The yellowing and poor settling performance of sludge may be caused by various reasons, and the following are some common reasons:
-Excessive sludge load: The daily amount of organic matter to be treated per unit mass of activated sludge is too high, and microorganisms are unable to effectively digest and degrade the organic matter in sewage, resulting in excessive sludge proliferation, unstable floc structure, and decreased settling performance.
-Toxic and harmful substances in the inflow, such as heavy metals, disinfectants, petroleum, etc., can inhibit microorganisms, reduce sludge activity, and thus affect sedimentation performance.
-Aging of activated sludge: After long-term operation, the activated sludge gradually ages, the activity decreases, and some activated sludge dies, producing yellow dissolved organic matter, which also leads to a decrease in sedimentation performance.
-The influence of metal ions: Metal ions such as iron, copper, and manganese contained in wastewater may form yellow precipitates during the treatment process.
-Nutritional imbalance: Imbalance in the proportions of C, N, P, etc. can lead to small floc particles that are difficult to settle.
-Filamentous bacteria sludge expansion: Microscopic examination can reveal a large number of filamentous bacteria, which can affect the settling performance of sludge.
-Non filamentous sludge expansion: mainly caused by low dissolved oxygen.
-Environmental factors, such as low temperature and decreased microbial enzymatic reaction rate, can reduce the activity of activated sludge and deteriorate its settling performance.
-Acidification treatment: Acidic environment causes changes in the surface charge of sludge particles, weakening the mutual exclusion of electric phases and reducing the synergistic effect, resulting in a decrease in sludge settling performance.
To improve the settling performance of sludge, the following measures can be taken: adjusting the sludge load, ensuring microbial activity, reducing the entry of toxic and harmful substances, preventing sludge aging, adding nutrients and trace elements to maintain sufficient nutrition, adjusting the aeration rate appropriately, stabilizing the dissolved oxygen content in the water, and fully utilizing the regulating tank to ensure uniform water quality. At the same time, regular testing and analysis of activated sludge should be conducted to promptly identify and solve problems.
