The weather has gradually cooled down, and the daily sun exposure has finally passed. It's time to say goodbye to summer. This is also good news for the masters in sewage treatment plants. Today, we will review these 6 major sewage treatment problems under high temperature weather. Have you encountered them.
Problem 1: As the temperature rises, the secondary sedimentation tank always experiences mud turning and floating
In summer, it is common for secondary sedimentation tanks to experience mud turning and floating in urban and industrial wastewater treatment. Not only does it affect the appearance of sewage treatment, but it can also easily lead to an increase in effluent SS, and even cause effluent to exceed the standard.
In summer, the settling performance of activated sludge decreases, the settling rate of layers decreases, and the secondary sedimentation tank is prone to sludge turnover, resulting in an increase in effluent SS.
As the temperature increases, the metabolic growth ability of microorganisms accelerates and oxygen consumption increases. Anaerobic or denitrification reactions are prone to occur in the secondary sedimentation tank, producing gas and causing sludge to float up.
Question 2: Why is it easy for sewage to exceed phosphorus standards in summer?
When the temperature is high in summer, the activity of bacteria is stronger, and the speed of polyphosphate accumulating by polyphosphate accumulating bacteria will also accelerate.
At this time, the sludge flow rate increases and the sludge age is short, resulting in polyphosphate accumulating bacteria being unable to remove phosphorus components in a timely manner during the anaerobic stage. When the remaining polyphosphate accumulating bacteria that have not fully released total phosphorus enter the secondary sedimentation tank with the sludge, the effluent phosphorus concentration will increase.
At this point, if the dosage of chemical agents is not increased to reduce the concentration of phosphorus in the effluent, the water quality is prone to exceeding the standard.
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Problem 3: The temperature is too high, causing the equipment to overheat quickly and dissipate heat slowly, which affects the normal operation of the equipment
And in summer, the water pump and fan operate at high load for a long time, which is one of the common faults. In addition, some electronic components, sensors, and pipelines are often damaged by high temperatures.
Taking the aeration blower as an example. In the hot summer, the blower will alarm and shut down due to high lubricating oil temperature caused by cooling problems, and will automatically reduce the air volume for safety reasons. This not only affects the effectiveness of sewage treatment, but also causes serious damage to the operation of the blower, reducing its service life.
Therefore, in high temperature weather, the staff of sewage treatment plants should do a good job in ventilation and cooling, as well as safety supervision of mechanical equipment in advance; Closely monitor the operation of the equipment, check the cooling system and heat dissipation of the equipment. If there are any heat dissipation problems with the equipment, install axial flow fans in a timely manner and take forced ventilation measures; Timely replace and drain the lubricating oil of the conveying equipment, and promptly handle any abnormalities found; Prepare a high-temperature emergency plan for equipment in advance, make every effort to ensure the safe and reliable operation of equipment, ensure the stable operation of mechanical equipment in sewage treatment plants, and avoid damage to equipment caused by high temperatures.
Question 4: What cooling measures are in place for the two-stage AO process, with a water temperature of 38-39 ° C in the O pool during summer?
The hot weather and high ambient temperature will inevitably increase the water temperature in the aerobic tank. To reduce the temperature of the pool water, it is necessary to control the inlet water temperature and lower the ambient temperature.
Installing a cooling tower at the front end of the aerobic tank can effectively reduce the inlet water temperature, ranging from 7-8 ℃ to 2-3 ℃.
The main aeration pipeline can also be treated by sprinkling water to reduce the temperature caused by fan heating. When the processing water volume is not large, methods such as heat exchangers and ice injection can also be considered.
At present, many sewage treatments have taken measures to cover and deodorize, which can lead to heat accumulation. When the temperature rises to 50 ℃, aerobic digestion and nitrification will stop, so it is necessary to take cooling measures in advance, such as spraying water, cooling fans, etc.
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Question 5: What should I do if the dissolved oxygen in the aeration tank decreases during high temperature weather?
The high temperature in summer makes oxygen difficult to dissolve in water, often leading to insufficient oxygen supply in water and causing microorganisms to be in a state of hypoxia. At the same time, within a certain range, it will accelerate the metabolic growth rate of microorganisms, increase oxygen consumption, and further exacerbate the degree of water hypoxia.
Therefore, in actual production operation, attention should be paid to changes in water temperature, especially sudden increases in water temperature. To prevent industrial wastewater with excessively high water temperature from having adverse effects on aerobic biological treatment, cooling treatment should be carried out.
Question 6: How to reduce the incidence of summer safety accidents and minimize production safety hazards?
It is the peak season for safety accidents in summer. Among them, the incidence of major accidents and general accidents accounts for a large proportion.
Therefore, in summer, in addition to inspecting the sewage treatment plant to ensure the normal operation of process equipment, the safety of employees should also be given top priority.
In June of this year, during the dredging of a sewage treatment tank in Sichuan, three workers fainted from inhaling biogas due to not wearing protective equipment;
In June of the same year, an explosion occurred in a sewage treatment workshop in Lanzhou, resulting in 6 deaths and 8 injuries;
In September last year, two workers from a food company in Dalian fainted while pumping water from the sludge tank and regulating tank of a sewage treatment plant, but died despite rescue efforts;
Last August, during a sewage treatment operation in a city in Anhui, one person died from poisoning and fell into a well, and two people died from blind rescue efforts.
In some enclosed and limited spaces, microorganisms metabolize and consume a large amount of oxygen, releasing toxic and harmful gases. Therefore, sewage treatment operators must take ventilation pre-treatment measures when working in limited spaces.
At the same time, it is necessary to strengthen the prevention of flammable and explosive materials, conduct self inspection of areas prone to explosion and fire such as distribution rooms, warehouses, and oil depots, and promptly discover and deal with hidden dangers. Conduct a comprehensive inspection of fire extinguishers, hydrants, and other firefighting equipment to ensure their proper functioning.
Of course, the problems of sewage treatment under high temperatures are far more than that. We need to take preventive measures in advance, as well as prepare emergency plans, respond to problems in a timely manner, and minimize risks and losses.
Develop emergency plans in advance for the high temperature season and deploy and implement various measures to ensure continuous and stable compliance with discharge standards under high water inflow conditions.
When problems or accidents occur, timely activate relevant emergency plans, adjust and schedule processes and production in a timely manner, and solve problems on site in case of emergencies.
