Energy Efficiency Analysis of Water Treatment Plants: Current Status and Future Trends

The energy efficiency of water treatment plants (WTPs) plays a key role in the sustainable management of water resources. In the face of increasing water demand, climate change, and increasingly stringent environmental regulations, optimising the energy consumption of treatment processes is becoming a priority for water system operators and decision-makers alike. Water treatment plants, depending on the type of water source served (groundwater, infiltration, surface water), vary considerably in terms of their technological design, which directly affects their energy efficiency and operating costs. According to the International Water Association, the water sector accounts for approximately 4% of global electricity consumption, a significant proportion of which is consumed by water treatment and distribution processes. Electricity is used in many process steps, such as water pumping, aeration, filtration, disinfection, and filter flushing. The energy consumption of a System for Upgrading Water (SUW) depends not only on the quality of taken raw water, but also on the size of the station, used technologies, and operation organisation. This study shows that implementing high-efficiency pumping systems and AI-based optimisation can reduce energy consumption in WTPs by 20–30%. The introduction of membrane filtration in surface water plants has demonstrated a reduction in energy use by up to 50%, while the use of biogas from sludge treatment has cut external energy demand by 15–25%. The results emphasise the potential to reduce CO 2 emissions by 10–20% compared to conventional treatment methods. However, achieving significant reductions in energy consumption in SUW requires a comprehensive understanding of the diversity of water facilities, technological processes, and specific energy requirements.