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National audience; Livestock transforms nitrogen from plants into animal products and releases a part of nitrogen in manure which can be recycled as fertilizer. Animal farming development has led to a concentration of production in some regions and consequently a concentration of nitrogen inputs and emissions, causing pollution in water, soil and air. This issue has been dealt with by European policies for 20 years. Nevertheless, what do we know about nitrogen flow dynamics in livestock farming? What are the options and the appropriate scale to reduce nitrogen emissions and impact on the environment without hampering competitiveness of animal productions? In 2010, these issues motivated French Ministries in charge of Agriculture and Ecology to request a collective scientific expert assessment from INRA, on nitrogen flow in livestock farming systems. This paper focuses on the main results concerning ruminant livestok farming; L'élevage transforme l'azote des végétaux en produits animaux et en rejette une partie sous forme de déjections, qui peuvent être utilisées comme engrais. Toutefois le développement des productions animales a conduit dans certains territoires à une concentration des apports et rejets d'azote, et une pollution des eaux, du sol et de l'atmosphère. Cette problématique est traitée depuis une vingtaine d'années par les politiques européennes. Que sait-on aujourd'hui de la dynamique des flux d'azote issus des élevages ? Quelles sont les pistes et les échelles pertinentes d'action pour réduire les émissions et leurs impacts sur l'environnement tout en préservant la compétitivité des productions animales ? Ces questions ont motivé de la part des ministères en charge de l'Agriculture et de l'Ecologie, au printemps 2010, une demande d'expertise scientifique collective auprès de l'INRA pour disposer d'un bilan des connaissances sur les différents flux d'azote associés aux activités d'élevage. Nous relatons ici les éléments majeurs concernant l'élevage des ruminants.

International audience; A model has been developed to predict pig manure evolution (mass, dry and organic matter, N, P, K, Cu and Zn contents) and related gaseous emissions (methane (CH4), nitrous oxide (N2O) and ammonia (NH3)) from pig excreta up to manure stored before spreading. This model forms part of a more comprehensive model including the prediction of pig excretion. The model simulates contrasted management systems, including different options for housing (slatted floor or deep litter), outside storage of manure and treatment (anaerobic digestion, biological N removal processes, slurry composting (SC) with straw and solid manure composting). Farmer practices and climatic conditions, which have significant effects on gaseous emissions within each option, have also been identified. The quantification of their effects was based on expert judgement from literature and local experiments, relations from mechanistic models or simple emission factors, depending on existing knowledge. The model helps to identify relative advantages and weaknesses for each system. For example, deep-litter with standard management practices is associated with high-greenhouse gas (GHG) production (+125% compared to slatted floor) and SC on straw is associated with high NH3 emission (+15% compared to slatted floor). Another important result from model building and first simulations is that farmer practices and the climate induce an intra-system (for a given infrastructure) variability of NH3 and GHG emissions nearly as high as inter-system variability. For example, in deep-litter housing systems, NH3 and N2O emissions from animal housing may vary between 6% and 53%, and between 1% and 19% of total N excreted, respectively Thus, the model could be useful to identify and quantify improvement margins on farms, more precisely or more easily than current methodologies.

International audience; In this study, a procedure accounting for degradation kinetics was developed to split the total COD of a substrate into each input state variable required for Anaerobic Digestion Model n(degrees)1. The procedure is based on the combination of batch experimental degradation tests ("anaerobic respirometry") and numerical interpretation of the results obtained (optimisation of the ADM1 input state variable set). The effects of the main operating parameters, such as the substrate to inoculum ratio in batch experiments and the origin of the inoculum, were investigated. Combined with biochemical fractionation of the total COD of substrates, this method enabled determination of an ADM1-consistent input state variable set for each substrate with affordable identifiability. The substrate to inoculum ratio in the batch experiments and the origin of the inoculum influenced input state variables. However, based on results modelled for a CSTR fed with the substrate concerned, these effects were not significant. Indeed, if the optimal ranges of these operational parameters are respected, uncertainty in COD fractionation is mainly limited to temporal variability of the properties of the substrates. As the method is based on kinetics and is easy to implement for a wide range of substrates, it is a very promising way to numerically predict the effect of design parameters on the efficiency of an anaerobic CSTR. This method thus promotes the use of modelling for the design and optimisation of anaerobic processes.

[Departement_IRSTEA]Ecotechnologies [Departement_IRSTEA]Territoires [Departement_IRSTEA]Eaux [TR1_IRSTEA]SEDYVIN [Axe_IRSTEA]Co TED-SOWASTE et TED-EPURE [TR2_IRSTEA]QUASARE [TR2_IRSTEA]SPEE [TR2_IRSTEA]TED [TR2_IRSTEA]INSPIRE [TR2_IRSTEA]DTAM [TR2_IRSTEA]MOTIVE [TR2_IRSTEA]SYNERGIE; Une énergie facilement disponible et bon marché a permis l'amélioration de notre qualité de vie au cours des deux derniers siècles. Cette disponibilité constitue un pilier fondateur de notre société technologique actuelle. Avec la croissance démographique mondiale qui portera à 9 milliards le nombre d'habitants sur la planète en 2050, comment faire face à l’augmentation mondiale des besoins en énergie alors que, dans le même temps, les énergies fossiles s'épuisent et que leurs usages intensifs augmentent la quantité de gaz à effet de serre dans l'atmosphère responsable en partie du réchauffement climatique ? Les énergies renouvelables sont un complément indispensable, une alternative crédible, y compris au plan économique. Ne peuvent-elles permettre au moins une transition énergétique ? Il faut pour cela accentuer les efforts de recherche.

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In this study, the maximum ratio of greasy sluvdge to incorporate with waste activated sludge was investigated in batch and CSTR experiments. In batch experiments, inhibition occurred with a greasy sludge ratio of more than 20-30% of the feed COD. In CSTR experiments, the optimal greasy sludge ratio was 60% of the feed COD and inhibition occurred above a ratio of 80%. Hence, batch experiments can predict the CSTR yield when the degradation phenomenon are additive but cannot be used to determine the maximum ratio to be used in a CSTR configuration. Additionally, when the ratio of greasy sludge increased from 0% to 60% of the feed COD, CSTR methane production increased by more than 60%. When the greasy sludge ratio increased from 60% to 90% of the feed COD, the reactor yield decreased by 75%.

International audience; The main objective of this study was to develop a methodology to predict the hydrogen sulphide content of raw biogas produced during anaerobic mono-digestion of a bioenergy feedstock. Detailed chemical and biological analyses were made on 37 different feedstocks originating from urban wastewater treatment plants, farms, agri-food facilities and municipal wastes. Total sulphur content ranged from 1 to 29.6mgS/kg of total solids, and 66% of the feedstocks analysed contained less than 5mgS/kg of total solids. The biochemical methanogenic potential and biochemical biogas potential of each feedstock combined with its S content were used to predict appearance of H 2S in the raw biogas. A model to link H 2S in biogas with the carbon:sulphur ratio was established. Based on this model, a minimum carbon:sulphur ratio of 40 is required in feedstock to limit the concentration of hydrogen sulphide in raw biogas to less than 2% (volume/volume).

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International audience; Modelling anaerobic digestion processes is a key aspect of studying and optimizing digesters and related waste streams. However, for the satisfactory prediction of biogas production and effluent characteristics, some parameters have to be calibrated according to the characteristics of the substrates. This article describes a calibration procedure for the IWA 'Anaerobic Digestion Model no. 1' applied to the modelling of a digester for treatment of pig slurry. The most sensitive parameters were selected and calibrated combining results from a continuous digester and from batch trials run with the sludge sampled from the digester and the addition of specific substrates. According to the sensitivity analysis, acetoclastic methanogenesis, acetogenesis of propionate and acidogenesis of sugars were identified as the main sensitive steps in our case. The calibration procedure led us to modify slightly acetogenesis of propionate kinetic. However, acetoclastic methanogenesis and acidogenesis of sugars kinetics were significantly reduced by decreasing km and increasing K-s. Indeed, for instance, a decrease of k(m_ac) from 8 to 7 day(-1) combined with an increase of K-s_ac from 0.15 to 1.5 kgCOD/m(3) was necessary. After calibration, ADM1 provides an accurate simulation of the continuous reactor results.

