Which waste stream is known to contain significant quantities of organic material?

• A. Industrial wastewater
• B. Stormwater runoff
• C. Domestic wastewater
• D. Groundwater

Answer: (C)

Domestic wastewater is known to contain significant quantities of organic material primarily because it includes the discharge from household activities. This waste stream typically includes human waste, food scraps, and other organic byproducts generated from daily living. Organic materials in domestic wastewater can include carbohydrates, proteins, fats, and other biodegradable substances.

These organic components are crucial for the biological processes used in wastewater treatment. The presence of organic matter is what allows for the activation of microbial populations that break down these substances, thus reducing pollution levels before the water is released back into the environment or reused.

In contrast, other waste streams like industrial wastewater can vary widely in their organic content depending on the types of processes involved and the specific industry. Stormwater runoff generally contains debris, sediments, and pollutants carried from surfaces but typically has lower concentrations of organic materials compared to domestic wastewater. Groundwater, which is water located beneath the earth's surface, does not normally contain significant organic material in a concentrated form unless it has been contaminated. Thus, domestic wastewater stands out as the waste stream most rich in organic content.