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Food waste (FW) storage influences its physical–chemical characteristics and anaerobic digestion (AD) performance. In this work we present the results of two weeks long experiment where two types of FW were stored in dedicated cells (10 L and 300 L). Air was evenly flushed on the top surface of the substrates and then analyzed to identify and quant...
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Citations
... Regarding the anaerobic digestion process, its feedstock is the biweekly collected household kitchen waste. Although this could be seen as a limiting factor for operating the anaerobic digestion process, the highly perishable household kitchen waste cannot be stored for a long time regardless (Degueurce et al., 2020). The biweekly collected amount of household kitchen waste m k is continuously processed via the anaerobic digestion process until the supply is depleted, ideally coinciding with a new collection round. ...
Biorefinery systems that are embedded in their local setting provide an attractive framework for the valorisation of locally available food- and other bio-waste streams. They can aid in the provision of local bio-waste processing facilities as well as the targeted revalorisation of local bio-waste feedstocks by converting them in locally desired biorefinery products. Since food- and other bio-waste feedstocks are often diffuse feedstocks, small-scale biorefineries that are tailored for their local setting are the most suitable biorefining system for their processing. Whereas small-scale biorefineries cannot rely on the economy-of-scale to be an economic sustainable endeavour, they need to be meticulously optimised according to multiple sustainability objectives. These objectives can be of economic, societal, or environmental nature. A commonly used optimisation criterion in these problems is the energy requirements of the entire biorefinery system. For many commonly used biorefinery processes mass balance models are available (which are often mechanistic models), however, energy balances are difficult to obtain. Chemical process simulators, like Aspen Plus, provide an extensive toolkit to easily model the mass- and energy balances of a multitude of chemical processes. However, especially in the context of multi-objective optimisation, the obtained white-box models are too complex to simulate the considered processes efficiently consecutively. Therefore, in this contribution, a critical analysis is presented of the use of white-box versus the black-box models in the context of the multi-objective optimisation of a small-scale biorefinery. An in-house developed biorefinery network is re-modelled in Aspen Plus and used as a digital twin for the development of a surrogate model. Eventually, the modelled biorefinery network is optimised using both models and a comprehensive evaluation is drafted.
... Such a storage step also occurs in decentralized FW management systems for supermarkets and restaurants [19,20]. Thus, the temporal storage of FW might influence not only its physical-chemical properties but also its microbial composition [21][22][23][24], which in turn might affect its valorization via DF and AD. For instance, stored FW can be pre-hydrolyzed/acidified to different extents depending on the storage conditions and FW composition, commonly leading to lactic fermentation [17,24] but the accumulation of fermentation products such as acetate, propionate, butyrate and ethanol may also exist [19,24,25]. ...
... Hence, it is of paramount importance to understand in detail how FW characteristics would change with storage conditions and how such latent changes would influence the yields and kinetics of biohydrogen and biogas production, in order to achieve an enhanced FW-to-bioenergy conversion process. In this context, great efforts have been made to investigate the storage of FW and its impact on bioenergy recovery [16,[17][18][19]21,23,24,[31][32][33]. It can be inferred from those studies that the maximum achievable bioenergy production from a given type of FW will greatly depend on the biotic and abiotic changes that the feedstock experiences from the time it is generated until its final valorization. ...
... Under both assessed FW storage conditions, acetate was the second most dominant organic acid with titers ranging from 1.1 to 1.3 g/L. In this context, previous studies in literature have shown a similar dominance of a primary lactate-type fermentation corresponding well with the tendency of the pH of FW to decrease over storage time [9,16,17,21,22,24]. ...
The present study investigated the physicochemical and microbiological changes occurring during the storage of simulated restaurant food waste (FW) and how such changes affected its biohydrogen and biogas production potential. FW was stored for 72 h in a closed atmosphere under two different scenarios: i) without and ii) with inoculation of a mixed microbial culture harboring lactic acid bacteria (LAB). Both storage scenarios resulted in similar biotic and abiotic changes in FW. Particularly, FW was pre-acidified and pre-hydrolyzed to some extent during the storage, resulting in a feedstock enriched in LAB (≈ 95 % total relative abundance) and lactate (10.5-12.3 g/L, 87.0-90.5 % selectivity). Biochemical hydrogen potential tests revealed that the use of stored FW resulted in similar or even higher hydrogen production efficiencies compared to that of non-stored FW, achieving up to 60 NmL H 2 /g VS added and a maximum volumetric hydrogen production rate of 9.7 NL H 2 /L-d. Metabolically , the conversion of lactate into hydrogen was crucial regardless of the use of non-stored or stored FW, albeit the presence of fermentable carbohydrates in the substrate was also essential either to produce lactate or to co-produce extra hydrogen. On the contrary, biochemical methane potential tests showed that the biogas production potential of FW was not affected by storage, yielding on average 400 NmL CH 4 /g VS added and revealing that lactate oxidation to methane precursors represented an important step in FW biomethanization.
