Ammoniacal Nitrogen Concentration Research Articles

Batch studies with Exiguobacterium aurantiacum degrading structurally diverse organic compounds and its potential for treatment of biomass gasification wastewater

Biomass gasification wastewater primarily consists of phenolics, nitrogen-heterocyclics and polynuclear aromatic hydrocarbons (PAHs). Biodegradation of these compounds present individually as sole substrate is studied in batch cultures in presence of Exiguobacterium aurantiacum. It demonstrated good potential for degrading phenol, pyridine, quinoline, benzene and naphthalene present at initial concentration (Cin) of 500 mg l−1. E. aurantiacum could also utilize 3- and 4-ring PAHs, phenanthrene, fluoranthene and pyrene as sole substrate present at 100 mg l−1 (Cin). While significant increase in absorbance was observed on 3 and 4-ring PAHs, the increase in number concentration of viable cells and extent of degradation was relatively low. E. aurantiacum could effectively degrade a synthetic biomass gasifier wastewater comprised of these compounds with a total COD of 1326 mg l−1 and biokinetic studies revealed applicability of Monod's kinetics for culture growth on gasifier wastewater. The half velocity constant (Ks) and maximum specific growth rate (μmax) were 651 mg l−1 and 1.86 d−1, respectively. All components in the wastewater were degraded simultaneously and compounds with comparable concentration depicted comparable degradation rates. E. aurantiacum could degrade the organics in biomass gasification wastewater even when the ammoniacal-nitrogen concentration was increased up to 1000 mg l−1. Bioaugmentation with E. aurantiacum can significantly enhance biological treatment of biomass gasification wastewater.

Efeito da torta de nabo forrageiro sobre a cinética de fermentação e degradação ruminal in vitro

Considering the need to give the correct destination to co-products generated in the production of biodiesel, as well as nutritionally characterize alternative sources of protein for cattle, the objective of this study was to evaluate ruminal parameters and nutritional value of diets containing 0, 2, 4 and 8 % replacement of cottonseed meal by radish cake utilizing a semi-automated in vitro gas production technique. The evaluation of rumen degradation kinetics, digestibility of DM, OM and NDF, as well as pH, volatile fatty acids and ammoniacal nitrogen determination were performed by incubating 0.3 g of sample in buffered medium. It was observed a cubic effect of the replacement level on the volume of gas corresponding to complete digestion of the substrate, with values of 1.69, 1.70, 1.53, 1.61 mL/mg DM, respectively, for levels 0, 2, 4 and 8 % of substitution. There was a quadratic effect of the level of cottonseed meal replacement by radish cake on the in vitro digestibility of DM, OM and NDF, with maximum points in 2.75, 2.70 and 2.63 % of radish cake, respectively. The cottonseed meal replacement by radish cake influenced total concentration of VFA, concentration of ammoniacal nitrogen and the molar ratio of acetic and propionic acid. The acetate: propionate ratio and pH were not influenced by the substitution of cottonseed meal by radish cake, with average values of 3.36 and 6.93, respectively. It is concluded that the replacement of 2.63 % of the cottonseed meal by radish cake provided better digestibility of DM, OM and NDF of the diets, suggesting that the radish cake can be used in rations of beef cattle, partially replacing the cottonseed meal.

Toxicity on Anabas Testudineus: A Case Study of Sanitary Landfill Leachate

In many parts of the developing world, leachate treatment system is not properly installed and managed that landfill leachate usually flows into existing water bodies. Consequently, heavy metal in leachate could lead to biomagnification of heavy metals as the components travel higher within the food chain. Thus, it is necessary to understand the characteristics of leachate and its toxicity potential prior to its release to the water bodies. This paper aims to determine the toxicity effect of different types of landfill leachate on Anabas testudineus. Also, the behavioural changes towards leachate toxicity will be recorded. To achieve the objectives, toxicity tests were conducted on A. testudineus. It involved three main stages namely acclimatisation, range finding test, and short-term definitive test. For the purpose of the study, leachate samples were collected from an active sanitary landfills and a closed sanitary landfill. Ten A. testudineus with average weight of 4.2g and average length of 4.0cm were introduced into leachate with five different concentrations ranging from 3.125% to 5.625%. The mortality rate was observed and recorded after 96 hours exposure. The LC50 of A. testudineus was calculated using EPA Probit software. Leachate from non-active landfill is alkaline (pH 8.2) as compared to that of the active landfill (pH 7.35). As expected, COD from the closed landfill is much lower (10,000mg/l) than the active landfill (24,800 mg/l) while the BOD5 was 3,500mg/l and 12,500mg/l, respectively. However, the result of ammoniacal nitrogen was highly different between these landfills, where closed landfill is releasing higher concentration of ammoniacal nitrogen (880mg/l) than the active landfill (0.085mg/l). The toxicity test indicated that both landfill leachates are highly toxic to A. testudineus. In fact, leachate from the closed landfill was more toxic than leachate from the active landfill. Results indicated that the LC50 of the leachate from closed landfill on A. testudineus was 4.71% v/v while LC50 of the leachate from active landfill was 5.1%. Discolouration of exposed fishes was observed in the study, and it could be due to the loss of colouring pigment caused by ammonia poisoning. Other observation of behavioural changes included swimming disorder, loss of equilibrium, unusual leaping action, and declination in the general activities. These are most probably due to neurotoxin effect inflected by the leachate exposure. In conclusion, leachate from active and nonactive landfills is toxic to A. testudineus based on the behavioural changes and the high mortality rate

Treatment of landfill leachate by using lateritic soil as a natural coagulant

In this research, the capability of lateritic soil used as coagulant for the treatment of stabilized leachate from the Penang-Malaysia Landfill Site was investigated. The evaluation of lateritic soil coagulant in comparison with commercialized chemical coagulants, such as alum, was performed using conventional jar test experiments. The optimum pH and coagulant dosage were identified for the lateritic soil coagulant and the comparative alum coagulant. It was found that the application of lateritic soil coagulant was quite efficient in the removal of COD, color and ammoniacal-nitrogen content from the landfill leachate. The optimal pH value was 2.0, while 14 g/L of lateritic soil coagulant was sufficient in removing 65.7% COD, 81.8% color and 41.2% ammoniacal-nitrogen. Conversely, the optimal pH and coagulant dosage for the alum were pH 4.8 and 10 g/L respectively, where 85.4% COD, 96.4% color and 47.6% ammoniacal-nitrogen were removed from the same leachate sample. Additionally, the Sludge Volume Index (SVI) ratio of alum and lateritic soil coagulant was 53:1, which indicated that less sludge was produced and was an environmentally friendly product. Therefore, lateritic soil coagulant can be considered a viable alternative in the treatment of landfill leachate.

Effect of low-dose liquid ozonation on gaseous emissions from pig slurry

The effect of low-dose liquid ozonation on gaseous emissions from pig slurry was investigated in a laboratory-scale ozonation chamber. The slurry samples were ozonated and/or mixed for 8 to 80 min in order to achieve ozone doses of 20–200 mg [O 3 ] l −1 of slurry. The hydrogen sulphide (H 2 S) emission rate from ozonated slurry samples was lower than from non-ozonated controls and had lower H 2 S emissions than the controls for at least 5 h after treatment. The highest H 2 S reduction in emission rate (98%) was reached when applying 80 mg [O 3 ] l −1 . This implies that ozonation of slurry could be used as a means of reducing H 2 S emissions during soil application and thereby the immediate odour nuisance, although there were no change to emissions of other odour compounds such as volatile fatty acids (VFA), phenols and indoles. The concentration of total ammoniacal nitrogen (TAN) was not affected by ozonation. However, the ammonia (NH 3 ) emission rate increased in proportion to mixing time, and slurry ozonation tended to increase the NH 3 emission rate even further, though the concentration of total ammoniacal nitrogen (TAN) was unchanged. Hence the risk of higher NH 3 emissions limits the application potential of slurry ozonation.

