Please have someone with experience take a look to see if the process is reasonable
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Steel rolling wastewater: Workshop ------- Pre-sedimentation ------- Reaction tank with polyaluminum added ------- Equipment for shallow air flotation with polymers added ------- Effluent. The quality of the effluent is generally poor; it is much less effective compared to chemical oil removers that also use flocculants and conventional sedimentation tanks. In my opinion, pre-sedimentation can only remove large particles such as iron oxide scales, while fine suspended particles – can those be removed using flocculants along with shallow air flotation? Air flotation should work well for oil removal, but what about suspended solids? On-site observation shows that there is a lot of floating debris in the water outside the air flotation unit. Is there a sludge collection device at the bottom of the air flotation unit? Based on my experience, it’s advisable to add a sedimentation tank with sludge discharge before the air flotation process.
The process is unreasonable. 1. Shallow air flotation is commonly used in papermaking wastewater (containing lignin); is it appropriate to use it in steel rolling wastewater? ； 2. Is the amount of PAC sufficient?
At present, shallow air flotation is widely used for papermaking wastewater, as it is highly effective at removing suspended solids; it can remove most of these solids with little to no need for PAC. Applying this method to steel rolling wastewater should not pose any major problems.
What LZ said is a bit like the absence of PAM; the PAC in the wastewater does not aggregate into larger particles and remains dispersed in the water, which results in a different effect on SS separation. Additionally, shallow air flotation operates on the same principle as regular air flotation; PAM needs to be added so that small SS particles can be aggregated into larger particles through the bridge effect, thereby facilitating their separation.
It includes PAM, and the process specifies the addition of polymers
Is there enough time for sedimentation after the PAC reaction? If not, it means the PAC is not effective enough; try another brand. I’ve seen a hot-rolling process that includes a laminar flow tank after air flotation.
1. The PH emission criteria are not taken into account. 2. The choice of flocculant needs to be considered; since steel rolling wastewater usually contains a high amount of metal ions, an anionic flocculant should be used. 3. Has mechanical stirring or air agitation facilities been considered for the flocculation reaction?
Be patient and tune it carefully. The quality of the raw water, the flow rate of inflow water, the flow rate of return water, the dissolved air volume, pH, the dosage of chemicals, and the sludge accumulation rate should be kept as stable as possible. It is advisable to have a sludge collection pipe at the bottom to facilitate sludge discharge during shutdowns and maintenance. Be cautious during normal operation to avoid affecting the flow pattern. After dosing pam (for example, using a metering pump), it is advisable to have a pipeline mixer.