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The rapid urbanization that took place in the last 60 years has led to a dramatic increase in the generation of Municipal Solid Waste (MSW). The biodegradable fraction of MSW mainly consists of food waste (FW) and corresponds to about 50% of the total MSW. The disposal of FW in the environment has become a significant challenge. On the other hand, FW is an excellent substrate for anaerobic digestion (AD). This manuscript reviews the different AD technologies for the treatment of FW. Different types of bioreactors and pretreatment methods used to enhance methane production through AD of FW are discussed. The current review gives special emphasis on the methods for biogas upgrading and on technologies for FW digestate valorization. Food waste valorization through anaerobic digestion offers a wide variety of options in all process steps. From the pre-treatment of the feedstock and the selection of the suitable anaerobic digestion technology to the configuration of the process based on the desired products and the valorization of the generated digestate, the design of an integrated anaerobic digestion plant is a challenging task, which necessitates a systematic design. A systematic approach is necessary for FW valorization. The simple single-stage AD process leads to underutilization of the feedstock. There are plenty of available technologies that could be combined for the development of an integrated biorefinery that will be optimized in terms of FW valorization towards the production of biofuels and high-added value products, while introducing a circularity in the nutrients contained in the FW. FW-to-biofuel conversion technologies are high Technology Readiness Level (TRL—9) technologies and anaerobic digestion is applied worldwide at commercial scale.

A major factor that determines the mixing pattern inside a reactor is the Residence Time Distribution (RTD). The aim of this paper is the study of the hydraulic behavior of a pilot-scale Periodic Anaerobic Baffled Reactor (PABR) through experimental RTD tests and the development of a CFD model. The tank in series model was used for the determination of the equivalent number (NR) of Continuous Stirred Tank Reactors (CSTR) that simulates the mixing pattern. The hydraulic “dead” space (Vd) was also calculated. Both experimental and simulation results indicate the flexibility of the reactor to perform as a CSTR (NR= 1, Vd= 38.6%–39.6%), as a Plug Flow Reactor (PFR) (NR= 10–16, Vd= 25%–35.4%) or intermediate between the two, depending on the operating parameters. The CFD model can be used for the optimization of the reactor's geometry and for the selection of the optimal operating parameters depending on the type of wastewater to be treated.

Valorization of a Food Residue Biomass product in a two-stage anaerobic digestion system for the production of hythane

This study concerns the production of hydrogen and methane from a Food Residue Biomass (FORBI) product (Papanikola et al. in 5th international conference on sustainable waste management systems, Athens, 2017), generated from pre-sorted HFW in a CSTR and in a PABR respectively. FORBI is generated by drying and shredding the fermentable fraction of household food waste collected door-to-door in the Municipality of Halandri, Greece. Hydrogen production from FORBI through anaerobic fermentation under acidogenic mesophilic conditions was carried out using a 4 L CSTR, operated at 12 h HRT under an organic loading of 15 g TS L−1. The H2-CSTR was operated for 40 days. During the operation of H2-CSTR the production of biogas reached up to 0.1026 Lbiogas gFORBI−1 and the percentage of hydrogen in the gas up to 48.2%. The conversion of FORBI into methane was carried out through the operation of a 77 L PABR operated under mesophilic methanogenic conditions at various operating parameters (OLR, HRT, T). Two different approaches were adopted for the pre-treatment of the feedstock. For the two first phases of the experimental procedure, a liquid extraction step was carried out before feeding the bioreactor with the separated liquid fraction, while in the subsequent three phases, a whole suspension of FORBI was used as feed. The mean biogas production rate was 0.158 ± 0.02 Lbiogas gFORBI−1 and the mean methane percentage in the biogas was 67.5 ± 2.1%, in the first two phases. The mean biogas production rate was 0.519 ± 0.03 Lbiogas gFORBI−1 and the mean methane percentage in the biogas was 66 ± 2.8%, when a whole suspension of FORBI was fed to the PABR.