Are ammonia emissions from field-applied slurry substantially over-estimated in European emission inventories?

Abstract. The EMEP/EEA guidebook 2009 for agricultural emission inventories reports an average ammonia (NH3) emission factor (EF) by volatilisation of 55% of the applied total ammoniacal nitrogen (TAN) content for cattle slurry, and 35% losses for pig slurry, irrespective of the type of surface or slurry characteristics such as dry matter content and pH. In this review article, we compiled over 350 measurements of EFs published between 1991 and 2011. The standard slurry application technique during the early years of this period, when a large number of measurements were made, was spreading by splash plate, and as a result reference EFs given in many European inventories are predominantly based on this technique. However, slurry application practices have evolved since then, while there has also been a shift in measurement techniques and investigated plot sizes. We therefore classified the available measurements according to the flux measurement technique or measurement plot size and year of measurement. Medium size plots (usually circles between 20 to 50 m radius) generally yielded the highest EFs. The most commonly used measurement setups at this scale were based on the Integrated Horizontal Flux method (IHF or the ZINST method (a simplified IHF method)). Several empirical models were published in the years 1993 to 2003 predicting NH3 EFs as a function of meteorology and slurry characteristics (Menzi et al., 1998; Søgaard et al., 2002). More recent measurements show substantially lower EFs which calls for new measurement series in order to validate the various measurement approaches against each other and to derive revised inputs for inclusion into emission inventories.

Co-digestion of source segregated domestic food waste to improve process stability

Cattle slurry and card packaging were used to improve the operational stability of food waste digestion, with the aim of reducing digestate total ammoniacal nitrogen concentrations compared to food waste only. Use of cattle slurry could have major environmental benefits through reducing greenhouse gas emissions associated with current management practices; whilst card packaging is closely linked to food waste and could be co-collected as a source segregated material. Both options increase the renewable energy potential whilst retaining organic matter and nutrients for soil replenishment. Co-digestion allowed higher organic loadings and gave a more stable process. A high ammonia inoculum acclimated more readily to cattle slurry than card packaging, probably through supplementation by trace elements and micro-organisms. Long-term operation at a 75-litre scale showed a characteristic pattern of volatile fatty acid accumulation in mono-digestion of food waste, and allowed performance parameters to be determined for the co-digestion substrates.

Aerobic stability of sugar cane silages with a novel strain of Lactobacillus sp. isolated from sugar cane

The objective of this research was to evaluate the effect of the addition of two Lactobacillus strains on the aerobic stability of the sugar cane (Saccharum spp.) silages. The experiment was carried out in a completely randomized design with three replicates in split-plot in time scheme, so that the treatments (silages without inoculant and with novel strain or commercial inoculants) were randomized on plot and in times of aerobic evaluation of the silages (zero, two, four, and six days after the opening of the silos) as subplots. The loss of stability of silages was continuous during the time of aerobic exposure. Inoculants influenced the changes in populations of lactic acid bacteria and yeasts and in the ammoniacal nitrogen, acetic acid and ethanol concentrations. The dry matter, crude protein, soluble carbohydrates contents and pH values showed similar changes in all three silages studied. A linear increase in crude protein content and pH values and decrease in the soluble carbohydrates content were observed. The dry matter contents increased to a maximum of 335 g/kg on fresh matter at four days, followed by reduction after six days. The results showed that the use of inoculants is recommended because it promoted higher production of acetic and propionic acids, reducing the population of yeast and, therefore, improving the aerobic stability of silages.

