Papermaking wastewater samples with similar colors can require different chemical combinations. These six laboratory cases record how PAC, Water Decoloring Agent, ferrous sulfate, anionic PAM, an oxidation reagent and activated carbon were used across different samples. The results include colorless and slightly yellow transparent supernatants, as well as one unsuccessful treatment sequence.
All chemical doses below are expressed per metric tonne of wastewater. The records describe dosing, pH conditions and visual observations after settling. Chemical product strengths and active-content corrections are not specified. Measured COD, color, suspended solids and ammonia nitrogen results are not provided, so removal percentages cannot be calculated from these observations.
| Case | Raw wastewater | Initial pH | Observed result |
|---|---|---|---|
| 1 | Black papermaking wastewater | 6-7 | Slightly yellow transparent supernatant with both methods. |
| 2 | Black papermaking wastewater | 7 | Pale yellow transparent supernatant. |
| 3 | Yellow papermaking wastewater | 8 | Colorless transparent supernatant. |
| 4 | Red papermaking wastewater | 7 | Slightly yellow transparent supernatant. |
| 5 | Black grass cellulose papermaking wastewater | Not recorded | The tested treatment sequence was unsuccessful. |
| 6 | Red papermaking wastewater | 7 | Colorless with Method 1; slightly yellow with Method 2. |
Raw wastewater: Black papermaking wastewater with an initial pH of 6-7.
Coagulation: Add PAC at 1000 g per tonne of wastewater to form flocs through charge neutralization and bridging.
Oxidation: Add Ammonia Nitrogen Remover at 125 g per tonne of wastewater to remove part of the color by oxidation.
pH adjustment: Add alkali at 120 g per tonne of wastewater and confirm a pH of 7. Neutralization and pH adjustment promote the reaction.
Flocculation: Add anionic PAM at 5 g per tonne of wastewater. Polymer bridging promotes floc settling.
Settling: Allow the sample to settle undisturbed. The supernatant is slightly yellow and transparent, with good solid-liquid separation.
Coagulation: Add ferrous sulfate at 1500 g per tonne of wastewater for coagulation.
Decolorization: Add Water Decoloring Agent at 200 g per tonne of wastewater to remove color through charge neutralization and destabilization.
pH adjustment: Confirm that the pH is greater than 7. If it is not, add alkali to establish alkaline conditions and promote the reaction.
Flocculation: Add anionic PAM at 5 g per tonne of wastewater to form flocs by bridging and promote settling.
Settling: Allow the sample to settle undisturbed. The supernatant is slightly yellow and transparent, with good solid-liquid separation.
Figure 1 Case 1 laboratory photograph
Raw wastewater: Black papermaking wastewater with an initial pH of 7.
Coagulation: Add PAC at 800 g per tonne of wastewater to neutralize charges and destabilize colloids.
Decolorization: Add Water Decoloring Agent at 200 g per tonne of wastewater to remove color from the water.
pH adjustment: Add alkali at 500 g per tonne of wastewater and confirm a pH of 7, neutralizing acidity to achieve neutral conditions.
Flocculation: Add anionic PAM at 30-40 g per tonne of wastewater to form large flocs through adsorption and bridging.
Settling: Allow the sample to settle undisturbed. The supernatant is pale yellow and transparent, with good solid-liquid separation.
Figure 2 Case 2 laboratory photograph
Raw wastewater: Yellow papermaking wastewater with an initial pH of 8.
Decolorization: Add Water Decoloring Agent at 150 g per tonne of wastewater to remove color through charge neutralization and destabilization.
Coagulation: Add PAC at 2500 g per tonne of wastewater. Adsorption and bridging bring flocs together and remove turbidity.
Flocculation: Add anionic PAM at 2 g per tonne of wastewater. Entrapment and sweep flocculation aggregate the flocs and promote settling.
Settling: Allow the sample to settle undisturbed. The supernatant is colorless and transparent, with good solid-liquid separation.
Figure 3 Case 3 laboratory photograph
Raw wastewater: Red papermaking wastewater with an initial pH of 7.
Oxidation: Add 01 Ammonia Nitrogen Remover at 2 kg per tonne of wastewater for strong oxidative decolorization.
Coagulation: Add PAC at 3 kg per tonne of wastewater. Charge neutralization, adsorption, and bridging accelerate floc settling.
pH adjustment: Add alkali at 500 g per tonne of wastewater and confirm a pH of 7-8. Increasing the pH promotes reaction and flocculation.
