How should the circulating wastewater in power plant cooling towers be treated to ensure it meets discharge standards?
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The COD level of the wastewater recycled by our plant is around 100; discharging it directly would result in COD levels exceeding the allowed limit (the COD emission standard is 60). Moreover, the BOD content of this recycled wastewater is very low, resulting in poor biochemical properties. I would like to ask how to handle this external wastewater so that its COD level meets the required standards for discharge? Thank you all.
You can give electrocoagulation a try; it’s being promoted a lot these days. QQ: 562885908
If the circulating water treatment method is not appropriate and high-voltage electrostatic treatment is used, it’s impossible for the COD level to exceed the limits; there is no need to discharge wastewater. It’s worth visiting other power plants to learn from their practices.
The circulating water zero-discharge technology can be used to prevent wastewater from being discharged over the long term, thus eliminating this problem.
Zero emissions is just a concept at the moment. It’s not fun.
Power plants and petrochemical facilities are both high-risk working environments, and immature zero-emission technologies can pose even greater risks, including accidents. Check the issue of bacterial and algal control in the circulating water; normal control of circulating water makes it easy to keep COD within the specified range, unless it is caused by abnormal makeup water or insufficient sterilization control. The process circulating water in power plants is mainly used to cool low-pressure steam, so even if there is a leak, it will not cause any abnormal readings. Unless the cooling medium is oil, or there is a leak or other process water entering the circulating water system, it is recommended to address the issue at its source and ensure proper sterilization.
Discharging circulating water is an important method for reducing chloride ions in the water, improving the vacuum level of the unit’s condenser, and adjusting the concentration ratio of the circulating water. Nowadays, zero wastewater discharge is advocated as an important approach to saving energy and reducing emissions; therefore, when it comes to discharging circulating water, the first thing to consider is the separated recovery and reuse of this water. Purification and membrane treatment techniques can be used to remove chloride ions and salts, after which the water can be reintroduced into the circulation system.
The membrane treatment method is too costly; it is not recommended unless one is very wealthy. Additionally, about 30% of the concentrated wastewater still needs to be treated.
This option was considered, but the concentrated water produced by reverse osmosis causes pollution and is difficult to handle.