Technical Note: Feasibility of Extracting Ammonia from Broiler Litter and Scale-Up Considerations

Air inside the broiler litter bed has high ammonia concentrations. The feasibility of extracting ammonia from the broiler litter bed for use as a fertilizer was investigated. Suction was applied to six -in. (12.7-mm) CPVC pipes with perforations placed 0.15 m below the litter surface in a pen stocked with 150 birds. Litter air was pulled into a phosphoric acid reactor where the ammonia was converted to ammonium phosphate, a fertilizer. Over 51 d, 72.6 g of ammonia was recovered and the pipes did not clog. Ammonia recovery could have been higher had litter ammonia concentrations been comparable with commercial broiler houses. Ammonia removal from the pen did not impact ammonia concentrations above the litter or bird performance. Placing the pipes close to the litter surface where total ammoniacal nitrogen concentrations would have been higher due to fecal loading may have reduced ammonia concentrations in the pen. Litter moisture content was reduced by the ammonia extraction system. A modified scaled-up system may be technically feasible but not cost-effective. Economic feasibility of the system can be improved if pipes placed closer to the surface improve bird performance by reducing in-house ammonia concentrations.

Influence of different mixing ratios on in-vessel co-composting of sewage sludge with horse stable straw bedding waste: maturity and process evaluation

Composting sewage sludge alone would reduce the decomposition efficiency due to free limited porosity in sludge. To alleviate this, the use of horse stable straw bedding waste (HSB) was evaluated as a co-composting material with sewage sludge in a 10 tonnes day(-1) in-vessel composter for a period of 7 days before curing in a static aeration pile. Sludge was mixed with HSB at 1 : 1.5 (HSL) and 1 : 2.9 (LSL) on a fresh weight basis. After a composting period of 56 days, both mixing ratios demonstrated to be feasible with LSL having a better organic decomposition and a shorter time to reach maturity. The overall decomposition rates were 52.0 and 58.9% (dry weight basis) for HSL and LSL, respectively. In both treatments, temperature in the in-vessel composters could reach 65°C, which was sufficient to remove the pathogens. Although both products were free of pathogens, HSL exhibited a higher ammoniacal nitrogen contents but a lower seed germination index than that of LSL indicating a higher phytotoxicity and a longer curing period would be required. It can be concluded that HSB provided a better composting conditions at a mixing ratio of 1 : 2.9.

Use of an algal consortium of five algae in the treatment of landfill leachate using the high-rate algal pond system

Five species of microalgae Chlorella vulgaris, Scenedesmus quadricauda, Euglena gracilis, Ankistrodesmus convolutus and Chlorococcum oviforme, were screened for their ability to grow in treated landfill leachate (TL) using shake flask cultures. The treated leachate had undergone previous treatment through mechanical aeration in treatment ponds at the landfill site. The five algae, except for C. oviforme, were able to grow in medium containing up to 50% TL. Two high-rate algal ponds (HRAP) equipped with paddlewheel were used for the semi-continuous cultures. A mixture of the five algae was used to inoculate one of two HRAPs for secondary treatment of TL. The other HRAP was filled with natural lake water containing mixed populations of algae. A volume of 400 mL (1%) from both ponds were removed daily and replaced with TL. The leachate loading rate was increased to 2% (0.8 L day−1) on day 197 and then to 4% (1.6 L day−1) on day 309, providing hydraulic retention time of 100, 50 and 25 days, respectively. Although higher biomass was obtained in the HRAP containing the consortium of five algae, there was no significant difference in reduction of pollutants between the two ponds. The HRAPs produced algal biomass ranging from 2.00 to 5.54 g dry weight L−1 with significant reduction in chemical oxygen demand (91.0%), ammoniacal nitrogen (99.9%) and orthophosphate (86.0%) contents. The HRAP offers a potential treatment system for TL which is simple, low cost, flexible in use and requiring low maintenance.

Concentration of ammoniacal nitrogen in effluent from wet scrubbers using reverse osmosis membrane

Sulphuric acid is commonly used in acid scrubbers as a highly efficient ammonia trap and results in the production of ammonium sulphate. The disposal of the large amount of effluent produced from an acid scrubber is one of the major issues that limit its application. Two reverse osmosis membranes were tested for their effectiveness in concentrating the ammoniacal nitrogen, which can be used as a fertiliser, from acid scrubber effluent. The permeate flux was substantially affected by membrane type, feeding total ammoniacal nitrogen (TAN) concentration, applied pressure, and feeding flow rate. However, TAN retention was only significantly affected by membrane type. The highest TAN retention of 98.1% was achieved with the SG membrane at a feeding TAN concentration of 6.4 g l−1, applied pressure of 5.5 MPa, and feeding flow rate of 3.1 l min−1.

