Anaerobic Lagoon Research Articles

Carbon footprint of dairy manure management chains in response to nutrient recovery by aerobic pre-treatment

Aerobic pre-treatment of liquid dairy manure has previously been reported as an effective nutrient export and emissions mitigation approach. The first objective of this study was to experimentally determine the optimal intermittent aeration ratio for nutrient recovery from liquid dairy manure through an on-site pilot-scale reactor to partially reduce the required energy for the aerobic process. The second objective was to theoretically investigate the total carbon footprints of direct manure spreading on croplands and permanent manure storage in open anaerobic lagoons in response to nutrient removal by the optimal determined intermittent aerobic treatment ratio. Four scenarios (S) were included; S1 was the traditional scenario of manure spread on croplands without the aerobic pre-treatment, S2 was the modified scenario of manure spread on croplands that included the aerobic pre-treatment, S3 was the traditional scenario of manure storage in lagoons, and S4 was the modified scenario of manure storage in lagoons that included the aerobic pre-treatment. The results showed that comparable nutrient removal efficiencies could be obtained with a 5:1 intermittent aeration ratio. Total nitrogen (TN) and total phosphorus (TP) were recovered were 41.5 ± 1.3% and 37.0 ± 4.0%, respectively, in ammonium sulfate and phosphorus-rich sludge, while 55.3 ± 1.4% of the chemical oxygen demand (COD) was removed. The estimated total carbon footprint for S1, S2, S3, and S4 were 24.4, 37.9, 45.3, and 45.9 kg CO2-eqton−1, respectively. However, the total carbon footprint of S2′ and S4′, which used renewable-based energy to run the reactor instead of fossil-based energy used in S2 and S4, were estimated to 29.5 and 37.5 kg CO2-eqton−1, respectively. Clearly, applying the aerobic pre-treatment increased the total carbon footprint of all cases except S4′, in which the total carbon footprint was mitigated by −17.2%. Accordingly, the aerobic pre-treatment is only recommended in the case of S4’ from a carbon footprint point of view although it is an effective nutrient recovery technology.

Distribution Patterns of Antibiotic Resistance Genes and Their Bacterial Hosts in a Manure Lagoon of a Large-Scale Swine Finishing Facility.

The spread of antibiotic resistance genes (ARGs) that are present in livestock manures, which are discharged into the environment, is a severe threat to human and animal health. Here, we used 16S rRNA gene profiling and metagenomic analysis to characterize microbial community composition and antibiotic resistance in a manure storage lagoon from a large-scale swine finishing facility. Manure samples were collected at intervals of two years. Both the prokaryotic community and the resistome were dominated by the Firmicutes, Proteobacteria and Bacteroidota. Metagenomic analysis of two samples revealed 726 and 641 ARGs classified into 59 and 46 AMR gene families. Besides multidrug efflux pumps, the predominating ARGs potentially encoded resistance to tetracyclines, macrolide-lincosamide-streptogramin, aminoglycosides, peptide antibiotics, rifamycin, chloramphenicol, and beta-lactams. Genes from all predominant AMR gene families were found in both samples indicating overall long-term stability of the resistome. Antibiotic efflux pumps were the primary type of ARGs in the Proteobacteria, while antibiotic target alteration or protection was the main mechanism of resistance in the Firmicutes, Actinobacteriota and Bacteroidota. Metagenome-assembled genomes (MAG) of four multidrug-resistant strains were assembled. The first MAG, assigned to Escherichia flexneri, contained 46 ARGs, including multidrug efflux pumps, modified porins, beta-lactamases, and genes conferring resistance to peptide antibiotics. The second MAG, assigned to the family Alcaligenaceae, contained 18 ARGs encoding resistance to macrolide-lincosamide-streptogramin, tetracyclines, aminoglycosides and diaminopyrimidins. Two other MAGs representing the genera Atopostipes and Prevotella, contained four and seven ARGs, respectively. All these MAGs represented minor community members and accounted for less than 0.3% of the whole metagenome. Overall, a few lineages originated from the gut but relatively rare in the manure storage lagoon, are the main source of ARGs and some of them carry multiple resistance determinants.

