Sewage treatment operation caused by sludge blackening for many reasons, such as due to the lack of dissolved oxygen in the aeration basin caused by sludge blackening, the influent water contains more pigmented substances.

Aeration tank sludge blackening is often caused by the lack of dissolved oxygen sludge, therefore, once the sludge blackening occurs, the first thing should be to check the dissolved oxygen content of the aeration tank, and then check the quality of the influent water, according to the results of the water quality inspection, specifically to determine what caused by what. Common causes of sludge blackening and countermeasures are as follows:

1、DO low sludge blackened

The corresponding solution is: increase the amount of oxygen supply to the aeration tank, so that the quality concentration of dissolved oxygen is greater than 2mg/L for a short period of time can reach 4 ~ 5mg / L as long as you improve the dissolved oxygen content of the aeration tank mixture, a few hours of time, the sludge will gradually return to normal.

2, caused by the feed water quality of the aeration basin sludge blackened

For example, when the feed water contains a large number of Fe2 +, at the same time, when the aeration pool dissolved oxygen is insufficient, the anaerobic interpretation of organic matter will release H2S, H2S and Fe2 + role in the generation of FeS, and FeS color for the black-brown, and thus will make the entire aeration pool sludge black.

The corresponding solution is: through the water quality testing to determine the causes of sludge black, and then the right medicine; at the same time, you can increase the amount of aeration and increase the reflux ratio to improve the aeration pool sludge black.

3, when the feed water contains toxic substances to microorganisms, will make microorganisms die, will also cause aeration tank sludge blackened.

The corresponding solution is: first of all, check the quality of influent water, if the influent water contains toxic substances that have a poisonous effect on microorganisms, it must be controlled from the front, and secondly, you can increase the aeration volume and increase the reflux to improve the aeration basin load resistance, and then improve the condition of sludge blackening for a large number of wastewater containing toxicity has entered into the system and caused the collapse of the system, the sludge should be replaced by the system. The sludge should be replaced.

4, sludge in the aeration tank to stay too long will also be due to sludge aging and the occurrence of aeration tank sludge blackened situation

The corresponding solution is: reduce the aeration volume appropriately, at the same time, pay attention to the residence time of the sludge in the aeration tank, and discharge the sludge in a timely manner. In addition, a sudden increase in the water load will also cause the blackening of the aeration tank sludge, this situation is relatively easy to cope with, as long as the reduction of water intake can significantly improve the blackening of the aeration tank sludge.

In short, caused by aeration pool sludge blackened for many reasons, the corresponding response measures are not the same, but, in general, the sludge blackened countermeasures: first check the water quality, if the water quality is not a problem, and then examine whether the process parameters are set properly; if the water quality of the feed water is a problem, you should also adjust the feed water and process parameters.

Sludge blackening causes and response to sewage station aeration pool sludge blackening and conventional aeration pool sludge blackening situation is not the same, the difference is that the sewage station of the first aeration pool sludge color is normal, only the second aeration pool blackening. Dissolved oxygen content measurement results show that the surface of the aeration basin dissolved oxygen quality concentration of 5mg / L or so, and thus is not aeration basin hypoxia caused by the sludge blackened; if it is due to a sudden change in the quality of incoming water caused by sludge poisoning, and then make the aeration basin sludge blackened, then the first level of aeration basin should also be blackened, rather than just the second level of the aeration basin sludge blackened; in addition, the usual situation will cause the blackening of the aeration basin sludge Possible reasons for the 2-stage A/O system in the first aeration tank sludge color is normal and is ruled out.

According to the daily experience: aeration basin sludge black causes many reasons, different reasons caused by the aeration basin sludge black response measures are different, but usually, encountered aeration basin sludge black situation, can be resolved through conventional measures, such as increasing the dissolved oxygen content and increase the reflux ratio to solve the problem. For the 2-level A/O system in the second aeration basin sludge black, conventional countermeasures can not be effective, need to increase the aeration basin by increasing the dissolved oxygen content, close the two sinking pool to the second aeration of the reflux valve, clean up the two sinking pool of decayed sludge as well as to the aeration pool to add nutrients to the aeration basin in order to make the two A/O system in the two aeration basin sludge black change the situation.