Chronic COD wastewater has been a challenging issue for industrial enterprises. To effectively address the issue of high COD levels in wastewater, let's first understand the reasons behind it:
1. The oxygen environment has changed
The sludge produced in the secondary sedimentation tank primarily originates from the detached biofilm. As the biofilm is mainly composed of aerobic bacteria, when the oxygen-rich environment transitions to anaerobic, a large number of aerobic bacterial cells rupture and their cytoplasm is released. Some of it is utilized by facultative and anaerobic bacteria to synthesize biomass, while a portion enters the water as undegraded COD. Due to the abundance of sludge, the COD in the secondary sedimentation tank actually increases instead of decreases.
2. Internal Factors
High levels of Chemical Oxygen Demand (COD) are produced during the manufacturing process, including food factory residues, acid pickling wastewater from electroplating industries, and reducing substances in chemical plants, all of which can lead to COD exceeding the standard.
3. Incompleteness in the craft
When the temperature and dissolved oxygen levels in wastewater are low, the activity of the bacteria in the wastewater decreases, preventing normal metabolism. Consequently, the Chemical Oxygen Demand (COD) in the wastewater cannot be decomposed normally. Once the COD concentration in the wastewater becomes too high, it poisons the bacteria in the biochemical pool. After the bacteria are damaged, the COD concentration rises, leading to a vicious cycle.
How to handle the issue of excessively high COD in wastewater?
Wastewater COD Treatment Methods
1. Filtration Adsorption Method
The filtration adsorption method involves pre-treating wastewater and then pumping it into a filter. After filtration, most of the undissolved high molecular polymer and suspended solids are removed. The filtered water then enters an activated carbon adsorption unit, where the COD value of the wastewater is reduced through the adsorption of organic matter by the activated carbon.
2. Oxidation Method
Oxidation methods involve the decomposition of organic and high-molecular compounds through the use of strong oxidizing conditions. Common oxidation methods include combustion, electrolytic oxidation, and chemical oxidation, among others.
3. Advanced Oxidation and Flocculation Secondary Treatment Method
The Acid Coagulation Secondary Treatment Method is a commonly used process for treating film/ink wastewater. It involves using high molecular polymer that, under acidic conditions, coagulates into a gel-like substance, which is then filtered and separated.
After implementing the above methods or other process equipment, it is challenging to achieve the discharge standards with the remaining COD continuing its process. CleanTech engineers suggest:
Wastewater with residual COD can be treated by adding chemicals to initiate oxidation, which rapidly decomposes organic matter. This method offers quick decomposition and treatment times, with minimal complex procedures.
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