Development of a point-source model to improve simulations of manure lagoon interactions with the environment

In recent decades animal agriculture in the U.S. has moved from small, distributed operations to larger, concentrated animal feeding operations (CAFOs). CAFOs are defined by federal regulations based on animal numbers and confinement criteria. Because of the size of these operations, the excessive amount of manure generated is typically stored in lagoons, pits, or barns prior to field application or transport to other farms. Water and air quality near CAFOs can be impaired through the overflow of lagoons, stormwater runoff, lagoon seepage or emissions, motivating the following research question: what manure lagoon parameters impact pollutant fate and transport across multiple mechanisms? To address this question, a CAFO lagoon module was developed to assess lagoon overflow risk, groundwater quality, and ammonia emissions of a dairy lagoon. The results from 10,000 Monte Carlo simulations indicated that lagoon overflow is a rare occurrence for simulated environmental conditions in Washington (3.17%). Second, we developed a groundwater module to complete a groundwater quality assessment of a Dairy Lagoon in Washington using analytical and semi-analytical solutions for groundwater solute transport. The long-term effects of this lagoon on water quality were explored as well as the effectiveness of improving the lagoon lining to reduce seepage. Doubling the lagoon liner thickness attenuated peak groundwater ammonia-N concentrations by 2.8. Lastly, we constructed an air quality module and found that ammonia emissions were not sensitive to changes in lagoon liner construction, but small reductions in lagoon pH significantly reduced yearly average ammonia emissions. The combined model can be used to improve understanding of the impacts of CAFO lagoon overflow and seepage and develop sustainable management practices at the field scale for these key components of the agricultural landscape.

Non-Contact In-Plane Movement Estimation of Floating Covers Using Finite Element Formulation on Field-Scale DEM

Unmanned aerial vehicle (UAV) assisted photogrammetry has been used to perform a non-contact measurement of the covers on the anaerobic wastewater lagoons at Melbourne Water Corporation’s Western Treatment Plant (WTP). These floating covers are valuable assets that eliminate odour and greenhouse gas emissions and harvest the methane-rich biogas as a renewable resource to generate electricity. Hence, the state of deformation of the floating covers becomes an important engineering factor for structural integrity assessment. UAVs have been deployed to scan these covers and photogrammetry has been used to process the aerial images to construct the floating covers’ orthophoto and digital elevation model (DEM). This paper proposes to adopt the finite element formulation to improve the quantification of the in-plane movement of a floating cover. Distinguishable features on the floating cover are first identified and their (x, y and z) coordinates are recorded over time. The results show that the technique can be used to quantify the short-term and long-term relative global lateral movement of the floating covers at WTP. More importantly, the results not only highlight the usefulness of this analysis for the integrity management of the floating cover but also show the value of clearly defined markers on the floating cover to facilitate the calculation of the cover’s state of strain.

Shear and solid-liquid separation behaviour of anaerobic digested sludge across a broad range of solids concentrations

Due to the non-homogeneous and multiphase nature of anaerobic lagoon constituents, CFD modelling for process optimisation requires continuous functions for shear and solid-liquid separation properties across a large range of solids concentrations. Unfortunately, measurement of existing material properties of anaerobic sludges is limited to only shear or solid-liquid separation, or to a limited solids concentration. In this work, the shear properties of an anaerobic sludge were measured from 0.4 to 12.5 vol%, which corresponds to the solids concentrations seen in lagoons. The sludge showed Newtonian behaviour at 0.4 vol% and Herschel-Bulkley yield stress fluid behaviour for higher concentrations ranging from 0.5 to 12 vol%. We compared multiple approaches to determine relationships between the model fitting parameters of consistency, k, flow index, n, and shear yield stress, τy with solids volume fraction ϕ.The solid-liquid separation properties were measured from sedimentation and filtration experiments to obtain compressibility and permeability properties across all the above-mentioned concentrations, enabling development of hindered velocity sedimentation curves. Comparison to full-scale anaerobic digestate identified that the pilot lagoon sludge had faster sedimentation at a given solids concentration in comparison to the digestate. This is the first study on simultaneous rheological characterisation and solid-liquid separation behaviour of an anaerobic sludge across a wide range of concentrations, thus enabling CFD modelling of the hydrodynamics and performance of anaerobic lagoons.