International audience; Le procédé actuellement retenu pour valoriser le phosphore des lisiers de porcs traités biologiquement est la dissolution du phosphore minéral particulaire par ajout d’acide formique suivi d’une séparation de phase par ajout de polymère et filtration sur tamis de 250 µm puis précipitation des phosphates en struvite (MgNH4PO4•6H2O) par ajout de magnésie (MgO). Le produit de cristallisation est récupéré dans des sacs filtrants de diamètre de coupure 100 µm. Le verrou de ce procédé est l’obtention de cristaux de struvite d’une taille supérieure à 100 µm. Un plan d’expérience en surface de réponse a été élaboré pour optimiser la précipitation de struvite en jar-test en faisant varier les paramètres procédés suivants : l’agitation, la température, l’ajout de MgO en fonction du ratio Mg :Ca et l’ajout d’ammonium en fonction du ratio N :P. Afin de s’affranchir dans un premier temps de la complexité de la matière organique, les essais ont été réalisé en milieu synthétique de composition ionique similaire au lisier de porcs traité biologiquement. La taille des cristaux est particulièrement influencée par la sursaturation et la température. Une faible sursaturation va promouvoir la formation de cristaux d’une taille supérieure à 100µm. La faible sursaturation doit être apportée par la dissolution de la magnésie et non par une moindre quantité d’ammonium. L’ammonium peut en effet se volatiliser en ammoniaque au cours de la réaction et ne doit donc pas être limitant. La température influence la dissolution de la magnésie et donc le pH de la solution, la volatilisation de l’ammoniaque et la solubilité des cristaux de struvite. Il est donc nécessaire de bien maitriser ce paramètre. La composition du solide obtenu est déterminée par spectroscopie Raman et par analyse morphologique. Les tests de calibration de cet appareil ont permis de valider cette méthode d’analyse.

Background: This paper describes results obtained for different participating research groups in an interlaboratory study related to biochemical methane potential (BMP). In this research work, all experimental conditions influencing the test such as inoculum, substrate characteristics and experimental conditions were investigated. The study was performed using four substrates: three positive control substrates (starch, cellulose and gelatine), and one raw biomass material (mung bean) at two different inoculum to substrate ratios (ISR). Results: The average methane yields for starch, cellulose, gelatine and mung bean at ISR of 2 and 1 were 350 ± 33, 350 ± 29, 380 ± 42, 370 ± 36 and 370 ± 35 mL CH4 g-1 VSadded, respectively. The percentages of biotransformation of these substrates into methane were 85 ± 8, 85 ± 7, 88 ± 9, 85 ± 8 and 85 ± 8%, respectively. On the other hand, the first-order rate constants obtained from the experimental data were 0.24 ± 0.14, 0.23 ± 0.15, 0.27 ± 0.13, 0.31 ± 0.17 and 0.23 ± 0.13 d-1, respectively. Conclusion: The influence of inocula and experimental factors was nearly insignificant with respect to the extents of the anaerobic biodegradation, while the rates differed significantly according to the experimental approaches. © 2011 Society of Chemical Industry.

International audience; This study aimed to develop a biochemical-test mainly to evaluate the hydrolytic-potential of different substrates and to apply this test to characterize various organic substrates. Outcome of this study can be used for optimization of the WWTPs through enhancement of N/P removal or anaerobic digestion. Out of four series of batch experiments, the first two tests were conducted to determine the optimal operating conditions (test duration, inoculum-ratio etc.) for the hydrolytic-potential test using secondary and synthetically-prepared sludges. Based on the results (generation of CODs, pH and VFA), test duration was fixed between 6 and 7 d allowing to attain maximum hydrolysis and to avoid methanogenesis. Effect of inoculum-ratios on acid fermentation of sludge was not significantly noticed. Using this methodology, third and fourth tests were performed to characterize various organic substrates namely secondary, pre-treated sludge, pig and two different cattle slurries. VFA production was shown to be substantially dependent on substrates types.

Performance of partial nitrification (PN) via nitrite (NO(2)(-)) pathway and the related nitrous oxide (N(2)O) emission during piggery wastewater treatment was investigated. Dissolved oxygen (DO) concentration and aeration pattern were selected as operational parameters to investigate the possibility of NO(2)(-) accumulation without affecting the overall N removal. To obtain PN, aeration was done for a maximum of 3h with a stopover of oxygenation, whenever DO concentration exceeds the threshold value of 2 mg O(2)L(-1). Ammonium (NH(4)(+)) consumption ended within 2h of reaction, and at the end of NH(4)(+) oxidation, about 70-80% of N was accumulated as NO(2)(-). Using PN, an average N removal of 74-75% was observed, which is comparable to that of complete nitrification-denitrification process. Regulating the aeration pattern not only benefit to the N removal in piggery wastewater, but also favoured reduction of oxygen and organic matter requirements for nitrification and denitrification. N(2)O emission was not encouraged even with 70-80% of NO(2)(-) accumulation.

International audience; Intensification of pig production in Brittany (France) led to high quantity of manure to be managed. In this context, a process combining anaerobic digestion and anoxic/oxic treatment was developed. The aim was to partially convert organic matter (OM) into a valuable energy, at the same time respecting the environmental constraints as regards nitrogen and reducing the energy costs at the farm scale. However, OM content of digested pig slurry is insufficient to allow a further complete denitrification of the mineral nitrogen content. Hence, three configurations were developed to manage the OM requirement and achieve denitrification such that (i) a fraction of the raw wastewater bypasses the digester and feed directly the anoxic/oxic reactor (Phase1), (ii) in addition to bypass, a recirculation was done from oxic reactor to digester (Phase 2 and 3), (iii) neither bypass nor recirculation (Phase 4). Partial nitrification (PN) was applied by regulating oxygen inflow time in Phase 3 and 4. Thus, the combined process allowed a removal of about 38-52% of CODt, 79-88% of CODs, 66-75% of TKN and 98-99% of NH4 +N concentrations. Anaerobic digester was able to produce 5.9 Nm3 of CH4/m3 of slurry added. Due to PN, the oxygen and OM requirements respectively for nitrification and denitrification were reduced. Comparison between each configuration was intrinsically difficult to make due to the difference observed in the slurry characterisation in each phase. However, a raw influent bypass between 20-30% combined with PN is suggested for piggery wastewater treatment in France, as the interest of recirculation from oxic reactor to digester is very limited using a CSTR.

The method used for the characterization of the biodegradability of pig slurry was improved by combining respirometric tests and the results obtained with a simplifi ed version of the ASM3 model that considers the intra-cellular storage of the easily biodegradable fraction. This method allowed for characterization of the biodegradability of three types of pig slurry encountered in a Quebec hog farm. The results showed that physico-chemically separated pig slurry is easily biodegradable organic matter while pig slurry separated under the slats is more slowly biodegradable. The results for raw pig slurry confi rmed the high variability of the organic components for this type of slurry., La méthode de caractérisation de la biodégradabilité du lisier de porc a été améliorée en jumelant la réalisation d'essais respirométriques avec l'utilisation d'une version simplifiée du modèle ASM3 prenant en compte le stockage intra-cellulaire de la fraction facilement biodégradable. Cette méthodologie a permis de caractériser la biodégradabilité de trois types de lisier de porc québécois. Les résultats ont permis de statuer que le lisier de porc séparé par voie physico-chimique avait un contenu assez facilement biodégradable. Le lisier séparé sous les lattes est caractérisé par un contenu beaucoup plus lentement biodégradable. Pour leur part, les résultats de la caractérisation du lisier brut confirment la grande variabilité des composantes de ce type d'effluent.

International audience; The technical feasibility of a dissolution/precipitation chemical phosphorus recycling process from piggery wastewater was assessed. Several combinations of acidifying/precipitating reactants were evaluated for their impact on liquid effluent quality and solids formed. Chloride and sodium concentration in the liquid effluent, which could contribute to soil salinisation, were reduced by a third by using acetic acid/magnesium oxide when compared to hydrochloric acid/sodium carbonate. Finally more than 95% of the initial dissolved phosphorus from the acidified supernatant was recovered. Struvite crystals and amorphous calcium phosphate were the main components in the solid, identified by X-ray diffraction, optical and SEM-EDS microscopy. The size and the shape of struvite crystals were increased by increasing the magnesium or ammonium/phosphate ratio which made them more suitable for the filtration and drying steps required to export phosphorus as a dry mineral product.

