Sewage Treatment Aerobic Tank Troubleshooting Strategy

Sewage Treatment Aerobic Tank Troubleshooting Strategy

The role of aerobic tanks in wastewater treatment is to allow activated sludge to perform aerobic respiration, further decompose organic matter into inorganic matter, and remove pollutants. Good operation requires controlling the oxygen content and other conditions required by microorganisms to be optimal, so that microorganisms can perform aerobic respiration with the greatest efficiency.

1.What abnormal phenomena may occur in aerobic pools?

① Aerobic sludge turns black or white (low or too high dissolved oxygen)

② The supernatant in the aerobic tank is turbid (the sludge adsorption performance deteriorates or the dissolved oxygen is too high, resulting in sludge disintegration, and the dissolved oxygen is too low to oxidize the organic matter)

③ The sludge foam returned from the secondary sedimentation tank becomes viscous (the sludge stays in the secondary sedimentation tank for too long, and the activity of the sludge after denitrification becomes poor)

④ The foam in the aerobic tank increases (the color and viscosity of the foam determine whether it is caused by changes in the sludge itself or by substances added in production)

⑤ The removal rate of the aerobic tank decreases (specific analysis reasons: sludge activity, sludge load, dissolved oxygen, sludge concentration, water temperature, etc.)

⑥ The sludge in the aerobic tank expands (by increasing the sludge discharge and adjusting the nutrients Add to control, stabilize the water intake, ensure sufficient dissolved oxygen and suitable water temperature)

⑦ When aerobic sludge is used for sedimentation ratio, the supernatant is turbid with more fine sludge (sludge load is too high or sludge disintegrates, microscopic sludge structure is loose, and bacterial flocs are thin)

⑧ Aerobic microorganisms become fewer, the structure is loose, and the bacterial flocs are thin (load is too low or too high, insufficient dissolved oxygen, sludge swelling occurs, and nutrients are insufficient)

⑨ The dissolved oxygen in the aerobic tank is high for a long time, and the effluent is turbid and the COD is high (sludge load is low for a long time, sludge disintegrates, bacterial flocs are oxidized, and oxygen is not consumed)

⑩ Sludge aging (the reasons for sludge aging include long sludge age and low load. Sludge aging makes the effluent worse, with more fine sludge and rotifers, and increased oxygen consumption)

2.Why is the supernatant clear but the COD high when sludge bulking occurs in aerobic tank sludge?

① Filamentous fungi have a strong adsorption effect. A large number of filamentous fungi have a net-catching effect, so the supernatant is clear

② A large number of filamentous fungi extend out of the bacterial flocs, blocking the bacterial flocs from obtaining sufficient oxygen and failing to oxidize organic matter into inorganic matter

③ The bacterial flocs cannot obtain sufficient oxygen, the reproduction activity is reduced, the bacterial flocs become thinner, and the activity decreases

Why is the supernatant clear but the COD high when sludge bulking occurs in aerobic tank sludge?

3.What is the reason for insufficient dissolved oxygen in the aerobic pool?

① The sludge concentration in the aerobic pool increases rapidly or the sludge ages, resulting in an increase in oxygen consumption

② The effluent from the anaerobic pool contains a lot of suspended solids, which consume a lot of dissolved oxygen after entering the aerobic pool

③ The blower fails and stops running or the blower pressure is insufficient (this situation rarely occurs)

④ The COD of the effluent from the anaerobic pool suddenly increases a lot, or the inlet water suddenly increases, resulting in a large impact load, which causes the load of the aerobic pool to increase

⑤ The aeration head is seriously damaged or blocked, and the aerobic pool has a lot of foam

4.What is the reason for sludge bulking in aerobic tanks?

① The dissolved oxygen in the aerobic pool is too low or too high for a long time (possible)

② The sulfide content of the raw water or anaerobic effluent is too high, resulting in the proliferation of sulfur bacteria

③ The load of the aerobic pool is too low or too high for a long time

④ The water temperature of the aerobic pool is too high

⑤ The nutrients are unbalanced or lack of nutrients (N and P are low)

⑥ The pH value of the influent

⑦ The sludge age of the aerobic pool is too long, and the oxygen consumption increases, resulting in insufficient dissolved oxygen

5.What is the reason for the disintegration of sludge and the presence of a lot of fine sludge in the supernatant in the aerobic tank?

① The sludge load in the aerobic pool is small, aeration is excessive, the sludge oxidizes itself, the sludge flocculation becomes poor, and the sludge structure is loose (clear, more fine sludge, low COD)

② The sludge load in the aerobic pool is too large, the sludge adsorption performance becomes poor, the organic matter is not completely decomposed, and the sludge structure under microscopic examination is loose (turbid, opaque, high COD)

③ The sludge discharge from the aerobic pool is too large, resulting in the sludge age of the aerobic pool being too short (the SVI value is suitable between 70 and 120, and within this range, there is less fine sludge in the secondary sedimentation tank)

④ The influent of the aerobic pool contains toxic substances or the sludge is aged, and the sludge age is long (turbid, with fine sludge, high COD, and many rotifers under microscopic examination)

⑤ Insufficient nutrients in the aerobic pool or the nutrient ratio is unbalanced (low N and P)

6.What is the reason for the large amount of foam in the aerobic pool?

① The raw water contains a large amount of surfactant components (due to substances added during the production process, the foam is white, the bubbles are small, light and non-sticky)

② Due to the tiny bubbles generated after the newly installed aeration head (short-term impact)

③ A large amount of lipid substances or microorganisms are produced during microbial reproduction (due to the growth and reproduction activities of microorganisms themselves, the foam is mud-colored, the bubbles are large and sticky)

④ Sludge denitrification foam (the foam produced after aerobic sludge stays in the secondary sedimentation tank for too long and denitrification is sticky and mud-colored)

What is the reason for the large amount of foam in the aerobic pool?

7.How to solve the sludge bulking problem in aerobic tanks?

①First increase the sludge discharge to solve the problem of poor sedimentation effect, and then increase the sludge concentration after improvement to reduce the sludge load

②Increase the discharge of sludge in the aerobic tank and reduce the sludge age (in severe cases, it should be maintained for about two months)

③ Control the water temperature within the appropriate range, stabilize the water intake, and maintain sufficient dissolved oxygen in the aerobic tank (must)

④ Increase the nutrient addition in the aerobic tank

⑤ If the mud layer in the secondary sedimentation tank is high, increase the return flow, adjust the water intake of each secondary sedimentation tank, or add polyaluminum and polypropylene (temporary control measures)