Wastewater and septage treatment assets play an important role in safeguarding public health and the environment, regardless of whether decentralized or centralized, or intensive or extensive treatment technologies are applied. However, it is important that the positive effects of such assets are measured and demonstrated.

Downstream human use and aquatic organisms both rely on water quality that comes from an acceptable performance of wastewater treatment assets. The capacity and design of treatment assets aside, it is critical that the target performance of assets is clear together with how to monitor and measure its performance and its obtained qualities.

Key performance indicators or KPIs are an easy way to measure performance, and it helps with the long-term planning of the asset during its operation. Ideally, at the beginning of a project, different KPIs are defined and linked to the required quality criteria, which can also be used to measure the efficiency of the process. Such KPIs can be as simple as effluent quality targets or contaminant removal rates or can be as detailed such as indicators on operator training, energy consumption, or unit costs.

Identifying KPIs at an early stage of the project is crucial. These indicators can drive decisions on design and equipment; for instance, whether extra equipment (e.g., flow meter in side streams or electricity sub-metering) or operator skills are necessary. However, some KPIs can be contradictory (e.g., minimizing energy and maximizing removal) and it is therefore important to set the right targets.

The last workshop of ASD 2021 showcased extensively used wastewater plant KPIs and some best practice examples that can assist participants in framing an indicator regime and asset performance improvement plans.