Flocculation: Add anionic PAM at 10 g per tonne of wastewater. Adsorption and bridging aggregate flocs and promote settling.
Settling: Allow the sample to settle undisturbed. The supernatant is slightly yellow and transparent, with good solid-liquid separation.
Figure 4 Case 4 laboratory photograph
Raw wastewater: Black wastewater from cellulose papermaking using Longjing grass.
Laboratory result: The sequence of Water Decoloring Agent, PAC, pH adjustment, and flocculation was unable to treat this wastewater successfully.
Figures 5 and 6 Case 5 laboratory photographs
Raw wastewater: Red papermaking wastewater with an initial pH of 7.
Decolorization: Add activated carbon at 2000 g per tonne of wastewater to remove color by adsorption.
Coagulation: Add PAC at 1000 g per tonne of wastewater to coagulate suspended solids.
pH adjustment: Add alkali and confirm a pH of 7. Neutralization and pH adjustment promote the reaction.
Flocculation: Add anionic PAM at 5 g per tonne of wastewater to form large flocs through bridging.
Settling: Allow the sample to settle undisturbed. The supernatant is colorless and transparent, with good solid-liquid separation.
Coagulation: Add Water Decoloring Agent at 300 g per tonne of wastewater to coagulate suspended impurities.
Decolorization: Add PAC at 600 g per tonne of wastewater to remove color from the water by adsorption.
pH adjustment: Add alkali and confirm a pH of 7-8 to neutralize and stabilize the water quality.
Flocculation: Add anionic PAM at 5 g per tonne of wastewater to form large flocs through bridging.
Settling: Allow the sample to settle undisturbed. The supernatant is slightly yellow and transparent, with good solid-liquid separation.
Figure 7 Case 6 laboratory photograph
The successful trials produced supernatants described as colorless, pale yellow or slightly yellow and transparent, with good solid-liquid separation. The grass cellulose wastewater sample did not respond successfully to the tested sequence. These results support sample-specific evaluation rather than a single treatment recipe for all papermaking wastewater.
In Case 1, PAC followed by oxidation and ferrous sulfate followed by Water Decoloring Agent both produced slightly yellow transparent supernatants. The coagulants, additional reagents and pH conditions differed. Without analytical results and chemical cost data, these observations do not establish equivalent pollutant removal or the more economical route.
In Case 6, the activated carbon route produced a colorless transparent supernatant, while the Water Decoloring Agent route produced a slightly yellow transparent supernatant. PAC dose and pH conditions also differed between the methods. The observed difference therefore should not be attributed to one chemical alone.
Case 2 used anionic PAM at 30-40 g per tonne of wastewater, while Case 3 used 2 g per tonne. These were different samples with different upstream treatment conditions. The records show why a PAM dose must be evaluated within the complete treatment sequence.
Case 5 is an important limit of the test program. Its chemical doses, initial pH and detailed operating conditions were not recorded. Further work would be needed to determine a suitable treatment route for that sample; the reported result should not be extended to every grass cellulose wastewater.
Use these cases to identify candidate chemical sequences for laboratory evaluation. Before full-scale application, verify the required water quality parameters, evaluate chemical consumption and sludge handling, and consider how chemical treatment connects with biological or advanced treatment. Clear appearance alone does not demonstrate discharge compliance or reuse suitability.
Bluwat Chemicals supplies Water Decoloring Agent, PAC and PAM for industrial wastewater applications. Sharing the wastewater source, current process, initial pH and treatment objective provides a practical basis for discussing laboratory chemical selection.
Case 3 used Water Decoloring Agent at 150 g per tonne, PAC at 2500 g per tonne, and anionic PAM at 2 g per tonne, followed by settling. Its initial pH was 8, and no pH adjustment step was listed.
Case 1 Method 2 used ferrous sulfate at 1500 g per tonne of wastewater. It should not be described as ferric sulfate.
No analytical ammonia nitrogen values are provided. Although Ammonia Nitrogen Remover was used as an oxidation reagent in some trials, the records do not allow an ammonia nitrogen removal rate to be calculated.
They are laboratory doses for specific samples. The actual wastewater, chemical product strengths, dosing sequence, pH conditions and full treatment objectives need to be evaluated before full-scale application.
