Data quantifying the behaviour of macro and trace elements along the feed - manure - treated waste continuum in pig production.

Manure from animal production is commonly spread on agricultural soil as an organic fertiliser to provide macro and trace elements to crops. However, some trace elements can accumulate in the soil and become toxic to plants and microorganisms. These elements include copper (Cu) and zinc (Zn), which can be applied in large quantities when pig manure is spread. The feeding strategy and manure management (e.g. through treatment chains) are two mechanisms identified to better control the use of these elements, but their fate from the feed to the soil in pig production remains poorly documented. Better understanding the fate of Cu and Zn, as well as that of other trace and macro elements, along the feed - excreta - waste chain is required to develop alternative ways to reduce their environmental impacts. This dataset provides insight into the composition (Cu, Zn and other trace and macro elements) of organic products along two contrasting manure management chains: (1) only storage or (2) in-building separation, anaerobic digestion (AD) of solids, and digestate drying. Feed, raw slurry, liquid and solid phases after separation of the manure and AD products were sampled and then analysed to measure their total compound contents.

Agronomic characterization of anaerobic digestates with near-infrared spectroscopy.

Anaerobic digestion is an increasingly widespread process for organic waste treatment and renewable energy production due to the methane content of the biogas. This biological process also produces a digestate (i.e., the remaining content of the waste after treatment) with a high fertilizing potential. The digestate composition is highly variable due to the various organic wastes used as feedstock, the different plant configurations, and the post-treatment processes used. In order to optimize digestate spreading on agricultural soils by optimizing the fertilizer dose and, thus, reducing environmental impacts associated to digestate application, the agronomic characterization of digestate is essential. This study investigates the use of near infrared spectroscopy for predicting the most important agronomic parameters from freeze-dried digestates. A data set of 193 digestates was created to calibrate partial least squares regression models predicting organic matter, total organic carbon, organic nitrogen, phosphorus, and potassium contents. The calibration range of the models were between 249.8 and 878.6 gOM.kgDM-1, 171.9 and 499.5 gC.kgDM-1, 5.3 and 74.1 gN.kgDM-1, 2.7 and 44.9 gP.kgDM-1 and between 0.5 and 171.8 gK.kgDM-1, respectively. The calibrated models reliably predicted organic matter, total organic carbon, and phosphorus contents for the whole diversity of digestates with root mean square errors of prediction of 70.51 gOM.kgDM-1, 34.84 gC.kgDM-1 and 4.08 gP.kgDM-1, respectively. On the other hand, the model prediction of the organic nitrogen content had a root mean square error of 7.55 gN.kgDM-1 and was considered as acceptable. Lastly, the results did not demonstrate the feasibility of predicting the potassium content in digestates with near infrared spectroscopy. These results show that near infrared spectroscopy is a very promising analytical method for the characterization of the fertilizing value of digestates, which could provide large benefits in terms of analysis time and cost.

Dataset on the characteristics of the liquid effluent issued from separation of faeces and urine under slats using V-shaped scraper in swine buildings.

Separation of faeces and urine under slats in swine buildings using different technologies such as V-shaped scraper is becoming popular. Indeed, such a separation can allow improving air quality in the building and can also facilitate management of manure through concentration of carbon and phosphorus in the solid phase. Though solid phase management is well established through anaerobic digestion, the liquid phase, mainly urine, is still to be recycled or disposed of. However, the characteristics of this kind of effluent are quite different compared to slurry obtained from conventional building and corresponding to a mix of urine and faeces. Such characteristics are poorly documented and very few data are available in the literature. This dataset provides insight on the characteristics of this effluent to achieve treatment or nutrient recovery. Nine pig farms equipped with a V-shaped scraper and using different farming practices were selected for the sampling of this liquid phase. Building characteristics including animal capacity and physiological stage of animals and feeding strategy were taken into account. The characterisation of this effluent focused on global parameters (pH, Alkalinity, TS, VS, TSS, VSS) but also on the carbon and nitrogen content (COD, TKN, TAN). Total compounds and dissolved ions were also analysed to round off the characterisation. Finally, the characteristics of such liquid effluent were compared to urine collected directly from animals without contact with faeces.

Comprehensive determination of input state variables dataset required for anaerobic digestion modelling (ADM1) based on characterisation of organic substrates.

