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The use of biochar as strategy to mitigate the NH3 emissions during the digestate storage
No full textIntroduction
The environmental impact of manure storage in terms of ammonia (NH3) emissions has recently become a subject of greater interest. In this context, a common mitigation strategy is to cover the surface of the storage tank with a variety of floating materials, including straw, sawdust, clay, and oil. A common issue associated with the use of covers is the financial cost and the necessity for maintenance over time. Biochar has recently been investigated as an alternative to floating covers due to its durability and hydrophobicity.
This work examines the potential of biochar as a floating cover to reduce NH3 emissions, providing an overview of different biochar applications, in terms of dosage and biochar characteristics.
Material and Methods
The simulation of digestate storage was conducted in a climate-controlled room, utilising 5 L glass vessels. Buffalo digestate was collected from an anaerobic digestion plant in Southern Italy and analysed according to Apha (2005). First and second tests were performed with a commercial biochar, produced via pyrolysis (30 minutes) at 550 °C, using as feedstock mixed wood chips from Piedmont. Three different biochar applications methods were compared: 140 g (2 cm layer) and 70 g of biochar applied on the surface, and 140 g of biochar mixed with the digestate. In the third test, biochar was produced in the laboratory, using two different pyrolysis temperatures: 285 and 450 °C. Wood chips of Poplar tree (Populus nigra) were used as feedstock. A 2 cm layer was adopted. NH3 emissions were monitored by means of the dynamic chamber technique, as described by Scotto di Perta et al. (2022). After tests, N adsorbed during the manure storage tests by the biochar was evaluated, as described by Scotto di Perta et al. (2024).
Results and Discussion
Biochar dosage and application method When the biochar layer is floating and compact, it reduces 78% NH3 released into the atmosphere with 2 cm layer thickness, since it introduces an additional resistance to the gas transfer. This aspect is even more effective than the N-NH4 + adsorption. Moreover, the results show that a 43% reduction in NH3 emissions can be achieved by using biochar as a floating cover of 2 cm rather than its mixing with digestate (Scotto di Perta et al., 2024).
Pyrolysis temperature
Biochar obtained at 450°C was characterized by the higher specific surface of the biochar, this can explain its higher N-NH4 + adsorption (2.86 ± 0.75 mg/gchar), since the possibility of interaction of the biochar with the ions present in the solution increases. On the other hand, the greater adsorption capacity of biochar at 450°C does not seem to have played a relevant role in the reduction of NH3 emissions, confirming that the "lid" action is prevailing in limiting the gaseous exchange. Biochar produced at 285 °C is more hydrophobic and durable, thus it emitted 42% less than the other one (Scotto di Perta et al., 2022).
Conclusions
In conclusion, the results demonstrate that the application of biochar on the manure surface is an effective method for reducing NH3 emission by up to 78%, with a 2 cm layer thickness. Furthermore, biochar functions as an adsorbent material. Biochar produced at a lower temperature resulted in a greater degree of hydrophilicity thus, a more durable product when applied as a floating cover
Identification of Marginal Landscapes as Support for Sustainable Development: GIS-Based Analysis and Landscape Metrics Assessment in Southern Italy Areas
No full textLandscape is increasingly characterized by a multifaced nature. In scientific literature and landscape governance, new landscape definitions are often coined to explain new meanings and to define specific intervention strategies and tools. The present study purposes a framework for the identification of hybrid landscapes as support for land-use planners, which aim to guarantee development opportunities as well as natural heritage preservation and valorization. “Marginal lands” were identified starting from EU Directives and scientific approaches, by means of multicriteria analysis. Different scenarios were built: (1) no-change; (2) energy crops; (3) green infrastructures. An ecosystem services approach, via landscape metrics analysis, was used to compare the possible effects of scenarios. About 20% of the study area, an internal area of the southern Apennines, was identified as suitable for land-use change in a medium-short time, and scenarios of land-use changes show a better condition, in terms of fragmentation, than as a current asset. Results showed the strategic role and potentialities of marginal lands, as a trade-off between nature conservation and development issues, suggesting new opportunities for green infrastructures and a renewable energies chain. The study allowed for deepening the close connection among landscape planning approaches, land use change scenarios building and environmental assessment, focused on the ex-ante evaluation stage
Energy crops in marginal areas: Scenario-based assessment through ecosystem services, as support to sustainable development
No full textStarting from the identification of marginal areas, this work presents a possible physical–mathematical approach as a support to landscape planning, based on the pragmatic determination of the predictable environmental effects connected to land use changes (LUC) and related to objective and quantitative ecological indicators for environmental impact assessment.