This research work concerns the production of Hydrogen and Methane from a Food Residue Biomass (FORBI) product, generated from pre-sorted Fermentable Household Food Waste in a Continuous Stirred Tank Reactor (CSTR). FORBI is generated by drying and shredding the fermentable fraction of household food waste, collected door-to-door in the Municipality of Halandri, Greece. Hydrogen production from FORBI through anaerobic fermentation under acidogenic mesophilic conditions was carried out using a 4L CSTR (H2-CSTR), operated at 4 hr and 3 hr Hydraulic Retention Times (HRT), with a feed concentration of 15 g TS/L. Volatile fatty acids (VFAs), Total and Volatile Suspended Solids (TSS and VSS), Total and Soluble Chemical Oxygen Demand (tCOD and sCOD), Total and Dissolved Carbohydrates, pH and hydrogen content in the biogas were monitored. The H2-CSTR operated for 32 days. During its operation, the biogas productivity reached 7.78 L/d, out of which 4.13 L/d was hydrogen (60%). This corresponds to a yield of 22Lbiogas/kgFORBI. The conversion of FORBI into methane was carried out through the operation of a CSTR (CH4-CSTR) with working volume 4L (CH4-CSTR). the reactor operated under mesophilic methanogenic conditions at 20,15 and 10 days HRT and an organic loading of 15 g TS/L. TSS, VSS, tCOD, sCOD, pH, alkalinity, VFAs and methane content in the biogas were monitored. The mean methane percentage in the biogas was up to 65%, with an average biogas productivity of 0.5Lbiogas/Lreactor/day, during the optimum operational conditions. The biogas productivity corresponds to a productivity of 477 Lbiogas/kgFORBI. The experimental results obtained were used as a basis for the development of a model by using AQUASIM [1] software, which was able to adequately simulate the operation of the bioreactors. Conclusively, FORBI was proved as a suitable feedstock material both for hydrogen and methane production, resulting in high biogas yields in both cases.

In the present study, modeling of the anaerobic digestion of food industry waste is examined. A very simple model was developed, assuming that the organic matter (in terms of COD) is composed of a hardly and an easily biodegradable COD fraction, which are consumed through different Monod kinetics towards methane production. Biochemical methane potential tests and continuous stirred tank experiments were carried out and used to estimate the values of the main kinetic parameters. In the sequel, the kinetic model is used to predict the behavior of a periodic anaerobic baffled reactor (PABR), also fed with the same waste. Only a single new parameter, the biomass retention factor is added in order to model the behavior of the high-rate reactor. Despite the structural and operational differences of the two anaerobic digesters, the simple model was able to satisfactorily predict methane production and COD consumption of both bioreactors over a wide range of operating conditions. Thus, the proposed modeling approach can be valuable in describing the behavior of different anaerobic digesters, using a minimal number of kinetic variables and kinetic/stoichiometric parameters.

The challenge for facing highly increasing environmental and health problems of modern society, caused by an ever increasing industrial development and economic growth worldwide, calls for a restructuring of waste management systems , using renewable resources and low-carbon solutions in agreement with the concept of circular economy. The main point of circular economy is the use of natural resource materials in a closed-loop, leading to zero-waste generation and sustainability (Ghisellini et al., 2016; Lieder and Rashid; 2016, Sauvé et al., 2016). The main concept of the HORIZON 2020 Waste4Think project is to introduce and promote 20 eco-innovative solutions that cover the whole waste value chain. These solutions will be applied and assessed in 4 European cities: Zamudio (Basque Country, Spain); Halandri (Greece); Seveso (Italy); and Cascais (Portugal) (Waste4Think, 2015). The eco-innovative solutions will provide: IT tools, apps for citizens, educational materials and serious games, tools for citizen, changes based on economic instruments and social actions, and finally implementation, valorization and reuse of alternatives for the recovery of high-grade materials (Figure 1). &nbsp

