Our friends who are engaged in environmental protection and sewage treatment must have encountered this kind of frustrating thing - sudden excessive ammonia nitrogen! The concentration of ammonia nitrogen in the incoming water skyrocketed like riding a roller coaster, and the effluent data directly "exploded". As soon as the online monitoring alarm sounded, the whole person was not feeling well. Don't panic! Today, I will talk to you about how to "revive" ammonia nitrogen after being impacted, and teach you step by step how to pull the sewage treatment system back from the brink of collapse!
1、 Let's first clarify: why does ammonia nitrogen get angry?
Suddenly exceeding the limit of ammonia nitrogen is like getting sick, we need to first find the root cause. The most common "causes" are as follows:
1. Sudden surge in inflow concentration: The factory illegally discharged high concentration wastewater, and a large amount of nitrogen-containing sewage mixed into the surrounding pipeline network, suddenly "feeding" the system. For example, some food factories suddenly increase production, and the protein in the cleaning wastewater decomposes into a large amount of ammonia nitrogen, which directly impacts the biochemical tank.
2. The temperature and pH values are not right: Nitrifying bacteria are like delicate babies, and the most suitable temperature for them to work is 25-30 ℃, with a pH value between 7.5-8.5. When the temperature drops in winter, the rate of nitrification reaction directly decreases by half; When the pH value of the incoming water drops below 6, nitrifying bacteria will "rot" and strike in minutes.
3. Insufficient dissolved oxygen: The nitrification process is a "oxygen rich" process, and if the dissolved oxygen in the aerobic tank is below 2mg/L, nitrifying bacteria will lack oxygen and "suffocate". Fan failure and blockage of aeration head may lead to insufficient oxygen supply.
4. Invasion of toxic substances: Heavy metals, fungicides, high concentrations of oils and fats, these "biochemical assassins", once they enter the system, nitrifying bacteria are directly "eradicated". Previously, wastewater from printing and dyeing factories mixed into the domestic sewage network, and the aniline substances inside paralyzed the entire biochemical system.
2、 Urgent action: Lower the indicators first!
If ammonia nitrogen exceeds the standard, don't panic at the first time and activate the emergency plan "firefighting":
1. Reduce the water intake load: If possible, pause the water intake. If not, reduce the water intake to "reduce the load" on the system. Just like when a person is overeating and needs to eat less to digest, let the biochemical pool take a breath first.
2. Add chemical agents for emergency treatment:
-Sodium hypochlorite/bleach powder: directly oxidizes ammonia nitrogen, rapidly reducing concentration. But the dosage needs to be strictly calculated. Adding too much will inhibit microbial growth and may also cause secondary pollution.
-Ammonia nitrogen remover: a composite agent on the market with fast reaction and obvious effect, but relatively high cost, suitable for emergency use.
3. Supplementing activated sludge: Pulling some "healthy" sludge from other stable sewage treatment plants is equivalent to "injecting blood" into the system. But be careful with transportation and domestication, don't let their sludge die too.
4. Adjust process parameters: increase aeration to raise dissolved oxygen to 3-4mg/L; Adjust the pH value and maintain the pH of the aerobic tank at around 7.8 using sodium hydroxide or hydrochloric acid; If it's winter, heat up as much as possible, or increase the sludge reflux ratio to 100% -150%, allowing the sludge to "wander" a few more times in the system.
3、 Long term recovery: revive the system with full health
Completing first aid is just the first step. To fully restore the combat effectiveness of the system, we need to solve the problem from the root:
1. Cultivate "durable" microorganisms:
-Silent aeration cultivation: Stop water inflow and continue aeration for 24 hours to allow microorganisms to consume all organic matter in the tank and activate activity. Afterwards, a small amount of water is added and the load is gradually increased, just like exercising and gradually adding weight.
-Adding microbial agents: There are now many specialized nitrifying bacteria and composite agents, known as "biochemical special forces". But don't blindly believe in advertising. It's best to conduct a small trial first, see the effect, and then invest on a large scale.
2. Optimize process operation:
-Segmented inflow: evenly distribute the inflow into different reaction tanks to avoid excessive local load. Just like chewing food slowly and letting microorganisms digest it slowly.
-Extend sludge age: Leave the sludge in the system for a few more days to allow nitrifying bacteria enough time to reproduce. But don't leave it too long, otherwise the sludge will age and affect the treatment effect.
3. Strengthen preprocessing:
-Source control: Sign agreements with upstream polluting enterprises, regularly inspect water quality, and report any illegal discharge directly.
-Add impurity removal equipment: Install grilles and sedimentation tanks at the inlet to block large particles of impurities and grease in advance; If possible, add a hydrolysis acidification tank to decompose large organic molecules into small ones and reduce the pressure of subsequent treatment.
4. Daily monitoring cannot be stopped:
-Measure the inflow ammonia nitrogen at least 3 times a day pH、 Dissolved oxygen, staring at data like a child doing homework.
-Regularly examine microorganisms under the microscope to see the status of indicator organisms such as nematodes and nematodes. If they all wilt, it means the system is going to have problems again.
4、 Prevention in advance: Stop ammonia nitrogen from acting like a demon again
Restoring the system is only a temporary solution, preventing ammonia nitrogen from exceeding the standard again is the root cause:
-Establish an early warning mechanism: Install an online monitoring device at the water inlet, set a threshold for ammonia nitrogen concentration alarm, and automatically warn when it exceeds the standard.
-Reserve emergency supplies: Keep sodium hypochlorite, alkali solution, and bacterial strains as "life-saving straws" in the warehouse, and be able to respond quickly in case of emergencies.
-Regular "physical examination" system: Conduct a comprehensive process evaluation every quarter to check whether the equipment is aging and whether the sludge activity is sufficient, just like regular physical examinations to detect minor problems in advance.
Although exceeding the limit of ammonia nitrogen can be a headache, as long as you understand its temperament and master scientific treatment methods, you can withstand even the biggest impact. Remember, sewage treatment is like keeping a pet. It requires patient observation and careful care to keep the system running smoothly! Next time you encounter ammonia nitrogen causing emotional distress, follow this set of methods to ensure a smooth pass!
