Microbiological groundwater quality in shallow wells before and after disinfection with peracetic acid

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The microbiological examination of water is used worldwide to monitor and control the quality and safety of various types of water. Peracetic acid (PAA) has garnered increasing attention as an alternative oxidant and disinfectant in water treatment due to the rising demand to reduce chlorine usage and control disinfection byproducts. The main aim of the research was to assess the well water microbiological quality before and after disinfection with PAA. The water samples were taken from 5 wells in the rural areas of Probishtip and Kocani regions of North Macedonia. Sampling was conducted twice (before and after disinfection) per season during the four seasons of the year. Water samples from 5 shallow wells were analysed for microbiological parameters using reference methods. The results were compared with the quality of control water and the permissible values according to the national legislation. Water quality parameters indicated that all well water samples failed to meet safe drinking water limits. A significant improvement in the microbiological quality of the water was observed during the seasons when a PAA working solution with concentrations of 0.05% and 0.1% was used. The regression statistical model revealed that disinfection with PAA and the seasonal variation in its concentration had a statistically significant influence on the microbiological quality of well water (p<0.001). Identification and management of groundwater quality are of utmost importance for maintaining freshwater resources, which are essential for sustainable rural development.