LESSONS LEARNED FROM WATER TREATMENT AND ITS USE IN DOMESTIC HOT WATER NETWORKS: ANALYSIS OF HEAT PUMP INTEGRATION, ADVANCED OZONATION AND MICROBIOLOGICAL CONTROL

This paper presents a comprehensive analysis of technical and sanitary challenges associated with using groundwater containing high Fe and Mn concentrations in domestic hot water (DHW) systems integrated with geothermal heat pumps. The study documents implementation of an advanced treatment system featuring ozonation (10g/h generator, Thomas 120 l/min medical-grade oil less compressor) combined with magnetic treatment and triple coaxial graduated filtration (0.5mm, 0.15mm, 0.07mm with automatic purging). Through computational simulations and cost-benefit modelling, we have investigated microbiological risks generated by moderate temperatures (28-40°C) in heat pump primary circuits during summer cooling mode, focusing on Legionella pneumophila development. Systematic review of international academic literature identifies validated microbiological control solutions. The study proposes strategic chlorination relocation from basin mixer to thermal plant for optimized final treatment, demonstrating 45-55% reduction in chemical consumption. Quantitative analysis reveals that low winter temperatures (6-8°C) are insufficient for bacterial inactivation, necessitating seasonal circuit separation or thermal disinfection cycles ≥60°C. Economic modelling shows proposed modifications achieve cost recovery within 5-6 years through reduced chemical consumption, decreased monitoring requirements, and elimination of outbreak-related liabilities. The integrated solution combines existing advanced treatment (ozonation + triple filtration) with strategic chlorination relocation and automated seasonal bifurcation, ensuring maximum microbiological safety while maintaining optimal energy efficiency. Results demonstrate 12-15% annual energy savings in summer operation while guaranteeing continuous DHW temperatures ≥60°C for complete Legionella control.