The correct answer is: A. Large area is required for construction.
Oxidation ponds are a type of wastewater treatment system that uses natural processes to remove pollutants from wastewater. They are typically large, shallow ponds that are filled with microorganisms that break down the organic matter in the wastewater. Oxidation ponds are a relatively simple and inexpensive type of wastewater treatment system, but they do have some disadvantages. One of the main disadvantages of oxidation ponds is that they require a large area of land. This can be a problem in areas where land is scarce or expensive.
Another disadvantage of oxidation ponds is that they can be slow to remove pollutants from wastewater. This is because the microorganisms that break down the organic matter in the wastewater work slowly. As a result, oxidation ponds may not be suitable for treating wastewater that is heavily polluted.
Finally, oxidation ponds can produce odors and attract flies. This can be a problem if the oxidation pond is located near residential areas.
Despite these disadvantages, oxidation ponds are a common type of wastewater treatment system. They are relatively simple and inexpensive to operate, and they can be effective at removing pollutants from wastewater. However, they do require a large area of land, and they can be slow to remove pollutants.
Here is a brief explanation of each option:
- Option A: Large area is required for construction. This is the main disadvantage of oxidation ponds. Oxidation ponds are typically large, shallow ponds that are filled with microorganisms that break down the organic matter in the wastewater. This requires a large area of land, which can be a problem in areas where land is scarce or expensive.
- Option B: Maintenance and operation cost are high. This is not necessarily true. Oxidation ponds are relatively simple and inexpensive to operate. However, they do require some maintenance, such as removing scum and sludge from the pond.
- Option C: BOD removal is very low. This is not true. Oxidation ponds can be effective at removing BOD (biological oxygen demand) from wastewater. BOD is a measure of the amount of oxygen that is required to break down the organic matter in the wastewater. Oxidation ponds can remove up to 90% of BOD from wastewater.
- Option D: None of the above. This is not the correct answer. The main disadvantage of oxidation ponds is that they require a large area of land.