What does a waste with a high BOD and low suspended solids indicate?

A waste with a high Biochemical Oxygen Demand (BOD) and low suspended solids indicates that the organic matter is predominantly dissolved rather than present in solid form. BOD measures the amount of oxygen that microorganisms will consume while decomposing organic matter in a water sample. A high BOD implies a significant amount of organic material that can deplete oxygen levels in water, which is critical for aquatic life.

The low suspended solids aspect indicates that, while there's a significant amount of organic material, it is not in the form of large solids but rather exists in a more dissolved state. This typically means that the organic pollutants are readily available for bacterial action, which contributes to the elevated BOD levels. Thus, this combination of high BOD and low suspended solids suggests that the majority of pollutants are soluble organic compounds rather than particulate solids.

In contrast, if a waste had high suspended solids along with high BOD, it could suggest the presence of significant amounts of solid organic matter requiring oxygen for decomposition. Similarly, other options like high pollutant levels or toxicity would not inherently relate to the specific combination of high BOD and low suspended solids. Hence, the primary interpretation stems from the relationship between BOD and the state of solids in the waste, affirming