What does a low ORP value generally suggest about the wastewater?

A low ORP (Oxidation-Reduction Potential) value suggests an environment that is more reductive, indicating that there is a higher potential for chemical reactions to favor the reduction process. In the context of wastewater, a low ORP typically correlates with the presence of organic matter and contaminants that can consume oxygen, making the environment less oxidizing. This often means that the wastewater has high levels of contaminants, as the presence of organic pollutants or certain inorganic substances can lower the ORP.

In contrast, high ORP values are indicative of better oxidizing conditions, which suggest that contaminants are being broken down and that there might be lower levels of organic pollutants present. Therefore, the interpretation of a low ORP value aligns with the understanding that the wastewater in question is likely polluted or contains high levels of chemical and biological contaminants.