Which analyses are typically performed by refining industries before discharge?

• A. Total Suspended Solids
• B. pH and Biochemical Oxygen Demand
• C. Total Suspended Solids and Biochemical Oxygen Demand
• D. Total Suspended Solids, pH and Biochemical Oxygen Demand

Answer: (C)

Before discharge, refining industries focus on two main pollutant burdens: the solids that can be carried into the receiving water and the organic matter that consumes oxygen as it degrades. Total Suspended Solids quantify the particulate load in the wastewater, which affects turbidity, settling, and the potential transport of adsorbed pollutants. Biochemical Oxygen Demand measures how much oxygen would be consumed by microorganisms breaking down biodegradable organic matter, indicating the potential for oxygen depletion in the environment and impact on aquatic life. Together, these two analyses provide a practical assessment of how much treatment the effluent will require and what environmental impact it may have. While pH is important for process control and corrosion prevention, the combination of solids and oxygen-demand indicators directly reflects the pollutant load entering the water, making it the best fit for typical pre-discharge analyses.