Α novel two-phase bioreactor for the microbial removal of Cr(VI) from wastewater with high chromium concentration (up to 1350 ppm) is developed. Among several potential solid-phase adsorbents tested, Cloisite® 30B, a natural montmorillonite modified with a quaternary ammonium salt that absorbs Cr(VI) in a reversible manner proved to be optimal as the solid phase of the bioreactor. Cloisite® 30B has no toxicity to the acclimated biomass and keeps the concentration of Cr(VI) ions at sub-inhibitory levels that ensure the efficient microbial removal of Cr(VI). The microbial removal of Cr(VI) was achieved using an acclimated mixed culture developed from anaerobic sludge. The novel bioreactor was operated as a Sequencing Batch Reactor (SBR) under anaerobic and mesophilic conditions for over 200 cycles, without further addition of the solid adsorbent, and led to even 100% removal of Cr(VI) with high removal rates for concentrations ranging from 900–1350 mg/L Cr(VI). The reduction of Cr(VI) to the less toxic Cr(III) was proved to be mediated by lactate, generated by a lactic acid bacterium, 99% similar to Pediococcus acidilactici as demonstrated by molecular methods The reduction of Cr(VI) took place extracellularly where it reacts with the lactic acid produced during the process of glycolysis.

The scope of the present study was to identify the most effective and less toxic combination of various organic solvents and extractants for the extraction of Cr(VI) from synthetic wastewaters with extremely high chromium concentration (up to 1,000 ppm) in order to be further used in a novel two-liquid-phase bioreactor for microbial reduction of Cr(VI). In terms of organic solvents, hexane, heptane, chloroform, ethyl-acetate, and kerosene were tested, whereas Aliquat 336, TOPO, and TPB were used as extractants. The effect of the pH of the aqueous phase and of the ratio of organic to aqueous phase were studied in terms of Cr(VI) extraction. The extraction capacities of different combinations of solvents/extractants and the addition of 1-hexanol as a stabilizer for the most effective separation of phases were also assessed. Moreover, the toxicity of each solvent was assessed using acclimated mixed consortia. The acclimated, enriched culture was further used as inoculums for the start up of a sequent...

Testicular metastasis of multiple myeloma is very rare and only 49 cases have been reported in the world literature. We report on a case of a 59-year-old man with a 9- month history of multiple myeloma who presented with painless swelling of the left testis. An ultrasound (US) examination was performed and the diagnosis was documented histologically. The US findings and the differential diagnosis are discussed in the light of color Doppler ultrasonography (CDUS).

This study concerns the production of hydrogen and methane from a Food Residue Biomass (FORBI) product [1], 11 generated from pre-sorted HFW in a CSTR and in a PABR respectively. FORBI is generated by drying and shredding 12 the fermentable fraction of household food waste collected door-to-door in the Municipality of Halandri, Greece. 13 Hydrogen production from FORBI through anaerobic fermentation under acidogenic mesophilic conditions was 14 carried out using a 4L CSTR, operated at 12 h HRT under an organic loading of 15 g TS·L-1. The H2-CSTR was 15 operated for 40 days. During the operation of H2-CSTR the production of biogas reached up to 0,1026 L biogas·g FORBI-1 16 and the percentage of hydrogen in the gas up to 48,2 %. 17 The conversion of FORBI into methane was carried out through the operation of a 77L PABR operated under 18 mesophilic methanogenic conditions at various operating parameters (OLR, HRT, T). Two different approaches were 19 adopted for the pre-treatment of the feedstock. For the two first phases of the experimental procedure, a liquid 20 extraction step was carried out before feeding the bioreactor with the separated liquid fraction, while in the subsequent 21 three phases, a whole suspension of FORBI was used as feed. The mean biogas production rate was 0,158±0,02 22 Lbiogas·gFORBI-1 and the mean methane percentage in the biogas was 67,5±2,1%, in the first two phases. The mean biogas 23 production rate was 0,519±0,03 Lbiogas·gFORBI-1 and the mean methane percentage in the biogas was 66±2,8%, when a 24 whole suspension of FORBI was fed to the PABR.

The main concept of the HORIZON 2020 Waste4Think project is to introduce and promote 20 eco-innovative solutions that cover the whole waste value chain. These solutions will be applied and assessed in 4 European cities: a) Zamudio (Basque Country, Spain); b) Halandri (Greece); c) Seveso (Italy); and d) Cascais (Portugal) (Waste4Think, 2015). The eco-innovative solutions will provide: IT tools, apps for citizens, educational materials and serious games, tools for citizen, changes based on economic instruments and social actions, and finally implementation, valorization and reuse of alternatives for the recovery of high-grade materials., The data set of the publication can be accessed at: http://doi.org/10.5281/zenodo.3906241

