02 Fakultät Bau- und Umweltingenieurwissenschaften
Permanent URI for this collectionhttps://elib.uni-stuttgart.de/handle/11682/3
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Item Open Access Food waste generation in Germany in the scope of European legal requirements for monitoring and reporting(2021) Leverenz, Dominik; Schneider, Felicitas; Schmidt, Thomas; Hafner, Gerold; Nevárez, Zuemmy; Kranert, MartinThe European Commission and the German government are committed to the United Nations SDG target 12.3 of reducing food waste along production chains and halving it at retail and consumer levels by 2030. European member states are required to monitor national food waste levels and report annual progress to the European Commission from 2020 onward. In this regard, the main objective of our study is to provide food waste quantities for Germany by applying methods meeting the legal requirements for monitoring and reporting within Europe-wide harmonized methodology. Our results refer to 2015 and are based on the best available data, using a combination of official statistics, surveys, and literature. We found that approx. 11.9 ± 2.4 million tonnes (144 ± 28 kg/(cap·year)) of food waste were generated in Germany, while the reduction potentials varied throughout the different sectors. Even though the underlying data show uncertainties, the outcome of the study represents a starting point for the upcoming monitoring activities in Germany by uncovering data and knowledge gaps. To meet the political reduction targets, a national food waste strategy was launched in 2019 by the German Federal Ministry of Food and Agriculture, which is an important step toward cooperation and exchange between actors along the entire food chain, raising awareness, and improving data quality, monitoring, and implementation of prevention measures in practice.Item Open Access Environmental impacts on soil and groundwater of informal e-waste recycling processes in Ghana(2024) Owusu-Sekyere, Karoline; Aladago, David Alatule; Leverenz, Dominik; Oteng-Ababio, Martin; Kranert, MartinThis study examines the environmental impacts of informal e-waste recycling processes in Agbogbloshie, Ghana, which is one of the most notorious e-waste recycling sites in sub-Saharan Africa. Despite being unsafe and unorganized, the informal sector is still actively involved in dismantling, extracting, and disposing of e-waste in unauthorized locations on a considerably large scale. However, the academic research on the environmental consequences of informal recycling practices is limited. Soil and groundwater samples for five important and representative informal e-waste recycling processes and one related oil process were collected and analyzed to determine heavy metal-, PBDEs, PCBs, CBs, and PAHs concentrations. Contamination indices were used to assess and compare the effects of informal recycling processes, thereby providing a geochemical evaluation of soil conditions. As a result, the manual dismantling of CRT and ICT devices is the major source of heavy metal pollution. Furthermore, the burning of e-waste plastic for waste reduction purposes and the oil collection process substantially contribute to the input of organic pollutants. Regulatory measures for CRT and ICT recycling would result in an 85% reduction of heavy metals and the enforcement of a compulsory collection system for plastic and oil would eliminate 86% of the organic pollutants.Item Open Access Experiments and modeling for flexible biogas production by co-digestion of food waste and sewage sludge(2020) Liu, Yiyun; Huang, Tao; Li, Xiaofeng; Huang, Jingjing; Peng, Daoping; Maurer, Claudia; Kranert, MartinThis paper explores the feasibility of flexible biogas production by co-digestion of food waste and sewage sludge based on experiments and mathematical modeling. First, laboratory-scale experiments were carried out in variable operating conditions in terms of organic loading rate and feeding frequency to the digester. It is demonstrated that biogas production can achieve rapid responses to arbitrary feedings through co-digestion, and the stability of the anaerobic digestion process is not affected by the overloading of substrates. Compared with the conventional continuous mode, the required biogas storage capacity in flexible feeding mode can be significantly reduced. The optimum employed feeding organic loading rate (OLR) is identified, and how to adjust the feeding scheme for flexible biogas production is also discussed. Finally, a simplified prediction model for flexible biogas production is proposed and verified by experimental data, which could be conveniently used for demand-oriented control. It is expected that this research could give some theoretical basis for the enhancement of biogas utilization efficiency, thus expanding the applications of bio-energy.Item Open Access Methane, nitrous oxide, and ammonia emissions on dairy farms in Spain with or without bio-activator treatment(2022) San Martin Ruiz, Macarena; González Puelles, Jesús Eugenio; Herra Bogantes, Juan; Rivera-Méndez, William; Reiser, Martin; Kranert, MartinIntensive livestock farming substantially impacts the environment, especially farm and slurry management. Slurries are significant sources of greenhouse gases and ammonia. The present study was conducted in an intensive livestock production system in Galicia, Spain. The measurements were taken at six different farms in that region along with one control using common management practices in Galicia without the addition of a bio-activator. This study aimed to quantify GHGs and NH3 fluxes and their reductions during slurry treatment using a dynamic chamber through FTIR analysis and to examine the potential of usage of bio-activators for slurry management. In addition, gas concentrations were measured at the barns and compared with their slurry management and architectural volume to obtain influences on their management and the architectural volume of the barns. Additionally, the effects of using a bio-activator in the barns inside the facility areas were addressed. Moreover, qPCR analysis was conducted to understand the correlations between syncoms and methanogen populations when a bio-activator is added to the slurry with at least a 30% reduction in methanogenic populations. The