1. Ammonia nitrogen caused by organic matter exceeds the standard

The high ammonia nitrogen wastewater with CN ratio less than 3 has been operated. Since the NITROGEN removal process requires CN ratio between 4 and 6, it is necessary to add carbon source to improve the completeness of denitrification. At that time, the carbon source added was methanol. Due to some reasons, the outlet valve of the methanol storage tank fell off, and A large amount of methanol entered pool A, leading to A lot of foam in the aeration tank, and the surge of effluent COD and ammonia nitrogen, and the system collapsed.

Analysis: A large number of carbon sources into pool A, denitrification can not be utilized, into the aeration tank, because of sufficient substrate, heterotrophic bacteria aerobic bolism, A large amount of oxygen and trace elements consumption, because nitrifying bacteria are autotrophic bacteria, poor bolism, oxygen is contested, can not form the dominant species, so the nitrification reaction is limited, ammonia nitrogen increased.

Solutions:

1, immediately stop the water inlet for stuffy aeration, internal and external reflux continuous open;

2, stop the mud to ensure the sludge concentration;

3. If organic matter has caused non-filamentous bacteria to swell, PAC can be added to increase sludge flocculation and defoaming agent can be added to eliminate impact foam.

2. Excessive ammonia nitrogen caused by internal reflux

At present, there are two reasons for excessive ammonia nitrogen caused by internal reflux: electrical failure of the internal reflux pump (there is still a running signal during the site skip stop), mechanical failure (the impeller falls off) and human reasons (the internal reflux pump has not tried positive and negative rotation, and the site is in reverse state).

Analysis: 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, resulting in only A small amount of nitrate nitrogen carried by external reflux in pool A, the overall anaerobic environment, carbon source will only hydrolyze acidification, but not completely bolized into carbon dioxide escape. So a large amount of organic matter into the aeration tank, resulting in the increase of ammonia nitrogen.

Solutions:

The problem of internal reflux is very good to find, you can judge whether it is caused by internal reflux through the data and trend: early O pool export nitrate nitrogen increased, A pool nitrate nitrogen reduced to 0, pH reduction, so the solution is divided into three cases:

1, timely discovery of problems, maintenance of internal reflux pump can be;

2. Internal reflux has led to the increase of ammonia nitrogen. Overhaul the internal reflux pump, stop or reduce water intake for stuffy aeration;

3. The nitrification system has collapsed, so stop the inlet stuffy aeration. If conditions are available and the situation is relatively urgent, biochemical sludge of similar denitrification system can be added to speed up the recovery of the system.

3, the pH is too low resulting in excessive ammonia nitrogen

At present, there are three cases of excessive ammonia nitrogen caused by low pH:

1, the return is too big or the back within aeration open too big, lead to carry A large amount of oxygen into A pool, destroy the hypoxia environment, aerobic denitrifying bacteria, organic matter is aerobic bolism, serious impact on the integrity of the denitrification, because denitrification can compensate nitration bolic off half of alkalinity, so the destruction of the environment leads to lack of oxygen to reduce alkalinity, The nitrification reaction was inhibited and ammonia nitrogen increased when pH was lower than the suitable pH of nitrifying bacteria. This situation may be encountered by some peers, but never from this aspect to find the reason.

2. The CN ratio of influent water is insufficient, which is also due to incomplete denitrification, less alkalinity generated and resulting in pH decline.

3. PH continuous decline caused by the decrease of influent alkalinity.

Analysis: The probability of ammonia nitrogen exceeding the standard caused by pH reduction is relatively low in practice, because the continuous decrease of pH is a process, and the general operation personnel began to add alkali to adjust pH when they did not find the problem

Solutions: