Increasing the PAC dosage does not reduce total phosphorus.
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The total phosphorus level in the effluent has been poor recently. A few days ago, the dosage of PAC was increased; based on past experience, the total phosphorus level should have dropped quickly. However, judging from the recent water quality, the total phosphorus level in the effluent still hasn’t decreased, and it’s even rising. So the questioner was confused, as it didn’t match previous experiences. I would like to ask the experienced seniors for advice: is it because I don’t get out of the mud fast enough? Or has the total phosphorus in the influent already been removed by PAC? Any additional amount will be of no use, and moreover, does the phosphorus contained in PAC affect the effluent quality? The poster is heartbroken, missing the days when the total phosphorus level in the water was only 0.2.
With the high temperatures at present, the biochemical sludge in the secondary sedimentation tank is prone to anaerobic reactions. It is possible that sludge removal is not timely, causing the sludge to remain in the secondary sedimentation tank for too long and to become anaerobic, which leads to the release of phosphorus. Phosphorus removal relies on sludge discharge; the sludge from the secondary sedimentation tank must be removed promptly and recycled. A quick solution is to add PAC to the secondary sedimentation tank.
First, it is necessary to confirm the change in inlet TP. If the influent TP is similar to normal levels, sludge discharge can be increased. Measure the dissolved oxygen in the secondary sedimentation tank; it should not be lower than 0.5 mg/l
I’ve encountered the same problem. We use hydrolysis-acidification plus contact oxidation to treat dairy wastewater. All other data are appropriate, but the phosphorus level in the water remains above the limit. Tests have shown that the phosphorus removal effect is not significant before and after contact oxidation; in fact, it even increases slightly. I’m not sure why, so I ask the original poster or other professionals to help explain this. We also tried adding PAC at the inlet of the sedimentation tank, at a dosage of about 100 mg/L, and the phosphorus removal effect was significant.