Effects of greywater discharges on shallow soil properties

Abstract

Discharge of detergent-containing wastewater (greywater) into soils is common in rural areas in Yucatan, Mexico since the majority of soils are shallow and bedrock makes the building of drainage systems a challenge. The aim of this study was to evaluate the effect of greywater discharges on shallow soil properties. Physical and chemical properties of soil samples collected from 100 household home gardens in the municipality of Hunucmá, Yucatan were analysed. Two soil samples were taken in each home garden, one in a soil affected by greywater discharges and one in unaffected soil. Average powdered detergent used was 7 kg / year / home garden. Our calculations indicated that 23 tons of sodium and 19 tons of phosphorus are verted annually in the Hunucmá municipality. Compared to unaffected soils, samples of greywater-affected soils contained significantly higher pH and electrical conductivity values and higher phosphorous and sodium contents, as well as lower REDOX potential and sand and silt contents. Greywater discharges modify the physical and chemical properties of shallow soils. Further research is needed to better understand the dynamics of the elements contained in the detergent-containing greywaters, systematically verted on soils, as well as their impacts on vegetation development and aquifer contamination.