outcomes suggest encouraging results for GHG reductions in the livestock sector, giving farmers future options for climate change mitigation among their standard practices.Item Open Access The impact of using co-compost on resource management and resilience of smallholder agriculture in South India(2022) Fendel, Veronika; Kranert, Martin; Maurer, Claudia; Garcés-Sánchez, Gabriela; Huang, Jingjing; Ramakrishna, GirijaAgriculture is the main source of income in India, with most farmers being smallholders and facing multiple challenges, such as climate change and land degradation. For the sustainable implementation of alternative circular approaches, it is important that agriculture benefits. To assess this, the impact of using co-compost (organic waste and black water consisting of feces and urine) was evaluated through surveys of 120 smallholder farmers in two case studies in South India. All 149 questions related to the overarching research question: what is the impact of using co-compost on closing loops in smallholder agriculture in terms of resource management and resilience. Secondary smallholder resources were found to be well managed and local networks and economies proved to be particularly effective in pandemics, reinforcing the potential for nutrient sources from urban areas. For most farmers, using co-compost improved yields (90%), soil (80%), plant health (93%) and, consequently, profits (67%), as well as water management (53%). Water management was significantly less of a problem for co-compost users (15%) than non-users (42%). In addition, the users of co-compost were able to save resources. Chemical fertilizer use was significantly reduced from 1.42 ± 2.1 to 0.9 ± 1.35 t (acre∙year)-1, with total savings ranging from 37 to 44%. Overall, 67% were able to reduce chemical fertilizer use and 25% were able to reduce chemical spray use. Additionally, 53% reduced water consumption by 30.3% ± 19.92%. The visible benefits could motivate others to try co-composting. The reservations of non-users were due to personal or societal aspects (25%). In addition, the desire of farmers to convert to organic farming and try alternative farming methods, such as using smart technologies, vermicomposting or co-compost, was high (43%) and was positively influenced by the profitable use of alternative circular concepts. Information dissemination was mainly promoted by advertising (60%) and demonstrations (27%), which influenced openness to alternative circular concepts and products. In conclusion, co-composting and co-recycling approaches have a positive impact on the resource management and resilience of smallholder agriculture and thus, contribute to achieving sustainability goals.Item Open Access Suitability of biowaste and green waste composts for organic farming in Germany and the resulting utilization potentials(2023) Gottschall, Ralf; Thelen-Jüngling, Maria; Kranert, Martin; Kehres, BertramIn this study, the suitability of biowaste and green waste composts in organic farming is presented based on quality assurance data of approximately 21,000 compost analyses from 2015 to 2020. The evaluation of compost suitability was based on both the legal regulations of the EU 2021/1165 and the requirements of the two largest German organic farming associations Bioland and Naturland. In 2020, 70.1% of the composts agreed with the above-mentioned regulations, 21.6% exceeded the limits for heavy metals and 7.3% exceeded the limits for foreign matter. The negative influence of the single elements regarding the suitability of composts for organic agriculture declined in the order Zn > Pb > Cd > Ni > Cu. In the bio-waste composts, the impurity content subsequently decreased by more than 50% from 2015 to 2020. In 2019 and 2020, approximately 2.5 million Mg fresh mass (FM) of the analyzed composts were suitable for organic farming. With an average compost application of 5 Mg FM per hectare (ha) and year, about 500,000 ha of arable land could have been supplied in 2020.Item Open Access Assessing data in the informal e-waste sector: The Agbogbloshie Scrapyard(2021) Owusu-Sekyere, Karoline; Batteiger, Alexander; Afoblikame, Richard; Hafner, Gerold; Kranert, MartinItem Open Access Stakeholder assessment on closing nutrient cycles through co-recycling of biodegradable household kitchen waste and black water between rural and urban areas in South India(2022) Fendel, Veronika; Kranert, Martin; Maurer, Claudia; Garcés-Sánchez, Gabriela; Huang, Jingjing; Ramakrishna, GirijaAgricultural land degradation, urban migration, increasing food demand and waste, and inadequate sanitation systems all affect farmers, local society, and the environment in South India. Joint recycling of biodegradable secondary household resources to close nutrient cycles between urban and rural regions can address all these challenges and thus several SDGs at the same time. Efforts are being made to this end, but many attempts fail. The central research question is, therefore: how can co-recycling concepts be evaluated in this context? For this purpose, composting plants, biogas fermenters, and a high-tech concept to produce plant charcoal, design fertilizer, and biopolymers are considered. The aim of this study is to evaluate the recycling concepts from the stakeholders’ perspective to avoid gaps between theory and practice. Six expert and one focus group interviews on two successful on-site case studies and 15 online expert interviews with thematic actors were qualitatively evaluated and presented in a social network analysis to identify preferences and indicators for the further evaluation of co-recycling concepts. The results show that the focus is on mature technologies such as compost and biogas. High-tech solutions are currently still in rudimentary demand but will play a more important role in the future. To evaluate such concepts, seven key indicators and their measured values were identified and clustered into the categories ecological, social, technical, economic, and connective. The results show that this methodology of close interaction with stakeholders and the evaluation of successful regional case studies minimize the gap between practice and theory, contribute to several goals of the SDGs, and thus enable such concepts to be implemented sustainably.