Seeking advice on wastewater treatment
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In our wastewater treatment plant, the quality of the effluent deteriorates every winter (from late December to mid-February), with a COD level exceeding 150. At that time, the temperature in the aeration tanks is around 15 degrees – is that low? Is there a good solution?
Low temperatures reduce the catalytic activity of enzymes in microorganisms, thereby decreasing their ability to process organic matter. It is possible to consider raising the temperature to 25–30 degrees; for example, hot wastewater can be used to adjust the temperature in the treatment tanks, or the treatment load can be reduced. This post was last edited by fyb_yjh on 2008-1-22 16:50.]
15 degrees is a bit low; considering raising the temperature might be a good idea. Circulating water at a higher temperature can be used as diluent water. At the same time, the load should be reduced in winter to minimize microbial death. :)
Where can he go to find hot water to dilute it? This temperature is good enough; it’s a bit low, but there’s nothing we can do about it. The best approach is to increase the return flow of activated sludge; even full return flow is possible. Additionally, you need to consider whether the organic load is too high; if so, the wastewater should be diluted.
The sludge return rate has always been high, the load has remained low, with an F/M ratio of around 0.01–0.05. Additionally, our SV30 value is consistently above 950, and the water quality from the sedimentation tank is acceptable. I would appreciate some advice from those with more experience!
Since changes in the quality of the water exiting the system are related to many factors, it’s not possible to make simple conclusions. However, if it is indeed bad every winter, then temperature could well be the direct cause. Based on personal experience, here is a rough speculation for reference only: 1. The temperature of 15 degrees is indeed a bit low, but it’s not low enough to be problematic. I’ve seen cases where the wastewater in a factory was around 10 degrees, and the plant still functioned fine. But as the person mentioned above said, at such temperatures the activity of enzymes is reduced, which in turn affects the activity of the sludge. Generally, the temperature maintenance in an aeration tank can come from three sources: first, the water itself, such as steam condensate or cooling water; second, additional heating, such as the introduction of low-pressure steam into the aeration tank; third, the heat released by the oxidation of sludge. It is recommended to use low-pressure steam. 2. MLSS: Your F/M ratio is very low. I’d like to ask what your MLSS level is. With such a low BOD load, the MLSS value shouldn’t be very high, right? 3. For SV30 of 950, sedimentation is practically minimal. To keep SVI below 120 based on this SV30 value, MLSS needs to be at least 7000 – which is too high. Therefore, your SVI must be quite high; the sludge is relatively fragmented, resulting in poor activity. 4. What does the maximum value for the sludge return ratio mean? I don’t understand why it has to be turned up to the maximum all the time. This reduces the room for adjustment one has, and it also increases the costs
First of all, thanks to the brother upstairs for his advice; thank you! Our MLSS is around 4500 mg/l, and we want to reduce it now, but the flocculation effect of the filter press is poor, resulting in severe sludge loss. The amount of PAM added is also considerable; it might be due to the low temperature. Our SVI has always been above 240, and this problem has not been properly resolved over the past few years. There is another issue as well: when the water temperature is low and it’s necessary to reduce the load, how should the sludge age be controlled? Should it be shortened or prolonged compared to normal conditions?
As I mentioned above, fillers can be added, and the IFAS technique can be employed to increase the MLVSS concentration and reduce the SVI (usually below 100). If necessary, we have the relevant technology and can discuss it.
I’m sorry, I still don’t quite understand. Could you be more specific? What filler to add? What is IFAS technology? Is our MLVSS around 4500 now, which is low? Moreover, the F/M is less than 0.05; how can SVI be reduced? The SV30 is currently around 990 – why can’t it go lower? I would appreciate your guidance; any specific advice you could provide would be greatly appreciated. Email: hdhy12501@163.com
Start by considering your own process; don’t rush to add fillers. With such a low F/M, the results will definitely not be good. Reduce the sludge age and ensure regular sludge removal. Temperature control should be determined based on actual conditions
SV30 has always been above 990; is this related to an excessively low F/M value?
Agree with the person above; you should first optimize the existing processes. From my experience, adding filler for modification definitely yields good results, but there is also the issue of cost.
Have you had a microscopic examination? I’m not sure if your microorganisms are growing normally. To be honest, 15 degrees isn’t really considered low at all. I’m wondering if there might be some substances in your wastewater that inhibit the growth of microorganisms Domestic wastewater or industrial wastewater? Your load isn’t high at all; perhaps a too short sludge age is also an issue. Conduct a microscopic examination first to take a look at the structure of the microorganisms.
15 degrees is a bit low; it might be worth considering raising it. Meanwhile, using maximum reflux isn’t a good approach – it can only serve as a supplementary measure. If the volume of flow increases, then the amount of reflux sludge will have to be reduced, which leads to greater operational fluctuations
The email address provided earlier is incorrect; it should be email:qdhy12501@163.com. Please share any good experiences or suggestions you may have with me. Thank you!
Does a higher load result in a higher water temperature in the aeration tank?
For biochemical bacteria, the water temperature is a bit low; it should normally be maintained between 16 and 25 degrees Celsius. Consider adding some steam at the water inlet. If such problems persist for a long time, considering sealing the biochemical tank may be an option. :handshake :handshake :victory: :victory:
The optimal temperature for organisms is generally around 30 degrees Celsius. The temperature you have is too low, which limits the growth of organisms. It is recommended that you introduce some high-temperature wastewater that is not in use into the system in order to raise the temperature of the wastewater slightly; this will improve the treatment results. If the temperature is low, the metabolism of organisms slows down, and it is normal for the treatment effect to be suboptimal.
The temperature is probably low; biochemistry works best at 25-35