“Fringe areas”, which are more suitable to change in a medium-short time frame, were determined through a spatial multicriteria decision analysis (S-MCDA) process. Three land use changes scenarios were identified and analysed, namely: the current situation, energy crop cultivation in marginal lands, and the possible abandonment of lands such as these. Energy crop cultivation in marginal lands is widely considered to be a useful opportunity for farmers, against the progressive risk of under-utilization or abandonment; nevertheless, the large areas needed can cause important environmental side-effects. In order to assess the possible variations in environmental components in the ex-ante planning phase, scenarios were assessed in terms of habitat and biodiversity ecosystems services (using both monetary and indexes approach), focusing also on possible environmental fragmentation analysis by means of landscape metrics, which are simple measures used to deepen landscape configuration and structure.
The S-MCDA process allowed about 10% of the study area with less favourable environmental conditions to be defined, where land use change is desirable in a medium-short time frame. For the energy crops scenario, the ecosystem services (ESs) approach highlights positive repercussions in terms of habitat quality and biodiversity value. Similar trends are highlighted by different ESs assessment methods adopted (monetary and indexes), confirming themselves. Also, landscape pattern analysis confirmed positive habitat connectivity trends: the delineation of fringe areas has preserved, in energy crops scenario, natural and semi-natural classes, reducing the risk of disturbance with respect to the biodiversity and habitat. This condition assumes that adopted S-MCDA method can contribute positively and significantly to the definition of LUC scenarios and land management.
In conclusion, marginal lands can become an opportunity to improve socio-economic conditions and to enhance land image, while respecting the environment. LUC scenarios building, and their assessment by means of ecological indicators become a dynamic and structured tool in the land use planning /management process to support decision maker choices and to re-calibrate interventions, with the aim of contributing to sustainable policies of land management (ecological corridors, compensation and / or mitigation measures, etc.), emphasizing land sustainable management benefits (such as climate change adaptation or disaster risk reduction)
Monitoring of NH3 and CH4 emissions from dairy cows under storage conditions
No full textCattle breeding is almost diffused around the world, with a growth of 7% in the last ten years. The increase in manure production makes cattle farms responsible for ammonia (NH 3 ) and methane (CH 4 ) emissions into the atmosphere. Many treatments have been adopted to reduce gaseous emissions, in order to comply with European regulations. Anaerobic digestion (AD) and solid-liquid separation (SLS) can modify the physical and chemical characteristics of manure, which are related to NH 3 and CH 4 emissions. The literature on the effect of the combination of both treatments on CH 4 and NH 3 emissions is still limited. Raw slurry (RS) and liquid fraction of digestate (LFD) were monitored during storage under controlled conditions, measuring NH 3 and CH 4 emissions with the dynamic chamber technique. The air sampled was analyzed using a gas-sensitive semiconductor and electrochemical sensors (Aeroqual, series 500). Results show that SLS and AD reduced the organic matter of manure, thus CH 4 emissions during storage, which accounts for 27% less than RS. On the other hand, AD increased the NH 3 emissions (48,5% more than RS) because of the higher Total Ammoniacal Nitrogen content of LFD. Only studying both gasses and considering the emissions in terms of CO 2 eq, it is possible to observe that RS is responsible for 11.4% of emissions in terms of CO 2 eq, more than LFD
Livestock Manure dIgestate Treatments to reduce GHGs and NH3 emissions and meet crop nutrients requirement - (LiMIT DGGAS)
No full textThe European Green Deal aims to get climate neutrality through a modern, resource-efficient and competitive economy where there are no net emissions of greenhouse gases within 2050. A specific challenge is posed for agriculture, that is responsible for 10.3% of the EU’s GHG emissions and about 94% of NH3 emissions, with nitrogen and phosphorous losses exceeding the European limit by a factor of 3.3, and 2.0, respectively, thus threatening terrestrial, aquatic, and atmospheric ecosystems. One cause can be found in the management of animal manure in livestock and crop production, which is one of the major causes of pollution due to nitrogen, phosphorus and carbon losses. In this sense, anaerobic digestion is a consolidated process that can provide an effective support in livestock manure management, ensuring the production of biomethane and more stabilized effluents for agricultural uses.