A design model for nitrification on structured cross flow plastic media trickling filters

AbstractAn empirical model has been developed to predict the effluent ammoniacal nitrogen concentration from structured cross flow plastic media trickling filters operated over the range of BOD loadings 0.12–0.38 kg/m3/day and ammoniacal nitrogen loadings of 0.06–0.23 kg/m3/day. The model gives good predictions based on 24‐h average effluent concentrations over a range of filter depths, organic and hydraulic loading rates. When incorporated with suitable hydraulic models, effluent ammoniacal concentration can be predicted through the diurnal range. The data gathering for the model included depth profiles on three filters. These have shown that at all but the very highest BOD loadings, nitrification commences from the very top of the filter in the presence of soluble BOD loadings previously thought to preclude the development of nitrifying biomass. Several reasons have been proposed to explain this, with the key argument being that the efficient oxygen transfer afforded by the media design is sufficient to satisfy heterotroph and autotroph oxygen demand simultaneously.

Similarity criteria for estimating gas emission from scale models

Similarity, or the relationship between a model and a prototype, is an important issue when using physical modelling techniques. The objective was to investigate similarity criteria using Reynolds number (Re) and jet momentum ratio (Rm) in two scale models (SM-1 of 1:6 and SM-2 of 1:12.5) of a pig house under isothermal conditions to predict airflow and ammonia emission. Experiments were conducted using two ventilation control strategies (constant inlet opening and constant inlet velocity) in SM-1 and SM-2 by (1) keeping the same inlet Re with constant inlet opening, and (2) keeping the same Rm with constant inlet opening and constant inlet velocity. Aqueous ammonia solutions, with four different total ammoniacal nitrogen (TAN) concentrations and two different pH levels, were used as emission sources inside the scale models. Non-dimensional normalised emission rate, defined as the ratio of the measured emission rate and the reference emission rate at inlet air velocity of 1 m s−1 of the scale models, was proposed for when using Re and Rm as similarity. Rm was found to be a better scaling parameter than Re for predicting the influence of airflow on ammonia emission rate when using the non-dimensional normalised emission rate in scale models with both ventilation control strategies and ammonia solutions of different TAN and pH.

The kinetics of ammonia disappearance from deep-placed urea supergranules (USG) in transplanted rice: the effects of split USG application and PK fertiliser

Deep placement of urea supergranules (USG) in transplanted rice cultivation can protect nitrogen from losses. In the 20 × 20 cm plant geometry, the 4 g urea application corresponds to 116 kg N ha−1. However, the ammoniacal nitrogen concentration at the placement sites increases as the mass of the USG increases, and with the 4 g USG it takes too long for the ammonia concentration to decrease to 10 mM, the concentration at which root uptake commences. Therefore, split applications (two applications of 2 g USG) were studied regarding the change of ammoniacal nitrogen concentration at the point of application. The first application was always at transplanting, at a depth of 10 cm; the second application was made 41 days after transplanting (DAT) (tillering stage) or 62 DAT (panicle initiation). These times correspond to the beginning or the end of ammonia disappearance (plant uptake) from the site of placement, respectively. Ammonia disappearance from the placement site is faster for the second application, and it appears that the rice roots took up ammonia at a higher concentration: 20 mM for the second application versus 10 mM for the first application. The kinetics of ammonia disappearance from a single application of 2 g granules at transplanting was also influenced by the PK application rate. The rate of ammonia disappearance, the number of tillers per hill, and grain yield all increased with PK rate. The constant which characterizes the first order rate of ammonia disappearance below 10 mM also increased with PK level, proportionally to the number of tillers.

