How to deal with excessive addition of carbon source

How to deal with excessive addition of carbon source

In the field of sewage treatment, accurate addition of carbon source is one of the key factors to ensure stable and efficient treatment effect. However, excessive addition of carbon source is a common operational error, which may trigger a series of chain reactions and affect the stability and effluent quality of the entire sewage treatment system.

Observation of the phenomenon of excessive addition of carbon source

Deterioration of sludge expansion and settling performance: After excessive addition of carbon source, microbial metabolism accelerates and the organic content in activated sludge increases, resulting in sludge volume expansion and a significant increase in sludge volume index (SVI). The sludge becomes loose, the settling speed slows down, the turbidity of the supernatant increases, and the effluent quality deteriorates.

Increased foam: Excessive carbon sources may stimulate the excessive reproduction of certain types of microorganisms and produce a large number of bubbles, resulting in abundant and long-lasting foam in the aeration tank. These foams not only occupy reactor space, but may also clog equipment and reduce treatment efficiency.

Abnormal water quality parameters: Monitor changes in chemical oxygen demand (COD), biochemical oxygen demand (BOD), total nitrogen (TN), total phosphorus (TP) and other indicators of the inlet and outlet water. It can be found that these indicators may be affected by excessive carbon sources. Abnormal fluctuations occur. In particular, the removal rate of nutrients such as nitrogen and phosphorus may decrease, indicating that the microbial community structure is destroyed.

Decreased dissolved oxygen concentration: Due to increased microbial activity, the demand for oxygen increases, resulting in excessive consumption of dissolved oxygen (DO) and the DO concentration continues to be lower than the set standard. This may lead to a lack of oxygen in the water body of the sewage treatment system, thereby affecting the treatment effect.

Microbial community imbalance: Using molecular biology methods to analyze the microbial population structure, it can be found that the number of heterotrophic bacteria has increased significantly, while the number of nitrifying bacteria and denitrifying bacteria has decreased. This unbalanced microbial community structure is not conducive to the nitrification-denitrification process and further affects the quality of the effluent.

Steps to deal with excessive carbon source addition

Immediately stop or reduce the addition of carbon source: Once it is found that the carbon source is excessively added, the addition of carbon source should be stopped or reduced immediately to prevent the situation from further deteriorating.

Adjust the influent carbon-nitrogen-phosphorus ratio (C/N/P): By adjusting the ratio of nutrient elements in the influent, ensure that C:N:P is in an appropriate range to inhibit the excessive reproduction of filamentous bacteria and restore the balance of the microbial community structure.

Optimize aeration control: Increase aeration time or intensity to increase the oxygen supply of sewage and accelerate the decomposition of organic matter in sewage, thereby alleviating the impact of excessive carbon source. At the same time, pay attention to avoid excessive redox potential to stimulate the growth of filamentous bacteria.

Adjust the sludge return ratio: By adjusting the sludge return ratio, controlling the residence time of activated sludge in the reactor, it helps to stabilize the sludge concentration and improve the sludge sedimentation performance.

Add coagulants and flocculants: If necessary, the dosage of coagulants such as iron salts, aluminum salts and flocculants can be appropriately increased to improve the sludge floc structure and enhance the sedimentation performance of the sludge.

Strengthen water quality monitoring and data analysis: Implement strict monitoring of operating parameters, including sludge settling ratio, SVI value, MLSS, etc., as well as changes in COD, BOD, TN, TP and other indicators of influent and effluent. Adjust the carbon source dosage and other operating parameters in real time according to the monitoring data.

In summary, excessive carbon source addition is an issue that needs to be highly valued in the sewage treatment process. By carefully observing the phenomenon and taking timely countermeasures, the adverse effects of excessive carbon sources can be effectively avoided, ensuring the stable operation of the sewage treatment system and the compliance of effluent quality.