The challenge for facing highly increasing environmental and health problems of modern society, caused by an ever increasing industrial development and economic growth worldwide, calls for a restructuring of waste management systems , using renewable resources and low-carbon solutions in agreement with the concept of circular economy. The main point of circular economy is the use of natural resource materials in a closed-loop, leading to zero-waste generation and sustainability (Ghisellini et al., 2016; Lieder and Rashid; 2016, Sauvé et al., 2016). The main concept of the HORIZON 2020 Waste4Think project is to introduce and promote 20 eco-innovative solutions that cover the whole waste value chain. These solutions will be applied and assessed in 4 European cities: Zamudio (Basque Country, Spain); Halandri (Greece); Seveso (Italy); and Cascais (Portugal) (Waste4Think, 2015). The eco-innovative solutions will provide: IT tools, apps for citizens, educational materials and serious games, tools for citizen, changes based on economic instruments and social actions, and finally implementation, valorization and reuse of alternatives for the recovery of high-grade materials (Figure 1)., {"references":["http://uest.ntua.gr/athens2017/proceedings/pdfs/Athens2017_Papadopoulou_Lyberatos_Lizarraga_Torre_etal.pdf"]}

This research work concerns the production of Hydrogen and Methane from a Food Residue Biomass (FORBI) product, generated from pre-sorted Fermentable Household Food Waste in a Continuous Stirred Tank Reactor (CSTR). FORBI is generated by drying and shredding the fermentable fraction of household food waste, collected door-to-door in the Municipality of Halandri, Greece. Hydrogen production from FORBI through anaerobic fermentation under acidogenic mesophilic conditions was carried out using a 4L CSTR (H2-CSTR), operated at 4 hr and 3 hr Hydraulic Retention Times (HRT), with a feed concentration of 15 g TS/L. Volatile fatty acids (VFAs), Total and Volatile Suspended Solids (TSS and VSS), Total and Soluble Chemical Oxygen Demand (tCOD and sCOD), Total and Dissolved Carbohydrates, pH and hydrogen content in the biogas were monitored. The H2-CSTR operated for 32 days. During its operation, the biogas productivity reached 7.78 L/d, out of which 4.13 L/d was hydrogen (60%). This corresponds to a yield of 22Lbiogas/kgFORBI. The conversion of FORBI into methane was carried out through the operation of a CSTR (CH4-CSTR) with working volume 4L (CH4-CSTR). the reactor operated under mesophilic methanogenic conditions at 20,15 and 10 days HRT and an organic loading of 15 g TS/L. TSS, VSS, tCOD, sCOD, pH, alkalinity, VFAs and methane content in the biogas were monitored. The mean methane percentage in the biogas was up to 65%, with an average biogas productivity of 0.5Lbiogas/Lreactor/day, during the optimum operational conditions. The biogas productivity corresponds to a productivity of 477 Lbiogas/kgFORBI. The experimental results obtained were used as a basis for the development of a model by using AQUASIM [1] software, which was able to adequately simulate the operation of the bioreactors. Conclusively, FORBI was proved as a suitable feedstock material both for hydrogen and methane production, resulting in high biogas yields in both cases.

This study concerns the production of hydrogen and methane from a Food Residue Biomass (FORBI) product [1], 11 generated from pre-sorted HFW in a CSTR and in a PABR respectively. FORBI is generated by drying and shredding 12 the fermentable fraction of household food waste collected door-to-door in the Municipality of Halandri, Greece. 13 Hydrogen production from FORBI through anaerobic fermentation under acidogenic mesophilic conditions was 14 carried out using a 4L CSTR, operated at 12 h HRT under an organic loading of 15 g TS·L-1. The H2-CSTR was 15 operated for 40 days. During the operation of H2-CSTR the production of biogas reached up to 0,1026 L biogas·g FORBI-1 16 and the percentage of hydrogen in the gas up to 48,2 %. 17 The conversion of FORBI into methane was carried out through the operation of a 77L PABR operated under 18 mesophilic methanogenic conditions at various operating parameters (OLR, HRT, T). Two different approaches were 19 adopted for the pre-treatment of the feedstock. For the two first phases of the experimental procedure, a liquid 20 extraction step was carried out before feeding the bioreactor with the separated liquid fraction, while in the subsequent 21 three phases, a whole suspension of FORBI was used as feed. The mean biogas production rate was 0,158±0,02 22 Lbiogas·gFORBI-1 and the mean methane percentage in the biogas was 67,5±2,1%, in the first two phases. The mean biogas 23 production rate was 0,519±0,03 Lbiogas·gFORBI-1 and the mean methane percentage in the biogas was 66±2,8%, when a 24 whole suspension of FORBI was fed to the PABR., The data set of the publication can be accessed at: http://doi.org/10.5281/zenodo.3906241

