Livestock Effluents Research Articles

Role of livestock effluent suspended particulate in sealing effluent ponds

Intensive livestock feed-lots have become more prevalent in recent years to help in meeting the predicted food production targets based on expected population growth. Effluent from these is stored in ponds, representing a potential concern for seepage and contamination of groundwater. Whilst previous literature suggests that effluent particulate can limit seepage adequately in combination with a clay liner, this research addresses potential concerns for sealing of ponds with low concentration fine and then evaluates this against proposed filter-cake based methodologies to describe and predict hydraulic reduction. Short soil cores were compacted to 98% of the maximum dry density and subject to ponded head percolation with unfiltered-sediment-reduced effluent, effluent filtered to <3 μm, and chemically synthesized effluent. Reduction in hydraulic conductivity was observed to be primarily due to the colloidal fraction of the effluent, with larger particulate fractions providing minimal further reduction. Pond sealing was shown to follow mathematical models of filter-cake formation, but without the formation of a physical seal on top of the soil surface. Management considerations based on the results are presented.

Evaluation of Biogas Plants by the Application of an Internal Rate of Return and Debt Service Coverage Approach

Energy production using renewable energy has an effect on environmental sustainability and on public expenditure. In fact, this industry is heavily assisted by public support from the European Union and the Italian State. Developing and applying a method to evaluate the return on investment for companies operating in the field of renewable energy allows them to quantify their efficient use of public resources. In this research we develop an assessment method that combines the rate of return on equity capital (IRRE) and financial viability (DSCR), in which IRRE > Ke and sub DSCR >1 for any given period of the investment. This method enables us to quantify both the equity capital return and financial sustainability. The method is applied to a case study of a company’s production of biogas from livestock effluents located in the province of Reggio Emilia, Italy. The analysis shows that biogas investment guarantees financial sustainability, even in the case of financial liabilities, in the case examined. It also shows that IRRE is higher than average, with a return on equity assured both by market average (MRP) and government bonds in the long term. The research could be further developed by quantifying the social welfare generated by public spending and private investment as equity capital, both in terms of its activation of the economy and in terms of assessing the environmental effects that qualify as externalities.

Water and nutrients recovering from livestock manure by membrane processes

Anaerobic digestion (AD) in a biogas plant is a well proven process in which livestock effluents break down naturally in the absence of oxygen to produce two valuable products: biogas and digestate. Three successive steps of membrane separation (UF, NF, RO) were carried out on digestate liquid fractions in order to recover molecules of interest and fresh water. Results demonstrate the capacity of a 300 kD filtration cut‐off to clarify and disinfect anaerobic digestion liquid phase, no suspended solids were detected in the permeate while more than 80 % of organic matters were removed. This clarification step allowed the use of downstream desalinating steps (NF, RO and NF/RO) which contribute to the achievement of fresh water production and ionic compounds of interest (phosphates, ammonium, potassium, magnesium…) concentration. NF and RO step allowed a total discoloration of treated water with a high removal of dissolved organic matter DOM (more than 90 %). The ion retention depends on the considered ion and the origin and composition of UF digestate. Nevertheless, a direct use of High Pressure Reverse Osmosis HPRO downstream UF step allowed an important retention of ions whatever the origin of digestate. The addition of RO downstream the NF step (NF/RO), increased the total salt rejection opening the door to a water reuse on site. The fresh water quality and the RO flux were higher for UF/NF/RO than UF/RO proving the interest for such a UF/NF/RO coupling.

Effects of changes in Italian bioenergy promotion schemes for agricultural biogas projects: Insights from a regional optimization model

Italy has witnessed an extraordinary growth in biogas generation from livestock effluents and agricultural activities in the last few years as well as a severe isomorphic process, leading to a market dominance of 999kW power plants owned by “entrepreneurial farms”. Under the pressure of the economic crisis in the country, the Italian government has restructured renewable energy support schemes, introducing a new program in 2013. In this paper, the effects of the previous and current support schemes on the optimal plant size, feedstock mix and profitability were investigated by introducing a spatially explicit biogas supply chain optimization model, which accounts for different incentive structures. By applying the model to a regional case study, homogenization observed to date is recognized as a result of former incentive structures. Considerable reductions in local economic potentials for agricultural biogas power plants without external heat use, are estimated. New plants are likely to be manure-based and due to the lower energy density of such feedstock, wider supply chains are expected although optimal plant size will be smaller. The new support scheme will therefore most likely eliminate past distortions but also slow down investments in agricultural biogas plants.

Mapping of Biomass Fluxes: A Method for Optimizing Biogas-Refinery of Livestock Effluents

This paper presents the topic of the management of livestock effluents and, therefore, nutrients (particularly N) in the framework of the biogas supply chain. The bio-refinery will be analyzed as a unique system, from the farm to the biomass produced and sent to anaerobic digestion, focusing on the fate/change of the flow of material and nutrients content through the system. Within four categories of farms considered in the article, integrated ones frequently have a breeding consistency from 90 to 320 heads, according to more extensive or intensive settings. These farms must manage from 3.62 to 12.81 m3 day−1 of slurry and from 11.40 to 40.34 kg day−1 of nitrogen (N) as the sum of excreta from all herd categories. By selecting a hypo-protein diet, a reduction of 10% and 24% for total effluent amount and for N excreted, respectively, can be achieved. Nitrogen can be reduced up to 45% if the crude protein content is limited and a further 0.23% if animals of similar ages, weights and (or) production or management are grouped and fed according to specific requirements. Integrated farms can implement farming activity with biogas production, possibly adding agricultural residues to the anaerobically-digested biomass. Average biogas yields for cattle effluents range from 200 to 400 m3 ton−1 VS (volatile solids). Values from 320 to 672 m3 day−1 of biogas can be produced, obtaining average values from 26 to 54.5 kWe (kilowatt-electric). This type of farm can well balance farm-production profit, environmental protection, animal husbandry well-being and energy self-sufficiency.

Produrre energia rinnovabile nelle aziende agro-zootecniche. Effetti economici dalle novità introdotte nella normativa del 2012

This study proposes an analysis to evaluate the effects on the future choices of the zootechnical entrepreneur in light of the new indications in the Ministerial Decree of the July 6, 2012 Execution of Art. 24 of the legislative decree 3 March 2011, no. 28 establishing incentives for the production of electricity from plants of renewable sources other than photovoltaic. Specifically, we will investigate the productive chain of biogas from anaerobic digestion and, in particular, the synergies that can be realized with the swine sector. The main objective is to assess what are the critical and the strength moments for the zootechnical entrepreneur in each stage of the chain, analyzing the opportunities of integration in order to gain an economic advantage in introducing innovative activities of process and transformation of livestock effluents; an economic profit can afford to enable virtuous practices on the part of the entrepreneur, also environmentally correct and able to make more sustainable the activities in the medium-long term.

Small-Scale Biogas-SOFC Plant: Technical Analysis and Assessment of Different Fuel Reforming Options

This paper investigates simulation results of the thermodynamic performance of a 25 kWel small-scale solid oxide fuel cell model fuelled with biogas. Hereby, biogas is produced from a predefined group of substrates, namely, livestock effluents, energy crops, agricultural waste, and organic waste. For the analysis, average methane (CH4) content is assumed to lie between 50 and 60 mol % as large seasonal and daily variations are observed which are independent of used matter. The main biogas contaminants are sulfur compounds, mostly in the form of H2S. Sulfur leads to fast catalyst deactivation in the reformer and fuel cell, which is why an effective gas-cleaning system is established. For this, ZnO and activated carbon are the most practical gas-cleaning solutions for small-scale plants. The energy model of the solid oxide fuel cell plant is designed and analyzed through detailed energy and mass balance calculations throughout all system components and streams. The above-mentioned model is set up in in such...

Evaluating Spatial and Temporal Variability of Fecal Coliform Bacteria Loads at the Pelahatchie Watershed in Mississippi

ABSTRACT Bacterial contaminations of surface waters are an increasing concern for scientists and public health agencies because pathogenic bacteria can cause adverse effects on human health. This research was performed to investigate spatial and seasonal variability of fecal coliform bacteria (FCB) concentrations in the Pelahatchie watershed (527 km2) in Mississippi, USA. Livestock manure, poultry litter, and effluent from failing septic systems were identified as major sources of FCB in the Pelahatchie watershed. The Soil and Water Assessment Tool (SWAT)/microbial sub-model was applied, and model-simulated FCB concentrations were compared with the monthly measured FCB concentrations (years 2001–2008) at the outlet of the watershed. New methodologies were introduced to incorporate bacteria loads into the bacteria model. Results showed coefficients of determination (R 2) of 0.71 to 0.75, and Nash-Sutcliffe efficiency index (NSE) of 0.67 to 0.75 during the bacteria model's calibration and validation periods, respectively. Seasonal analysis of the model-simulated results determined the highest bacteria concentrations in January, whereas the lowest concentrations were simulated in June. Furthermore, the FCB contributions to the watershed outlet from the sources of contamination varied with time of year. This study will help watershed managers to implement best management practices for improvement of water quality.

A farm-scale pilot plant for biohydrogen and biomethane production by two-stage fermentation

Hydrogen is considered one of the possible main energy carriers for the future, thanks to its unique environmental properties. Indeed, its energy content (120 MJ/kg) can be exploited virtually without emitting any exhaust in the atmosphere except for water. Renewable production of hydrogen can be obtained through common biological processes on which relies anaerobic digestion, a well-established technology in use at farm-scale for treating different biomass and residues. Despite two-stage hydrogen and methane producing fermentation is a simple variant of the traditional anaerobic digestion, it is a relatively new approach mainly studied at laboratory scale. It is based on biomass fermentation in two separate, seuqential stages, each maintaining conditions optimized to promote specific bacterial consortia: in the first acidophilic reactorhydrogen is produced production, while volatile fatty acids-rich effluent is sent to the second reactor where traditional methane rich biogas production is accomplished. A two-stage pilot-scale plant was designed, manufactured and installed at the experimental farm of the University of Milano and operated using a biomass mixture of livestock effluents mixed with sugar/starch-rich residues (rotten fruits and potatoes and expired fruit juices), afeedstock mixture based on waste biomasses directly available in the rural area where plant is installed. The hydrogenic and the methanogenic reactors, both CSTR type, had a total volume of 0.7m3 and 3.8 m3 respectively, and were operated in thermophilic conditions (55􀀀 2 °C) without any external pH control, and were fully automated. After a brief description of the requirements of the system, this contribution gives a detailed description of its components and of engineering solutions to the problems encountered during the plant realization and start-up. The paper also discusses the results obtained in a first experimental run which lead to production in the range of previous laboratory results, with a typical hydrogen and methane specific productivity of 2.2 and 0.5 Nm3/m3reactor per day, in the first and second stage of the plant respectively. At our best knowledge, this plant is one of the very first prototypes producing biohydrogen at farm scale, and it represents a distributed, small scale demonstration to obtain hydrogen from renewable waste-sources.

Biogas Upgrading: Analysis and Comparison between Water and Chemical Scrubbings

Biomethane is a renewable energy source that can be used, e.g., for transportation or injection in the natural gas grids. It is obtained from proper biogas treatment. Biogas is a mixture of mainly methane and CO2 that can be produced from livestock effluents, municipal and industrial sewage sludge, energy crops, agro-industrial wastes, MSW landfills (in this case the gas is commonly called “landfill gas”) etc. In order to obtain biomethane, CO2 and other compounds must be removed from biogas. The type and the amount of pollutants depend upon the biogas source and determine which cleaning and upgrading techniques are the most suitable for gas purification. “Cleaning” is referred to as the pretreatment that allows the removal of all pollutants but carbon dioxide, while “upgrading” is the treatment for CO2 removal. Since there are no clear guidelines for choosing among different upgrading techniques, this work analyzes two of the most commonly used processes: the water scrubbing and the chemical scrubbing (using amine solutions). By means of process simulation with commercial packages (such as Aspen Plus), a comparison among the performances of the two techniques is made.

A farm-scale pilot plant for biohydrogen and biomethane production by two-stage fermentation

Hydrogen is considered one of the possible main energy carriers for the future, thanks to its unique environmental properties. Indeed, its energy content (120 MJ/kg) can be exploited virtually without emitting any exhaust in the atmosphere except for water. Renewable production of hydrogen can be obtained through common biological processes on which relies anaerobic digestion, a well-established technology in use at farm-scale for treating different biomass and residues. Despite two-stage hydrogen and methane producing fermentation is a simple variant of the traditional anaerobic digestion, it is a relatively new approach mainly studied at laboratory scale. It is based on biomass fermentation in two separate, seuqential stages, each maintaining conditions optimized to promote specific bacterial consortia: in the first acidophilic reactorhydrogen is produced production, while volatile fatty acids-rich effluent is sent to the second reactor where traditional methane rich biogas production is accomplished. A two-stage pilot-scale plant was designed, manufactured and installed at the experimental farm of the University of Milano and operated using a biomass mixture of livestock effluents mixed with sugar/starch-rich residues (rotten fruits and potatoes and expired fruit juices), afeedstock mixture based on waste biomasses directly available in the rural area where plant is installed. The hydrogenic and the methanogenic reactors, both CSTR type, had a total volume of 0.7m3 and 3.8 m3 respectively, and were operated in thermophilic conditions (55􀀀 2 °C) without any external pH control, and were fully automated. After a brief description of the requirements of the system, this contribution gives a detailed description of its components and of engineering solutions to the problems encountered during the plant realization and start-up. The paper also discusses the results obtained in a first experimental run which lead to production in the range of previous laboratory results, with a typical hydrogen and methane specific productivity of 2.2 and 0.5 Nm3/m3reactor per day, in the first and second stage of the plant respectively. At our best knowledge, this plant is one of the very first prototypes producing biohydrogen at farm scale, and it represents a distributed, small scale demonstration to obtain hydrogen from renewable waste-sources.