International audience; 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.

International audience; Animal wastes have been successfully employed in anaerobic biogas production, viewed as a pragmatic approach to rationalize energy costs in animal farms. Effluents resulting from that process however are still high in nitrogen such that attempts were made to couple biological nitrogen removal (BNR) with anaerobic digestion (AD). The demand for organic substrate in such system is partitioned between the anaerobic metabolism in AD and the heterotrophic denitrification cascade following the autotrophic nitrification in BNR. Investigation of underlying N-converting taxa with respect to process conditions is therefore critical in optimizing N-removal in such treatment system. In this study, a pilot-scale intermittently aerated BNR bioreactor was started up either independently or in series with the AD bioreactor to treat high-strength swine waste slurry. The compositions of NH3-oxidizing bacteria (AOB), NO2-oxidizing bacteria (NOB) and denitrifiers (nosZ gene) were profiled by polymerase chain reaction-capillary electrophoresis/single strand conformation polymorphism (PCR-CE/SSCP) technique and clone library analysis. Performance data suggested that these two process configurations significantly differ in the modes of biological N-removal. PCR-CE/SSCP based profiling of the underlying nitrifying bacteria also revealed the selection of distinct taxa between process configurations. Under the investigated process conditions, correlation of performance data and composition of underlying nitrifiers suggest that the stand-alone BNR bioreactor tended to favor N-removal via NO3- whereas the coupled bioreactors could be optimized to achieve the same via a NO2- shortcut.

International audience; Due to the water pollution and in order to reduce the nitrogen load applied on soils, biological nitrogen removal treatment of piggery wastewaters was developed in Brittany (France), with 250-300 units running actually. Four types of treatment processes were built including a biological reactor allowing to remove about 60-70% of the nitrogen content as gas by nitrification/denitrification. The addition of different mechanical separators (screw-press, centrifuge decanter ...) led to concentrate phosphorus in exportable solid phase, allowing a reduction up to 80% of the phosphorus applied locally on soils. Moreover, a reduction of the gaseous emissions was observed using this management process as compared to conventional management (storage + land spreading) including ammonia (up to 68%) and greenhouse gases (55%). Finally, the level of enteric and pathogenic bacteria was also decreased with the treatment process as compared to conventional management systems. However, in spite of these results, the important cost of the treatment must be underlined and alternative systems including anaerobic digestion will have to be studied.

Cet article résume les apports du programme « Porcherie verte » dans la connaissance et la maîtrise du devenir de l’azote, du phosphore et des éléments traces métalliques qui ont, à des titres divers, un impact sur l’environnement. La diminution de la teneur en protéines de l’aliment permet de réduire fortement les quantités d’azote excrétées par les animaux. Une part importante de l’azote est éliminée sous forme gazeuse lorsque les animaux sont placés sur litière ou lorsque le lisier est composté. L’importance de ces pertes d’azote peut cependant varier fortement selon les techniques utilisées et la nature des substrats. Le traitement biologique abat la majeure partie de l’azote et certains types de stations permettent de capter le reste dans des coproduits potentiellement exportables. La bonne valorisation agronomique des effluents nécessite de bien connaître leur valeur fertilisante azotée, ce que facilite l’approche typologique mise au point dans le cadre du programme. Un certain nombre de leviers alimentaires permettent de diminuer la fraction du phosphore alimentaire qui est excrétée dans les effluents : ajustement des apports alimentaires grâce à une meilleure connaissance des besoins des animaux, amélioration de la digestibilité du phosphore alimentaire par une meilleure connaissance de sa disponibilité dans les diverses matières premières ou via l’adjonction de phytase exogène. Les traitements biologiques avec séparation de phases permettent de capter le phosphore dans des coproduits potentiellement exportables et la valeur fertilisante phosphatée des effluents est en général très élevée et facile à prédire. Les éléments traces métalliques (cuivre et zinc) sont souvent ajoutés dans l’aliment à des concentrations dépassant largement les besoins stricts des animaux (pour éviter les carences) afin de bénéficier de leur effet protecteur vis-à-vis des pathologies digestives. La supplémentation par des éléments traces métalliques est utile pendant la phase de post-sevrage, mais pas au-delà et l’adjonction de phytase microbienne à l’aliment améliore la disponibilité du zinc pour l’animal. Les traitements biologiques avec séparation de phases permettent de capter le zinc et le cuivre dans des coproduits potentiellement exportables. Après épandage, les éléments traces métalliques sont peu mobiles dans le sol alors que les apports au sol excèdent en général largement les capacités d’exportation par les plantes, ce qui peut conduire à des situations de phytotoxicité à plus ou moins long terme. En fin de compte, la manière la plus simple et la plus économique de gérer les effluents d’élevage reste d’utiliser au mieux leur valeur fertilisante, ce qui s’obtient par un bon équilibre entre la quantité d’animaux produits et la capacité des sols à recevoir leurs effluents. En l’absence d’un tel équilibre, l’abattement de l’azote excédentaire par l’utilisation de litières ou par le compostage du lisier a un impact environnemental important alors même que ces solutions ne résolvent rien en termes de phosphore et d’éléments traces métallique. Les traitements biologiques les plus sophistiqués permettent d’éliminer le phosphore et une partie des éléments traces métalliques dans des coproduits potentiellement exportables, mais ils ont un coût économique et écologique très élevé., This paper summarises the contributions that the "Porcheric verte" programme makes to our knowledge and control of nitrogen, phosphorus and trace metals, which each have an impact on the environment. The decrease in protein content of feed reduces the amount of nitrogen excreted by animals. An important part of nitrogen is eliminated as a gas when the animals are placed on floor litter or when the manure is used as compost. The importance of these nitrogen losses, however. varies according to the techniques used and the nature of the substrates. The biological treatment capts most of the nitrogen and some farms can capt the rest in potentiallv exportable co-products. The good agronomic valorisation of waste requires good knowledge of the nitrogen fertilisation value, which makes the typological approach developed within the framework of the programme easier. A certain number of food levers decrease the fraction of food phosphorus that is excreted in waste: adjusting food intake by a better knowledge of the animal's needs, improvement of digestibility v of food phosphorus by improved knowledge of its availability in different raw materials or by adding exogenous phytase. Biological treatments with phase separation capt phosphorus in potentially exportable co-products and phosphate fertilising value of waste is generally very high and easy to predict. Trace metals (copper and zinc) are often added to feed in concentrations much higher than those needed by the animal (to avoid deficiency) in order to benefit from their protective effects against digestive pathologies. Supplementation of trace metals is useful during the post-weaning phase, but not beyond and the addition of microbial phytase in feed improves the availability of zinc for the animal. Biological treatments with phase separation capture zinc and copper in the potentially exportable co-products. After spreading, trace metals are little mobile in the soil whereas soil supply generally exceeds the export capacities of plants. This can therefore lead to phytotoxicity Situations on a short to long term. Finally, the best way and most economic to manage breeding waste is the adapted use of fertilising value, which is obtained by a good balance between the quantity of animal products and the capacity of soil to absorb waste. Without such a balance, capting excess waste by using litter or composting manure has an important impact on the environment even though these solutions do not resolve anything in terms of phosphorus and trace metals. The most sophisticated biological treatments eliminate phosphorus and a part of the trace metals in the potentially exportable co-products but they have a very high cost for the economy and ecology.

