show how differently cutting fluid wastewater can respond to chemical treatment. The tested routes included 08A demulsification, PAC coagulation, nonionic or anionic PAM flocculation, Compound 202 decolorizing agent, and PolyDADMAC. Several samples produced transparent supernatants, while another showed oil–water separation but remained turbid.

The cases below record the treatment sequence and dosage used for each sample. They are individual test results rather than a universal dosing formula. PAC denotes polyaluminum chloride, and PAM denotes polyacrylamide. All dosages are per metric tonne of wastewater.

Color and clarity were assessed visually. CODCr results are available for Case 5. A transparent supernatant alone does not establish that the treated water meets discharge or reuse requirements.

Case 1 08A With PAC and Nonionic PAM632

1. Demulsification: 08A was added in its original, undiluted form at 30 kg/t to destabilize the emulsion and initiate oil–water separation.

2. Coagulation: PAC was added at 2.5 kg/t to destabilize dispersed particles, increase floc size, and accelerate settling.

3. pH adjustment: Alkali was added at 600 g/t to adjust the pH to 7 and promote the combined action of the demulsifier and flocculant under neutral conditions.

4. Flocculation: Nonionic PAM632 was added at 20 g/t to increase floc compactness and mechanical strength and reduce floc breakage and redissolution.

5. Solid–liquid separation: The sample was allowed to settle, producing a colorless, transparent supernatant with good sludge–water separation.

Result: The treated supernatant was colorless and transparent, with color approaching zero by visual assessment. No abnormal coloration or milky opalescence was observed, and the result met the customer’s decolorization requirement.

Figures 1 and 2 Case 1 floc formation and clarified supernatant

Case 2 08A With Anionic PAM

The untreated wastewater was white and turbid, with a pH of 9–10.

1. Demulsification: 08A was added in its original, undiluted form at 200 kg/t to disrupt the interfacial film, destabilize the emulsion, and promote droplet coalescence.

2. pH adjustment: Alkali was added as required to adjust the pH to 7 and promote the combined treatment effect under neutral conditions.

3. Flocculation: Anionic PAM was added at 50 g/t to promote bridging and aggregation and accelerate settling.

4. Solid–liquid separation: The sample was allowed to settle, producing a colorless, transparent supernatant with good sludge–water separation.

Result: Treatment produced a colorless, transparent supernatant, with color approaching zero by visual assessment. No abnormal coloration or milky opalescence was observed, and the result met the customer’s decolorization requirement.

Figure 3 Case 2 floc formation and clarified liquid

Case 3 Compound 202 With Anionic PAM

The untreated wastewater was white and turbid, with a pH of 8.

1. Demulsification and decolorization: Compound 202 decolorizing agent was added at 50 kg/t to break the emulsion and remove color in one step.

2. pH adjustment: Alkali was added as required to adjust the pH to 7 and establish suitable reaction conditions for demulsification, decolorization, and flocculation.

3. Flocculation: Anionic PAM was added at 600 g/t to promote bridging and adsorption and achieve effective sludge–water separation.

4. Solid–liquid separation: The sample was allowed to settle, producing a slightly yellow, transparent supernatant with good sludge–water separation.

Result: Color decreased substantially. The supernatant was pale yellow and transparent, with no abnormal coloration or milky opalescence on visual inspection, and met the customer’s decolorization requirement.

Figure 4 Case 3 untreated wastewater and treatment result

Case 4 PAC Before Demulsifier Addition

The untreated wastewater was brown and turbid, with a pH of 8.

1. Coagulation: PAC was added at 35 kg/t to compress the electrical double layer, initiate destabilization, and form primary flocs.

2. Demulsification: Demulsifier was added at 3 kg/t to further break down the emulsion and accelerate oil droplet coalescence and separation.

3. pH control: The wastewater pH was confirmed at 7 to maintain suitable reaction conditions and promote the combined chemical treatment effect.

4. Flocculation: Anionic PAM was added at 100 g/t to promote rapid floc aggregation and accelerate settling.

5. Solid–liquid separation: The sample was allowed to settle, producing a colorless, transparent supernatant with good sludge–water separation.