The Effects of Dietary Protein Content and Manure Handling Technique on Ammonia Emissions During Short-Term Storage of Dairy Cow Manure

An improved understanding of the potential for dietary protein manipulation to reduce ammonia emissions from dairy farms during various stages of manure handling is needed for both modeling and policy-making efforts. The objective of this study was to assess the effects of dietary protein manipulation on ammonia emissions from relatively freshly voided dairy cow manure in three types of removal systems: scraped manure removal systems, flushed manure removal systems, and flushed manure removal systems with a solids separator. Emissions were measured using a dynamic flux chamber for 12 h or more. Ammonia fluxes and emission factors per mass of manure were not affected by dietary protein content because fluxes depended mainly on total ammoniacal nitrogen (TAN) concentration, which did not vary with diet. However, emissions on a per-cow basis were 12% lower with the diet containing 15.0% crude protein as compared to the one with 17.8% (a change in crude protein of 16%) due to reduced urine output. The largest absolute impact of dietary protein manipulation would be with separated liquids because their emission factor was approximately four times higher than for the other types of manure. While dietary protein manipulation can reduce ammonia emissions from manure during long-term storage, its effectiveness in the hours immediately after manure is excreted is limited because emissions are more sensitive to other factors, including temperature and extent of mixing of the manure, that vary widely under real operating conditions on a farm.

Researches Regarding the Dynamics of some the Proteolytic Changes in Meat Products during Preparation and Storage

During the thermal treatment meat and meat products suffer significant changes which lead to the improvement of their organoleptic proprieties (texture, colour, flavour), of their digestibility and to the increase of the digestive use ratio. By heating of meat there occur physical and chemical changes of the muscular proteins which, in their turn, have an influence on the water retention capacity, pH value and ions redistribution. Following to the thermal treatment up to 100 C the most important changes occur in proteins which are denaturised. The denaturation process leads to a structural change of proteins but preserves their integrity and respectively their molecular weight. There have been performed physical and chemical analyses in order to assess the progress of proteolysis on 10 samples of sausage (brand name: Cârnaţi trandafir) and 10 samples of salami (brand name: Salam de vara), during fabrication and storage at 10-12° C up to their expiry date. There have been assessed: the water content, pH value, total nitrogen, proteins content, ammoniacal nitrogen content and the protein splitting rates by standardized methods. During the fabrication of meat products the pH value changes in accordance with the fabrication phase and with the proteolytic changes suffered by meat, half-finished products, filling paste and the final product in a range from 5.85 up to 5.93 and from 6.11 to 6.23 during the storage. During the fabrication and storage as final product, the water content decreases from 68.3 to 49.5 %. The total nitrogen content decreases during the fabrication and storage from 54.9 to 53.1 for the sausage brand Cârnaţ Trandafir and from 52.9 to 49.5 % for the salami brand Salam de vara. There has been recorded a proportional decrease of the proteins content. The ammoniacal and urea nitrogen moderately increase up to the delivery and intensively during the storage. The value of the protein splitting rates changes proportionally with the values of urea and ammoniacal nitrogen and in inverse ratio to the total nitrogen content. The proteolytic activity is not highlighted during the thermal treatment process due to the inactivation of some proteolytic enzymes but after fabrication and during the storage the proteolytic activity increases and is characterized by a decrease of total nitrogen and an increase of urea and ammoniacal nitrogen and of the proteins splitting rates.

Enhanced denitrification and organics removal in hybrid wetland columns: Comparative experiments

This study investigated three lab-scale hybrid wetland systems with traditional (gravel) and alternative substrates (wood mulch and zeolite) for removing organic, inorganic pollutants and coliforms from a synthetic wastewater, in order to investigate the efficiency of alternative substrates, and monitor the stability of system performance. The hybrid systems were operated under controlled variations of hydraulic load (q, 0.3-0.9 m3/m2 d), influent ammoniacal nitrogen (NH4-N, 22.0-80.0 mg/L), total nitrogen (TN, 24.0-84.0 mg/L) and biodegradable organics concentration (BOD5, 14.5-102.0 mg/L). Overall, mulch and zeolite showed promising prospect as wetland substrates, as both media enhanced the removal of nitrogen and organics. Average NH4-N, TN and BOD5 removal percentages were over 99%, 72% and 97%, respectively, across all three systems, indicating stable removal performances regardless of variable operating conditions. Higher Escherichia coli removal efficiencies (99.9%) were observed across the three systems, probably due to dominancy of aerobic conditions in vertical wetland columns of the hybrid systems.

