What is the main detrimental effect infiltration/inflow has on plant performance?

Infiltration and inflow (I/I) refers to the unwanted water that enters the wastewater collection system from the surrounding environment. This can be rainwater or groundwater that seeps into pipes through cracks or other vulnerabilities. The primary detrimental effect of this can be seen in how it reduces the hydraulic detention time in treatment plants.

Hydraulic detention time is the period that wastewater spends in a treatment facility, which is crucial for allowing the necessary biological processes to occur effectively. When excess water enters the system due to infiltration/inflow, the volume of wastewater increases significantly. This influx of additional water can lead to a situation where the treatment plant operates at or near its design capacity.

As a result, the hydraulic detention time is compromised; there is less time for solids to settle and for biological reactions to take place. This can lead to incomplete treatment, since treatment processes such as biological oxidation or nutrient removal rely on adequate retention of wastewater to achieve desired efficiencies. Consequently, reduced hydraulic detention times can lead to poorer quality effluent being discharged, potentially affecting compliance with regulatory standards.

The other options suggest positive outcomes relating to costs and treatment efficiency, which do not align with the challenges presented by increased I/I. Therefore, the primary impact of infiltration/inflow is notably