The effects of incubations conditions (dilution, mixing, incubation time and inoculum amount and origin) on the determination of the maximum methane producing capacity (B(0)) from various livestock slurries were evaluated. For this purpose, the methane yields of different livestock slurries were determined using batch anaerobic incubations performed at 30 degrees C as regard these different conditions. The B(0) and the methane (CH(4)) generation as a function of time were used to study the processes and to determine the best incubation conditions. Methanogenesis was identified as the major rate-limiting step during the anaerobic degradation of slurries, probably due to inhibition by volatile fatty acids. In some cases, high free NH(3) concentrations were suspected to inhibit the hydrolysis process. The addition of inoculum and/or the dilution of the substrate reduced the inhibition and allowed to reach the B(0) more rapidly. However, the addition of inoculum must be minimized to reduce the possible errors made by considering a similar production by the inoculum with and without the substrate. All experiments performed during this study allowed to define the incubation conditions required for the determination of the B(0) from livestock slurries. Applying these conditions, the B(0) values determined for swine slurries varied from 244 to 343L CH(4)kg V(added)(-1), from 204 to 296L CH(4)kg V(added)(-1) for dairy cattle slurries and equalled 386 and 319L CH(4)kg VS(added)(-1) respectively for calves and duck slurries.

Laboratory-scale experiments were conducted to examine the N 2 O emission during the denitrification process. For each of the 6 runs carried out, synthetic effluent was fed in a 10 l batch mixed liquor to investigate the effect of nitrite on N 2 O emission and Helium was continuously bubbled through the reactor at constant rate (0.12 l/min) to favour N 2 O transfer and detection. An increasing COD/NO 3 − -N influent ratio from 3 to 7 was firstly applied (runs 1–3). Secondly, NO 2 − pulse additions were performed during run 4 and 5 (10 and 20 mg N/l, respectively). Finally, the reactor was fed with influent containing both NO 2 − and NO 3 − . We showed that N 2 O emission was detected shortly after NO 2 − accumulation, few minutes after the substrate feeding. The highest emission occurred at the lower COD/NO 3 − -N ratio (=3) and at the higher NO 2 − addition (20 mg N/l). In addition, the higher nitrogen conversion to N 2 O gas (14.4%) was obtained with an influent containing initially both NO 2 − and NO 3 − . Our results suggest a direct effect of the NO 2 − concentration on the N 2 O emission. We have also confirmed the inhibitory effect of NO 2 − concentration on N 2 O reduction.

[Departement_IRSTEA]MA [TR1_IRSTEA]TED / EPURE; International audience; To increase the phosphorus recycling potential from swine slurry, mineral phosphorus products which could be used as fertilizers should be obtained and new processes need to be investigated. A routine method is needed to better evaluate the dissolved and solid mineral phosphorus in swine slurry. Cold perchloric acid extraction method previously developed for wastewater or sludge analysis was adapted. Ionic chromatography was used to measure orthophosphate in extracts. Only one extraction step was needed to distinguish between mineral and organic phosphorus in slurry. Reproducibility of the method was high (less than 5% of variation on the measured fractions). Selectivity was assessed by adding several organic and mineral phosphorus sources in the slurry. Cold perchloric extraction followed by ionic chromatography was very selective in quantifying both the mineral and organic forms of phosphorus in swine slurry.

International audience; In order to deal with the environmental problems associated with animal production industrialization and at the same time considering energy costs increasing, a piggery wastewater treatment process consisting of combined anaerobic digestion and biological nitrogen removal by activated sludge was developed. This contribution presents a modelling framework in order to optimize this process. Modified versions of the well established ASM1 and ADM1 models have been used. The ADM1 was extended with biological denitrification. pH calculation and liquid gastransfer were modified to take into account the effect of associated components. Finally, two interfaces (ADMtoASM and ASMtoADM) were built in order to combine both models. These interfaces set up the COD, nitrogen, alkalinity and charge fractionation between both models. However, for the mass balances between both models, some hypotheses were considered and might be evaluated.

A new methodology based on (1) national data concerning livestock and rearing practices and (2) a mass-flow approach was developed to quantify ammonia (NH 3 ), methane (CH 4 ) and nitrous oxide (N 2 O) emissions resulting from manure management in France. A literature review was performed to determine emission factors for each animal type and each management stage. A Microsoft Access® database containing these emission factors, the census data and manure compositions was then developed, allowing the calculation of gaseous emissions by the mass-flow approach. From this database, a national gas emissions inventory resulting from manure management was drawn up for the year 2003. Total NH 3 emissions were estimated at 382 kt N, mainly arising from cattle (72%). Greenhouse gas emissions were estimated at 14.0 Tg CO 2 -eq. for N 2 O and 10.2 Tg CO 2 -eq. for CH 4 . Most of the N 2 O emissions occurred after the deposition of manure on soil during cattle grazing, while the CH 4 was mainly produced during the period where cattle manure remained in livestock buildings and in outside storage facilities. Moreover, an evaluation of the uncertainty was performed considering the standard deviation obtained for the emission factors.

[Departement_IRSTEA]MA [TR1_IRSTEA]TED / EPURE; International audience; During this study, a mathematical model simulating piggery wastewater treatment was developed, with the objective of process optimisation. To achieve this, the effect of temperature and free ammonia concentration on the nitrification rate were experimentally studied using respirometry. The maximum growth rates obtained were higher for ammonium-oxidising biomass than for nitrite-oxidising biomass for the temperatures above 20 °C ; values at 35 °C were equal to 1.9 and 1.35 day-1, respectively. No inhibition of nitrification was observed for free ammonia concentrations up to 50 mgN/L. Using these data with others experimental data obtained from a pilot-scale reactor to treat piggery wastewater, a model based on a modified version of the ASM1 was developed and calibrated. In order to model the nitrite accumulation observed, the ASM1 model was extended with a two-step nitrification and denitrification including nitrite as intermediate. Finally, the produced model called PiWaT1 demonstrated a good fit with the experimental data. In addition to the temperature, oxygen concentration was identified as an important factor influencing the nitrite accumulation during nitrification. Even if some improvements of the model are still necessary, this model can already be used for process improvement.

12 pages, 1 figure, 4 tables., Intensification increases the environmental impact of livestock production systems. Efforts to recycle nutrients in livestock manure for crop production will effectively reduce several pollution problems, although general solutions are difficult to devise in view of the diversity in production systems, management strategies and legislation between countries and regions. This paper argues that a whole-farm perspective taking side-effects and on-farm interactions into account is needed to determine the cost-effectiveness of strategies to mitigate pollution from livestock manure management. Animal feeding plays a key role in the control of nutrient flows on livestock farms, since the diet affects the composition of excreta. There is a great potential for manipulating manure composition by diet manipulations. Manure is a significant source of heavy metals in soil, and in Europe the permitted levels of Cu and Zn in livestock diets have been lowered to reduce their environmental impact. A variety of environmental technologies are being developed for treatment of manure, many of which have a significant potential for reducing nutrient losses. Internationally agreed and enforced regulations that link pollution control with the adoption of best available technologies could provide the demand that is needed to drive research and development. In the past, policy-makers have typically focused on individual environmental problems. It is essential, however, that the efforts to close nutrient cycles on the farm are accompanied by a corresponding reduction in total inputs, otherwise losses after field application will increase. Integrated assessment tools are needed which can evaluate all internal flows of nutrients, imports and exports, energy use, hygienic risks and contaminants, as well as costs, at the farm-scale and beyond. It is important to consider pollution control strategies for a farm in the framework of local and regional pollution control planning.

Organic farming methods are claimed to be more environmentally friendly than conventional methods and the EU MIDAIR project had an overall aim to compare emissions from organic dairy farming with conventional methods of milk production. Manure stores are the second largest source of methane emissions (after enteric fermentation) on European dairy farming. The aim of this project was to measure green house gas (GHG) emissions from manures in covered and uncovered slurry stores and farm yard manure (FYM) heaps. The chosen method for measuring these emissions was the tracer ratio method, using sulphur hexafluoride (SF6) as the tracer gas, the limitations of this method prevented successful measurements being made on some of the stores and a modified method was used on the covered stores. The difference in concentration of the upwind and downwind samples and interfering sources were limiting factors. FYM emission measurements were successful only when the manure was stored indoors. Methane emissions were successfully measured over a 12 month period from the uncovered slurry stores. Emission rates from the uncovered slurry stores on the conventional farm and the organic farm ranged from 14.4 to 49.6 and from 12.4 to 42.3 g C m(-3) d(-1), respectively, with the mean CH4 emission rates of 35 and 26 g C m(-3) d(-1). On both farms, nitrous oxide emissions were close to zero. Methane emissions measured from the indoor organic FYM in summer were 17.1 g C m(-3) d(-1) and the nitrous oxide emission was 411 mg N m(-3) d(-1). The covered slurry stores were in such close proximity to other GHG sources that the tracer ratio method was unsuitable and the air-injection method was adopted. The measured emissions from covered slurry stores of CH4, CO2 and NH3 were, respectively, 14.9 g C m(-3) d(-1), 12.9 g C m(-3) d(-1) and 18.6 mg NH3 m(-2) d(-1) of slurry in February and 12.0 g C m(-3) d(-1), 9.5 g C m(-3) d(-1) and 335 mg NH3 m(-2) d(-1) slurry in March. No nitrous oxide production could be measured. (c) 2005 Elsevier B.V. All rights reserved.

