When do intermittent discharges typically occur?

Intermittent discharges typically occur during the disposal of reject products, as this process often involves the release of materials that do not meet quality or safety standards. When industries produce goods, there may be byproducts or rejected items that are deemed unsuitable for sale or use. The management of these reject products can involve discharging materials into treatment systems or directly into the environment, especially if they cannot be recycled or reused. This type of discharge is unpredictable and can vary based on production cycles, which is characteristic of intermittent discharges.

In contrast, during environmental audits and routine inspections, the focus is on assessing compliance and operational practices rather than generating discharges. Additionally, system upgrades usually involve modifications to existing systems and may include temporary shutdowns or changes in processes, which are not typically associated with discharges of materials. Thus, the disposal of reject products is the scenario that most closely aligns with the occurrence of intermittent discharges.