Result: The treated supernatant was colorless and transparent. Visual inspection showed no abnormal coloration or milky opalescence, and the result met the customer’s decolorization requirement.

Figure 5 Case 4 untreated wastewater and separated sludge

Case 5 Chemical Treatment With Measured COD Removal

The untreated wastewater was grayish white and turbid, with a pH of 8–9.

1. Coagulation: PAC was added at 20 kg/t to compress the electrical double layer, initiate destabilization, and form primary flocs.

2. Demulsification: Demulsifier was added at 10 kg/t to further break down the emulsion and accelerate oil droplet coalescence and separation.

3. pH adjustment: Caustic soda flakes were added at 1.2 kg/t to adjust the wastewater pH to 7 and maintain suitable conditions for the combined chemical treatment.

4. Flocculation: Anionic PAM was added at 200 g/t to promote rapid floc aggregation and accelerate settling.

5. Solid–liquid separation: The sample was allowed to settle, producing a pale yellow, transparent supernatant with good sludge–water separation.

Result: The supernatant was pale yellow and transparent, with no abnormal coloration or milky opalescence on visual inspection. The result met the customer’s decolorization requirement. CODCr decreased from 212,600 to 33,750 mg/L, corresponding to 84.13% removal.

COD test results

Figure 6 Case 5 untreated wastewater and treatment result

Case 6 Two Stages of PAC and PAM Treatment

The untreated wastewater was black and turbid and was strongly alkaline. Treatment was carried out in two stages.

Stage 1 Primary Coagulation and Flocculation

1. pH adjustment: Acid was added to adjust the pH to 7–8 and establish the selected range for PAC coagulation.

2. Coagulation: PAC was added at 30 kg/t to destabilize the wastewater and form primary flocs.

3. pH verification: The wastewater pH was confirmed to remain above 7 to prevent pH drift from impairing coagulation.

4. Flocculation: Anionic PAM was added at 120 g/t to aggregate the flocs and accelerate settling.

5. Solid–liquid separation: After settling, the supernatant remained turbid. A second treatment stage with adjusted conditions was therefore used for further decolorization.

Stage 2 Further Coagulation and Flocculation

1. Further coagulation: PAC was added to the Stage 1 supernatant at 6 g/t to destabilize residual colloids and form fine flocs.

2. pH adjustment: Alkali was added to adjust the pH to 7–8 and maintain suitable reaction conditions.

3. Further flocculation: Anionic PAM was added at 20 g/t to aggregate the flocs and accelerate settling.

4. Solid–liquid separation: After settling, the supernatant was yellow and transparent and met the turbidity requirement.

Result: After two treatment stages, color decreased substantially and the supernatant was yellow and transparent. No abnormal coloration or milky opalescence was observed on visual inspection.

Figures 7 and 8 Case 6 Stage 1 result on the left and Stage 2 result on the right

Case 7 PolyDADMAC for Oil Water Separation

The untreated wastewater was gray and turbid, with a pH of 7–8.

1. Demulsification and flocculation: PolyDADMAC was added at 10 kg/t. Oil–water separation occurred and the sludge floated, leaving a brown, turbid liquid phase.

Result: The trial produced clear evidence of oil–water separation.

Figure 9 Case 7 oil–water separation after PolyDADMAC treatment

What These Trials Show

The samples required different chemical combinations and substantially different dosages. Both demulsifier-first and PAC-first sequences produced transparent supernatants in individual trials. The two-stage case improved the clarity of a first-stage supernatant that remained turbid.

The results also distinguish separation from final water quality. PolyDADMAC produced oil–water separation in Case 7 without a clear liquid phase. Case 5 achieved 84.13% CODCr removal, but residual CODCr was still 33,750 mg/L. Process selection should therefore consider both the separation result and measured water quality.

Arrange a Wastewater Treatment Discussion

Contact Bluwat Chemicals with your wastewater sample information, available analysis data, and treatment targets. The next step is to compare chemical combinations and dosages through bench-scale testing for your specific wastewater.