Treated wastewater viability of use in green areas according to nitrogen compounds concentration

Abstract

Treated wastewater is commonly used for park irrigation in arid zones of Mexico without considering groundwater contamination. The objective was to investigate the possibility of nitrogen compounds leaching into the groundwater and their subsequent reactions in the main types of soils. Lysimeters samples were taken to scrutinize the soil characteristics of the green areas irrigated with treated wastewater from the Northern Wastewater Treatment Plant in the city of Chihuahua. Testing samples were setup to recreate treated wastewater irrigation conditions. Nitrogen-based compounds were identified and measured before and after percolation through the soil columns. Based on the results, one meter of sand column was sufficient to remove 68 to 100% of nitrogen compounds present in the residual water. The removal of all nitrogen-based compounds as they percolate through one meter of clay soil column was not enough, due to the biochemical reactions that occur through the percolation process. Results indicate minimal risk of nitrate and nitrite leach into the aquifer, since the average static level depth is 20 m which provide broad filtration. This demonstrates an opportunity for in-situ investigations to reevaluate the standards for soil aquifer treatment recharge, based on the soil type and water quality of the area.

Evolution of the groundwater system in the Chihuahua-Sacramento aquifer due to climatic and anthropogenic factors

“…In addition, this aquifer system is comprised of several stratigraphic units, such as rhyolite, basalts, sandstones, limestone rocks, conglomerates, and andesites. The climate in the study area is dry, similar to a desertic type, the mean annual temperature is 16.1 °C and the mean precipitation is 441.2 mm yr À1 for the years range 1950-2010(Sánchez-Navarro et al 2019. Regarding the annual distribution of precipitation, almost 70% of rainfall occurs in July, August, and September.…”

“…Groundwater in Chihuahua, Mexico, is the most important source of drinking water and plays a vital role in the region, however, a few studies have been carried out about human influence on groundwater detriment in Chihuahua (Reyes et al 2017;CONAGUA 2018;Sánchez-Navarro et al 2019;Mendieta-Mendoza et al 2020). Moreover, it is essential to identify which indicators of climate variability and human activities affect groundwater depletion and sustainability.…”