Discover insights from thousands of peer-reviewed papers on microbial electrochemical systems
Silvia Sancho Navarro, Ruxandra Cimpoia, Guillaume Bruant et al.
Frontiers in Microbiology · 2016
Syngas generated by thermal gasification of biomass or coal can be steam reformed and purified into methane, which could be used locally for energy needs, or re-injected in the natural gas grid. As an alternative to chemical catalysis, the main components of the syngas (CO, CO2, and H2) can be used as substrates by a wide range of microorganisms, to be converted into gas biofuels, including methane. This study evaluates the carboxydotrophic (CO-consuming) methanogenic potential present in an anaerobic sludge from an upflow anaerobic sludge bed (UASB) reactor treating waste water, and elucidates the CO conversion routes to methane at 35 ± 3°C. Kinetic activity tests under CO at partial pressures (pCO) varying from 0.1 to 1.5 atm (0.09-1.31 mmol/L in the liquid phase) showed a significant carboxydotrophic activity potential for growing conditions on CO alone. A maximum methanogenic activity of 1 mmol CH4 per g of volatile suspended solid and per day was achieved at 0.2 atm of CO (0.17 mmol/L), and then the rate decreased with the amount of CO supplied. The intermediary metabolites such as acetate, H2, and propionate started to accumulate at higher CO concentrations. Inhibition experiments with 2-bromoethanesulfonic acid (BES), fluoroacetate, and vancomycin showed that in a mixed culture CO was converted mainly to acetate by acetogenic bacteria, which was further transformed to methane by acetoclastic methanogens, while direct methanogenic CO conversion was negligible. Methanogenesis was totally blocked at high pCO in the bottles (≥1 atm). However it was possible to achieve higher methanogenic potential under a 100% CO atmosphere after acclimation of the sludge to CO. This adaptation to high CO concentrations led to a shift in the archaeal population, then dominated by hydrogen-utilizing methanogens, which were able to take over acetoclastic methanogens, while syntrophic acetate oxidizing (SAO) bacteria oxidized acetate into CO2 and H2. The disaggregation of the granular sludge showed a negative impact on their methanogenic activity, confirming that the acetoclastic methanogens were the most sensitive to CO, and a contrario, the advantage of using granular sludge for further development toward large-scale methane production from CO-rich syngas.
Aidan Francis Meese, Jae‐Hong Kim, Xuanhao Wu et al.
ACS ES&T Engineering · 2021
As the impact of water scarcity in the United States (U.S.) continues to grow through the 21st century, it is critical to develop strategies to reduce water use and improve the security of water resources. One such strategy is to diversify the sources from which water is supplied. Industrial withdrawals represent the fourth largest category of U.S. water use, the majority of which is sourced from fresh surface and groundwater. In this study, we critically explore the potential of industrial wastewater to serve as an alternative water resource through direct treatment and reuse. We begin by reviewing the state of the art of water use, treatment, and reuse across six representative industries: food and beverages, primary metals, pulp and paper, petroleum refining, chemicals, and data centers and campuses, highlighting key challenges and opportunities toward the expansion of reuse. We then employ a technoeconomic assessment of water treatment processes to analyze the capital investment, operating and maintenance costs, levelized cost of water, and electricity consumption of three specific industrial plants as case studies to better understand where research can promote impactful innovation. Finally, drawing together the results of our literature review and technoeconomic analyses, we provide a broad outlook on the future of industrial water reuse and discuss strategies for its expansion.
Yuko Goto, Naoko Yoshida
Water · 2019
Conventional aerobic treatment of swine wastewater, which generally contains 4500–8200 mg L−1 of organic matter, is energy-consuming. The aim of this study was to assess the application of scaled-up microbial fuel cells (MFCs) with different capacities (i.e., 1.5 L, 12 L, and 100 L) for removing organic matter from swine wastewater. The MFCs were single-chambered, consisting of an anode of microbially reduced graphene oxide (rGO) and an air-cathode of platinum-coated carbon cloth. The MFCs were polarized via an external resistance of 3–10 Ω for 40 days for the 1.5 L-MFC and 120 days for the 12L- and 100 L-MFC. The MFCs were operated in continuous flow mode (hydraulic retention time: 3–5 days). The 100 L-MFC achieved an average chemical oxygen demand (COD) removal efficiency of 52%, which corresponded to a COD removal rate of 530 mg L−1 d−1. Moreover, the 100 L-MFC showed an average and maximum electricity generation of 0.6 and 2.2 Wh m−3, respectively. Our findings suggest that MFCs can effectively be used for swine wastewater treatment coupled with the simultaneous generation of electricity.
Nikunj Sharma, Daris P. Simon, Aracely Maribel Diaz-Garza et al.
Frontiers in Marine Science · 2021
The benefits of the complex microscopic and industrially important group of microalgae such as diatoms is not hidden and have lately surprised the scientific community with their industrial potential. The ability to survive in harsh conditions and the presence of different pore structures and defined cell walls have made diatoms ideal cell machinery to produce a variety of industrial products. The prospect of using a diatom cell for industrial application has increased significantly in synch with the advances in microscopy, metabarcoding, analytical and genetic tools. Furthermore, it is well noted that the approach of industry and academia to the use of genetic tools has changed significantly, resulting in a well-defined characterization of various molecular components of diatoms. It is possible to conduct the primary culturing, harvesting, and further downstream processing of diatom culture in a cost-effective manner. Diatoms hold all the qualities to become the alternative raw material for pharmaceutical, nanotechnology, and energy sources leading to a sustainable economy. In this review, an attempt has been made to gather important progress in the different industrial applications of diatoms such as biotechnology, biomedical, nanotechnology, and environmental technologies.
