Reasons for own production:
1. The corpses of animals and plants in the surface water cannot be completely decomposed, and the eutrophication of the water body will cause COD to exceed the standard.
2. During the production process of the enterprise, such as the residue of excess food in food factories and water bodies, the reducing substances S ions and chloride ions in chemical plants. And the electroplating wastewater will cause the sewage COD to exceed the standard during the pickling process.
Defects of water treatment process:
1. The water temperature is too low during biochemical treatment: When the temperature is too low, the activity of the bacteria will also be low, thereby reducing the decomposition of cod.
2. Insufficient dissolved oxygen in water: When the dissolved oxygen in water is not enough to meet the metabolism of the bacteria itself, it will cause the lack of bacteria. Reduce COD treatment efficiency.
3. The concentration of a certain indicator in the wastewater is too high: a certain indicator (ammonia nitrogen, cod, heavy metals) in the wastewater will poison the bacteria in the biochemical pool and make the cod unable to degrade.
4. Increased carbon source for denitrification
5. Other parameters of the biological pool have equipment problems. The influent COD concentration is too high, exceeding the processing capacity of the system
6. Insufficient aeration of biological tank aeration system
7. The amount of influent water is too large, and the retention time in the biological pond is insufficient
8. The sludge is lost in the biological pond, and the sludge concentration is too low.