PACT - Powder Activated Carbon Treatment of Activated Sludge Process - Series Two

Application of PACT process and attention issues

The PACT process has been widely used in the Treatment of Industrial Wastewater, such as oil refining, petrochemical, printing and dyeing Wastewater, coking Wastewater, and organic chemical Wastewater, due to its economic and efficiency advantages.

In addition, the PACT method for municipal Wastewater Ttreatment can significantly improve the nitrification effect, which is better than the activated sludge method, and can increase the total removal efficiency of the system and greatly improve the effluent quality.

1. The application of PACT process on industrial Wastewater

China mainly applies the PACT process to the actual industrial Wastewater Ttreatment.

For example, using PACT process to treat pretreated PAM production Wastewater can improve the efficiency of oxygen utilization, improve the settling performance of sludge, and the removal effect of organic matter is over 80%.

A chemical park adopts PAC-enhanced activated sludge method to treat "three high" hard-to-degrade integrated chemical Wastewater, and the removal effect of COD is nearly doubled and the removal rate of chromaticity reaches 60-70%.

Using A2/O (PACT) process to treat the printing and dyeing Wastewater after hydrolysis and acidification can effectively improve the winter operation effect of the system, and enhance the treatment effect of characteristic organic pollutants such as benzene ring, thick ring and heterocyclic, and have more obvious promotion effect on the removal of large molecules.

For example, a domestic pharmaceutical company used the PACT process to treat pharmaceutical Wastewater containing benzothiazole, and the removal rates of TOC and COD by the PACT process were increased from 54.8% and 45.6% to 86.13% and 76.34%, respectively, compared with the activated sludge method without the addition of Activated Carbon. It improved the tolerance of the system to shock load and had a screening effect on the benzothiazole degrading bacteria in the system.

2. Problems to be noted in the application of PACT process.

(1) Consider when selecting materials for sludge disposal equipment. pact adds powdered Activated Carbon to the activated sludge aeration tank, and the remaining sludge discharged is PAC-biological sludge, which is abrasive and has high wear resistance requirements for the pump body, tank body, secondary sedimentation tank scraping machinery, and sludge disposal equipment.

(2) Due to the high density of sludge generated by this process, the design of the scraping machinery of the secondary sedimentation tank and the sludge disposal equipment should adopt a high torque limit value.

(3) When the amount of Charcoal cast is large, the effluent contains a high level of PAC particles. To improve this situation, it is recommended to use an SBR system or add a tertiary filter tank, or use a membrane separation unit instead of a secondary sedimentation tank.

(4) The adsorption capacity of PAC in PACT system is different from the value predicted by intermittent isothermal adsorption test, so continuous flow treatment test should be conducted to obtain relevant data for design.

(5) Because the adsorption capacity of PAC is very strong, such as direct exposure to air is very easy to adsorb substances in the surrounding environment, so that the adsorption site is accounted for PAC failure, so in production or testing must pay attention to airtight storage.