Low-performance diagnosis of covered anaerobic lagoons as a waste management strategy in the intensive dairy industry.

Covered anaerobic lagoons (CALs) are Latin America's main livestock waste treatment systems. Mexico has 680 CALs that present low biogas yields (0.05 m3 m-3 digester d-1) and low COD removal rates (< 60%). This work focused on diagnosing CAL´s low performance in dairy farms by determining and analyzing operational parameters. Seven CALs located in the main dairy basin of Mexico were analyzed. The sampling areas for each CAL were the supernatant, the active zone, settled sludge, and digester inlet and outlet. The variation of the process parameter values corroborated that CALs appeared stratified and not working as expected. The sludge zone, comprising 50-58% of total solids content and 1-15% of total CALs volume, showed an elemental compounds content suitable for organic fertilizer (340, 48, and 5 kg t-1 of C, N, and S, respectively). However, this zone contained, at least, 85% of the slowly hydrolysable material; the methanogenic potential was less than 87 mL CH4 g VS-1, and the C/N ratio ranged from 4.9 to 17, outside of the optimal range. The biogas produced did not exceed 60% of methane content and more than 3000 ppm of H2S. The sludge zone significantly influences the lagoon's dynamics since it is a nutrient sink. Furthermore, the lack of agitation is the leading cause for the low energy yield and the low removal of organic matter rate. This work provides valuable information to address the operational problems within the CALs improving our understanding that shall allow proposing reactivation alternatives.

Assessment of livestock greenhouse gases in Colombia between 1995 and 2015.

The livestock sector in Colombia significantly participates in national economic dynamics but makes significant worldwide contributions to greenhouse gas emissions. Hence, climate change mitigation in this sector is essential. This study aims to assess the greenhouse gas in the livestock sector. The results are reported in methane emissions (CH4) and nitrous oxide (N2O) from enteric fermentation, and N2O by manure management based on the information from the Emission Database for Global Atmospheric Research (EDGAR), in all cases expressed as dioxide of carbon (CO2eq). The emissions obtained from the EDGAR database for 2015 were proportional to the values of the National Inventory of Greenhouse Gases published by the Institute of Hydrology, Meteorology, and Environmental Studies (IDEAM) in 2016. Colombia is the 12th on global, 4th in America and 2nd in South America position by livestock GHG emission, and is the dominant source in all economic sector. The results showed higher records for CH4 emissions during the years 2010 and 2015, while the N2O emissions were higher during 2015. The regions with the highest emissions of CH4 and N2O corresponded to the northwestern area of Colombia. The Spearman correlation test showed a positive correlation between the CH4 emissions, and the age groups studied. The post hoc analysis of the Kruskal-Wallis test showed a more significant influence on CH4 emissions.

Epidemiological determinants of Chrysomya (Diptera: calliphoridae) infestation in layer farms of Minas Gerais, Brazil / Determinantes epidemiológicos da infestação por Chrysomya (Diptera: Calliphoridae) em granjas avícolas de postura de Minas Gerais, Brasil

Aspects related to the epidemiology of Diptera belonging to genus Chrysomya were studied in order to determine predisposing factors for their occurrence in commercial laying hens farms from the state of Minas Gerais, Brazil. An observational, analytical and sectional survey was conducted to verify the main epidemiological determinants of infestations by Chrysomya spp. Forty-three farms were visited in 2012 and these 13 (30,23%) were infested by Chrysomya putoria, 4 (9,30%) by Chrysomya megacephala and 2 (4,65%) by Chrysomya albiceps and in 2 farms (4,65%) was not possible to identify the species of Chrysomya. The epidemiological determinants for the occurrence of infestations by Chrysomya spp. were investigated using multiple logistic regression models. Housing clustering type and its conditions were important factors involved in epidemiology of these species (OR=5.05, 95% CI = 2.66 to 9.58, p = 0.000). It was also observed that the increase of the humidity of manure leads to increase chances of infestations (OR = 1.81, 95% CI = 1.36 to 2.40, p = 0.000). The presence of the beetle "lesser mealworm" (Alphitobiusdiaperinus) (OR = 0.15, 95% CI = 0.067 to 0.36, p = 0.000) was characterized as a protective factor against infestations, probably due to predation behavior of the beetle. Some regions of the state were characterized as lower risk areas for Chrysomya spp. infestation as compared to other regions. Management measures, such as constant monitoring of water leaks on manure, adequate composting of dead poultry and periodic removal of manure could assist in decreasing the presence of Chrysomya spp. inside the laying houses.

Aspectos relacionados à epidemiologia das infestações por dípteros do gênero Chrysomyaforam estudados com o objetivo de determinar os fatores predisponentes para sua ocorrência em granjas comerciais de postura do estado de Minas Gerais, Brasil. Foi realizado um estudo observacional, analítico e seccional para verificar os principais determinantes epidemiológicos das infestações por Chrysomya spp. Foram visitadas 43 granjas avícolas em 2012 e dessas 13 (30,23%) apresentaram infestação por Chrysomya putoria, 4 (9,30%) por Chrysomya megacephala, 2 (4,65%) por Chrysomya albiceps e em 2 granjas (4,65%) não foi possível identificar as espécies de Chrysomya. A verificação dos determinantes epidemiológicos foi realizada utilizando modelos de regressão logística múltipla. Diferenças entre os núcleos das granjas avícolas e que não foram avaliadas neste estudo, apresentaram-se importantes na epidemiologia destas moscas (OR=5.05 95% IC = 2.66 a 9.58, p = 0.000). Observou-se também que o aumento na umidade do esterco dos aviários aumenta as chances de ocorrência de infestações (OR = 1.81, 95% IC = 1.36 a 2.40, p = 0.000). A presença de coleópteros popularmente conhecidos como "Cascudinhos", Alphitobiusdiaperinus (OR = 0.15, 95% IC = 0.067 a 0.36, p = 0.000), foi caracterizada como um fator protetor contra infestações, provavelmente devido ao comportamento predador deste coleóptero. Algumas regiões do estado apresentaram menores chances de ocorrência de infestações por Chrysomya spp. quando comparadas a outras regiões. Algumas medidas de manejo, como monitoramento constante de vazamentos de água no esterco, compostagem adequada de aves mortas e remoção periódica do esterco, poderiam auxiliar na diminuição da presença de Chrysomya spp. no interior dos galpões de postura.