The scope of the present research work was to evaluate the potential of valorizing a biomass product (FORBI, Food Residue Biomass) through thermal and mechanical treatment for the production of a solid fuel (pellets). FORBI is generated through a drying/shredding process of door-to-door source-separated Household Food Waste (HFW). The quality of pellets depends on two general factors: 1.the characteristics of the raw material (FORBI) itself, directly related to its chemical composition 2.the operative variables of the pelletization process, which influence the physical and mechanical properties of the pellets produced. A suitable combination of these two factors is necessary to obtain a qualified energy product. The European Union has established standards, guidelines and thresholds for solid biofuels in order that they can be properly used and marketed as renewable fuels.

Valorization of a Food Residue Biomass product in a two-stage anaerobic digestion system for the production of hythane, The data set of the publication can be accessed at: http://doi.org/10.5281/zenodo.3906241

This research work concerns the production of Hydrogen and Methane from a Food Residue Biomass (FORBI) product, generated from pre-sorted Fermentable Household Food Waste in a Continuous Stirred Tank Reactor (CSTR). FORBI is generated by drying and shredding the fermentable fraction of household food waste, collected door-to-door in the Municipality of Halandri, Greece. Hydrogen production from FORBI through anaerobic fermentation under acidogenic mesophilic conditions was carried out using a 4L CSTR (H2-CSTR), operated at 4 hr and 3 hr Hydraulic Retention Times (HRT), with a feed concentration of 15 g TS/L. Volatile fatty acids (VFAs), Total and Volatile Suspended Solids (TSS and VSS), Total and Soluble Chemical Oxygen Demand (tCOD and sCOD), Total and Dissolved Carbohydrates, pH and hydrogen content in the biogas were monitored. The H2-CSTR operated for 32 days. During its operation, the biogas productivity reached 7.78 L/d, out of which 4.13 L/d was hydrogen (60%). This corresponds to a yield of 22Lbiogas/kgFORBI. The conversion of FORBI into methane was carried out through the operation of a CSTR (CH4-CSTR) with working volume 4L (CH4-CSTR). the reactor operated under mesophilic methanogenic conditions at 20,15 and 10 days HRT and an organic loading of 15 g TS/L. TSS, VSS, tCOD, sCOD, pH, alkalinity, VFAs and methane content in the biogas were monitored. The mean methane percentage in the biogas was up to 65%, with an average biogas productivity of 0.5Lbiogas/Lreactor/day, during the optimum operational conditions. The biogas productivity corresponds to a productivity of 477 Lbiogas/kgFORBI. The experimental results obtained were used as a basis for the development of a model by using AQUASIM [1] software, which was able to adequately simulate the operation of the bioreactors. Conclusively, FORBI was proved as a suitable feedstock material both for hydrogen and methane production, resulting in high biogas yields in both cases., The data set of the publication can be accessed at: http://doi.org/10.5281/zenodo.3906241

Valorization of a Food Residue Biomass product in a two-stage anaerobic digestion system for the production of hythane

The scope of the present research work was to evaluate the potential of valorizing a biomass product (FORBI, Food Residue Biomass) through thermal and mechanical treatment for the production of a solid fuel (pellets). FORBI is generated through a drying/shredding process of door-to-door source-separated Household Food Waste (HFW). The quality of pellets depends on two general factors: 1.the characteristics of the raw material (FORBI) itself, directly related to its chemical composition 2.the operative variables of the pelletization process, which influence the physical and mechanical properties of the pellets produced. A suitable combination of these two factors is necessary to obtain a qualified energy product. The European Union has established standards, guidelines and thresholds for solid biofuels in order that they can be properly used and marketed as renewable fuels., The data set of the publication can be accessed at: http://doi.org/10.5281/zenodo.3906241