This article contains the data of 11 organic substrates including physicochemical, biochemical and nutritional characterisations. Additionally, it includes for all substrates the data of organic matter fractionation into easily biodegradable, slowly biodegradable and inert fractions performed with anaerobic respirometry method. Finally, based on physicochemical characterisations and organic matter fractionation, a detailed methodology for the determination of input state variables required for the anaerobic digestion model N°1 (ADM1) was presented and the dataset for all substrates is provided. An example of calculation for one substrate illustrates the methodology for the determination of these variables. Data provided in this article could be useful to any person interested in modelling anaerobic digestion and particularly co-digestion. Data could be also used for implementation of a database for anaerobic digestion modelling.

Modelling hydrolysis: Simultaneous versus sequential biodegradation of the hydrolysable fractions.

Hydrolysis is considered the limiting step during solid waste anaerobic digestion (including co-digestion of sludge and biosolids). Mechanisms of hydrolysis are mechanistically not well understood with detrimental impact on model predictive capability. The common approach to multiple substrates is to consider simultaneous degradation of the substrates. This may not have the capacity to separate the different kinetics. Sequential degradation of substrates is theoretically supported by microbial capacity and the composite nature of substrates (bioaccessibility concept). However, this has not been experimentally assessed. Sequential chemical fractionation has been successfully used to define inputs for an anaerobic digestion model. In this paper, sequential extractions of organic substrates were evaluated in order to compare both models. By removing each fraction (from the most accessible to the least accessible fraction) from three different substrates, anaerobic incubation tests showed that for physically structured substrates, such as activated sludge and wheat straw, sequential approach could better describe experimental results, while this was less important for homogeneous materials such as pulped fruit. Following this, anaerobic incubation tests were performed on five substrates. Cumulative methane production was modelled by the simultaneous and sequential approaches. Results showed that the sequential model could fit the experimental data for all the substrates whereas simultaneous model did not work for some substrates.

Microalgae and cyanobacteria modeling in water resource recovery facilities: A critical review.

Microalgal and cyanobacterial resource recovery systems could significantly advance nutrient recovery from wastewater by achieving effluent nitrogen (N) and phosphorus (P) levels below the current limit of technology. The successful implementation of phytoplankton, however, requires the formulation of process models that balance fidelity and simplicity to accurately simulate dynamic performance in response to environmental conditions. This work synthesizes the range of model structures that have been leveraged for algae and cyanobacteria modeling and core model features that are required to enable reliable process modeling in the context of water resource recovery facilities. Results from an extensive literature review of over 300 published phytoplankton models are presented, with particular attention to similarities with and differences from existing strategies to model chemotrophic wastewater treatment processes (e.g., via the Activated Sludge Models, ASMs). Building on published process models, the core requirements of a model structure for algal and cyanobacterial processes are presented, including detailed recommendations for the prediction of growth (under phototrophic, heterotrophic, and mixotrophic conditions), nutrient uptake, carbon uptake and storage, and respiration.

Physico-chemical, biochemical and nutritional characterisation of 42 organic wastes and residues from France.

The data presented in this article regroup characterisation of organic matter and nutritional composition of 42 organic wastes and residues usually used as substrates for anaerobic digestion. Those wastes have different origins from agro-industrial, agricultural and urban sectors in France including: algae, slaughterhouse waste, fat, food waste, fruits and vegetables residues, green waste, slurry, manure, wastewater treatment plant sludge and agricultural residues. The properties of organic matter are distinguished between global parameters (pH, total solids, volatile solids, COD and BMP), organic matter fractionation (biochemical and Van Soest) and the main nutrients content (N, P, K, Mg, Ca and S).

Treatment of swine wastewater in continuous activated sludge systems under different dissolved oxygen conditions: Reactor operation and evaluation using modelling.

Swine wastewater was treated in two continuously aerated activated sludge (AS) systems at high (AS1: 1.7-2.6 mg/L) and low (AS2: 0.04-0.08 mg/L) dissolved oxygen (DO), and at three temperatures (10, 20, and 30 °C). Biochemical oxygen demand (BOD) removal was >94.8%. Meanwhile, total nitrogen (N) removal was significantly higher in AS2, at 64, 89, and 88%, than in AS1, at 12, 24, and 46%, for 10, 20, and 30 °C, respectively. The experimental data were considered in a simulation study using an AS model for BOD and N removal, which also included nitrite, free ammonia, free nitrous acid, and temperature. Simulations at high-DO showed that ammonium was partly oxidized into nitrate but not removed, whereas at low-DO ammonium was removed mainly through the nitrite shortcut in simultaneous nitrification-denitrification. This study demonstrates that treatment at low-DO is an effective method for removing N, and modelling a helpful tool for its optimization.

