Data Sheet 1_Influence of physicochemical properties and ionic composition on bacterial abundance in treated wastewater and post-irrigation agricultural drainage water: a case study from Al-ahsa, Saudi Arabia.pdf

Introduction<p>This study investigated the relationships between physiochemical properties and bacterial abundance in treated wastewater and post-irrigation agricultural drainage water in Al-Ahsa, Saudi Arabia.</p>Methods<p>Six water samples were collected from treated wastewater (n = 3) and agricultural drainage water (n = 3), and four tap water samples were included as a microbiological reference. Major ions, trace elements, organic matter, total viable counts (TVC), and total coliforms were determined.</p>Results<p>Agricultural drainage water exhibited higher salinity, sodium dominance, chloride (1,520–1850 mg/kg), sulfate (820–980 mg/kg), and organic matter (0.65%–0.72%) than treated wastewater (chloride = 314–333 mg/kg; sulfate = 206–218 mg/kg; organic matter = 0.17–0.19%).

Despite these physiochemical differences, both water sources contained comparable microbial abundance, with TVC ranging from 2.51 to 3.17 log₁₀ CFU/mL and total coliforms from 1.93 to 2.87 log₁₀ CFU/mL. Conversely, tap water contained consistently low microbial counts (0.70 log₁₀ CFU/mL). Spearman’s correlation analysis revealed significant positive relationships between total coliforms and major ions, while principal component analysis (PCA) clearly separated agricultural drainage water from treated wastewater based primarily on physiochemical parameters.</p>Discussion<p>The findings demonstrate that microbial abundance is associated with multiple interacting physiochemical factors rather than individual ions alone.