This book includes the main available technical knowledge on aerobic biological treatment of pig slurry. After a short introduction of the regimentation, technical informations are presented mainly on: - Pig slurry composition - Manure management before treatment - Separation devices - Biological mechanisms involved - Process management - Trouble shooting and technical solutions - By-products characteristics and outlets., Ce guide aborde les différents aspects du traitement biologique en boues activées du lisier de porc. Après avoir établi un inventaire des mesures réglementaires et législatives en cours ou en projet, il fait le point sur les connaissances disponibles sur le procédé : - rappels sur la composition du lisier ; - influence des étapes de stockage et d`homogénéisation sur l`évolution des caractéristiques du lisier ; - les différents systèmes de séparation solide/liquide et la composition des produits obtenus ; - les principes de fonctionnement d`un réacteur de traitement en boues activées par aération séquentielle ; - des conseils pour la conduite du procédé, les principales sources de dysfonctionnements et la façon d`y remédier ; - les caractéristiques et l`utilisation possible des produits du traitement. Un rappel des principes théoriques et un point sur les travaux de recherche en cours est présenté simultanément.

In Britanny, land application of livestock wastes from confined animal operations is seen as a major source of nitrogen in agricultural drainage channels. In this context, treatment aiming at removal of nitrogen from livestock wastes, particularly pig slurry, is becoming increasingly common in France. The aim of this study was to evaluate the fate of nitrogen, phosphorus, copper and zinc during biological treatment of pig slurry, including the separation of the raw and/or treated pig slurry. Based on the experimental data obtained, a predictive model was developed to calculate the nutrient fluxes according to the plant characteristics. According to the results obtained in this study, the biological aerobic treatment technique is efficient in Brittany for pig slurry treatment, particularly for nitrogen removal (60-70%). The treatment produces final products that need to be managed by the farmer. The solid separated fractions could be exported out of the farm. Supernatant could be used for irrigation on the farm with a reduced environmental risk compared with the use of raw slurry. The biological sludge, could be spread on the farm as organic fertilizer. However, the use of the sludge on a nitrogen basis as fertilizer could overload the fields with phosphorus, copper and zinc. Moreover, exportation of the solid separated fractions could be more and more difficult due to their heavy metals content. A reduction of the copper and zinc levels in pig diets is then necessary.

International audience; The fate of phosphorus distribution in the products obtained from biological aerobic treatment of pig slurry, e.g. separated solids, liquid effluent and sludge, was monitored in three different farm-scale units. Samples of raw slurry, solid products, aerated slurry, liquid effluent and sludge were characterised and analysed for their concentration in total phosphorus, nitrogen content and heavy metals (Cu and Zn). At each treatment stage, nitrogen, phosphorus and heavy metals mass balance between input and output was established. Moreover, liquid products were characterised and analysed both for their total and dissolved ortho-phosphate content. Separated solids, sluge and liquid effluent represented 5%, 15-40% and 75-83% of the mass of the raw slurry, respectively. A mechanical separation step prior to aeration allowed the export of 25-30% of total phosphorus for further use as organic fertiliser. A large amount of total phosphorus (e.g. 60-70%) was located in sludge while phosphorus remaining in liquid effluent was about 15-25%. Raw slurry separation and sufficient aeration allowed phosphorus to concentrate in the sludge. Insufficient aeration resulted in the release of phosphorus as dissolved ortho-phosphate within the liquid effluent. Finally, relevance of the agronomic use of the products was discussed and improvements of biological aerobic treatment to enhance phosphorus removal and/or recovery were considered.

Due to legislation (EU nitrate directive and national application), treatment of pig slurry for nitrogen removal is largely used in Brittany (France). Among available techniques, biological aerobic treatment represents more than 90% of the farm treatment units. This kind of treatment generates new products (solid phase from separation of raw slurry, supernatant and sludge) which could be managed by the farmer. A survey on the built units was performed and allowed to identify four main types of treatment units: (1) intermittent aeration without any separation, (2) intermittent aeration followed by sedimentation of aerated slurry, (3) mechanical separation of raw slurry followed by intermittent aeration of the liquid fraction and sedimentation of aerated slurry and (4) mechanical separation of raw slurry followed by intermittent aeration of the liquid fraction and mechanical separation of the aerated slurry. Among the 26 treatment units built in Brittany (June 1999), three were studied for 8 weeks. This monitoring period allowed to establish mass balances for nitrogen, phosphorus, copper and zinc. Between 60 and 70 % of the nitrogen was removed in gaseous form. Phosphorus, copper and zinc were accumulated mainly in the sludge resulting from separation of aerated slurry (60-90%). This accumulation led to a high concentration of copper and zinc up to 160 and 340 g/ton, respectively. The use of this product on the farm as organic fertilizer led to an overload with regard to agronomic requirements and export was difficult due to the high copper and zinc content., Afin de répondre aux différentes législations (Directive nitrates,...), le traitement du lisier de porcs en vue d'éliminer l'azote est largement répandu en Bretagne (France). Parmi les techniques disponibles, le traitement biologique représente plus de 90% des systèmes utilisés. Cette technique engendre de nouveaux co-produits (phase solide issue de la séparation du lisier brut, surnageant et boues) qui doivent être gérés par l'agriculteur. Une enquête sur les systèmes en fonctionnement a permis d'identifier les 4 principales filières de traitement : (1) aération séquentielle sans séparation de phase, (2) aération séquentielle suivie d'une décantation du lisier aéré, (3) séparation mécanique du lisier brut suivie d'une aération séquentielle puis d'une décantation du lisier aéré et (4) séparation mécanique du lisier brut suivie d'une aération séquentielle puis d'une séparation mécanique du lisier aéré. Parmi les 26 stations existantes (juin 1999), trois ont été étudiées pendant 8 semaines. Cette étude a permis d'établir des bilan matières pour l'azote, le phosphore, le cuivre et le zinc. Entre 60 et 70% de l'azote est éliminé sous forme gazeuses. Le phosphore, le cuivre et le zinc s'accumulent principalement dans les boues issues de la séparation du lisier aéré (60-90%). Cette accumulation conduit à des concentrations importantes de cuivre et de zinc pouvant atteindre 160 et 340 g/tonne, respectivement. L'utilisation de ces produits à la ferme comme fertilisants organiques conduit à une surcharge par rapport aux besoins agronomiques et leur exportation est difficile au vue des teneurs élevées en cuivre et en zinc.