Utilizations of Food Waste as an Anaerobic Digester Feedstock

For many years, anaerobic digestion has been utilized in order to treat the odorous, pathogenic, and dissolved-oxygen-reducing-characteristics of both anthropogenic and livestock effluent waste streams. In addition to this beneficial biological treatment, such digestion provides both methane gas and digestate which serve as a valuable fuel and fertilizer, respectively. However, food waste also has the potential to serve as a useful feedstock for anaerobic digestion due to its high volatile (combustible) solids content and propensity for rapid biodegradation. There are a number of parameters of concern when using food waste for such digestion which increases the operation complexity of digester systems, but if such devices are properly monitored and adjusted, food waste has the potential to serve as a sole feedstock or as part of a dual manure-food waste input; both cases provide an improvement in gas generation production.

Co-digestion of livestock effluents, energy crops and agro-waste: Feeding and process optimization in mesophilic and thermophilic conditions

In this study the optimization of the biogas yield from anaerobic co-digestion of manures and energy crops was carried out using four pilot scale CSTRs under different operating conditions. The effect on biogas yield of the partial substitution of energy crops with agro-waste was also investigated. For each substrate used during the continuous trials, BMP batch assays were also carried out to verify the maximum methane yield theoretically obtainable. Continuous operation results indicated that the co-digestion of manures, energy crops and agro-waste was viable at all operating conditions tested, with the greatest specific gas production of 0.54m3/kgVSfed at an organic load rate of 2kgTVS/m3rd consisting of 50% manure, 25% energy crops and 25% agro-waste on VS basis. No significant differences were observed between high and low loaded reactors suggesting the possibility of either improving the OLR in existing anaerobic reactors or reducing the design volumes of new reactors.

Modeling organic matter stabilization during windrow composting of livestock effluents

Composting is a complex bioprocess, requiring a lot of empirical experiments to optimize the process. A dynamical mathematical model for the biodegradation of the organic matter during the composting process has been developed. The initial organic matter expressed by chemical oxygen demand (COD) is decomposed into rapidly and slowly degraded compartments and an inert one. The biodegradable COD is hydrolysed and consumed by microorganisms and produces metabolic water and carbon dioxide. This model links a biochemical characterization of the organic matter by Van Soest fractionating with COD. The comparison of experimental and simulation results for carbon dioxide emission, dry matter and carbon content balance showed good correlation. The initial sizes of the biodegradable COD compartments are explained by the soluble, hemicellulose-like and lignin fraction. Their sizes influence the amplitude of the carbon dioxide emission peak. The initial biomass is a sensitive variable too, influencing the time at which the emission peak occurs.

Identification of estrogenic activity change in sewage, industrial and livestock effluents by gamma-irradiation

In this study, reduction of estrogenic activity in three different types of effluents from sewage, industrial and livestock wastewater treatment plants by gamma-irradiation was investigated using the yeast two-hybrid assay. After gamma-ray treatment at a dose of 10kGy, estrogenic activities of sewage, industrial and livestock effluents decreased from 4.4 to 3.0, 1.5 to 1.0 and 16 to 9.9ng-EEQL−1, respectively. The substantial reduction of estrogenic activity in livestock effluent was attributable to the degradation of 17β-estradiol (E2), estrone (E1) and 17α-ethynylestradiol (EE2). Although bisphenol A (BPA) was found at the highest concentration in all effluents, its contribution to the estrogenic activity was not significant due to its low relative estrogenic potency. Meanwhile, the calculated estrogenic activity based on concentrations of E2, E1, EE2 and BPA in the effluents significantly differed from the measured ones. Overestimation may have resulted by dissolved organic matters in effluents inhibiting the estrogenic activity of E2, E1, EE2 and BPA, whereas underestimation was likely due to estrogenic by-products generated by gamma-irradiation.

Future Perspectives for Bio-Energy Production in the Province of Turin

The present work investigates waste management in the Province of Turin and discusses different policy instruments, taking into account the potential of biogas obtained from Municipal Solid Waste (MSW), separated source collection, livestock effluents and energy crops. MSW from a large Turin landfill can produce 98.8 kWhe/t and the energy yearly produced correspond to 3.85% of the domestic requirements for the whole province. As far as the separated source collection is concerned, a substantial decrease in the production of biogas in landfills has been observed. The organic fraction instead could be sent to anaeroblic digestion plants to produce energy. Finally, waste from livestock and agricultural products could make a significant contribution to energy recovery (even more than 5% of the domestic requirements).

Production of renewable energies and biomolecules from livestock and agro-industrial waste: the BIOMOLENER Project

The BIOMOLENER project is focused in the combination of physical and biological treatments of livestock effluents and whey to exploit their potential as a direct source of commodity chemicals, or as a pabulum for fermentations, aimed at reaching biofuels or microbial biomasses from which biomolecules can be extracted. Processing of these waste give a contribution to the reduction of polluting characteristics.

Technical and economical assessment of formic acid to recycle phosphorus from pig slurry by a combined acidification–precipitation process

Dissolution by acidification followed by a liquid/solid separation and precipitation of phosphorus from the liquid phase is one possibility to recycle phosphorus from livestock effluents. To avoid increase of effluent salinity by using mineral acids in the recycling process, the efficiency of two organic acids, formic and acetic acid, in dissolving the mineral phosphorus from piggery wastewater was compared. The amount of formic acid needed to dissolve the phosphorus was reduced three fold, compared to acetic acid. The amount of magnesium oxide needed for further precipitation was decreased by two with formic acid. Neither the carbon load nor the effluent salinity was significantly increased by using formic acid. An economical comparison was performed for the chemical recycling process (mineral fertilizer) vs. centrifugation (organic fertilizer) considering the centrifugation and the mineral fertilizers sold in the market. After optimisation of the process, the product could be economically competitive with mineral fertilizer as superphosphate in less than 10 years.

Challenges and innovations on biological treatment of livestock effluents

Intensification of animal production led to high amounts of manure to be managed. Biological processes can contribute to a sustainable manure management. This paper presents the biological treatments available for the treatment of animal manure, mainly focusing on swine manure, including aerobic processes (nitrification, denitrification, enhanced biological phosphorus removal) and anaerobic digestion. These processes are discussed in terms of pollution removal, ammonia and greenhouse gas emissions (methane and nitrous oxide) and pathogen removal. Application of emerging processes such as partial nitrification and anaerobic ammonium oxidation (anammox) applied to animal manure is also considered. Finally, perspectives and future challenges for the research concerning biological treatments are highlighted in this paper.

Removal of Phosphorus from Livestock Effluents

For removal of phosphorus (P) from swine liquid manure before land application, we developed a treatment process that produces low P effluents and a valuable P by-product with minimal chemical addition and ammonia losses. The new wastewater process included two sequential steps: (i) biological nitrification and (ii) increasing the pH of the nitrified wastewater to precipitate P. We hypothesized that by reduction of inorganic buffers (NH(4)(+) and carbonate alkalinity) via nitrification, P could be selectively removed by subsequent hydrated lime [Ca(OH)(2)] addition. The objective of the study was to assess if this new treatment could consistently reduce inorganic buffer capacity with varied initial concentrations of N (100-723 mg NH(4)(+) L(-1)), P (26-85 mg TP L(-1)), and alkalinity (953-3063 mg CaCO(3) L(-1)), and then efficiently remove P from swine lagoon liquid. The process was tested with surface lagoon liquids from 10 typical swine farms in North Carolina. Each lagoon liquid received treatment in a nitrification bioreactor, followed by chemical treatment with Ca(OH)(2) at Ca rates of 0, 2, 4, 6, 8, 10, and 12 mmol L(-1) to precipitate P. This configuration was compared with a control that received the same Ca rates but without the nitrification pretreatment. The new process significantly reduced >90% the inorganic buffers concentrations compared with the control and prevented ammonia losses. Subsequent lime addition resulted in efficient pH increase to > or = 9.5 for optimum P precipitation in the nitrified liquid and significant reduction of effluent total P concentration versus the control. With this new process, the total P concentration in treated liquid effluent can be adjusted for on-farm use with up to >90% of P removal. The recovered solid Ca phosphate material can be easily exported from the farm and reused as P fertilizer. Therefore, the new process can be used to reduce the P content in livestock effluents to levels that would diminish problems of excess P accumulation in waste-amended soils.