Pollutants from pig farms in Mexico have caused problems in many surface water reservoirs. Growing concern has driven the search for low-cost wastewater treatment solutions. The objective of this research was to evaluate the potential of an in-series constructed wetland to remove nutrients from wastewater from a pig farm. The wetland system had a horizontal flow that consisted of three cells, the first a surface water wetland, the second a sedimentation cell, and the third a subsurface flow wetland. The vegetation used was Thypa sp. and Scirpus sp. A mix of soil with red volcanic rock (10–30 mm diameter) and yellow sand (2–8 mm diameter) was used as a substrate for the vegetation. The experiments were carried out in duplicate. Water samples were collected at the inflow and outflow of the cells. Two hydraulic retention times (HRT) (5 and 10 days) and three treatments were evaluated: 400, 800, and 1200 mg·L⁻¹ of chemical oxygen demand (COD) concentration. Data was collected in situ for temperature, pH, dissolved oxygen (DO), electrical conductivity (EC), and total dissolved solids (TDS). COD, total Kjeldahl nitrogen (TKN), ammonia nitrogen (NH₃–N), and total phosphorous (TP) were analyzed in the laboratory. The results showed that the in-series constructed wetland is a feasible system for nutrient pollutant removal, with COD removal efficiency of 76% and 80% mg·L⁻¹ for a 5- and 10-day HRT, respectively. The removal efficiency for TKN, NH₃–N, and TP reached about 70% with a 5-day HRT, while a removal of 85% was obtained with a 10-day HRT. The wetland reached the maximum removal efficiency with a 10-day HRT and an inflow load of 400 mg·L⁻¹ of organic matter. The results indicate that HRT positively affects removal efficiency of COD and TDS. On the other hand, the HRT was not the determining factor for TP removal. Treatment one, with an initial COD concentration of 400 mg·L⁻¹, had the highest removal of the assessed pollutants, allowing for the use of water for irrigation according to Mexican regulatory standards (NOM-001). The water quality resulting from treatments two and three (T2 = 800 mg·L⁻¹ of COD and T3 = 1200 mg·L⁻¹ of COD) did not comply with minimal requirements for irrigation water.

Anaerobic digesters generate effluent containing about 3000 mg L⁻¹ of organic matter in terms of chemical oxygen demand (COD). This effluent must be treated before being reused or discharged into the environment. The objective of this study was to evaluate the efficiency of a trickling filter packed with red volcanic rock for the treatment of anaerobic digester effluent with COD concentrations of around 3000 mg L⁻¹. The trickling filter consisted of an aluminum cylinder, 2 mm thick, 3 m high, and 1 m in diameter. To evaluate the efficiency of the treatment system, there were three experimental runs, each lasting 20 days (d). The predictor variable was the initial COD concentration, which ranged from 2002 to 3074 mg L⁻¹. The hydraulic retention time was 9 h. The influent flow was 2.2 L min⁻¹, which amounts to a hydraulic load of 4033 m³ m⁻² day⁻¹ and an organic load of 0.006342 to 0.009738 kg m⁻³ day⁻¹ of COD. Independent of the initial concentration, COD removal efficiency was very high, varying from 90 to 96%. Final effluents met all the maximum permissible limits to be used as irrigation water, as well as for its release into natural or artificial water reservoirs, stored for agricultural crop irrigation.

Despite the key role of water in livestock growth and reproduction, there is little information on water quality for Mexico s beef cattle ranches. The objective of this study was to evaluate drinking water quality for beef cattle in the cow-calf operation through calculation of a water quality index (WQI) that relates water physical-chemical composition with common cattle drinking water sources. The study was conducted in 25 cattle ranches of the cow-calf system in seven municipalities of Chihuahua, Mexico. In all cattle ranches, water samples were collected from the main water sources, and physical and chemical parameters were analyzed. Statistical analyses were done through Kruskal-Wallis test, considering water sources (WS) as a source of variation. The WQI was calculated considering the parameters closely related to animal health and productivity and following standard procedures. Most parameters showed high variation among WS. The only parameters in uenced by WS were pH, As (p < 0.05) and Co (p < 0.01). The parameters that surpassed the optimum level for cattle drinking were turbidity for all WS and Mn for earthen tank and spring/river water. Groundwater showed the best quality with a 50.34 WQI, corresponding to good class. Earthen tank water also corresponded to good class with a 98.8 WQI, while spring/river water was classi ed as poor water for cattle with a 114.47 WQI.

Las herramientas de evaluación de pastizales presentan limitantes que las hacen difíciles de utilizar. El objetivo de este trabajo fue proponer y describir una metodología sencilla y confiable para evaluar pastizales. La propuesta consiste en la elaboración de un índice de contribución ecológica del pastizal (ICEP) a través de la estimación de cuatro indicadores. Se estudiaron 29 ranchos ganaderos, en los cuales se determinó la condición de los pastizales y el ICEP. La condición de los pastizales fue calculada mediante la metodología de COTECOCA. El ICEP se obtuvo a través de estimaciones visuales de la cobertura general de vegetación, cobertura de especies forrajeras perennes, capacidad de retención de agua y estabilidad de suelos. Los datos obtenidos fueron sometidos a pruebas de chi cuadrada, análisis de correspondencias y regresión logística para determinar su confiabilidad. No se obtuvieron evidencias estadísticas que sustenten la independencia entre los datos generados mediante el método propuesto y los del método tradicional (p<0.01; Chi cuadrada de Pearson) en los tres tipos de vegetación estudiados. De igual manera, los análisis de correspondencias y de regresión logística ordinal (gama de Goodman-Kruskal = 0.91; p<0.01) mostraron que existe una relación estrecha entre los resultados del ICEP y los de la condición del pastizal.