Papermaking wastewater samples with similar colors can require different chemical combinations. These six laboratory cases record how PAC, Water Decoloring Agent, ferrous sulfate, anionic PAM, an oxidation reagent and activated carbon were used across different samples. The results include colorless and slightly yellow transparent supernatants, as well as one unsuccessful treatment sequence.
All chemical doses below are expressed per metric tonne of wastewater. The records describe dosing, pH conditions and visual observations after settling. Chemical product strengths and active-content corrections are not specified. Measured COD, color, suspended solids and ammonia nitrogen results are not provided, so removal percentages cannot be calculated from these observations.
| Case | Raw wastewater | Initial pH | Observed result |
|---|---|---|---|
| 1 | Black papermaking wastewater | 6-7 | Slightly yellow transparent supernatant with both methods. |
| 2 | Black papermaking wastewater | 7 | Pale yellow transparent supernatant. |
| 3 | Yellow papermaking wastewater | 8 | Colorless transparent supernatant. |
| 4 | Red papermaking wastewater | 7 | Slightly yellow transparent supernatant. |
| 5 | Black grass cellulose papermaking wastewater | Not recorded | The tested treatment sequence was unsuccessful. |
| 6 | Red papermaking wastewater | 7 | Colorless with Method 1; slightly yellow with Method 2. |
Raw wastewater: Black papermaking wastewater with an initial pH of 6-7.
Coagulation: Add PAC at 1000 g per tonne of wastewater to form flocs through charge neutralization and bridging.
Oxidation: Add Ammonia Nitrogen Remover at 125 g per tonne of wastewater to remove part of the color by oxidation.
pH adjustment: Add alkali at 120 g per tonne of wastewater and confirm a pH of 7. Neutralization and pH adjustment promote the reaction.
Flocculation: Add anionic PAM at 5 g per tonne of wastewater. Polymer bridging promotes floc settling.
Settling: Allow the sample to settle undisturbed. The supernatant is slightly yellow and transparent, with good solid-liquid separation.
Coagulation: Add ferrous sulfate at 1500 g per tonne of wastewater for coagulation.
Decolorization: Add Water Decoloring Agent at 200 g per tonne of wastewater to remove color through charge neutralization and destabilization.
pH adjustment: Confirm that the pH is greater than 7. If it is not, add alkali to establish alkaline conditions and promote the reaction.
Flocculation: Add anionic PAM at 5 g per tonne of wastewater to form flocs by bridging and promote settling.
Settling: Allow the sample to settle undisturbed. The supernatant is slightly yellow and transparent, with good solid-liquid separation.
Figure 1 Case 1 laboratory photograph
Raw wastewater: Black papermaking wastewater with an initial pH of 7.
Coagulation: Add PAC at 800 g per tonne of wastewater to neutralize charges and destabilize colloids.
Decolorization: Add Water Decoloring Agent at 200 g per tonne of wastewater to remove color from the water.
pH adjustment: Add alkali at 500 g per tonne of wastewater and confirm a pH of 7, neutralizing acidity to achieve neutral conditions.
Flocculation: Add anionic PAM at 30-40 g per tonne of wastewater to form large flocs through adsorption and bridging.
Settling: Allow the sample to settle undisturbed. The supernatant is pale yellow and transparent, with good solid-liquid separation.
Figure 2 Case 2 laboratory photograph
Raw wastewater: Yellow papermaking wastewater with an initial pH of 8.
Decolorization: Add Water Decoloring Agent at 150 g per tonne of wastewater to remove color through charge neutralization and destabilization.
Coagulation: Add PAC at 2500 g per tonne of wastewater. Adsorption and bridging bring flocs together and remove turbidity.
Flocculation: Add anionic PAM at 2 g per tonne of wastewater. Entrapment and sweep flocculation aggregate the flocs and promote settling.
Settling: Allow the sample to settle undisturbed. The supernatant is colorless and transparent, with good solid-liquid separation.
Figure 3 Case 3 laboratory photograph
Raw wastewater: Red papermaking wastewater with an initial pH of 7.
Oxidation: Add 01 Ammonia Nitrogen Remover at 2 kg per tonne of wastewater for strong oxidative decolorization.
Coagulation: Add PAC at 3 kg per tonne of wastewater. Charge neutralization, adsorption, and bridging accelerate floc settling.
pH adjustment: Add alkali at 500 g per tonne of wastewater and confirm a pH of 7-8. Increasing the pH promotes reaction and flocculation.