Effects of organic matter on crystallization of struvite in biologically treated swine wastewater.

A sustainable way to recover phosphorus (P) in swine wastewater involves a preliminary step of P dissolution followed by the separation of particulate organic matter (OM). The next two steps are firstly the precipitation of struvite crystals done by adding a crystallization reagent (magnesia) and secondly the filtration of the crystals. To develop the process successfully at an industrial scale, the control of the mechanisms of precipitation is the key point in order to obtain high value-added products, that is, big struvite crystals easy to harvest and handle. Experiments with process parameters optimized previously in a synthetic swine wastewater were performed on real swine wastewater to assess the role of the OM on struvite crystallization. After 24 h, with a pH increase to 6.8 only, 90% of the initial P was precipitated and 60% was precipitated as struvite. 80% of the solid recovered was in the fraction > 100 µm. The other forms recovered were brushite, amorphous calcium phosphate, NaCl, KCl and OM. The influence of OM on struvite precipitation in acidified swine wastewater was negative on the reaction kinetics but positive on the size of the struvite crystals. The presence of colloidal particles increased the size of the struvite crystals but slowed down the kinetics due to the viscosity induced by the repulsive force of the colloids. The maximum size of single struvite crystals (200 µm) was observed with the presence of particulate OM.

Control of nitrogen behaviour by phosphate concentration during microalgal-bacterial cultivation using digestate.

The cultivation of microalgae with digestate supernatant is a promising process for the recovery of mineralized nutrients (P, N) from anaerobic digestion. Nevertheless, the variability of phosphorus concentration in the influent could limit this process. The impact of initial N:P ratios between 3 and 76gNgP(-1) was studied and proved no growth limitation over 14-day batch experiments even when P was depleted. Nitrogen assimilation was not affected by phosphorus concentrations and reached 10.1mgNL(-1)d(-1) whereas phosphorus removal ranged from 0.6 to 2.0mgPL(-1)d(-1). The biomass N:P ratio was found to be a function of the influent N:P ratio. Phosphorus storage by microalgae was thus confirmed. Nitrification was found to be highly dependent on the initial phosphorus concentration. The evolution of microalgae communities was also monitored and revealed the advantage of Scenedesmus over Chlorella when the media was phosphorus-depleted.

Digestate color and light intensity affect nutrient removal and competition phenomena in a microalgal-bacterial ecosystem.

During anaerobic digestion, nutrients are mineralized and may require post-treatment for optimum valorization. The cultivation of autotrophic microalgae using the digestate supernatant is a promising solution; however the dark color of the influent poses a serious problem. First, the color of the digestates was studied and the results obtained using three different digestates demonstrated a strong heterogeneity although their color remained rather constant over time. The digestates absorbed light over the whole visible spectrum and remained colored even after a ten-fold dilution. Secondly, the impact of light and of substrate color on the growth of Scenedesmus sp. and on nitrogen removal were assessed. These experiments led to the construction of a model for predicting the impact of influent color and light intensity on N removal. Maximum N removal (8.5 mgN- [Formula: see text]  L(-1) d(-1)) was observed with an initial optical density of 0.221 and 244 µmolE m(-)² s(-1) light and the model allows to determine N removal between 15.9 and 22.7 mgN- [Formula: see text]  L(-1) d(-1) in real conditions according to the dilution level of the influent and related color. Changes in the microalgae community were monitored and revealed the advantage of Chlorella over Scenedesmus under light-limitation. Additionally microalgae outcompeted nitrifying bacteria and experiments showed how microalgae become better competitors for nutrients when phosphorus is limiting. Furthermore, nitrification was limited by microalgae growth, even when P was not limiting.

Kinetics of struvite precipitation in synthetic biologically treated swine wastewaters.

An experimental design was set up to understand the influence of five process parameters on the kinetics of struvite precipitation in synthetic swine wastewaters. The responses studied were the kinetics of phosphorus (P) removal, the struvite precipitation rate and the dissolution rate of amorphous calcium phosphates (ACP). The kinetic study showed that the P-removal was complete in less than 1 h and was influenced positively by the added MgO. The precipitation of struvite with MgO was confirmed to follow a first-order kinetic. This study showed that ACP co-precipitated with struvite during the first 30 min. Afterwards, ACP dissolved to maintain the phosphates balance limiting the struvite growth. An initial Mg:Ca > 1.5 induced a complete dissolution of ACP in 1 h. Another experiment was conducted and it validated the results of the statistical model. This experiment also determined that 7-10 h was the best time to recover large crystals. After 10 h, the crystals were broken by stirring.