Recovery of ammonia from anaerobically digested manure using gas-permeable membranes

Nitrogen (N) can be recovered from different types of wastewaters. Among these wastewaters, anaerobically digested swine manure (digestate) has the highest N content in ammonia form (NH3). It is desirable to reduce N in digestate effluents to safely incorporate them in arable soil in N vulnerable zones (NVZ) and to mitigate NH3 emissions during N land application. Additional benefit is to minimize inhibition of the anaerobic process by removing NH3 during the anaerobic digestion process. This work aimed to apply the gas-permeable membrane technology to evaluate ammonia (NH3) recovery from high-ammonia digested swine manure. Anaerobically digested swine manure with NH4+ content of 4,293 mg N L1 was reduced by 91 % (to 381 mg N L1) during the 32-day experiment. Although the results showed a total N recovery efficiency of 71 %, it is possible to increase this recovery efficiency to > 90 % by adjusting the area of the membrane system to match the high free ammonia concentration (FA) in digested swine manure. Moreover, final digestate pH and alkalinity were kept around 8.1 and 8,923 mgCaCO3 L1, which are convenient for the anaerobic process or incorporation in arable soil when the process is finished.

Recovery of ammonia from anaerobically digested manure using gas-permeable membranes

Nitrogen (N) can be recovered from different types of wastewaters. Among these wastewaters, anaerobically digested swine manure (digestate) has the highest N content in ammonia form (NH3). It is desirable to reduce N in digestate effluents to safely incorporate them in arable soil in N vulnerable zones (NVZ) and to mitigate NH3 emissions during N land application. Additional benefit is to minimize inhibition of the anaerobic process by removing NH3 during the anaerobic digestion process. This work aimed to apply the gas-permeable membrane technology to evaluate ammonia (NH3) recovery from high-ammonia digested swine manure. Anaerobically digested swine manure with NH4+ content of 4,293 mg N L1 was reduced by 91 % (to 381 mg N L1) during the 32-day experiment. Although the results showed a total N recovery efficiency of 71 %, it is possible to increase this recovery efficiency to > 90 % by adjusting the area of the membrane system to match the high free ammonia concentration (FA) in digested swine manure. Moreover, final digestate pH and alkalinity were kept around 8.1 and 8,923 mgCaCO3 L1, which are convenient for the anaerobic process or incorporation in arable soil when the process is finished.(AU)

Environmental implications of anaerobic digestion for manure management in dairy farms in Mexico: a life cycle perspective.

The environmental profile of milk production in Mexico was analysed for three manure management scenarios: fertilization (F), anaerobic digestion (AD) and enhanced anaerobic digestion (EAD). The study used the life cycle assessment (LCA) technique, considering a 'cradle-to-gate' approach. The assessment model was constructed using SimaPro LCA software, and the life cycle impact assessment was performed according to the ReCiPe method. Dairy farms with AD and EAD scenarios were found to exhibit, respectively, 12% and 27% less greenhouse gas emissions, 58% and 31% less terrestrial acidification, and 3% and 18% less freshwater eutrophication than the F scenario. A different trend was observed in the damage to resource availability indicator, as the F scenario presented 6% and 22% less damage than the EAD and AD scenarios, respectively. The magnitude of environmental damage from milk production in the three dairy manure management scenarios, using a general single score indicator, was 0.118, 0.107 and 0.081 Pt/L of milk for the F, AD and EAD scenarios, respectively. These results indicate that manure management systems with anaerobic digestion can improve the environmental profile of each litre of milk produced.

Economies of scale in the production of swine manure

Manure production on grower/finisher swine operations in the United States was examined using data from 184 grower/finisher swine operations that participated in the United States National Animal Health Monitoring System's 1995 National Swine Study. Two methods were used: one, assuming that pigs produced 8.4% of their body weight in manure each day; another using the difference between feed fed and weight gained as a proxy variable to study manure production. Using this latter approach, a production function was developed. The function exhibited diminishing returns to scale when food waste was not fed to pigs, but constant returns to scale when food waste was included in their diets. The difference between feed fed and weight gained was lower on operations that restricted entry to employees only.

A produção de dejetos em granjas de crescimento e terminação de suínos nos Estados Unidos foi avaliada utilizando dados de 184 granjas participantes de um estudo nacional de 1995 do "United States National Animal Health Monitoring System". Dois métodos foram usados: um considerando que suínos produzem 8,4% do seu peso corporal de dejetos por dia e o outro usando a diferença entre o alimento ingerido e o ganho de peso como um indicador para o estudo da produção de esterco. Através desse último procedimento, desenvolveu-se uma função de produção.