The Effect of Treated Municipal Wastewater and Fresh Water on Saturated Hydraulic Conductivity of a Clay-Loamy Soil

The effect of irrigating with treated municipal wastewater (TMW) and fresh water (FW) on saturated hydraulic conductivity (Ks) was investigated. Ks was determined in undisturbed soil samples, collected from the upper soil layer (0–15 cm) of an illitic clay-loamy soil, after two irrigation periods. Soil samples were analyzed for a number of factors potentially affecting Ks. Analysis of variance for each of these factors was performed between the two treatments in order to detect their differences. Statistically significant differences were found for pH, ECe, SAR, ESP and the concentrations of K⁺, Na⁺, Mg²⁺ which are elements related with TMW and FW quality-characteristics. Correlation between all factors and Ks showed that this was positive for soil ECe, CaCO₃ and negative for SAR, ESP, and bulk density. Although the influence of each separate factor was investigated and the differences between the two treatments were verified, their quantitative characteristics could not explain based on existing criteria, (the Ks reduction observed between the TMW-Ks and FW-Ks). The 2:1 type clay minerals which are more susceptible to SAR increase and EC decrease affected Ks values between the two treatments. Our findings are in line with some recently reported results and in this sense, more specific research is needed to clarify all aspects relevant to Ks and the use of TMW for irrigation purposes.