What are the common problems in STP and its solutions?
People now prefer to live in communities and large groups as the population grows. This has led to the establishment of decentralized sewage treatment plants in India in order to address treatment issues on a larger scale. These systems are fantastic because they provide an alternative to a centralized sewage treatment plant. However, the issue arises when the plant is not operated correctly.
Several problems that are faced in sewage treatment plants are as following:
1. Downstream Equipment Failure
In the very first step of the sewage treatment process, downstream equipment is used. The screening process is in charge of filtering out floating solids that are not biodegradable in nature. These solids, such as paper, tin, plastic, rags, wood, and containers, are commonly found in wastewater treatment plants.
As a result, you must remove these wastes from the water in order to protect downstream equipment from potential damage such as pipe blockage, unnecessary wear and tear, and the accumulation of unwanted materials that impede the wastewater treatment process.The equipment used in the screening process can be cleaned both mechanically and manually.
2. Treated Effluent Failing to Meet Total Phosphorous Target
In terms of total phosphorus, the sewage treatment plants in India is used for the following:
· To reduce the use of chemicals
· To reduce operational costs
· To obtain the TP license limits
There is a specific chemical dosage that must be followed in order to remove or level the total phosphorous target. You can use the quick analysis below to evaluate the treatment facility and determine which chemical will work best.
Pre-precipitation: To remove the Phosphorous from the settling tank, a chemical dosing process is used. When this occurs prior to the biological process, in the primary stage, it is referred to as pre-precipitation. To determine the amount of phosphate in your water, perform an online phosphate measurement between the primary settling and aeration tanks.This will allow you to gain feedback control.
Post-precipitation occurs when chemical dosing is performed after the biological process to remove phosphorus from final clarifiers or effluent filters. The measurement should be taken with feedback control between the final clarifier and the aeration tank.
Simultaneous: In this case, chemical dosing occurs both before and after the biological process. This contributes to the achievement of low phosphorus limits in the effluent.
3. Drained sludge has a low dry matter content
Indeed, much depends on the composition and dry matter of sludge at the inlet of the dewatering line in this part of WWTPs. For example, the centrifuge is designed slightly differently for sludge with a higher fat content than for conventional biological sludge. It is critical for the supplier to consult on the flocculants suitability for the process as well as its dosage.
One of the fundamental distinctions is between cationic and anionic or nonionic flocculants. Because of their quantity and variety, it is recommended that the wastewater be flocculated as well. The formation of flakes, as well as their strength, must be addressed so that they do not fall apart during the dewatering process.
4. Blower overheating and a lack of air in the system
Long-term low oxygen concentrations in the tanks (1.0 mg / l) are a common problem in the treatment plant. However, short-term fluctuations (a few tens of minutes) may not be a problem.
However, if the amount of oxygen is low over time, it can cause drainage parameters to deteriorate, foam formation on the surface, and other issues.
This could be due to a variety of factors. For example, the WWTP receives more pollution than was calculated in the design, resulting in overburdening of the plant. This occurs when the connected village expands or when a new facility is added to it.
The second possibility is that the piping network and aeration elements have become clogged during continuous operation and must be cleaned.
5. Leakage of sludge from the settling tank
This phenomenon could be caused by a lack of oxygen or nutrients. The bacteria then begin to adapt to new, less favorable conditions and form chains. They are intertwined at the same time and form parts with poor sedimentation properties due to the lower density of the sludge mixture.It can also be harmed by the long residence time in sedimentation tanks, during which de-nitrification bacteria can begin to produce nitrogen gas.
If the conditions are favorable (enough COD, enough N-NO3, anoxic environment, and so on), they begin decomposing the nitrates into gaseous nitrogen. It will move to the surface in the form of small bubbles, causing swirling, or bubbles will pull up sludge flakes and bring them to the surface.
Inadequate sludge removal from the system could also be a cause of those issues. In this case, optimizing the "recirculation ratio" parameter, which affects the sludge's residence time in the system, is a good idea. As a result, there is more sludge in the settling tank, forming a high cloud in the tank. If the flow at the treatment plant's entrance increases, the volume of water flowing into the settling tank increases, and the sludge cloud expand and leak into the outlet.
The solution could be more frequent sludge removal or even the addition of an equalizing tank to the system, which would dampen the hydraulic imbalance.
For more information, contact Netsol Water.