How to ensure stable effluent quality during sewage treatment has always been a research topic for environmental workers. In the study, it was found that technical indicators such as sludge settling rate and settling performance are key to the effectiveness of sewage treatment, and the testing of sludge settling ratio is a critical control measure that affects these indicators. It is an important parameter for process operation and plays a very important role in guiding operation management.
The sludge settling ratio refers to the volume ratio of settled sludge to mixed liquid after settling in a certain amount of measuring cylinder for a certain period of time. It is one of the important indicators for evaluating the characteristics of activated sludge.
There are many factors that affect the operational efficiency of wastewater treatment processes in treatment stations using activated sludge technology. In the absence of empirical data and relevant testing equipment support, operation and maintenance personnel usually use the settling ratio as the main process parameter to guide operation, judge the operation of the aeration tank based on the settling ratio, and control the wastewater treatment effect.
At present, the activated sludge process is the most commonly used sewage treatment method for treating domestic sewage, urban sewage, and organic industrial wastewater. The settling performance of activated sludge directly affects the operational efficiency of this industrial process. Based on years of operation practice of CNNC instruments in sewage treatment monitoring, the reasons and control measures for poor settling performance of activated sludge have been summarized. Reasons for differential sludge settling
1. Nutritional imbalance, imbalance of C, N, and P ratios, resulting in small floc particles that are difficult to settle; 2. Filamentous sludge expansion occurred, and a large number of filamentous bacteria were found through microscopic examination; 3. Non filamentous sludge swelling occurs mainly due to low dissolved oxygen levels; 4. High organic load and enhanced sludge activity lead to an increase in dispersed bacteria, resulting in excessive proliferation of free bacteria and small protozoa, leading to a decrease in sludge sedimentation; 5. Sludge aging or excessive aeration leads to non settling bacterial colonies in the supernatant.
Improvement measures for sludge settling difference
1. Add certain nutrients and trace elements to maintain sufficient nutrition; 2. Adjust the aeration rate appropriately to reduce filamentous bacteria; 3. Stabilize the dissolved oxygen content in water; 4. Investigate the cause and observe whether there is bacterial poisoning or malnutrition; 5. Give full play to the role of the regulating tank, try to make the water quality uniform as much as possible, and maintain the sludge activity.
In short, to improve the sedimentation of sludge, on the one hand, stable aeration should be ensured to stabilize the dissolved oxygen content; On the other hand, the biochemical tank should maintain sludge activity and pH value as high as possible above 7.0. Finally, the settling ratio can only preliminarily reflect the characteristics of sludge in the wastewater treatment process, thus making a simple judgment of problems that may arise in the treatment process engineering. To accurately analyze and judge the sludge properties and process conditions, other monitoring data must be combined to make the final determination.
