Browsing by Author "Kranert, Martin"

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Open Access
Assessing data in the informal e-waste sector: The Agbogbloshie Scrapyard
(2021) Owusu-Sekyere, Karoline; Batteiger, Alexander; Afoblikame, Richard; Hafner, Gerold; Kranert, Martin
Open Access
Composting and methane emissions of coffee by-products
(2021) San Martin Ruiz, Macarena; Reiser, Martin; Kranert, Martin
In the last 20 years, the demand for coffee production has increased detrimentally, heightening the need for production, which is currently driving the increase in land cultivation for coffee. However, this increase in production ultimately leads to the amplification of waste produced. This study aims to develop an experimental methodology for sustainable coffee by-products (Pulp (CP)) in Costa Rica for nutrient-rich compost. The performance of the experiments is to explore and optimize composting processes following its key parameters. This will allow quantifying the emissions rate to obtain an emission factor for CP during the open composting process and optimizing the conditions to minimize CH4 emissions using P and green waste (GW) materials. Five CP and GW mixtures were analyzed for the composting process for ten weeks, acting P as primary input material as a by-product. Quantification of the methane emissions was performed in two areas: composting area and open field deposition. Peak temperatures of compost appeared at twenty-five days for control and five days for GW added treatments. CP emission factors provide a similar result with the standard values recommended by the literature, accomplishing the emission reductions. Thus, this study designed and validated a sustainable protocol for transforming coffee by-products into compost.
Open Access
Emission determination by three remote sensing methods in two release trials
(2021) Elpelt-Wessel, Imke; Reiser, Martin; Morrison, Daniel; Kranert, Martin
Open Access
Enhanced composting as a way to a climate-friendly management of coffee by-products
(2020) San Martin Ruiz, Macarena; Reiser, Martin; Kranert, Martin
This study investigated the performance of aerobic windrow systems by using coffee by-products and green waste to reduce gaseous emissions. Thereafter, a comparison with the current treatment and gaseous emissions at a Coffee Mill in Costa Rica was made. Two different studies where performed in Germany (pile I and II) and one study in a Coffee Mill in Costa Rica (pile III). Temperature, water content, and pH were the key parameters controlled over 35 days in all the systems. Moreover, CH4 emission rates were quantified by a FTIR and by a portable gas detector device where the emissions reached values 100 times higher when coffee by-products as a unique material for the composting process was used. Results show that highest emission rates during the composting process for pile I was 0.007 g(m2)-1 h-1, for pile II 0.006 g(m2)-1 h-1, and for pile III 3.1 g(m2)-1 h-1. It was found that CH4 emissions could be avoided if the mixture and the formation of the windrow piles were performed following the key parameter for composting, and the usage of additional material is used. With this, the reduction of CH4 emissions at the Mill in Costa Rica could be achieved in the future.
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, Martin
This 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.
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, Martin
This 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.
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, Martin
The 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.
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, Girija
Agriculture 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.
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, Martin
Intensive 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.
Open Access
Microplastics persist in an arable soil but do not affect soil microbial biomass, enzyme activities, and crop yield
(2022) Schöpfer, Lion; Möller, Julia N.; Steiner, Thomas; Schnepf, Uwe; Marhan, Sven; Resch, Julia; Bayha, Ansilla; Löder, Martin G. J.; Freitag, Ruth; Brümmer, Franz; Laforsch, Christian; Streck, Thilo; Forberger, Jens; Kranert, Martin; Kandeler, Ellen; Pagel, Holger
Microplastics (MP, plastic particles <5 mm) are ubiquitous in arable soils due to significant inputs via organic fertilizers, sewage sludges, and plastic mulches. However, knowledge of typical MP loadings, their fate, and ecological impacts on arable soils is limited. We studied (1) MP background concentrations, (2) the fate of added conventional and biodegradable MP, and (3) effects of MP in combination with organic fertilizers on microbial abundance and activity associated with carbon (C) cycling, and crop yields in an arable soil. On a conventionally managed soil (Luvisol, silt loam), we arranged plots in a randomized complete block design with the following MP treatments (none, low‐density polyethylene [LDPE], a blend of poly(lactic acid) and poly(butylene adipate‐co‐terephthalate) [PLA/PBAT]) and organic fertilizers (none, compost, digestate). We added 20 kg MP ha-1 and 10 t organic fertilizers ha-1. We measured concentrations of MP in the soil, microbiological indicators of C cycling (microbial biomass and enzyme activities), and crop yields over 1.5 years. Background concentration of MP in the top 10 cm was 296 ± 110 (mean ± standard error) particles <0.5 mm per kg soil, with polypropylene, polystyrene, and polyethylene as the main polymers. Added LDPE and PLA/PBAT particles showed no changes in number and particle size over time. MP did not affect the soil microbiological indicators of C cycling or crop yields. Numerous MP occur in arable soils, suggesting diffuse MP entry into soils. In addition to conventional MP, biodegradable MP may persist under field conditions. However, MP at current concentrations are not expected to affect C turnover and crop yield.
