Rental of AI-based systems, comprising of one or more of the following, namely, optical equipment, electronic equipment, control units with electric and electronic components, hardware devices, and designated software used for real-time and online measuring and monitoring of physical-chemical separation processes in sewage, water, wastewater and sludge, including measuring the chemicals involved in treatment processes of sewage, water, wastewater and sludge, providing alerts of changes in the quality of the processes and changes in the chemical dosages and changing the chemical dosages by remote control, and including real time collection and analysis of data relating to the quality of the processes and to the chemical dosages, and issuing reports and recommendations to improve the processes.