Differentiating fouling from ageing for a condition-based diffuser maintenance.

Diffuser maintenance such as cleaning and membrane replacement are key to energy-efficient aeration at water resource recovery facilities (WRRFs). In previous research, fouling and ageing effects on diffuser performance have been lumped together by only comparing new and used membranes. But meaningful diffuser maintenance requires that fouling (mitigated by cleaning) can be separately assessed from ageing (calling for membrane replacement).

Comparison of guideline- and model-based WWTP design for uncertain influent conditions.

In this study, two methods for wastewater treatment plant (WWTP) dimensioning were compared: (1) a traditional guideline-based approach, and (2) a mechanistic model-based approach. The design outputs depended on uncertainties in correlated influent concentrations, which emphasises the importance of uncertainty analysis. The results showed that model-based design could simplify and reduce the time required for uncertainty and sensitivity analysis compared to a conventional design approach, in which the equations are solved manually and iteratively.

To calibrate or not to calibrate, that is the question.

Sensors used for control have become widespread in water resources recovery facilities during the strive for resource efficient operations. However, their accuracy is reliant on uncertain laboratory measurements, which are used for calibration and, in turn, to correct for sensor drift. At the same time, current sensor calibration practices are lacking clear theoretical understanding of how measurement uncertainties impact the final control action.

Model-based monitoring of diffuser fouling using standard sensors.

Fouling of fine-pore diffusers can cause substantial aeration energy wastage. It remains challenging to monitor their condition and decide the optimal time for labour-intensive and costly cleaning actions. In this study, we show that data from standard sensors (airflow rate, dissolved oxygen concentration, pressure and airflow valve position), which are fed to simple models, can track the diffuser's condition.