Flocculation: Add anionic PAM at 10 g per tonne of wastewater. Adsorption and bridging aggregate flocs and promote settling.
Settling: Allow the sample to settle undisturbed. The supernatant is slightly yellow and transparent, with good solid-liquid separation.
Figure 4 Case 4 laboratory photograph
Raw wastewater: Black wastewater from cellulose papermaking using Longjing grass.
Laboratory result: The sequence of Water Decoloring Agent, PAC, pH adjustment, and flocculation was unable to treat this wastewater successfully.
Figures 5 and 6 Case 5 laboratory photographs
Raw wastewater: Red papermaking wastewater with an initial pH of 7.
Decolorization: Add activated carbon at 2000 g per tonne of wastewater to remove color by adsorption.
Coagulation: Add PAC at 1000 g per tonne of wastewater to coagulate suspended solids.
pH adjustment: Add alkali and confirm a pH of 7. Neutralization and pH adjustment promote the reaction.
Flocculation: Add anionic PAM at 5 g per tonne of wastewater to form large flocs through bridging.
Settling: Allow the sample to settle undisturbed. The supernatant is colorless and transparent, with good solid-liquid separation.
Coagulation: Add Water Decoloring Agent at 300 g per tonne of wastewater to coagulate suspended impurities.
Decolorization: Add PAC at 600 g per tonne of wastewater to remove color from the water by adsorption.
pH adjustment: Add alkali and confirm a pH of 7-8 to neutralize and stabilize the water quality.
Flocculation: Add anionic PAM at 5 g per tonne of wastewater to form large flocs through bridging.
Settling: Allow the sample to settle undisturbed. The supernatant is slightly yellow and transparent, with good solid-liquid separation.
Figure 7 Case 6 laboratory photograph
The successful trials produced supernatants described as colorless, pale yellow or slightly yellow and transparent, with good solid-liquid separation. The grass cellulose wastewater sample did not respond successfully to the tested sequence. These results support sample-specific evaluation rather than a single treatment recipe for all papermaking wastewater.
In Case 1, PAC followed by oxidation and ferrous sulfate followed by Water Decoloring Agent both produced slightly yellow transparent supernatants. The coagulants, additional reagents and pH conditions differed. Without analytical results and chemical cost data, these observations do not establish equivalent pollutant removal or the more economical route.
In Case 6, the activated carbon route produced a colorless transparent supernatant, while the Water Decoloring Agent route produced a slightly yellow transparent supernatant. PAC dose and pH conditions also differed between the methods. The observed difference therefore should not be attributed to one chemical alone.
Case 2 used anionic PAM at 30-40 g per tonne of wastewater, while Case 3 used 2 g per tonne. These were different samples with different upstream treatment conditions. The records show why a PAM dose must be evaluated within the complete treatment sequence.
Case 5 is an important limit of the test program. Its chemical doses, initial pH and detailed operating conditions were not recorded. Further work would be needed to determine a suitable treatment route for that sample; the reported result should not be extended to every grass cellulose wastewater.
Use these cases to identify candidate chemical sequences for laboratory evaluation. Before full-scale application, verify the required water quality parameters, evaluate chemical consumption and sludge handling, and consider how chemical treatment connects with biological or advanced treatment. Clear appearance alone does not demonstrate discharge compliance or reuse suitability.
Bluwat Chemicals supplies Water Decoloring Agent, PAC and PAM for industrial wastewater applications. Sharing the wastewater source, current process, initial pH and treatment objective provides a practical basis for discussing laboratory chemical selection.
Case 3 used Water Decoloring Agent at 150 g per tonne, PAC at 2500 g per tonne, and anionic PAM at 2 g per tonne, followed by settling. Its initial pH was 8, and no pH adjustment step was listed.
Case 1 Method 2 used ferrous sulfate at 1500 g per tonne of wastewater. It should not be described as ferric sulfate.
No analytical ammonia nitrogen values are provided. Although Ammonia Nitrogen Remover was used as an oxidation reagent in some trials, the records do not allow an ammonia nitrogen removal rate to be calculated.
They are laboratory doses for specific samples. The actual wastewater, chemical product strengths, dosing sequence, pH conditions and full treatment objectives need to be evaluated before full-scale application.
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