Water scarcity has been and will continue to be a global-scale environmental issue . This concern has motivated strategies and solutions for water reuse/recycling to treat and recover water from various sources for beneficial purposes such as agriculture, water supply, groundwater replenishment, industrial processes, and environmental restoration.
Wastewater treatment plants (WWTPs) are one of the solutions for cleaning wastewater (urban or industrial) so that it can be safely returned to the environment. Various physicochemical and biological processes and treatments must be performed on the wastewater to remove contaminants and suspended solids, break down organic matter, and disinfect the liquid. Currently, WWTPs use Cyber-Physical Systems (CPSs) and the Internet of Things (IoT) to monitor, control, and automate different processes in the plant. Devices such as sensors (e.g., level, temperature, or pH sensors), and actuators (e.g., motors, valves, or alarms) are deployed in different water treatment processes to collect real-time data and control operations. Additionally, multi-layer IoT systems that leverage edge and fog computing also deploy nodes or compute units (located in the plant) to run lightweight applications and databases that store some of the collected information. Finally, some cloud servers are also provisioned for the deployment and execution of the resource-intensive applications, such as AI algorithms.
Although several operating units (such as biological reactors, decanters, thickeners, etc.) are involved in wastewater treatment, the whole plant should be considered as an integrated process to study improvements in processes such as sludge control, primary sedimentation effects, and energy and nutrient recovery . Therefore, WWTPs are represented by a single process block diagram that illustrates the treatments, stations, operation units, and flow of water and sludge.