Economic and Environmental Assessment of Different Biogas Conversion Technologies for Cassava Pulp Treatment in Thailand: A Case Study

This research investigates the economic and environmental impact of various suitable biogas conversion technologies and their energy utilization options (electrical and thermal) on cassava pulp treatment. The results showed that the anaerobic cover lagoon (ACL), modified cover lagoon (MCL), and anaerobic baffled reactors (ABR) were the most suitable options in terms of the investment cost, which was the major factor influencing the selection of biogas technology. The ACL and MCL technologies had the highest values of NPV, a high IRR and a short payback period regardless of the energy utilization options due to their low investment and operating costs.

Stabilization of Sludge in Zakho Municipal Wastewater by Anaerobic Digestion for Biogas Production in Kurdistan Region, Iraq

Raw wastewater sludge samples were collected from two sanitary point sources in Zakho city wastewater pipes. Anaerobic digestion is utilized sludge stabilization as it was effective in reducing the volume of sludge and cheap source of clean biogas. the sludge of municipal wastewater of Zakho district is worth to be used for the generation of biogas and just 15 -17 kg sludge produced 233 to 350 m3 gas in solid retention time of 18 and 24 day respectively. Suspended solid is close related to the amount of COD that removed from sludge and approximately 1 kg COD generate 0.5-0.55 Kg suspended solid in the water. Volatile solid (VS) /total solid (TS) ratio is 0.46 after anaerobic digestion which locate in the range of anaerobic lagoon stabilization. Anaerobic digestion lead to reduction in total solid of wastewater especially organic or volatile suspended solid. Specific gravity of the sludge solid is1.5 which indicate that the sludge is stabilized by anaerobic digestion. Sludge volume index (SVI) indicate that the settleable biosolids are old, good quality and low turbidity. Sludge density index (SDI) increased from 1.83 to 2.9 ml/g after stabilization by anerobic digestion. CO2 and H2S are reduced to zero after stabilization by anaerobic digestion. Nutrients N, P, Ca, Mg, Cl are elevated significantly in final stabilized sludge to be used as organic fertilizer, except sulfate is decreased to acceptable ranges after stabilization.

Formation mechanisms and mechanical properties of anaerobic lagoon scum

The formation of a floating scum layer on the liquid surface of covered anaerobic lagoons prevents optimal and efficient lagoon operation. Scum can reduce hydraulic retention time, inhibit biogas capture and cause damage to lagoon covers. Managing the negative impact of scum requires understanding what scum is, how it forms and how it consolidates.This paper presents measurements of the physical and mechanical properties of scum and sludge samples from two covered anaerobic lagoons that alternatively treat municipal and abattoir waste. Both scum samples consisted of a large proportion of suspended solids that sank once the sample was diluted, degassed and mixed, indicating that sludge flotation and buoyancy due to biogas generation is a major contributor to scum accumulation. Total and soluble chemical oxygen demand and volatile solids in the scum are approximately 90 % higher than in sludge, which indicates that scum has a large proportion of undigested solids. Fourier-transform infrared spectroscopy demonstrates that scum and sludge have similar organic matter, with both including fats, oils, greases, proteins, and polysaccharides.Scum formation due to gas buoyancy implies that scum accumulation is inevitable and controlling fats, oils, and greases at the source of the wastewater is not enough to stop scum formation. Scum accumulation increases due to buoyancy, which drives scum compaction and increases the strength of the scum, as demonstrated by the measurement of scum compressional rheology. Scum management techniques that disturb the scum layer early enough to release the entrapped gas enable the scum to sink and get digested, thus minimising the impact of scum formation.