Efeito da adição de própolis e monensina sódica na digestibilidade e características ruminais em bubalinos alimentados com dieta à base de forragem

Objetivou-se avaliar o efeito da administração de produtos à base de monensina sódica ou de própolis LLOSB3 e LLOSC1 em duas concentrações (B e C, em que B foi menos concentrado que C) e duas extrações alcoólicas (1 e 3, em que 1 foi menos concentrado que 3) sobre o consumo, a digestibilidade total e parcial e as características ruminais em bubalinos alimentados com dieta à base de forragem. Foram utilizados quatro búfalos castrados mestiços com 459,3 ± 44,5 kg em delineamento quadrado latino 4 x 4, com quatro dietas (controle, monensina, LLOSC1 e LLOSB3) e quatro períodos. A dieta continha 80% de volumoso (silagem de milho e feno de capim-tifton) e 20% de concentrado, com 11,1% de PB e 66% de nutrientes digestíveis totais (NDT). Os consumos de matéria seca (MS) e nutrientes não diferiram entre os aditivos testados. A adição de LLOSC1 propiciou maiores coeficientes de digestibilidade total em relação ao controle para MS (62,8% vs 59,4%), FDN (58,6% vs 54,3%), carboidratos totais (65,1% vs 61,5%) e NDT (65,8 vs 62,3%). A dieta com monensina não diferiu da controle e aquela com LLOSB3 foi semelhante a todas as outras. Aumento no fluxo e maior digestibilidade de PB nos intestinos foram verificados com o uso dos aditivos em relação à dieta controle. Após a alimentação, às 2,18 horas, não houve diferença na concentração de nitrogênio amoniacal no rúmen entre dietas e o valor máximo foi de 21,26 mg/100 mL. Menor valor de pH ruminal (6,48) e maiores concentrações de acetato e de butirato foram verificados para LLOSB3. A taxa de passagem de líquido não diferiu entre as dietas, porém, maior volume ruminal foi verificado com o uso dos aditivos. O aditivo LLOSC1 é superior à monensina em aumentar a energia digestível para bubalinos alimentados com dietas à base de forragem.

Global sensitivity analysis of a process-based model for ammonia emissions from manure storage and treatment structures

The development of process-based models to estimate ammonia emissions from animal feeding operations (AFOSs) is sought to replace costly and time-consuming direct measurements. Critical to process-based model development is conducting sensitivity analysis to determine the input parameters and their interactions that contribute most to the variance of the model output. Global and relative sensitivity analyses were applied to a process-based model for predicting ammonia emissions from the surface of anaerobic lagoons for treating and storing manure. The objectives were to compare global sensitivity analysis (GSA) to relative (local) sensitivity analysis (RSA) on a process-based model for ammonia emissions. Based on the first-order coefficient, both GSA and RSA showed the model input parameters in order of importance in process model for ammonia emissions from lagoon surfaces were: (i) pH, (ii) lagoon liquid temperature, (iii) wind speed above the lagoon surface, and (iv) the concentration of ammoniacal nitrogen in the lagoon. The GSA revealed that interactions between model parameters accounted for over two-thirds of the model variance, a result that cannot be achieved using traditional RSA. Also, the GSA showed that parameter interactions involving liquid pH had more impact on the model output variance than the single parameters: (i) temperature, (ii) wind speed, or (iii) total ammoniacal nitrogen. This study demonstrates that GSA provides a more complete analysis of model input parameters and their interactions on the model output compared to RSA. A comprehensive tutorial regarding the application of GSA to a process model is presented.