Reasons and solutions for excessive ammonia nitrogen!

1. Excessive ammonia nitrogen caused by organic matter 　　I have operated high ammonia nitrogen wastewater with a CN ratio of less than 3. Because the denitrification process requires a CN ratio of 4 to 6, it is necessary to add a carbon source to improve the completeness of denitrification. At that time, the carbon source added was methanol. For some reason, the outlet valve of the methanol storage tank fell off, and a large amount of methanol entered the A tank, resulting in a lot of bubbles in the aeration tank, the effluent COD and ammonia nitrogen soared, and the system collapsed. Analysis: A large amount of carbon source enters the A tank, which cannot be used for denitrification. It enters the aeration tank because of the sufficient substrate and the aerobic metabolism of heterotrophic bacteria, which consumes a lot of oxygen and trace elements, because the nitrifying bacteria are autotrophic bacteria with poor metabolism. Oxygen is contended and the dominant bacteria cannot be formed, so the nitrification reaction is restricted and the ammonia nitrogen increases.

Solution:

1. Immediately stop the water inflow for boring exposure, and continuously open the internal and external reflux;

2. Stop pressing sludge to ensure sludge concentration;

3. If the organic matter has caused the expansion of non-filamentous bacteria, PAC can be added to increase the flocculation of sludge, and defoamer can be added to eliminate impact foam.

2 Excessive ammonia nitrogen caused by internal reflux

At present, there are two reasons for the excessive ammonia nitrogen caused by the internal reflux: electrical failure of the internal reflux pump (there is still running signal when the on-site tripping stops), mechanical failure (the impeller falls off) and man-made reasons (the internal reflux pump does not try to rotate forward and backward. The scene is in reverse state).

Analysis: The excessive ammonia nitrogen caused by internal reflux can also be attributed to the impact of organic matter. Because there is no reflux of nitrification liquid, there is only a small amount of nitrate nitrogen carried by external reflux in Pool A. The overall environment is anaerobic. The carbon source will only be hydrolyzed and acidified. Will not be completely metabolized into carbon dioxide and escape. Therefore, a large amount of organic matter enters the aeration tank, resulting in an increase in ammonia nitrogen.

Solution:

The problem of internal reflux is very easy to find. You can judge whether it is caused by internal reflux through the data and trend: the initial nitrate nitrogen at the outlet of O tank increases, the nitrate nitrogen of A tank decreases to 0, and the pH decreases. three conditions:

1. If the problem is found in time, the internal return pump can be overhauled;

2. The internal reflux has caused the ammonia nitrogen to rise. Check and repair the internal reflux pump, stop or reduce the inflow of water for smothering;

3. The nitrification system has collapsed, stop the inflow of water, if conditions are more urgent, you can add biochemical sludge similar to the denitrification system to speed up the recovery of the system.

3. Excessive ammonia nitrogen caused by low pH

There are three cases of excessive ammonia nitrogen caused by low pH currently encountered:

1. The internal reflux is too large or the aeration at the internal reflux is too large, causing a large amount of oxygen to enter the A pool, destroying the hypoxic environment, aerobic metabolism of denitrifying bacteria, and aerobic metabolism of some organic matter, which seriously affects denitrification Because denitrification can compensate for half of the alkalinity metabolized by the nitrification reaction, the destruction of the hypoxic environment leads to a decrease in alkalinity and a decrease in pH. After the pH is lower than the appropriate pH for nitrifying bacteria, the nitrification reaction is inhibited and the ammonia nitrogen increases. . This situation may be encountered by some colleagues, but never find the reason from this aspect.

2. Insufficient CN ratio in the influent is also due to incomplete denitrification, resulting in low alkalinity, resulting in a drop in pH.

3. The pH continuously drops due to the decrease in the alkalinity of the influent.

Analysis: The excessive ammonia nitrogen caused by the decrease of pH has a relatively low probability of occurrence in practice, because the continuous decrease of pH is a process, and the general operators start to add alkali to adjust the pH when the problem is not found.

Solution:

1. The problem of low pH is actually very simple. It is to start adding alkali to maintain the pH when the pH drops continuously, and then analyze to find the cause.

2. If the pH is too low, it has caused the system to collapse. At present, the author has been exposed to the situation that the nitrification system has not collapsed when the pH is between 5.8 and 6, but the pH should be replenished in time. Sterilize or add the same type of sludge.