Predicting long-term solid accumulation in waste stabilisation lagoons through a combined CFD-process model approach

Sludge accumulation in anaerobic lagoons is one of the major issues determining long-term operating costs. However, very little mechanistic analysis has been done on long-term sludge behaviour. A coupled hydrodynamic-biochemical model was developed using computational fluid dynamics (CFD), and results from this applied to a compartmental based model (CBM) for long-term simulation. The CFD model incorporates a mixture method for the spatial-and temporal evolution of fluid and solids with a non-Newtonian rheology. CFD was used to evaluate short term hydrodynamics, and a common CBM used to understand the fluid movement and sludge behaviour of full-scale anaerobic lagoons (with varying depths, sidewall slopes, and loading rates), operating in commercial piggeries located in Southern Queensland and Southern New South Wales, Australia. The results found that the lagoons had varying hydrodynamics, and sludge accumulates rapidly in sloped sidewall lagoons, forming a variable depth bed which occupied a substantial fraction of the lagoons. Shallow lagoons were dominated by significant surface recirculation dynamics, and were susceptible to solids accumulation, while deep lagoons allowed the formation of a well developed settled fraction. Predicted lagoon lifetimes varied substantially, but predicted long-term accumulation rates were approximately double that observed, due to long-term degradation of slowly degradable material.

Simulation and economic evaluation of process alternatives for biogas production and purification from sugarcane vinasse

Vinasse, which is the main residue of ethanol production, is a promising alternative for the generation of biogas, due to its high generation rate and limited application. The objective of the present work is to simulate and economically compare alternative processes for the production and treatment of biogas from the anaerobic digestion of vinasse. Different water, H2S and CO2 removal technologies were evaluated: condensation, membrane separation, washing, Pressure Swing Adsorption (PSA), adsorptions with silica gel, activated carbon and metallic oxides, absorptions with triethylene glycol (TEG), ethylenediaminetetraacetic acid iron (III) (Fe/EDTA) and diethylamine (DEA). It was shown that an anaerobic lagoon is preferable over a set of Upflow Anaerobic Sludge Blanket (UASB) reactors due to the large processing scale, reducing the capital costs. Among the 12 evaluated routes, the best process alternative for biogas treatment was water removal through silica gel adsorption, followed by simultaneous H2S and CO2 absorption in a Fe/EDTA solution. In the best scenario, the entire biomethane production plant would require an investment of US$ 3.6 million, resulting in an annual net profit of US$ 1.99 million, with payback in the first year of operation.

PIG FARMS AND THEIR SURROUNDINGS AS A FACTOR IN THE SPREAD OF ANTIMICROBIAL RESISTANCE

In recent decades, in modern intensive animal husbandry, there has been a worrying trend towards the selection and spread of bacterial strains resistant to antibiotics. This global phenomenon has not only a certain negative effect on therapeutic practice, but also poses a serious risk to the spread of resistance in the food chain and in humans. Various genera from the family Enterobacteria like Salmonella, Shigella, Klebsiella, Yersinia, Citrobacter, etc. and especially Escherichia coli have a special place in this process. The most commonly used antibiotics for treatment of patients with complicated Salmonella infections are ceftriaxone and ciprofloxacin, to which the bacteria has already developed antibiotic resistance. For Escherichia coli, significantly increased resistance is developed to the third-generation cephalosporins, aminoglycosides, as well as combined resistance to three key antimicrobial groups (fluoroquinolones, third-generation cephalosporins and aminoglycosides). Resistance among Yersinia spp. against tetracyclines and fluorochinolones has been reported to the scientific community in numerous studies on human and animal isolates. By using the raw manure as fertilizer, these microorganisms may be transmitted to soil, wastewater or others environmental niches. Further, they can be transmitted via the food chain to humans and animals. Considering that the horizontal gene transfer is one of the most important mechanisms for transmitting of antimicrobial resistance, then after consumption of contaminated food, water, etc., genetically determined antibiotic resistance in animals can easily affect resistance among people, which makes vital drugs ineffective against serious illnesses. For the possible spread of antimicrobial resistance in pigs and related ecological niches - pig farms, manure lagoons, wastewater and soils, large-scale studies are being conducted to clarify their ecological and health significance. In addition, the results obtained will contribute to the development of an effective national strategy for the control of antimicrobial resistance.