... In general, countries with a very good and good level of food security are those with high and medium income, while countries with a moderate and weak level of food security are those with a reasonable and low-income level. The reasons for FLW in high/medium-income countries are related to consumer behavior and a lack of coordination between actors in the FSC [8,67,68]; for example, leftover waste, food not used in time, personal preferences, spoilage, or burning [20,29]. In contrast, in countries with moderate/low-income levels, the reasons for FLW are financial and managerial, some limitations are related to harvesting techniques, lack of storage, and cooling facilities in countries with difficult climatic conditions, infrastructure, packaging, and marketing systems [69,70]. ...
Worldwide, the number of people suffering from hunger is around 702 and 828 million, and 2.3 billion people have moderate or severe food insecurity. This situation is striking, considering that the vast amount of food discarded globally equals 1.3 billion tons annually. For this reason, in 2015, world leaders agreed to a global agenda for 2030, adopting the Sustainable Development Goals (SDGs). Among its objectives, are to fight against poverty, hunger, and gender inequality worldwide and achieve environmental sustainability. With this framework, this article uses a top-down mass balance approach to calculate food loss and waste (FLW) by country’s food security level. In addition, it explores the causes of FLW and its impacts on natural resources, climate change, food security, and the SDGs in countries with a weak and moderate level of food security. The estimated global FLW was 1498 million tons of food in 2017. The most food discarded was concentrated in countries with good food security, 894.3 million tons. In contrast, the lowest food discard occurred in countries with a weak level of food security, 11.4 million tons. The primary outcome of this paper is to establish a link between the levels of food security and food loss in different countries, which may serve as a guide for the design of specific public policies.
... These anaerobic cultures usually do not use genetic engineering methods, such that this method has room for optimization by using genetic engineering introduced in this review. To achieve a sustainable society, we have to solve some problems other than the development of biological methods such as the storage of food waste [119,120]. In addition, consumption of ammonia is important for creating sustainable environment. ...
Ammonia is an important chemical that is widely used in fertilizer applications as well as in the steel, chemical, textile, and pharmaceutical industries, which has attracted attention as a potential fuel. Thus, approaches to achieve sustainable ammonia production have attracted considerable attention. In particular, biological approaches are important for achieving a sustainable society because they can produce ammonia under mild conditions with minimal environmental impact compared with chemical methods. For example, nitrogen fixation by nitrogenase in heterogeneous hosts and ammonia production from food waste using microorganisms have been developed. In addition, crop production using nitrogen-fixing bacteria has been considered as a potential approach to achieving a sustainable ammonia economy. This review describes previous research on biological ammonia production and provides insights into achieving a sustainable society.
... FW composting leads to improved soil physical properties and physicochemical parameter variations during the composting of FW [64,65]. Anaerobic digestion is an outstanding technology as it is environmentally friendly in contrast to the primary current FW management practices, i.e. landfilling, incineration, or composting, mainly when focusing on global warming potential [66,67]. During anaerobic digestion of FW, organic wastes and various biomass are converted into biogas (30%-40%) carbon dioxide, (60%-70%) CH 4 , and traces of other gases such as hydrogen and hydrogen sulfide). ...
Continuous population growth associated with sanitation, food waste (FW), and domestic wastewater (DWW) is becoming critical globally. Crucial efforts and appropriate measures to utilize the FW and DWW for resources are needed. This paper reviews the conventional treatment techniques, challenges, and associated merits for treating FW and DWW. In the context of this review, DWW is often referred to as blackwater (BW)/feces. Due to the rationale for resource amplification, the review proposed that both mixtures (FW and DWW) be stored in a sub-surface storage tank for several months or years. They are further biodegraded in a bioprocess to generate energy with stabilized digestates. The effluent’s peculiar features are low organic acids with a low pH4 value, offering a stabilized and sanitized effluent. The second proposed route was to integrate anaerobic digestion, composting, and pyrolysis. Anaerobic digestion will offer bioenergy and digestates. Composting will cater to compost production and avert digestate drying and heating costs during pyrolysis. The pyrolysis of the digestates will generate biochar and bioenergy materials, while improved bioprocess performance is attained with the simultaneous biochar utilization in the bioprocess. The integrated technological routes can valorize DWW and FW for maximum resource recovery and sustainable development in a real-world context. The concept can be applied to an existing facility to create a cleaner and more efficient DWW with FW recycling. However, a comprehensive techno-economic analysis must be conducted.