Nevertheless, some constraints are still reported in the application of anaerobic digestion in livestock farming since it is a process that does not affect the total N and P content of fed animal manure. Given the importance of the implementation of such a process devoted to producing methane and organic fertilizers, further treatments are strategic to ensure the achievement of Eu Green Deal’s targets.Specifically, great attention has to be posed to the valorization of the field agronomic utilization of digestate while avoiding the release of gases (NH3, N2O, CH4, and CO2) in the atmosphere.Based on these premises, this project is aimed to test two promising treatment strategies based on the recovery of nutrients in digestate, in order to produce new types of fertilizers or amendments. Moreover, the project is aimed to assess the fertilization efficiency of effluents and to monitor gaseous emissions from various phases of the treatment plants, and after the application of treated digested to the soil. With specific regards to soil application of digestate and ammonia emissions, data will be collected according to dataset provided by ALFAM2 model, to improve results for digestate use in Mediterranean climate. For the project’s purpose, two existing treatment plants will be tested in order to overcome the existing gap in the technology and to reduce their environmental impact or enhance their cost-effectiveness. Expected
results of the projects are 1) reducing constraints of treatment strategies for valorizing nutrients from digestate; 2) Evaluating fertilization efficiency of treated digestate; 3) Estimation of NH3 e GHGs emissions from relevant phase of livestock manure digestate chain; 4) Providing dataset for ALFAM2 model; 5) Techno-economic analysis and territorial assessment of treatment strategies adopted. Accordingly, the project will trace the road for a control on by-products quality, valorization of agronomic utilization of digestate, reduction of environmental effects due to the release of pollutant gases, as required from policy-makers and stakeholders
Diachronic analyses on land use changes and vernacular architecture distribution, to support agricultural landscape development
No full textRural buildings have shaped for centuries the landscape. In the last decades, however, the traditional balance between vernacular architectures and agricultural areas was often altered, without a correspondence between productions and buildings. Identifying the rural buildings distribution, recognizing the changes in land uses and understanding the criteria and processes which characterize them, are strategic both to protect the traditional and cultural heritage and to support a suitable landscape development. The main aims of the work are: to support the identification of vernacular architectures in Mediterranean costal and less productive contexts; to recognize the land use changes and their impacts on landscape structure; and to support the decision makers activity considering both the historical building heritage and the local community development issues. In the study area, the Sorrento’ Peninsula (Southern Italy), at local scale, due to the absence of a regional archive on rural buildings, the buildings identification (in the last fifty years) inside the agricultural areas and their comparison with topographic, aesthetic and connectivity indices were developed; at regional scale, land uses changes recognition and their impact assessment, in terms of landscape metrics were assessed. A considerably huge area (20 %) was subjected to land use changes, mainly due to urban and forested areas increase and agricultural lands decrease. As fragmentation process results, the landscape structure is more complex and disaggregated, consisting of smaller, numerous and isolated parcels. Furthermore, despite the reduction in agricultural areas, the number of buildings has more than doubled, highlighting the strong pressure to which the territory is subjected today due to land consumption. The results stand out the need for decision-makers to monitor these contexts to stem the effects, and the vernacular architecture preservation and the agricultural uses improvement can be the support for new different socio-economic activities and opportunities. The present work proved to be useful for meta-analysis of rural buildings distribution compared with land use changed driving forces, allowing a significant reduction in analysis costs and times. The approaches and methods integration allows providing a replicable model for other Mediterranean and European regions. The combination of traditional knowledge and modern technology offers a comprehensive approach to support a landscape management that respects both the past and the future, fostering resilience and sustainable development in rural areas
The landscape approach as support to the livestock manure management. the buffalo herds case-study in Sele plain, Campania region
No full textThe buffalo breeding and mozzarella cheese production are crucial for the economic asset of Campania region (Southern Italy). The recent awareness about the meaningful environmental impacts of livestock sector and related manure management, together with the law regulations and new limitations imposed at the EU and national level, require the control and reduction of ammonia emissions as well as other gases such as VOCs in the primary sector. For this purpose, this paper proposes a framework of tools and activities/processes, typical of the landscape/land-use planning approaches, which could be strategic for the livestock manure management chain. Algorithm's development, GIS environment parameters definition, probabilistic multi-criteria approach and spatial modelling methods, were used as support for the rural land governance. The work, in a delicate phase of adaptation of the livestock sector, according to the EU Green Deal (2020) and the regional Council Decree (2017) calls, aims to raise the awareness of policy makers, administrators and operators, to the environmental sustainability of the livestock sector. The aim is to promote good agricultural practices, which can protect the environmental system and, furthermore, become an additional economic resource. The results are remarkably: on the one hand, the suitable areas for the livestock manure treatment plants have been identified; on the other hand, suitable areas for manure spreading were also identified and evaluated. The framework allows approaching the manure management issue from the point of view of sustainability and mitigation of the environmental impacts of, basing not only on the production perspective but also considering socio-economic and environmental criteria
Effect of Ammoniacal Nitrogen on One-Stage and Two-Stage Anaerobic Digestion of Food Waste.
