The phenomenon of microbial sludge is difficult to settle in paper wastewater is common, occurring in wastewater treatment systems. Reduces the treatment efficiency of the treatment system and does not guarantee the quality of the output wastewater. Moreover, if we do not treat in time, the microorganisms will be weak and die, and the technical staff will need a lot of time to remove the sludge and the new raise.

Therefore, BioFix Fresh hopes to share some of its experiences to solve the above problem in the article below.

1. Characteristics of microbial sludge that is difficult to settle in paper wastewater.

It is a common phenomenon in secondary clarifiers and aeration tanks. Therefore, we need to recognize some of the signs in advance to avoid the above situation such as the mud becoming smooth, settling slowly, being light yellow, having an unpleasant odor, etc.

2. Causes of difficult-to-settle microbial sludge

There are many reasons for this situation. However, the main cause is the excessive proliferation of filamentous bacteria in the paper wastewater treatment system. Creates lattice structures for solids to adhere to and forms connecting rods that prevent the mass formation of sludge particles. And with their excellent oxygen absorption ability, it will cause the microorganisms to be deprived of oxygen leading to the above phenomenon.



Besides, dissolved oxygen (DO) concentration is also one of the factors to ensure good sludge settling in the aeration tank. Because if they are < 2 mg/l, it will cause inhibition of aerobic microorganisms and reduce the effectiveness of management. From there, the formation and proliferation of filamentous bacteria affect the system. And vice versa, when the dissolved oxygen concentration is > 4 mg/l, it will affect the flocculation of the microbial sludge.



In addition, lack of nutrition in microorganisms is also the cause of sludge becoming smooth. Because the organic matter in the tank is too low, the microbial sludge loses its activity, causing growth retardation or even no growth.

3. How to solve the above phenomenon.

a) Adding microbial strains capable of competing with filamentous bacteria.

Because to limit the growth environment of filamentous bacteria, we need to reduce the amount of organic load in the wastewater, typically a high BOD concentration. By adding good microorganisms to control filamentous bacteria. And maintain a good environment in the tank with pH = 7, C: N:P – 100:5:1 to reduce the amount of hard-to-settle sludge in 2-3 weeks.

In addition, we can add microbial products BioFix Ammonia. To accelerate the decomposition of complex organic substances, and reduce odors. Moreover, the nitrification process happens quickly, helping to bring the concentration of Nitrogen, Phosphorus to the specified level. It effectively handles the filamentous bacteria present in the aeration tank.

b) Ensure adequate aeration

For microorganisms to fully absorb oxygen in the floc, we need to ensure that the aeration system is working efficiently. The optimal levels are from 2 to 3.5 mg/l. However, the amount of oxygen supplied should not be too high because continuous stirring will make the floc not settle.