Secondary treatment accomplish and common process?

Secondary treatment accomplish and common process?

• A. Biological oxidation of dissolved organics; activated sludge is a common secondary process
• B. Filtration-only
• C. Chemical precipitation
• D. Primary clarifiers alone

Answer: (A)

Secondary treatment focuses on biologically reducing the remaining organic matter in wastewater after primary treatment. Its main aim is biological oxidation of dissolved organics, turning them into biomass, CO2, and water. The most common secondary process is the activated sludge system, where air is supplied to keep microorganisms in suspension so they metabolize the organics. The mixture then goes to secondary clarifiers, where the biomass settles as sludge that’s recycled to maintain the microbial population. This step dramatically lowers BOD/COD and improves effluent quality. Filtration-only lacks the biological degradation of dissolved organics and isn’t a typical secondary approach. Chemical precipitation targets specific contaminants and isn’t the general secondary process. Primary clarifiers remove settleable solids from the influent but do not address dissolved organics, so they don’t accomplish secondary treatment.

Secondary treatment focuses on biologically reducing the remaining organic matter in wastewater after primary treatment. Its main aim is biological oxidation of dissolved organics, turning them into biomass, CO2, and water. The most common secondary process is the activated sludge system, where air is supplied to keep microorganisms in suspension so they metabolize the organics. The mixture then goes to secondary clarifiers, where the biomass settles as sludge that’s recycled to maintain the microbial population. This step dramatically lowers BOD/COD and improves effluent quality. Filtration-only lacks the biological degradation of dissolved organics and isn’t a typical secondary approach. Chemical precipitation targets specific contaminants and isn’t the general secondary process. Primary clarifiers remove settleable solids from the influent but do not address dissolved organics, so they don’t accomplish secondary treatment.