What is a common treatment method for reducing BOD in wastewater?

The activated sludge process is a widely used method for reducing biochemical oxygen demand (BOD) in wastewater treatment. This process involves the cultivation of microorganisms in aerated tanks to break down organic pollutants present in the wastewater. As the microorganisms consume the organic material, they effectively reduce the BOD, which is a crucial measurement of the organic matter that can be biologically degraded in water.

In the activated sludge system, untreated wastewater is mixed with a population of aerated microorganisms, creating an environment suitable for biological treatment. With proper aeration, these microorganisms metabolize the organic substances within the wastewater, leading to a significant decrease in BOD levels. The treated water is then separated from the sludge, which can be recycled back into the treatment process to maintain a sufficient microbial population.

The other methods listed, while related to water treatment, do not specifically address BOD reduction in the same effective manner as the activated sludge process. Chlorination is primarily a disinfection method used to kill pathogens, reverse osmosis is a filtration process useful for removing specific contaminants and does not significantly reduce BOD, and flocculation is a process used to aggregate suspended particles rather than focusing primarily on organic material decomposition.