A vermifiltration system for low methane emissions and high nutrient removal at a California dairy

Liquid storage of manure is a leading cause of methane emissions from the dairy sector and an important source of air and water pollution. This study monitored the effect of vermifiltration on methane emissions and water quality at a California dairy that uses an anaerobic lagoon. Methane fluxes and wastewater removal rate of volatile solids, N species, salinity, major ions, and trace elements were monitored for 12 months. Vermifiltration reduced methane emissions relative to an anaerobic lagoon by 97–99% and removed 87% of the volatile solids, contaminants such as salts and trace elements, P (83%) and N (84%) from the wastewater. Vermifiltration of dairy wastewater demonstrated to be a useful tool to mitigate methane emissions, regulate excess nutrients and improve water quality at dairy farms.

Evaluating California dairy methane emission factors using short-term ground-level and airborne measurements

Robust air pollutant emission reduction strategies rely on accurate source characterizations. Studies have reported that the methane (CH 4 ) emissions from California’s dairy sector are highly variable, and raised questions regarding the representativeness of the statewide CH 4 emission estimates. To address these questions, a multi-tiered field study was conducted to evaluate the dairy CH 4 emission factors (EFs) used in the California Air Resources Board (CARB) emission inventory. These EFs for dairy cow enteric fermentation and anaerobic lagoons are 144 and 332 kg of CH 4 per animal head per year. CH 4 emissions from dairies located within the San Joaquin Valley (SJV) were characterized through the analysis of ground-level mobile measurements collected in the summer and the fall of 2019. We developed a novel dispersion modeling-based approach that uses the ground-level mobile measurements of ambient CH 4 levels to generate a metric that evaluates the CARB CH 4 EFs. The analysis was further expanded using airborne measurements collected between September 2017 and May 2020. The multi-tiered measurements resulted in 126 whole-farm CH 4 emission estimates for 107 dairies, making this study the most comprehensive mobile research study focused on CH 4 emissions from California dairies to date. CARB CH 4 EFs represented dairy CH 4 emissions captured in this study fairly well; emissions observed in ground-level mobile measurements in summer and fall, and airborne measurements were greater than the inventory-reported values by only 8% (95% Confidence Interval [CI 95% ]: -7%–31%), 3% (CI 95% : -11 – 21%), and 10% (CI 95% : -7 – 45%), respectively. The results underline the effects of meteorology on dairy emissions and suggest that CH 4 EFs from dairies with different ranges of herd sizes did not vary significantly. Future evaluation of the CARB CH 4 emission inventory must incorporate facility-level data and leverage mechanistic approaches that capture the temporal variation of emissions from California’s dairy farms. Such improvements would enable research studies to better inform the emission inventory and help track the emissions changes from the implementation of new manure management technologies across California. • Methane emissions from 107 California dairies were characterized. • The most comprehensive mobile study on California dairies methane emissions. • Emission factors used in the emission inventory explained the collected data well. • Meteorological parameters, e.g. temperature and wind speed, impact dairy emissions. • Facility-level data and process-based models can inform the emission inventory.

Artificial Intelligence Approach for Estimating Dairy Methane Emissions.

California's dairy sector accounts for ∼50% of anthropogenic CH4 emissions in the state's greenhouse gas (GHG) emission inventory. Although California dairy facilities' location and herd size vary over time, atmospheric inverse modeling studies rely on decade-old facility-scale geospatial information. For the first time, we apply artificial intelligence (AI) to aerial imagery to estimate dairy CH4 emissions from California's San Joaquin Valley (SJV), a region with ∼90% of the state's dairy population. Using an AI method, we process 316,882 images to estimate the facility-scale herd size across the SJV. The AI approach predicts herd size that strongly (>95%) correlates with that made by human visual inspection, providing a low-cost alternative to the labor-intensive inventory development process. We estimate SJV's dairy enteric and manure CH4 emissions for 2018 to be 496-763 Gg/yr (mean = 624; 95% confidence) using the predicted herd size. We also apply our AI approach to estimate CH4 emission reduction from anaerobic digester deployment. We identify 162 large (90th percentile) farms and estimate a CH4 reduction potential of 83 Gg CH4/yr for these large facilities from anaerobic digester adoption. The results indicate that our AI approach can be applied to characterize the manure system (e.g., use of an anaerobic lagoon) and estimate GHG emissions for other sectors.

