What are the reasons for excessive COD in wastewater?
Release time:
2024-04-30
High COD refers to the situation that the effluent COD concentration of the wastewater treatment station is close to the discharge standard. When the COD concentration is high, the effluent of the system has the risk of exceeding the standard. Therefore, it is necessary to investigate the reason for the high COD to prevent the occurrence of COD exceeding the standard.
High COD refers to the situation that the effluent COD concentration of the wastewater treatment station is close to the discharge standard. When the COD concentration is high, the effluent of the system has the risk of exceeding the standard. Therefore, it is necessary to investigate the reason for the high COD to prevent the occurrence of COD exceeding the standard.
The main reasons for the high COD are water inflow and system operation:
1. water inflow reason
1. The influent COD rises suddenly. The insufficient treatment capacity of the system leads to the increase of COD in the effluent, which can be found out by reverse checking the COD data of the influent.
2. There are toxic substances in the water. After the toxic substances enter the biochemical system, the activated sludge of the system is inhibited and the degradation ability of COD decreases, so that the effluent COD will increase.
3. It is difficult to degrade COD in the influent. Due to the adsorption capacity of the activated sludge in the biochemical pond, the refractory COD will be enriched in the activated sludge, and COD may accumulate slowly, resulting in high COD.
Reasons for 2. system operation
1. The effluent is muddy. Ordinary secondary sedimentation tank effluent with mud, resulting in high effluent COD. In this kind of situation, COD can be measured after filtering the effluent from the secondary sedimentation tank. If COD reaches the standard, it is caused by floating mud from the secondary sedimentation tank.
2. Insufficient dissolved oxygen. When the dissolved oxygen in the system is insufficient, the removal capacity of the system for COD will also decrease. At this time, attention can be paid to whether the sludge color is black and whether the dissolved oxygen in the pool is <1mg/L, and whether the COD is high due to insufficient dissolved oxygen can be determined.
3, dissolved oxygen is too high, resulting in sludge aging. Excessive aeration of sludge will cause sludge aging. After sludge aging, it will lead to sludge cracking and release COD.
4. Excessive denitrification carbon source dosage. In the process of denitrification, the biochemical system needs to add carbon source for denitrification. When too much carbon source is added in the system, the effluent COD may be on the high side.
5. Abnormal pH value of the system. The nitrification reaction in the biochemical system will reduce the pH value, and the denitrification reaction will increase the pH value. When one of the reactions continues without intervention, the pH value of the system may be high or low, resulting in the inhibition of activated sludge, and the COD will be high.
6. Excessive mud discharge system. When the system sludge is excessive, the amount of sludge in the system is reduced and the COD treatment capacity is also reduced, resulting in high COD.
The reason for the high COD needs specific analysis. If your sewage treatment needs this aspect, please contact Hongsen Environmental Protection.
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