Feasibility and interest of the anammox process as treatment alternative for anaerobic digester supernatants in manure processing--an overview.

Completely autotrophic nitrogen removal (ANR) is based on the combination of partial nitritation (PN) and anaerobic ammonium oxidation (anammox). It is a promising alternative for the subsequent treatment of biogas digester supernatants in livestock manure processing and nitrogen surplus scenarios. However, as no full-scale experiences in the treatment of manure digestates by ANR have been published to date, future field studies addressing treatment of this kind of effluent would be of great interest. Some topics to be considered in these studies would be coupling anaerobic digestion and ANR, analysis of the factors that affect the process, comparing reactor configurations, microbial ecology, gas emissions, and achieving robust performance. This paper provides an overview of published studies on ANR. Specific issues related to the applicability of the process for treating manure digestates are discussed. The energy requirements of ANR are compared with those of other technological alternatives aimed at recovering nitrogen from digester supernatants. The results of the assessment were shown to depend on the composition of the supernatant. In this regard, the PN-anammox process was shown to be more competitive than other alternatives particularly at concentrations of up to 2 kg NH4(+)-N m(-3).

Optimization of struvite precipitation in synthetic biologically treated swine wastewater--determination of the optimal process parameters.

A sustainable way to recover phosphorus (P) in swine wastewater involves a preliminary step of P dissolution followed by the separation of particulate organic matter. The next two steps are firstly the precipitation of struvite crystals done by adding a crystallization reagent (magnesia) and secondly the filtration of the crystals. A design of experiments with five process parameters was set up to optimize the size of the struvite crystals in a synthetic swine wastewater. More than 90% of P was recovered as large crystals of struvite in optimal conditions which were: low Mg:Ca ratio (2.25:1), the leading parameter, high N:P ratio (3:1), moderate stirring rate (between 45 and 90 rpm) and low temperature (below 20 °C).These results were obtained despite the presence of a large amount of calcium and using a cheap reactant (MgO). The composition of the precipitates was identified by Raman analysis and solid dissolution. Results showed that amorphous calcium phosphate (ACP) co-precipitated with struvite and that carbonates were incorporated with solid fractions.

Prediction of hydrogen sulphide production during anaerobic digestion of organic substrates.

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 29.6 mg S/kg of total solids, and 66% of the feedstocks analysed contained less than 5 mg S/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(2)S in the raw biogas. A model to link H(2)S 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).

Anaerobic hydrolysis and acidification of organic substrates: determination of anaerobic hydrolytic potential.

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 7d 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.

Nitrogen removal via nitrite pathway and the related nitrous oxide emission during piggery wastewater treatment.

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.

Combined anaerobic and activated sludge anoxic/oxic treatment for piggery wastewater.

A process combining anaerobic digestion and anoxic/oxic treatment was developed to treat pig slurry in-order-to partially convert organic matter (OM) into a valuable energy and simultaneously to comply with the environmental constraints as regards to nitrogen removal. However, OM content of digested pig slurry is insufficient to allow a further complete denitrification of the mineral nitrogen content. Hence, four different configurations were designed and evaluated to manage the OM requirements and achieve denitrification. Partial nitrification (PN) of ammonium to nitrite was also applied by regulating oxygen inflow time. Thus, the combined process could remove 38-52% of CODt, 79-88% of CODs, 66-75% of TN and 98-99% of NH(4)(+)N concentrations depending on the slurry characteristics. Anaerobic digestion was able to produce 5.9 Nm(3) of CH(4)/m(slurry added)(3). PN allowed a reduction in the oxygen and OM requirements respectively for nitrification and denitrification. Thus, this process trims-down the energy costs at the farm scale.

Challenges and innovations on biological treatment of livestock effluents.

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

Evolution of N-converting bacteria during the start-up of anaerobic digestion coupled biological nitrogen removal pilot-scale bioreactors treating high-strength animal waste slurry.

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 NH(3)-oxidizing bacteria (AOB), NO(2)(-)-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 NO(3)(-) whereas the coupled bioreactors could be optimized to achieve the same via a NO(2)(-) shortcut.