Digestión anaeróbica de residuos agroindustriales: Lagunas anaerobias en América Latina

The valorization of agro-industrial wastes (AW) by means of waste-to-energy strategies through anaerobic digestion (AD) is a reality in developed countries. In Latin America, there are different problems in the management of AW from intensive livestock farming. This study aims to provide a pseudo-radiography of AD management systems with a focus on anaerobic lagoons in Latin America (LATAM). Using data science, quantitative and qualitative data from 1003 scientific papers were synthesized and analyzed to form a database; which allowed evaluation of the congruence of the scientific research with the real problems of LATAM management. The results showed that anaerobic lagoons in the region are the main AW management systems (mainly bovine and swine manure) and that scientific research in this sector does not address the related problems. 38 types of inhibition phenomena with a total of 5264 mentions were addressed in the database. Nitrogen-related AR inhibition phenomena represented 21% of the incidences in this study, besides being the most significant phenomenon in anaerobic lagoons in LATAM

Reconstructing the historical expansion of industrial swine production from Landsat imagery

In the USA, historical data on the period over which industrial swine farms have operated are usually only available at the county scale and released every 5 years via the USDA Census of Agriculture, leaving the history of the swine industry and its potential legacy effects on the environment poorly understood. We developed a changepoint-based workflow that recreates the construction timelines of swine farms, specifically by identifying the construction years of swine manure lagoons from historical Landsat 5 imagery for the period of 1984 to 2012. The study focused on the Coastal Plain of North Carolina, a major pork-producing state in the USA. The algorithm successfully predicted the year of swine waste lagoon construction (+ /− 1 year) with an accuracy of approximately 94% when applied to the study area. By estimating the year of construction of 3405 swine waste lagoons in NC, we increased the resolution of available information on the expansion of swine production from the county scale to spatially-explicit locations. We further analyzed how the locations of swine waste lagoons changed in proximity to water resources over time, and found a significant increase in swine waste lagoon distances to the nearest water feature across the period of record.

Emissions of H2S from Hog Finisher Farm Anaerobic Manure Treatment Lagoons: Physical, Chemical and Biological Influence

Hydrogen sulfide (H2S) from hog operations contributes to noxious odors in the surrounding environment and can be life-threatening. There is, however, limited understanding of what influences H2S emissions from these farms. Emissions of H2S were measured periodically over the course of two years at hog finisher farms in humid mesothermal (North Carolina, NC, USA) and semi-arid (Oklahoma, OK, USA) climates. Emissions were determined using an inverse dispersion backward Lagrangian stochastic model in conjunction with line-sampled H2S concentrations and measured turbulence. Daily emissions at the two lagoons were characterized by low emissions on most days with occasional days of high emissions. Mean annual area-specific emissions were much lower for the NC lagoon (1.32 µg H2S m−2 s−1 ± 0.07 µg H2S m−2 s−1) than the OK lagoon (6.88 µg H2S m−2 s−1 ± 0.13 µg H2S m−2 s−1). Mean annual hog-specific emissions for the NC lagoon were 0.75 g H2S hd−1 d−1 while those for the OK lagoon were 1.92 g H2S hd−1 d−1. Emissions tended to be higher during the afternoon, likely due to higher mean winds. Daily H2S emissions from both lagoons were greatest during the first half of the year and decreased as the year progressed and a reddish color (indicating high populations of purple sulfur bacteria (PSB)) appeared in the lagoon. The generally low emissions at the NC lagoon and higher emissions at the OK lagoon were likely a result of the influence of wind on mixing the lagoon and not the presence of PSB.