A laboratory experiment was designed to determine the fate of 15N-labelled slurry ammonium (15NH4-N) and compare soil inorganic-N distribution following surface applied or injected pig slurry. A system of cylindrical volatilisation chambers equipped to allow continuous trapping of ammonia (NH3) was used. Undisturbed soil columns were placed in the chambers prior to the application of slurry. A nitrogen balance including soil, air and plant analysis was established for both treatments, eight days after application. Average cumulative emissions of NH3 were 15% and 11% of the total ammoniacal-N added with the surface and injected treatments, respectively. After 8 days 55 % of the 15NH4-N applied through slurry injection was recovered in the soil inorganic-N pool: 37 % as 15NH4-N and 18 % as 15NO3-N. These figures compare with only 25% 15N-NH4 recovered with the surface applied slurry treatment: 7 % as 15NH4-N and 17 % as 15NO3-N. Immobilisation into soil organic-N accounted for 8 % of the 15NH4-N applied for the injected treatment and 6 % of the surface applied slurry-15N. 15N uptake by the grass was 2 % and 7 % for the injected and surface applied treatments, respectively. The percentage of added 15N accounted for was 76 % for the injected treatment and 53 % for the surface applied slurry treatment., Un essai en laboratoire a été effectué dans le but de déterminer le devenir de l'azote ammoniacal du lisier (marqué au 15N-NH4) et de comparer la distribution des formes minérales de l'azote selon la méthode d'apport du lisier, soit en surface, soit par injection. Un système de chambres de volatilisation équipées pour permettre le piégeage de l'ammoniac a été utilisé. Des colonnes de sol non remaniées sont placées dans les chambres avant l'apport de lisier. Un bilan azoté incluant le sol, l'air et les analyses de végétaux a été établi pour les 2 traitements, 8 jours après l'apport. Les émissions cumulées d'ammoniac s'établissent à 15% et 11% de l'N total ammoniacal apporté pour respectivement l'apport en surface et par injection. Après 8 jours, 55% de l'N ammoniacal marqué sont retrouvés dans le pool d'N inorganique du sol : 37% sous la forme ammoniacale et 18% sous forme de nitrates marqués. Ces résultats sont à comparer avec seulement 25% de l'N-NH4 retrouvés dans le sol pour le traitement avec apport de lisier en surface : 7% sous forme ammoniacale et 17% sous forme nitrique. L'immobilisation dans le sol sous forme N-organique représente 8% de l'15N-NH4 apporté par le traitement injecté et 6% pour l'apport en surface. Le prélèvement d'N par les végétaux s'établit à 2% et 7% respectivement pour l'apport injecté et en surface. Le pourcentage de recouvrement de l'N marqué apporté s'établit à 76% pour l'apport par injection et à 53% pour l'apport en surface.

A study of the biological aerobic treatment of pig slurry in Brittany (France) was done. This study included : - a survey of available data - results obtained on three treatment site - a study of nitrification and denitrification kinetics According to the data available, 26 aerobic stations ran in Brittany (June 1999). Four main type of station were identified according to their complexity. Solid phase resulting from mechanical separation of raw slurry represented near 5% of the initial mass of the slurry. This phase contained 8-10% of nitrogen and 24-30% of phosphorus. Intermittent aeration and consequently nitrification and denitrification led to nitrogen removal in the reactor of 60-70% of the initial content of the raw slurry. Solid/liquid separation of the aerated slurry concentrated 63-73% of phosphorus and 60-90% of copper and zinc in the sludge phase. Agricultural management of this by-product seems to be difficult on the farm and exportation will be necessary. Energy consumption for the treatment varied between 17 and 28 kWh/m3 of slurry. The main conclusions of this report were: - a good quality of the treated slurry was obtained using biological aerobic treatment, - carbon content of the raw slurry is the main factor which influence the treatment, particularly nitrogen removal. Also, variation of raw slurry characteristics required manual intervention in order to maintain the quality of effluent Nitrification kinetic observed was comprised between 6-8 mgN/l.h. Feeding the reactor at the beginning the anoxic stage with raw or separated slurry allowed improvement of the treatment., Ce rapport regroupe les principaux résultats de suivi des stations de traitement biologique aérobie du lisier de porcs obtenus au cours : - d'une synthèse des données existantes (SATESE, DSV, Constructeurs) ; - d'un suivi approfondi de 3 stations de traitement ; - d'une étude des cinétiques de nitrification et de dénitrification. D'après les données existantes, 26 installations de traitement biologique aérobie du lisier de porcs sont en fonctionnement, en Bretagne, en juin 1999, ce qui représente un traitement d'environ 2% de l'azote des effluents d'élevage porcin. Parmi ces stations, nous avons distingué 4 types de traitement en fonction de la complexité des équipements. Les performances de ces 4 types de traitement pour l'élimination d'azote sont proches. Les principales différences se situent au niveau des quantités gérées, de la qualité et de la gestion des co-produits issus de la filière de traitement. Les paramètres de dimensionnement et de fonctionnement sont très variables d'une station à l'autre, mais cela n'affecte pas les performances épuratoires globales de ces stations. La séparation de phase du lisier brut permet d'extraire une partie des matières en suspension de ce lisier. La phase solide obtenue représente environ 5% de la masse initiale de lisier brut. Ce procédé permet de retenir dans la phase solide environ 8-10 % de l'azote et 24-30% du phosphore. L'alternance de phases d'aération et de " non aération " dans le réacteur de traitement entraîne une élimination d'azote de l'ordre de 60-70% de l'azote initial du lisier brut, en favorisant la nitrification de l'azote ammoniacal du lisier puis la dénitrification. La séparation de phase du lisier aéré concentre une partie des éléments " non biodégradable " dans la phase boue ; 63-73% du phosphore, 60-90% du cuivre et du zinc. La gestion agronomique de ce co-produit apparaît alors délicate au niveau de l'exploitation et le développement de filières de valorisation de ces produits s'avèrent nécessaires. La consommation énergétique pour le fonctionnement de ces stations de traitement du lisier de porcs se situe, selon la complexité des équipements, entre 17 et 28 kWh.m-3 de lisier. Les suivis hebdomadaires effectués sur trois stations types nous ont permis de montrer que : - la qualité des effluents en sortie de la filière de traitement est correcte pour l'ensemble des stations étudiées et correspond au cahier des charges initial. - la charge carbonée du lisier brut est le facteur principal influençant les processus de traitement, notamment l'élimination de l'azote par nitrification et dénitrification. Ainsi, les variations importantes des caractéristiques du lisier brut nécessitent des interventions régulières afin de maintenir les performances de traitement. L'étude des cinétiques de nitrification et dénitrification montre qu'une synchronisation entre les cycles d'aération/anoxie et les cycles d'alimentation permet des conditions optimums aussi bien pour la nitrification que pour la dénitrification. Les vitesses de nitrification observées sont de l'ordre de 6 à 8 mgN.l-1.h-1.

Total phosphorus and dissolved ortho-phosphate was monitored in three different farm-scale biological aerobic treatment plants. For each step of treatment, a mass balance was established. Samples of raw slurry, solid products, aerated slurry, liquid effluent and sludge were analysed for their concentration in total phosphorus. Liquid products were analysed for their dissolved ortho-phosphate content. Three major streams result from the treatment system : separate solids, sludge and liquid effluent which represent 5% , 15-40% and 75-83% of the raw slurry, respectively. A mechanical separation step prior aeration allowed to export 25-30% of total phosphorus as organic fertiliser. A large amount of total phosphorus (e.g. 60-70%) was located in sludge. Phosphorus remaining in liquid effluent is about 15-25%. Raw slurry separation and sufficient aeration allowed to concentrate phosphorus in sludge. Insufficient aeration led to release phosphorus as dissolved ortho-phosphates within liquid effluent. Improvements of biological aerobic treatment to enhance phosphorus removal and/or recycling ability are considered.

Western France, is identified as one of the major centres of animal production in Europe. Animal effluents are an important source of fertilizers but are also potential water, air and soil pollutants. Nitrate pollution is of particular concern in France. In this context, several treatment strategies for livestock effluents have been defined and recommended in order to prevent water pollution. For pig slurry, biological aerobic treatment is becoming a common practice. Different types of farm scale units based on aeration have been developed. A survey including collection of technical data of all operating units were conducted with the manufacturers and/or farmers. The study of these data led to the identification of four major types of units design which were subsequently monitored. Three types of treatment farm units were evaluated during a two month period as regards carbon and nitrogen removal efficiency and quality of co-products generated by treatment (C, N, P, K, Cu, Zn). Total nitrogen removal up to 60-70% of the initial total nitrogen content of the raw slurry was observed. Concurrently, removal of total and soluble COD of 49% and 90%, respectively, was obtained. Although liquid effluent represented the more important co-product on a weigh basis (85% of the initial mass), a large part of the "non-biodegradable" elements was accumulated in the sludge which represented only 10% of the initial mass. On average, 70-80% of the total Cu and Zn and 60-70% of total phosphorus were located in the sludge phase. The accumulation of these compounds in the sludge led to high concentration of Cu, Zn and phosphorus up to 140g/tonne, 340 g/tonne and 6.6 kgP/tonne, respectively. According to these results, the management of the sludge phase seems to be difficult without exportation out of the farm.