... The generation of leachate for 4 and 7 days was similar, although there was an increase of around 15% from 4 days to 7 days. Degueurce et al. 33 evaluated a storage pretreatment for OFMSW and observed that the conversion from solid to leachate ranged from 15 to 27% for different substrates after 2 weeks of storage, and the largest degraded portion (about 15%) occurred in the first 3 days. In addition, during a period of 5-8 days of storage and considering substrates of different compositions, the percentage of solid matter converted to leachate was 17.5%, 34 corroborating the present study. ...
... This fact indicated that a storage time of around 1 week is an appropriate pretreatment before AD. 33 ...
Food waste represents a relevant fraction of municipal solid organic waste, and anaerobic digestion can be an eco‐friendly alternative for sustainable management in a circular economy framework. One of the challenges to the implementation of anaerobic digestion is the availability of easily degradable compounds in the substrate, which can be solved by the application of pretreatment to increase methane production. In this study, the influence of aerobic storage time and forced continuous aeration pretreatment on the biochemical methane potential of food waste was evaluated. The results demonstrate an increase in the methane production concerning the total volatile solids (TVS) of food waste stored for 7 days (425 NmL CH4 g⁻¹ TVS) compared with fresh samples without pretreatment (375 NmL CH4 g⁻¹ TVS). The adoption of forced and continuous aeration pretreatment on food waste for 4 days produced 456 NmL CH4 g⁻¹ TVS for the leachate, 1.22‐fold higher than that for the food waste without storage. In conclusion, the application of aeration pretreatment previous to anaerobic digestion can be an alternative to increase the methane potential from food waste. © 2022 Society of Chemical Industry and John Wiley & Sons, Ltd.
... The physicochemical characteristics of the biowaste change and the hydrolysis process starts, which leads to aerobic and anoxic conditions that are already in the produced biowaste within the storage time. A study performed by Degueurce et al., (2020) showed that 61-70% of the initial material remains at the end of the storage period and leads to a 44% decrease in the BMP potential [24]. This study's results show a similar trend that must be optimized for a more efficient process. ...
Although the benefits of the Lean Six Sigma (LSS) methodology have been proven for more than 20 years, it is still underutilized in environmental science, (e.g., in anaerobic digestion and biogas production). In order to obtain a structural and data-oriented perspective for process optimization in the renewable energy sector, LSS application must be considered one of the most valuable tools. To inform this paper, the LSS analysis phase was conducted in a scaled-down environment through detailed laboratory experiments. Results showed not only the feasibility of LSS application in biogas
technology, but also some useful findings such as possible root causes for low production, such as impurities, waiting time, and existing pre-treatment methods for the defined problem. The results of the experiments show that the use of old substrates can reduce the biogas production up to half of the production with fresh substrates, and that even a 10% sand content can reduce the production up to 14.2%, which shows the need for a solution to these two issues.
... The CF define the ST of the FW; Fisgativa et al. (2017) showed that the ST before collection could induce pre-biodegradation, seems to impact several biochemical characteristics and could improve the biodegradability of FW; Ren et al. (2018) shows too that ST can affect the hydrolysis, that is the limiting step in the AD of solid waste such as FW (AD-FW), and the methane potential production. Degueurce et al. (2020) too studied the effect of the ST on 2 types of FW: (i) FW collected from a restaurant had a higher BMP for an 8-day ST than fresh FW (72 ± 6 and 62 ± 1 NLCH 4 kg ww −1 , respectively). However, a 14-day ST reduced the BMP to 59 ± 3 NLCH 4 kg ww −1 . ...
... By contrast, the 4-day ST (A4) resulted in slight increases in the VFA and TA, which explained the decrease in the VS of 6 to 7% and the COD of 2.6 to 6% compared to the corresponding results for the other ST (A1, A2 and A3). Fisgativa et al., (2020) reported that FW storage containers reduce available O 2 , promoting the anaerobic transformation of lactic acid (LA) to acetic acid (AA); additionally, authors such as Zhao et al., (2016) have reported the initial presence of LA-producing bacteria in FW which, according to Degueurce et al., (2020), may increase LA formation for long ST. Lü et al., (2016) observed a slight increase in the AA content for a 12-day ST, which may be related to the development of acetogenic bacteria (acid-oxidation bacteria) that proliferate under strict anaerobic conditions. ...