Isotopic Signatures of Methane Emissions From Dairy Farms in California’s San Joaquin Valley

AbstractIn this study, we present seasonal atmospheric measurements of δ13CCH4 from dairy farms in the San Joaquin Valley of California. We used δ13CCH4 to characterize emissions from enteric fermentation by measuring downwind of cattle housing (e.g., freestall barns, corrals) and from manure management areas (e.g., anaerobic manure lagoons) with a mobile platform equipped with cavity ring‐down spectrometers. Across seasons, the δ13CCH4 from enteric fermentation source areas ranged from −69.7 ± 0.6 per mil (‰) to −51.6 ± 0.1‰ while the δ13CCH4 from manure lagoons ranged from −49.5 ± 0.1‰ to −40.5 ± 0.2‰. Measurements of δ13CCH4 of enteric CH4 suggest a greater than 10‰ difference between cattle production groups in accordance with diet. Isotopic signatures of CH4 were used to characterize enteric and manure CH4 from downwind plume sampling of dairies. Our findings show that δ13CCH4 measurements could improve the attribution of CH4 emissions from dairy sources at scales ranging from individual facilities to regions and help constrain the relative contributions from these different sources of emissions to the CH4 budget.

Mathematical modeling of algal blooms due to swine CAFOs in Eastern North Carolina

<p style='text-indent:20px;'>Dramatic strides have been made in treating human waste to remove pathogens and excess nutrients before discharge into the environment, to the benefit of ground and surface water quality. Yet these advances have been undermined by the dramatic growth of Confined Animal Feeding Operations (CAFOs) which produce voluminous quantities of untreated waste. Industrial swine routinely produce waste streams similar to that of a municipality, yet these wastes are held in open-pit "lagoons" which are at risk of rupture or overflow. Eastern North Carolina is a coastal plain with productive estuaries which are imperiled by more than 2000 permitted swine facilities housing over 9 million hogs; the associated 3,500 permitted manure lagoons pose a risk to sensitive estuarine ecosystems, as breaches or overflows send large plumes of nutrient and pathogen-rich waste into surface waters. Understanding the relationship between nutrient pulses and surface water quality in coastal environments is essential to effective CAFO policy formation. In this work, we develop a system of ODEs to model algae growth in a coastal estuary due to a manure lagoon breach and investigate nutrient thresholds above which algal blooms are unresolvable.</p>

Occurrence and Diversity of Listeria monocytogenes Isolated from Two Pig Manure Treatment Plants in France.

The presence of Listeria monocytogenes in piggery effluents intended for irrigation crops may be a source of bacterial dissemination in agriculture. The occurrence and diversity of L. monocytogenes in the farm environment were examined in two pig manure treatment systems (S1 and S2). Samples collected over the course of one year consisted of manure, the liquid fraction of treated manure (lagoon effluent), and soil surrounding the lagoon. L. monocytogenes was enumerated using the Most Probable Number (MPN) method, serotyped by PCR, genotyped by pulsed-field gel electrophoresis (PFGE), and sequenced for multilocus sequence typing (MLST). L. monocytogenes was detected in 92% of manure samples and in approximately 50% of lagoon effluent and soil samples. Concentrations ranged between 5 and 103 MPN 100‍ ‍mL-1. Serogroups IIa, IIb, and IVb were identified. Diversity was high with 44 PFGE profiles (252 isolates) and 17 clonal complexes (CCs) (96 isolates) with higher diversity in manure at site S1 supplied by four farms. Some PFGE profiles and CCs identified in manure or in pig feces from a previous study were also detected in lagoons and/or soil, reflecting pig L. monocytogenes circulation throughout the manure treatment and in the vicinity of the sampling sites. However, some PFGE profiles and CCs were only found in the lagoon and/or in soil, suggesting an origin other than pigs. The present study highlights the limited ability of biological treatments to eliminate L. monocytogenes from pig manure. The persistence of some PFGE profiles and CCs throughout the year in the lagoon and soil shows the ability of L. monocytogenes to survive in this type of environment.