[Departement_IRSTEA]EEE [TR1_IRSTEA]21 - TECHNEAU / EPURE; International audience; In order to elucidate and quantify nitrogen transformations occurring during aerobic treatment of pig slurry, two laboratory experiments were carried out with contrasting levels of aeration, high level of aeration (experiment 1) and low level of aeration (experiment 2). During these experiments, after reaching steady state conditions, a single pulse of NO3--15N tracer was added directly in the reactor. When nitrification conditions were prevailing (experiment 1), no transformation of added NO3--15N occurred (98.7% 15N-recovery as nitrates in the liquid slurry). Moreover, the unlabelled nitrous oxide (N2O) measured (7.4% of the total nitrogen content of the raw slurry) strongly demonstrated that the source of N2O emitted was nitrification. During simultaneous nitrification and denitrification conditions (experiment 2), the added NO3--15N was found in gaseous nitrogen forms (N2O-15N: 27%; N2-15N: 18%) and in the liquid (TN-15N: 54%). From this result, it was evident that N2O was mainly emitted by denitrification process. Using the decrease of the isotopic excess of the NO3--15N we calculated that 92% of NO2-- N was directly denitrified (as gaseous forms) without any previous oxidation to nitrate.; Afin de quantifier les transformations de l'azote au cours du traitement aérobie du lisier de porc, 2 essais en laboratoire ont été effectués en utilisant des niveaux d'oxygénation fort (essai 1) et faible (essai 2). Au cours de ces expériences, après avoir atteint l'équilibre dans le réacteur, une faible quantité de 15N- NO3- a été ajoutée dans le réacteur. Lorsque les réactions de nitrifications sont favorisées (essai 1), aucune transformation du 15N- NO3- n' a été observée (recouvrement de 98.7% du 15N- NO3- ajouté). De plus, le protoxyde d'azote émis était non marqué, ce qui prouve que la principale source de N2O était, dans ces conditions, la nitrification. Lorsque la nitrification et dénitrification simultanées sont favorisées (essai 2), le 15N- NO3- ajouté se retrouve partiellement sous forme gazeuse (N2O-15N: 27%; N2-15N: 18%) et sous forme liquide. D'après ces résultats, il apparaît que dans ces conditions, la principale source de N2O est la dénitrification. En utilisant les équations relatives à la dilution isotopique, nous avons calculé que 92% des nitrites étaient directement dénitrifiés (sous forme gazeuse) sans oxydation préalable en nitrates.

The different types of farm scale units developed in France are described:aeration - aeration + natural separation - mechanical separation + aeration + natural separation - mechanical separation + aeration + mechanical separation Mass balance and co-products characteristics were studied as regards as N, P, Cu and Zn for two farm units. For both units, nitrogen removal as gas was near 70% of the total nitrogen. The solid phase from mechanical separation of raw slurry contained 8-10% of the initial total nitrogen, 24-30% of the initial total phosphorus and 8-11% of the initial copper and zinc. After the separation of the aerated slurry, a large party of the nutrient were in the sludge: 20-30% of the initial total nitrogen, 70% of the initial total phosphorus and 80-90% of the initial zinc and copper. Less than 2% of the initial total nitrogen and 10-15% of the initial copper and zinc were contained in the liquid phase from the separation of aerated slurry. The accumulation of phosphorus, copper and zinc in the sludge and the landspreadind of this product in the farm will probably lead, in future, to environmental problems., Un recensement auprès des différents constructeurs de stations de traitement biologique aérobie du lisier de porcs a permis d'identifier 4 types de filières de traitement : - traitement aérobie simple, - traitement aérobie + décantation, - séparation mécanique + traitement aérobie + décantation, - séparation mécanique + traitement aérobie + séparation mécanique. Deux de ces filières, (types 3 et 4), ont fait l'objet d'un bilan matière et d'une étude de la répartition des éléments (N, P, Cu, Zn) dans les différents co-produits issus du traitement (refus de séparation, surnageant, boues biologiques). Dans les deux cas, on observe une élimination d'azote sous formes gazeuses de l'ordre de 60-70% de l'azote total du lisier brut. La séparation de phase du lisier brut permet de " capturer " dans la phase solide, 8-10% de l'azote initial, 24-30% du phosphore et 8-11% du cuivre et du zinc. Suite à la séparation de phase du lisier aéré, la majeure partie des éléments se retrouve dans les boues biologiques : 20-30% de l'azote initial, 70% du phosphore initial et 80-90% du cuivre et du zinc, alors que le surnageant est épuré de ces éléments : moins de 2% de l'azote initial, 10-15% du phosphore et des concentrations en cuivre et en zinc inférieures au seuils de détection. A long terme, l'accumulation du phosphore, du cuivre et du zinc dans les boues biologiques et la gestion de ces boues à l'échelle de l'exploitation risquent d'engendrer des accumulations importantes de ces éléments dans les sols agricoles.

A laboratory treatment system was designed to study the fate of nitrogen during aerobic treatment of pig slurry. Different aeration strategies, and more particularly the influence of residence time and aeration level, were manipulated. A series of six experiments was carried out to determine the nitrogen mass balance, including measurement of the gaseous nitrogen forms particularly ammonia and nitrous oxide. Further nitrogen transformations were examined during the subsequent anaerobic storage of aerated pig slurry at 7, 21 and 60 days. Aeration level and carbon content of raw slurry were identified as the main factors influencing nitrogen transformation during treatment. A high aeration level (2-4 mg O2/l) and/or low carbon content (Biological oxygen demand of the raw slurry was about 2 g/kg) resulted in nitrite accumulation (up to 33% of the total nitrogen content of the raw slurry) while a low level of aeration (redox potential = 0 mVAg/AgCl) and high carbon content (BOD of the raw slurry was about 16 g/kg) led to simultaneous nitrification and denitrification which removed 66% of the total nitrogen in the raw slurry. Nitrous oxide emissions were observed in all treatments and represent up to 30% of the total nitrogen content of the raw slurry. Both nitrification and denitrification appear to be sources of nitrous oxide during the treatment. Further nitrous oxide emissions were recorded during subsequent storage and especially when the biological oxygen demand to NOx--N ratio was lower than 1.3. However, during closed storage experiments, the nitrous oxide emitted was dissolved into the slurry and finally reduced to di-nitrogen after 60 days of storage., Un pilote de laboratoire a été mis au point pour étudier le devenir de l'azote au cours du traitement aérobie du lisier de porcs. Différentes stratégies d'aération, et plus particulièrement l'influence du temps de séjour et du niveau d'aération, ont été testées. Une série de six expériences a été effectuée afin de déterminer le devenir de l'azote, notamment sous forme gazeuses (ammoniac et protoxyde d'azote). Un suivi des transformations pendant le stockage anaérobique du lisier aéré a également été effectué après 7, 21 et 60 jours. Le niveau d'aération et la teneur en carbone du lisier brut ont été identifié comme les principaux facteurs influençant les transformations de l'azote au cours du traitement. En effet, une aération forte (2-4 mgO2/l) et/ou une teneur faible en carbone (DBO du lisier brut environ 2 g/kg) a conduit à une accumulation de nitrite (jusqu'à 33% de l'azote total du lisier brut) tandis qu'une faible aération et une teneur élevée en carbone (DBO du lisier brut environ 16 g/kg) a permis d'obtenir la nitrification et la dénitrification simultanément ce qui a conduit à une élimination de 66% de l'azote total du lisier. Des émissions de protoxyde d'azote ont été observées au cours de tous les traitements et représentaient jusqu'à 30% de l'azote total du lisier brut. La nitrification et la dénitrification apparaissent comme des sources potentielles de protoxyde d'azote au cours du traitement. Des émissions de protoxyde d'azote ont également été enregistrées pendant le stockage ultérieur, notamment lorsque le ratio DBO/N-NOx- est inférieur à 1,3. Cependant, au cours de ces expériences en flacons 60 fermés, le protoxyde d'azote émis s'est redissous dans le lisier et a finalement été réduit en azote moléculaire après 60 jours de stockage.

