After accumulating experience from operating wastewater treatment systems, Nanoen has summarized practical knowledge in handling biological incidents as follows:
1. WHITE FOAM THICKENS ON THE SURFACE OF THE ACTIVATED SLUDGE TANK
Figure 1: Activated sludge tank experiencing shock loading (Source: Nano Environmental Company; photo taken from the actual site on May 4, 2021)
Phenomenon: There is a significant amount of white foam on the surface of the tank, and when touched, the foam does not feel viscous.
Cause: High F/M ratio, excessively low MLSS concentration, high organic loading.
Remedial measures:
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Control the amount of foam by reducing the loading.
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Add more sludge to the system.
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Gradually increase the influent flow rate.
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Check and adjust the F/M ratio.
2. OXYGEN-LACKED ACTIVATED SLUDGE IS BLACK
Phenomenon: Sludge flocs are black, scattered, sludge concentration decreases, the water layer after settling still has many suspended flocs.
Cause: The concentration of dissolved oxygen in wastewater is low, in the aerobic tank there are dead areas (oxygen does not diffuse to it). The frequency of returning sludge from the biological settling tank is low.
Figure 2: Activated sludge lacking oxygen is black (Source: Nano Environment Company; photo taken from actual construction site on June 25, 2019)
Remedial measures:
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Recheck DO concentration, adjust DO to appropriate range;
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Check the gas distribution system (pipes, gas distribution discs);
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Increase the frequency of returning sludge from the biological settling tank;
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Check the ability to collect sludge to the bottom of the settling tank, avoid keeping the sludge at the bottom of the settling tank for too long.
Read more: Common problems of wastewater treatment systems
3. RESOLVED DISTRIBUTED ACTIVATED SLUDGE
Phenomenon: Fine sludge flakes, very slow settling, high sludge index, little clear water layer after settling.
Cause: Because the input wastewater source has a high concentration of pollution, microorganisms tend to disperse to use synthetic food sources to enter cells and reproduce new bacterial cells.
Figure 3: Activated sludge is dispersed and settles slowly
(Source: Nano Environment Company; photo taken from actual construction site on March 10, 2019)
Remedial measures:
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Reduced organic matter loading;
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Adding a primary treatment cluster before entering the biological tank;
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Increase the volume of biological tanks;
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Add additional microbial media.
Read more: Mud that's difficult to settle and resurfaces - How to handle it
4. FOAM AND FLOATING SLUDGE WITH VISCOSITY
Figure 4: Activated sludge flocs float thick brown foam on the tank surface
(Source: Nano Environment Company; photo taken from actual construction site on April 22, 2022)
Phenomenon: The layer of foam floating on the surface is brown, dragging mud flocs. When touched, the flocs have high viscosity.
Cause: The system lacks N and P nutrients at which time filamentous bacteria grow or the input wastewater contains a lot of grease.
Remedial measures:
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Adding more nutrients to the tank requires calculation to determine the additional dosage;
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If the cause is grease, the grease needs to be removed from the wastewater.
For a wastewater treatment system to operate effectively, not only does it require good equipment and technology, but the operator must also be knowledgeable about the system. From the above understanding, operators can quickly respond to any arising incidents, helping machinery and equipment be more durable, have a longer system life and avoid many unnecessary costs.
A reputable provider of environmental dossier services and construction, operation, maintenance, and servicing of wastewater treatment systems
Nanoen is a reputable provider of environmental dossier services and construction of wastewater treatment systems. Over the years, Nanoen has earned the trust of customers through honesty, dedication, and responsibility towards both customers and company products. With experienced staff, Nanoen offers comprehensive services from environmental dossier consulting to design and construction, operation of environmental treatment systems, provision of microbial products, and sludge dewatering services.
Nanoen is committed to providing the best service experience tailored to the needs of customers.
Nanoen
Address: 661E/29, Vo Van Kiet Street, Binh Yen A Quarter, Long Hoa Ward, Binh Thuy District, Can Tho City
Hotline: 0941.777.519 - 0907.803.678 - 0901.229.798
Email: nanoentech@gmail.com
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