Final answer:
Improper functioning of an aeration tank in a sewage treatment plant will lead to ineffective treatment of sewage, resulting in higher BOD in the effluent. This can cause oxygen depletion and harm aquatic environments, as the aeration process is essential for the breakdown of organic matter by microorganisms.
Step-by-step explanation:
If the aeration tank of a sewage treatment plant is not functioning properly, it will significantly impact the treatment of sewage and the Biochemical Oxygen Demand (BOD) of the effluent. Aeration is crucial for providing oxygen to aerobic microorganisms that break down organic contaminants in wastewater. In a properly functioning system, these organisms decompose organic matter and absorb nutrients, which reduces BOD - a measure of the amount of dissolved oxygen needed by aerobic biological organisms to break down organic material in a given water sample at a certain temperature over a specific time period.
Without adequate aeration, the microorganisms cannot efficiently decompose the sewage's organic content, leading to incomplete treatment and potentially higher BOD in the released effluent. Higher BOD means that more oxygen will be required for the decomposition of this organic matter in the receiving water body, which can lead to oxygen depletion and subsequent adverse effects on aquatic life. Furthermore, the activated sludge process would be disrupted, affecting the settling of the microorganisms in the secondary clarifier and reducing the overall efficiency of the wastewater treatment process.
The consequences of poor aeration include higher levels of organic pollutants and nutrients like nitrogen and phosphorus in the effluent, which can result in eutrophication of water bodies, where excessive nutrients stimulate algal blooms that deplete oxygen in the water, causing harm to aquatic environments. Therefore, the proper function of the aeration tank is essential for effective sewage treatment and maintaining low BOD levels in the effluent, contributing to the overall health of ecosystems and compliance with environmental regulations.