Improving sludge concentration in activated sludge process has multiple benefits, mainly reflected in the following aspects:
1. Improving the efficiency of pollutant removal and enhancing the ability to degrade organic matter. Increasing sludge concentration can increase the number and types of microorganisms, thereby improving the ability to degrade organic matter. Higher microbial concentration means stronger adsorption and metabolic capacity, enabling more efficient removal of chemical oxygen demand (COD) and biochemical oxygen demand (BOD) from wastewater. Improving denitrification and phosphorus removal efficiency can increase the concentration of nitrifying and denitrifying bacteria in high sludge concentration, thereby enhancing the efficiency of nitrification and denitrification reactions. In the anaerobic zone, high sludge concentration is beneficial for the growth and phosphorus release process of polyphosphate accumulating bacteria, thereby improving the effectiveness of biological phosphorus removal.
2. Enhancing the impact resistance of the system to adapt to water quality fluctuations. High sludge concentration means that the total amount of microorganisms in the system is greater, which can better cope with sudden changes in incoming water quality, such as a significant increase in organic matter concentration or the entry of toxic substances. This helps maintain the stable operation of the system and prevent the deterioration of effluent quality. When the water volume increases, high concentration activated sludge can more effectively treat more sewage and avoid water quality problems caused by untimely treatment.
3. Optimizing the biological treatment process can shorten the reaction time. High sludge concentration can shorten the time of nitrification and denitrification reactions and reduce the effective volume of the anoxic section. In the anoxic stage, high sludge concentration can better utilize organic matter as a carbon source for denitrification reactions, especially in the case of insufficient carbon sources, which is particularly important. The microbial flocs that promote high sludge concentration in simultaneous denitrification have a larger diameter and are prone to forming an anoxic environment inside, thereby promoting the occurrence of simultaneous denitrification reactions.
4. Improve the stability and flexibility of the system to enhance sedimentation performance. Within an appropriate range of sludge concentration, the sedimentation performance of sludge will be better, which will help improve the sludge water separation effect of the secondary sedimentation tank. Optimizing operating parameters to increase sludge concentration can reduce the demand for dissolved oxygen, thereby reducing aeration energy consumption. In addition, high sludge concentration can further optimize the treatment efficiency of the system by adjusting the sludge age.
5. Improve the economy and adaptability of the system to reduce the demand for treatment units. Under high sludge concentration conditions, the system can treat sewage more efficiently, thereby reducing the need for additional treatment units and lowering construction and operating costs. Adapting to low-temperature environments, the activity of microorganisms will decrease under low-temperature conditions, but by increasing sludge concentration, the negative impact of reduced activity can be offset, thereby ensuring the treatment efficiency of the system. Although increasing sludge concentration has many benefits, the following issues should also be noted: risk of sludge swelling: Excessive concentration may cause sludge swelling, affecting settling performance. Increased aeration demand: Higher sludge concentration requires higher aeration volume to maintain sufficient dissolved oxygen. Sludge aging: Excessive sludge concentration may lead to sludge aging, affecting system operation. In summary, increasing the sludge concentration reasonably can significantly improve the treatment efficiency and system stability of the activated sludge process, but it needs to be optimized and adjusted according to specific operating conditions.