... Seswoya et al., (2018) also found that a 7-day ST decreased the VS content and reduced methane production by 17%. Degueurce et al., (2020) showed that the effect of the ST on the BMP depends on the type of FW. The highest BMP (72 ± 6 NLCH 4 kg ww −1 ) for restaurant FW was recorded for an 8-day ST. ...
The storage time (ST) of food waste (FW) influences the anaerobic digestion (AD) process. This study evaluated the effect of the ST (A1:0 — fresh FW; A2:2, A3:3 and A4:4 days) on the substrate characteristics, the biochemical methane potential (BMP), the substrate hydrolysis (kh) and the FW energy potential, considering two energy potential scenarios (A: energy use for electricity production and B: use of methane as biofuel) against C: final disposal in landfills, in terms of greenhouse gas (GHG) emissions and transportation costs. Although ST reduced the lignin content of the substrate (by 20%) for A4, this favoured the subsequent formation of humic substances (HS) and increased acidogenic activity, inhibiting the methanogenesis, being the BMPs for A1 and A2 (103.3 and 110.40 NmLCH4 gVS⁻¹) higher than for A3 and A4 (14 and 34% respectively, p < 0.05,); additionally, the kh values for A3 and A4 were 39 and 73% lower than A2, with the highest kh (0.101 day⁻¹). The scenarios A and B would avoid FW transport to the landfill and reduce annual diesel consumption costs by 639 and 1005%, respectively, while C would increase GHG emissions by 258 and 812% over scenarios A and B, respectively, being the least desirable option.
... About the few studies available on the specific topic of this research, Lü et al. [29] stored OFMSW for 0 to 12 days, and then found an increasingly high biochemical methane potential (BMP), as preliminary storage time increased (285-308 NmL·g VS −1 for storage of 2-4 days, and 618-696 NmL·g VS −1 for 5-12 days of storage). Degueurce et al. [30] found that OFMSW stored for a time up to 16 days lost up to 30% of its initial weight, although its specific methane production increased by about 25%. Feng et al. [31] report that pre-fermentation for 3 days did not influence significantly the BMP of food waste but biomethane production for pre-fermented substrate was faster in the first days. ...
... Presumably, throughout the early days of storage, hydrolysis facilitated the subsequent digestion process, while, if the storage was prolonged, a higher share of organic matter would have been lost. These results are basically in agreement with other studies [29,30], where the maximum BMP was recorded after storage of 5-7 days. ...
Anaerobic digestion (AD) is a suitable management option for the energy valorization of many wastes, including the organic fraction of municipal solid waste (OFMSW). However, in some cases, long storage after the separate collection of this waste is required for management reasons, especially when the amount of waste to be treated temporarily exceeds the capacity of available AD plants. This study evaluates the biochemical methane potential (BMP) of the OFMSW after preliminary storage of 2, 6, and 10 days, in order to assess whether they are still suitable for AD or not. Moreover, the accuracy of three kinetic models (first order, Gompertz, and logistic models) in estimating the methane yield of stored OFMSW is tested. The resulting methane yield was between about 500 and 650 NmL·gVS−1 and slightly increased with the increase of the storage time after collection. Overall, this study has demonstrated that storage of OFMSW, when the collected amount of solid waste exceeds the treatment capacity of AD plants, a storage time up to 10 days does not impact the methane yield of the process.
... A pre-digester tank to store the feedstock collected and to feed the AD is required to buffer the irregularly collected volume of biowaste; however, the storage duration that may affect the AD performance and odor should be controlled [113]. Gonzalez et al. [112] reported that a temperature increase of the feed to process conditions requires a significant amount of thermal energy, which strongly affects the efficiency of the process when operated at a low organic load. ...
Cities are producers of high quantities of secondary liquid and solid streams that are still poorly utilized within urban systems. In order to tackle this issue, there has been an ever-growing push for more efficient resource management and waste prevention in urban areas, following the concept of a circular economy. This review paper provides a characterization of urban solid and liquid resource flows (including water, nutrients, metals, potential energy, and organics), which pass through selected nature-based solutions (NBS) and supporting units (SU), expanding on that characterization through the study of existing cases. In particular, this paper presents the currently implemented NBS units for resource recovery, the applicable solid and liquid urban waste streams and the SU dedicated to increasing the quality and minimizing hazards of specific streams at the source level (e.g., concentrated fertilizers, disinfected recovered products). The recovery efficiency of systems, where NBS and SU are combined, operated at a micro-or meso-scale and applied at technology readiness levels higher than 5, is reviewed. The importance of collection and transport infrastructure, treatment and recovery technology, and (urban) agricultural or urban green reuse on the quantity and quality of input and output materials are discussed, also regarding the current main circularity and application challenges.
