1 Overview
Our company is a pulp manufacturing company and there was a problem with the pretreatment of the coagulation reaction. After the administration of TSS and COD, the COD rose compared to the non-administered TSS. To this end, we conducted different experiments on the company's wastewater, and achieved significant experimental results, and strive to provide the experimental basis for the company's wastewater treatment and subsequent process improvement, and also provide reference for similar companies.
APMP wastewater contains high levels of COD and TSS because it contains lignin and its derivatives. The coagulation reaction includes two processes of mixing and agglomeration. The factors affecting these two factors are the type of coagulant, mixing speed, PH value, and water quality characteristics. The pH of the coagulant dosage has the greatest influence. It also determines the order of anaerobic treatment load and effluent indicators. In this paper, the coagulation of APMP wastewater was studied in terms of PH value and coagulant dosage.
2. Wastewater sources and medicines
Our company APMP pulping wastewater PH7.9-8.3 temperature about 52 degrees Celsius TCOD9000-13000mg/L PAC [polyaluminum chloride] content 10% PAM solution content 1.6 ‰
3, experimental methods
Take 200ml of raw water to precipitate for 1 hour, and take the supernatant to analyze its TCOD, TSS, and turbidity. Take 200ml raw water to adjust its different PH value and different dosing amount, stable temperature of 52 degrees Celsius, dosing stirring for 10 minutes, let stand for 1 hour, take the supernatant to analyze TCOD, TSS, turbidity, and the original water sample Contrast the conclusion.
4. Effect of pH on APMP Wastewater
The raw water is adjusted to 3, 3.5, and 4 with PAC 1 ‰ PAM at a pH of 8.0 and a temperature of 52.4 degrees Celsius. The TCOD, TSS and turbidity of the same dosing are changed at different pH values.
When the PH value is constant, the effect of different dosing amount on the effluent index results in the best dosage of APMP effluent at 1 Torr. COD has a good rate of removal at 1 day. Discussion of the coagulation mechanism, the hydrolysates of aluminum salts at different pH values ​​have different pH values. pH of hydrolyzed aluminum salts is 3.753.75 At pH 4, the surface hydration of lignin molecules is further weakened. After the flocculating agent, the lignin molecules began to precipitate. At this time, the effect of the pH value was far greater than that caused by adding the coagulant. The addition of the coagulant had the effect of destabilizing or accelerating the precipitation of the macromolecular material.
5 Conclusion
pH is the main factor that affects the coagulation of lignin. The best PH value is below 6. The lower PH value is more conducive to the occurrence of coagulation reaction.
The best dosage of PAC is 1 ‰. PAM can accelerate the coagulation reaction.
In practical applications, the joints of pH and dosing can be selected according to specific conditions, which can reduce operating costs and achieve high COD removal rates.
Our company is a pulp manufacturing company and there was a problem with the pretreatment of the coagulation reaction. After the administration of TSS and COD, the COD rose compared to the non-administered TSS. To this end, we conducted different experiments on the company's wastewater, and achieved significant experimental results, and strive to provide the experimental basis for the company's wastewater treatment and subsequent process improvement, and also provide reference for similar companies.
APMP wastewater contains high levels of COD and TSS because it contains lignin and its derivatives. The coagulation reaction includes two processes of mixing and agglomeration. The factors affecting these two factors are the type of coagulant, mixing speed, PH value, and water quality characteristics. The pH of the coagulant dosage has the greatest influence. It also determines the order of anaerobic treatment load and effluent indicators. In this paper, the coagulation of APMP wastewater was studied in terms of PH value and coagulant dosage.
2. Wastewater sources and medicines
Our company APMP pulping wastewater PH7.9-8.3 temperature about 52 degrees Celsius TCOD9000-13000mg/L PAC [polyaluminum chloride] content 10% PAM solution content 1.6 ‰
3, experimental methods
Take 200ml of raw water to precipitate for 1 hour, and take the supernatant to analyze its TCOD, TSS, and turbidity. Take 200ml raw water to adjust its different PH value and different dosing amount, stable temperature of 52 degrees Celsius, dosing stirring for 10 minutes, let stand for 1 hour, take the supernatant to analyze TCOD, TSS, turbidity, and the original water sample Contrast the conclusion.
4. Effect of pH on APMP Wastewater
The raw water is adjusted to 3, 3.5, and 4 with PAC 1 ‰ PAM at a pH of 8.0 and a temperature of 52.4 degrees Celsius. The TCOD, TSS and turbidity of the same dosing are changed at different pH values.
When the PH value is constant, the effect of different dosing amount on the effluent index results in the best dosage of APMP effluent at 1 Torr. COD has a good rate of removal at 1 day. Discussion of the coagulation mechanism, the hydrolysates of aluminum salts at different pH values ​​have different pH values. pH of hydrolyzed aluminum salts is 3.753.75 At pH 4, the surface hydration of lignin molecules is further weakened. After the flocculating agent, the lignin molecules began to precipitate. At this time, the effect of the pH value was far greater than that caused by adding the coagulant. The addition of the coagulant had the effect of destabilizing or accelerating the precipitation of the macromolecular material.
5 Conclusion
pH is the main factor that affects the coagulation of lignin. The best PH value is below 6. The lower PH value is more conducive to the occurrence of coagulation reaction.
The best dosage of PAC is 1 ‰. PAM can accelerate the coagulation reaction.
In practical applications, the joints of pH and dosing can be selected according to specific conditions, which can reduce operating costs and achieve high COD removal rates.
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