Joana Cassidy

By leveraging performance assessment systems (PASs) and incorporating targeted strategies, utilities can enhance the overall effectiveness, reliability, efficiency, and environmental performance of their wastewater treatment facilities. This work presents the results obtained from a comprehensive analysis of treatment reliability and energy performance of three wastewater treatment plants (WWTPs). The results allowed identifying, for each WWTP, improvement needs related to the aeration energy requirements, as well as to determine the effluent concentration targets required to achieve higher reliability levels while potentially reducing running costs. By analysing reliability combined with energy efficiency, this methodology allowed identifying the WWTPs’ performance-limiting stages or dysfunctions that affect both effectiveness and efficiency, to estimate the investment needs and prioritize the rehabilitation or even retrofitting of facilities’ assets.

Digitalization and knowledge management in the water sector, and their impacts on performance, greatly depend on two factors: human capacity and digital maturity. To understand the link between performance, human capacity, and digital maturity, six AGS water retail utilities were compared with all Portuguese utilities using Portuguese benchmark data (2011–2019). AGS utilities achieved better results, including in compound performance indicators, which are assumed to be surrogates for digital maturity. These compound indicators were also found to correlate positively with better performance. In fact, AGS utilities show levels of non-revenue water (NRW) (<25%) below the national median (30–40%), with network replacement values similar to the national median (<0.5%). These results seem to imply that higher digital maturity can offset relatively low network replacement levels and guarantee NRW levels below the national average. Furthermore, regarding personnel aging index and digital maturity—two internally developed indicators—there was an increase in the digital maturity and aging of the staff, which, again, raises questions about long-term sustainability. The growing performance and the slight increase in digital maturity can be attributed to group-wide capacity building and digitalization programs that bring together staff from all AGS utilities in year-long activities.

Efficiency optimization of urban water systems is a growing concern for water utilities worldwide. This case study aimed at evaluating the impact of using cloud-based tools on the reduction of both real (real-time network monitoring) and apparent water losses (integrated customer meters management) in two water utilities. The incorporation of smart water solutions with a methodology for the management and operation of the systems allowed us to diagnose, prioritize areas and define actions to improve efficiency. Using a real-time monitoring tool allowed us to categorize bursts and to evaluate their impact on water loss volumes and to identify operational inefficiencies regarding detection and repair times, particularly in small and medium bursts. Additionally, the implementation of an integrated customer meters management tool allowed for an optimized meter management reducing apparent losses by estimating metering errors more accurately, enabling the water utilities to replace meters based on specific lifespan. Digitalization, through the implementation of optimized algorithms and early warning systems, allowed the analysis of data in a methodical and prompt manner resulting in non-revenue water reduction up to 8% in 3 years while improving the digital organization of data and its quality (reliability and accuracy), interdepartmental organization and communication, capacity building and utilities’ image among stakeholders.

Efficiency is a key topic nowadays in the water sector as customers' expectations are continuously increasing, legislation becomes more demanding, utilities become more exposed to public opinion and expectations are increasing towards a high-quality service at an affordable cost and both combined with high risk avoidance. The implementation of efficiency projects, such as Non-Revenue Water (NRW) reduction projects are fundamental both from an economic and an environmental perspective. However, decisions on the implementation of these projects are often reduced to short-term economic criteria or to a cost-benefit analysis at best, not considering an adequate timeframe that would potentially allow the accommodation of the adopted NRW reduction measures (capital and operational expenditures). Infrastructure asset management requires a strategic view on water systems based on the long-term balance of performance, cost and risk aiming at the adequate management of utilities' physical, human, technological and intangible assets. Water managers should take these principles into consideration when deciding whether to implement efficiency projects since the long-term effect of current water systems' inefficiencies can translate in significant capital expenditures in the future. This paper presents an evaluation on tangible and intangible gains which result from NRW reduction projects and why intangible gains should be part of decision-making processes on whether to implement them or not.

In the sulphate-reducing process, bioprocess control can be used to regulate the competition between microbial groups, to optimize the input of the electron donor and/or to maximize or minimize the production of sulphide. As shown in this review, modelling and monitoring are important tools in the development and application of a bioprocess control strategy. Pre-eminent literature on modelling, monitoring and control of sulphate-reducing processes is reviewed. This paper firstly reviews existing mathematical models for sulphate reduction, focusing on models for biofilms, microbial competition, inhibition and bioreactor dynamics. Secondly, a summary of process monitoring strategies is presented. Special attention is given to in situ sensors for sulphate, sulphide and electron donor concentrations as well as for biomass activity and composition. Finally, the state of the art of the bioprocess control strategies in biological sulphate reduction processes is overviewed.