Open Access
Neue Ansätze zur Umgestaltung der Hausmüllentsorgung
(2006) Kranert, Martin; Fischer, Klaus; Hafner, Georg; Escalante Mora, Nicolás
Die Hausmüllentsorgung soll in der Zukunft einfacher und kostengünstiger werden. Die bestehenden hohen Umweltstandards sollen beibehalten, die Nutzung von Wertstoffen optimiert werden. Am Lehrstuhl für Abfallwirtschaft und Abluft des Instituts für Siedlungswasserbau, Wassergüte- und Abfallwirtschaft wurde im Jahr 2006 ein Forschungsprojekt abgeschlossen, in dem neue konzeptionelle Ansätze für Baden-Württemberg untersucht wurden. Ziel des Forschungsprojektes war die Erarbeitung von Empfehlungen für eine nachhaltige Abfallwirtschaft. Hierbei sollten einerseits die bestehenden Umweltstandards aufrecht erhalten und andererseits eine Vereinfachung der Abfallwirtschaft insbesondere für die Haushalte erreicht werden.
Open Access
Nitrous oxide emission fluxes in coffee plantations during fertilization : a case study in Costa Rica
(2021) San Martin Ruiz, Macarena; Reiser, Martin; Kranert, Martin
The main source of N2O emissions is agriculture, and coffee monocultures have become an important part of these emissions. The demand for coffee has increased in the last five decades. Thus, its production in agricultural fields and the excess of fertilizers have increased. This study quantified N2O emissions from different dose applications and types of nitrogen fertilizer in a region of major coffee production in Costa Rica. A specific methodology to measure N2O fluxes from coffee plants was developed using Fourier-transform infrared spectroscopy (FTIR). Measurements were performed in a botanical garden in Germany and plots in Costa Rica, analyzing the behavior of a fertilizer in two varieties of coffee (Catuai and Geisha), and in a field experiment, testing two types of fertilizers (chemical (F1) and physical mixture (F2)) and compost (SA). As a result, the additions of synthetic fertilizer increased the N2O fluxes. F2 showed higher emissions than F1 by up to 90% in the field experiment, and an increase in general emissions occurred after a rain event in the coffee plantation. The weak levels of N2O emissions were caused by a rainfall deficit, maintaining low water content in the soil. Robust research is suggested for the inventories.
Open Access
The potential of the co-recycling of secondary biodegradable household resources including wild plants to close nutrient and carbon cycles in agriculture in Germany
(2022) Fendel, Veronika; Maurer, Claudia; Kranert, Martin; Huang, Jingjing; Schäffner, Benjamin
The aim of this study is to evaluate the potential for conserving natural resources (fossil resources, mineral fertilizer, fertile soil and biodiversity) with alternative circular concepts in order to contribute to the achievement of global sustainability goals. This study examines the potential contribution of substituting conventional products for three alternative circular economy concepts. This includes the household resources black water, kitchen and green waste for the production of design fertilizer, plant charcoal, biopolymers (concept 1) and biogas (concept 2), as well as the combination of household kitchen waste with wild plants for the production of biogas (concept 3). For evaluation, literature values were combined with analyzed parameters of input streams and biogas tests. The production and consumption values determined all relate to the functional unit of a person and year in Germany. Concept 1 has the highest potential for substitution in terms of the amount of recycled products. Co-recycling of organic household waste can account for 20% of NPK (nitrogen, phosphorus, potassium) mineral fertilizer, 19% of plastic consumption and 11% as a soil improving measure in soils in agriculture that are at risk of degradation. Concept 2 has the potential to contribute 12% of the final energy consumption in private households, which is an alternative solution regarding energy recovery due to the extensive practical experience. The joint recycling generates 141 kWh without, and 174 kWh with, fermentable green waste. If 75%, by weight, of fresh wild plants are added to the kitchen waste in concept 3, a wild plant area of 5 m2 is required, which could replace 41% of the biogas corn area, which is concept 3. This mix generates 193 kWh with the potential to reach 78% of corn energy production. The share of wild plants in kitchen waste of 50 or 25% by weight has the potential to achieve 115 or 104% of the corn energy yield, which is a promising concept for rural areas regarding energy recovery from an ecological point of view. The results show a considerable contribution potential of household resources in alternative cycle concepts to increase resource efficiency, and indirectly to diversify the agricultural landscape.
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, Girija
Agricultural 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.
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, Bertram
In 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.