No full textThis research compares the operation of one-stage and two-stage anaerobic continuously stirred tank reactor (CSTR) systems fed semi-continuously with food waste. The main purpose was to investigate the effects of ammoniacal nitrogen on the anaerobic digestion process. The two-stage system gave more reliable operation compared to one-stage due to: (i) a better pH self-adjusting capacity; (ii) a higher resistance to organic loading shocks; and (iii) a higher conversion rate of organic substrate to biomethane. Also a small amount of biohydrogen was detected from the first stage of the two-stage reactor making this system attractive for biohythane production. As the digestate contains ammoniacal nitrogen, re-circulating it provided the necessary alkalinity in the systems, thus preventing an eventual failure by volatile fatty acids (VFA) accumulation. However, re-circulation also resulted in an ammonium accumulation, yielding a lower biomethane production. Based on the batch experimental results the 50% inhibitory concentration of total ammoniacal nitrogen on the methanogenic activities was calculated as 3.8. g/L, corresponding to 146. mg/L free ammonia for the inoculum used for this research. The two-stage system was affected by the inhibition more than the one-stage system, as it requires less alkalinity and the physically separated methanogens are more sensitive to inhibitory factors, such as ammonium and propionic acid
Assessment of Hydrogen and Volatile Fatty Acid Production from Fruit and Vegetable Waste: A Case Study of Mediterranean Markets
No full textThis study investigates the dark fermentation of fruit and vegetable waste under mesophilic conditions (30–34 °C), as a valorization route for H2 and volatile fatty acids production, simulating the open market waste composition over the year in two Mediterranean countries. Specifically, the study focuses on the effect of the (i) seasonal variability, (ii) initial pH, and (iii) substrate/inoculum ratio on the yields and composition of the main end products. Concerning the seasonal variation, the summer and spring mixtures led to +16.8 and +21.7% higher H2 production than the winter/autumn mixture, respectively. Further investigation on the least productive substrate (winter/autumn) led to 193.0 ± 7.4 NmL of H2 g VS−1 at a pH of 5.5 and a substrate/inoculum of 1. With the same substrate, at a pH of 7.5, the highest acetic acid yield of 7.0 mmol/g VS was observed, with acetic acid corresponding to 78.2% of the total acids. Whereas a substrate/inoculum of 3 resulted in the lowest H2 yield, amounting to 111.2 ± 7.6 NmL of H2 g VS−1, due to a decrease of the pH to 4.8, which likely caused an inhibitory effect by undissociated acids. This study demonstrates that dark fermentation can be a valuable strategy to efficiently manage such leftovers, rather than landfilling or improperly treating them
GIS-based analysis to assess biogas energy potential as support for manure management in Southern Italy
Full text linkAnaerobic digestion can provide a valuable aid to manure management while producing renewable energy. Biogas production is highly dependent on the size and composition of livestock farms, and the availability of fresh manure can vary throughout the year, limiting reliable assessment of potential production. The aim of this study is to develop an affordable GIS-based analysis to support manure management, based on a highly detailed livestock farm database. Databases refer to the years 2013 and 2019 and report the herd consistency and the age of each class head. Kernel density (KD) was used to identify emerging hotspot areas with potentially high concentrations of nitrogen applied to the field. Three KD classification methods were compared: defined interval (DI) into 3 classes (0-170, 170-340, > 340 kg N/ha), quantile (Q) and natural break (NB). The results show that the DI and NB areas correspond to 40 % and 84 % of the total N of buffalo origin in the Campania region, with a N surplus in the hotspot areas localized in nitrate vulnerable zones of 55 and 6 % respectively. The biogas produced from 50 % of the buffalo manure in these areas generates sufficient energy to allow the removal of the N surplus
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