A floating rectangular polyvinyl chloride (PVC) open bottom chamber coupled with a molecular sieve trap was designed to measure the amounts of nitrous oxide gas (N20) emitted during aerobic treatment or storage of liquid animal slurries. A number of outdoor calibration trials, using water and a standard gas mixture, resulted in an average N20 recovery of 79 % (±8%). Further experiments carried out on a farm scale aerobic treatment unit confirmed the reliability an ease of use of the method., Une chambre flottante ouverte en PVC couplée avec un piège moléculaire a été mise au point afin de quantifier les émissions de protoxyde d'azote (N2O) au cours du traitement aérobie ou du stockage des déjections animales liquides. Une série de calibrations en conditions contrôlées ont permis d'établir un pourcentage de recouvrement de l'ordre de 79 % (± 8). Des essais sur des sites grandeurs réelles ont été menés afin de vérifier la facilité d'utilisation de ce dispositif méthodologique.

Different forms of nitrogen : dissolved inorganic-N (or total ammonium-N), suspended organic-N and dissolved organic-N were followed during anaerobic storage of N-15 labelled pig slurry. The kinetics of nitrogen transformations were recorded at 0, 1, 3, 7, 14, 28, 63 and 84 days during a laboratory incubation. At day O, 15N enriched urea (150 mgN/kg of slurry with a isotopic excess of 50%) was added to the slurry. After a rapid total hydrolysis of the urea (within 1 day), a continuous decay of the suspended organic-N fraction was observed concurrently with the increase in the total ammonium-N pool. This mineralization reached 19% of the initial total organic-N fraction, resulting in an increase of the total ammoniacal nitrogen content from 2 410 to 2 780 mgN-NH4+/kg of slurry. Labelling techniques allowed measurement of a simultaneous slight immobilization (into the suspended organic-N fraction) of 4.6 % of the initial ammoniacal-N., L'évolution de différentes formes azotées : N-minéral dissous (i. e. azote ammoniacal), N-organique en suspension et N-organique dissous a été suivie au cours du stockage anaérobie du lisier de porc. Après une hydrolyse rapide de l'urée enrichie en 15N (moins de 1 jour), une minéralisation continue de la fraction N-organique en suspension a été observée et simultanément une augmentation du pool d'azote ammoniacal, qui passe de 2 410 à 2 780 mg N-NH4+/kg de lisier. L'utilisation d'azote marqué permet de mesurer une immobilisation faible de l'orde de 4,6% de l'azote ammoniacal total initial.

La methanisation prend de plus en plus d’importance en France. Cependant, ce phenomene etant relativement recent, il est interessant de voir quels choix de production de biogaz sont faits et comment ce biogaz est valorise.

En France, et ce principalement pour des raisons economiques, la methanisation des boues d’epuration est encore peu appliquee dans les stations de petite et moyenne capacite. Pour ameliorer le bilan economique de la digestion anaerobie des boues d’epuration dans ce type de station, il est possible de completer les alimentations du digesteur par d’autres substrats organiques a plus fort potentiel energetique et deja presents sur le territoire. Quels sont les impacts de tels procedes et comment optimiser leur integration dans la filiere de traitement des eaux ?

[Departement_IRSTEA]MA [TR1_IRSTEA]TED / EPURE; International audience; The effect of the nitrification on dissolved phosphorus during the treatment of piggery wastewater by a modified sequencing batch reactor has been observed in a previous study. The high solid mineral phosphorus content in the piggery wastewater and the chemical mechanism induced by the fall in pH during the nitrification were proposed to explain this effect. In this work, trials using modified sequencing batch reactors were performed to study the influence of the amount of nitrified nitrogen on pH (and thus solubility of the phosphorus) and determine whether the pH was the main cause of the increased phosphorus dissolving. The dissolved phosphorus was found to increase (up to 3 fold) with the increase in nitrified nitrogen. However, even if the pH was regulated this dissolving still occurred. This could be due to local variations of the pH near the bacterial floc. The modified sequencing batch reactor process management (hydraulic retention time and anaerobic/aerobic step duration) allowed the control of the amount of nitrogen nitrified in one cycle and hence the amount of the phosphorus dissolved.

National audience; Cet article résume les apports du programme « Porcherie verte » dans la connaissance et la maîtrise du devenir de l'azote, du phosphore et des éléments traces métalliques qui ont, à des titres divers, un impact sur l'environnement. La diminution de la teneur en protéines de l'aliment permet de réduire fortement les quantités d'azote excrétées par les animaux. Une part importante de l'azote est éliminée sous forme gazeuse lorsque les animaux sont placés sur litière ou lorsque le lisier est composté. L'importance de ces pertes d'azote peut cependant varier fortement selon les techniques utilisées et la nature des substrats. Le traitement biologique abat la majeure partie de l'azote et certains types de stations permettent de capter le reste dans des coproduits potentiellement exportables. La bonne valorisation agronomique des effluents nécessite de bien connaître leur valeur fertilisante azotée, ce que facilite l'approche typologique mise au point dans le cadre du programme. Un certain nombre de leviers alimentaires permettent de diminuer la fraction du phosphore alimentaire qui est excrétée dans les effluents : ajustement des apports alimentaires grâce à une meilleure connaissance des besoins des animaux, amélioration de la digestibilité du phosphore alimentaire par une meilleure connaissance de sa disponibilité dans les diverses matières premières ou via l'adjonction de phytase exogène. Les traitements biologiques avec séparation de phases permettent de capter le phosphore dans des coproduits potentiellement exportables et la valeur fertilisante phosphatée des effluents est en général très élevée et facile à prédire. Les éléments traces métalliques (cuivre et zinc) sont souvent ajoutés dans l'aliment à des concentrations dépassant largement les besoins stricts des animaux (pour éviter les carences) afin de bénéficier de leur effet protecteur vis-à-vis des pathologies digestives. La supplémentation par des éléments traces métalliques est utile pendant la phase de post-sevrage, mais pas au-delà et l'adjonction de phytase microbienne à l'aliment améliore la disponibilité du zinc pour l'animal. Les traitements biologiques avec séparation de phases permettent de capter le zinc et le cuivre dans des coproduits potentiellement exportables. Après épandage, les éléments traces métalliques sont peu mobiles dans le sol alors que les apports au sol excèdent en général largement les capacités d'exportation par les plantes, ce qui peut conduire à des situations de phytotoxicité à plus ou moins long terme. En fin de compte, la manière la plus simple et la plus économique de gérer les effluents d'élevage reste d'utiliser au mieux leur valeur fertilisante, ce qui s'obtient par un bon équilibre entre la quantité d'animaux produits et la capacité des sols à recevoir leurs effluents. En l'absence d'un tel équilibre, l'abattement de l'azote excédentaire par l'utilisation de litières ou par le compostage du lisier a un impact environnemental important alors même que ces solutions ne résolvent rien en termes de phosphore et d'éléments traces métallique. Les traitements biologiques les plus sophistiqués permettent d'éliminer le phosphore et une partie des éléments traces métalliques dans des coproduits potentiellement exportables, mais ils ont un coût économique et écologique très élevé.

International audience; L'intensification de l'agriculture et de l'élevage a conduit, via la gestion des déjections animales, à des accumulations de nutriments dans les sols et des transferts de polluants vers les eaux de surface. De plus, le stockage et l'épandage de ces déjections engendrent diverses pollutions dont les émissions d'ammoniac et de gaz à effet de serre. Des filières de traitement ont été développées à partir des années 90 afin de répondre à la problématique des excédents d'azote puis de phosphore. La réduction des émissions gazeuses et l'abattement des micro-organismes pathogènes observés sur ces filières confirment que cette phase de traitement doit être vue comme une possibilité d'améliorer la gestion globale des déjections. Plus récemment, face à la prise en considération de nouveaux paramètres incluant notamment l'effet de serre et le problème énergétique, la méthanisation des déjections animales est de nouveau perçue comme une alternative incontournable. La rentabilité économique de cette technique nécessite toutefois l'ajout d'autres substrats organiques et une bonne valorisation de l'énergie produite. Enfin, les techniques de séparation/concentration des nutriments (N et P notamment) permettant leur transport/recyclage doivent également être considérées comme des alternatives intéressantes.