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.
Groundwater is the main source of water in arid cities where precipitations are low and not evenly distributed. The combined impact of climate variability and intensive human activities has caused a substantial decline in groundwater levels. Understanding the response of groundwater levels to meteorological and anthropogenic factors is a key step to propose water management alternatives. Meteorological and groundwater data were used to design a multi-step approach to assess the influential factors on the groundwater system in the City of Chihuahua, Mexico. The analysis of historical groundwater levels and climate showed a clear increase in meteorological drought, as well as a groundwater abstraction trend since 1986. Rainfall, groundwater recharge, and groundwater level displayed a significant decrease. Overall, the groundwater depth is continuously increasing with a strong correlation with groundwater abstraction. Despite having a significant trend, the changes in land-cover, groundwater recharge, and meteorological drought were not the main factors inducing the decreased level of water in the aquifer. The continuous abstraction of groundwater from 1986 to 2010 has led to a depletion of groundwater levels from 32 to 92 m. The findings of this study lay a foundation for future water resource management in the study area.
Water is getting scarce and irrigation practices should become more efficient. Mango orchards require great quantities of water, and policies in developing countries are substituting surface gravity irrigation by pressurized systems. A commercial orchard having mature 25-year-old trees and a 10-year-old HD high-density section were irrigated with micro sprinklers using 100% ETc (crop evapotranspiration) and reduced deficit irrigation treatments of 75% and 50% ETc. Water soil measurements were made with EC-5 probes at 10 and 35 cm in depth to study the effect of the different irrigation treatments. After the 2020 harvest, mature trees were trimmed without achieving pruning severity greater than 1.3. Canopy volume, mango size, fruit yield and water-use efficiency WUE were analyzed during 2020 and 2021. Sporadic storms produced sprinkler watering problems as weeds proliferated within trees. A controller with a fuzzy algorithm optimized orchard management and saved water in trees without decreasing yield and fruit size. It was found that one year after mature trees were trimmed by taking away the larger internal branch, more light penetrated the canopy, increasing yield by 60%; pruning in HD trees presented a yield increase of 5.37%. WUE (water-use efficiency) also increased with pruning and its value increased to 87.6 when the fuzzy controller and the 50% DI treatments were used in mature trees. This value was 260% greater than the one obtained in pruned trees without the controller. HD trees presented a lower WUE and yield per hectare than mature trees.
In intermittent drinking water distribution systems, large volumes of the water are wasted due to leaks in the distribution networks. Similarly, user service is not always satisfied in the time required to fill the storage, nor with sufficient pressure. Hence the importance of this study. Measuring the variability of pressure in the distribution network and determining the factors that influence the definition of a sufficient minimum hours of service, is a first step to change to a continuous service 24/7, in order to minimize the volumes of lost water and meet demand. 347 pressure sensors were placed in a network to detect changes in pressure and obtain data for three years. This study presents a new approach to determine the operating policy of the operating agency that provides the service intermittently. Two objectives are pursued: pressure variability – to minimize Leaks – and define the minimum hours of service. The analysis was performed using multivariate statistical techniques, including Principal Component Analysis, Correlation Matrix and ANOVA's, to explore the association between objectives. The results obtained show that the pressure distribution has a Gaussian behavior and that the hours of service has a Poisson distribution.
Cities in developing countries that do not consider water resources as the basis for sustainable growth usually accept intermittent water supply (IWS) as the alternative to satisfy the demand of the population. Networks designed as constant water supply (CWS) operated as IWS hinder a safe and reliable water supply, thus, feasible alternatives to return the operation to CWS are required. This paper presents a methodology based flow/pressure control to accomplish an efficient transformation from an IWS sector to a CWS, in the City of Chihuahua, Mexico. The management of pressure at sector entrance and critical supply points leads to successful improvement of service, ensuring water availability with adequate pressure at the peak of demand, as well as reducing the supply of water volume by 58% compared to the sector operated in IWS. The methodology allowed the improvement of decision-making and operating policy for the water operating agency (WOA), fixing service deficiency, avoiding the loss of water volumes, and maintaining competent management control. Nonetheless, resistance to the transition of using automation and setting the volume/pressure consumption based on reliable data persists. The change process will be successful to the extent that the WOA efficiently channels the participation of the personnel.
Since 2000, the city of Chihuahua had a distribution system of treated wastewater for irrigation of green areas and has replaced this water for processes that do not require the consumption of drinking water. This replacement was necessary in order to meet the growing demand for potable water, which has exceeded the current supply of 700 L (184,88 gallons) per second. Nowadays it is necessary to identify and assess the risks to public health and the environment due to the substitution of drinking water by treated wastewater in the last 10 yr. Treated wastewater contains compounds whose effects have not been evaluated when used for irrigation in public green areas. Therefore, it is not known whether there is a danger to the health of park visitors due to exposure and/or inhalation of the emitted gases, accidental ingestion of water, or impact to the environment. The purpose of the research, using an experimental prototype, is to identify the changes from nitrogen present in the treated wastewater to nitrous oxide. The research objective is the generation of data to simulate a regional scale at this stage, which will be analyzed and statistically validated using Minitab and Origin software. The experiment was performed using three different samples to compare water quality: drinking water, treated wastewater, and water with nitrogen-based fertilizer (urea). Prototypes were filled with two types of soil: sand and clay. Each type of water was sprinkled on the prototype, grass was planted in it, and the prototype was equipped with samplers to capture the gas in the root zone. The authors found high emissions of nitrous oxide in the clay-filled lysimeters, and climate and growing conditions of vegetation were the most important factors for producing nitrous oxide.Implications: Major problems in the ecosystem arise from solutions that are not based on environmental public policy research or experimentation. For example, before application a specific policy or regulation, research should be performed to evaluate long term effects to the ecosystem and this can be done through close monitoring.This study raises awareness about the public policy of substituting potable water with treated wastewater for irrigation of green areas in Chihuahua City. The present study was performed during a sufficient period of time in order to assess the impact to the environment.
Las organizaciones mundiales estiman que el 50% de la población mundial vive bajo estrés hídrico. En la actualidad, el reúso del agua es ampliamente aceptado para sustituir de agua de primer uso o para actividades que no requieren calidad de agua para consumo humano. Sin embargo, son pocos los estudios realizados a la fecha sobre los impactos en la generación de gases de efecto invernadero por el uso del agua residual tratada. El objetivo de este trabajo fue determinar la existencia de estos impactos. Dada la complejidad y características de la calidad de agua residual tratada; el trabajo se centró en la transformación de los compuestos nitrogenados inorgánicos como son: nitrógeno amoniacal, nitritos, nitratos y óxido nitroso. Abordar a este último, el cual es un gas de efecto invernadero permite una visión holística de los procesos de los compuestos analizados. El muestreo, así como el análisis, fue realizado en la Ciudad de Chihuahua. La interpretación se realizó con modelos de estadísticos multivariados, ANOVAS y de Análisis de Componentes Principales. Los resultados muestran que existe un impacto que puede ser mitigado o controlado con medidas durante el manejo y operación del re-uso.
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