Shahida Anusha Siddiqui, Zeki Erol, Jerina Rugji et al.
Bioresources and Bioprocessing · 2023
Fermentation is thought to be born in the Fertile Crescent, and since then, almost every culture has integrated fermented foods into their dietary habits. Originally used to preserve foods, fermentation is now applied to improve their physicochemical, sensory, nutritional, and safety attributes. Fermented dairy, alcoholic beverages like wine and beer, fermented vegetables, fruits, and meats are all highly valuable due to their increased storage stability, reduced risk of food poisoning, and enhanced flavor. Over the years, scientific research has associated the consumption of fermented products with improved health status. The fermentation process helps to break down compounds into more easily digestible forms. It also helps to reduce the amount of toxins and pathogens in food. Additionally, fermented foods contain probiotics, which are beneficial bacteria that help the body to digest food and absorb nutrients. In today's world, non-communicable diseases such as cardiovascular disease, type 2 diabetes, cancer, and allergies have increased. In this regard, scientific investigations have demonstrated that shifting to a diet that contains fermented foods can reduce the risk of non-communicable diseases. Moreover, in the last decade, there has been a growing interest in fermentation technology to valorize food waste into valuable by-products. Fermentation of various food wastes has resulted in the successful production of valuable by-products, including enzymes, pigments, and biofuels.
J.D. Marin-Batista, J.A. Villamil, Juan J. Rodrı́guez et al.
Bioresource Technology · 2018
Anjana Pandey, Saumya Srivastava, Priya Rai et al.
Scientific Reports · 2019
The burgeoning organic waste and continuously increasing energy demands have resulted in significant environmental pollution concerns. To address this issue, the potential of different bacteria to produce biogas/biohydrogen from organic waste can be utilized as a source of renewable energy, however these pathogenic bacteria are not safe to use without strict contact isolation. In this study the role of safe food grade lactic acid bacteria (Lactobacillus spp.) was investigated for production of biogas from cheese waste with starting hexose concentration 32 g/L. The bacterium Lactobacillus acidophilus was identified as one of the major biogas producers at optimum pH of 6.5. Further the optimum inoculum conditions were found to be 12.5% at inoculum age of 18 h. During the investigation the maximum biogas production was observed to be 1665 mL after 72 hours of incubation at pH 6.5. The biogas production was accompanied with production of other valuable metabolites in the form of organic acids including pyruvate, propionate, acetate, lactate, formate and butyrate. Thus this research is paving way for nonpathogenic production of biohydrogen from food waste.
Steffi Formann, Alena Hahn, Leandro Janke et al.
Frontiers in Energy Research · 2020
Sugarcane is the most produced agricultural commodity in tropical and subtropical regions, where it is primarily used for the production of sugar and ethanol. The latter is mostly used to produce alcoholic beverages as well as low carbon biofuel. Despite well-established production chains, their respective residues and by-products present unexploited potentials for further product portfolio diversification. These fully or partially untapped product streams are a) sugarcane trash or straw that usually remain on the fields after mechanized harvest, b) ashes derived from bagasse combustion in cogeneration plants, c) filter cake from clarification of the sugarcane juice, d) vinasse which is the liquid residue after distillation of ethanol, and e) biogenic CO 2 emitted during bagasse combustion and ethanol fermentation. The development of innovative cascading processes using these residual biomass fractions could significantly reduce final disposal costs, improve the energy output, reduce greenhouse gas emissions, and extend the product portfolio of sugarcane mills. This study reviews not only the state-of-the-art sugarcane biorefinery concepts, but also proposes innovative ways for further valorizing residual biomass. This study is therefore structured in four main areas, namely: i) Cascading use of organic residues for carboxylates, bioplastic, and bio-fertilizer production, ii) recovery of unexploited organic residues via anaerobic digestion to produce biogas, iii) valorization of biogenic CO 2 sources, and iv) recovery of silicon from bagasse ashes.
Thu Hang Duong, Katja Grolle, Tran Thi Viet Nga et al.
Biotechnology for Biofuels · 2019
The findings in this study can help to set a suitable solid retention time to accomplish anaerobic degradation of protein-rich wastewaters in continuous reactor systems. For example, if the target is harvesting VFAs, methanogens can be washed-out for a shorter retention time while amino acid fermentation, instead of hydrolysis as assumed previously, will govern the design and solutions to improve the system dealing with dissolved proteins.
Jin Hu, Hu Zhang, Zhiwei Zhou et al.
Biotechnology and Bioengineering · 2019
Although production of biodiesels from microalgae is proved to be technically feasible, a commercially viable system has yet to emerge. High-cell-density fermentation of microalgae can be coupled with photoautotrophic cultivation to produce oils. In this study, by optimizing culturing conditions and employing a sophisticated substrate feed control strategy, ultrahigh-cell-density of 286 and 283.5 g/L was achieved for the unicellular alga Scenedesmus acuminatus grown in 7.5-L bench-scale and 1,000-L pilot-scale fermenters, respectively. The outdoor scale-up experiments indicated that heterotrophically grown S. acuminatus cells are more productive in terms of both biomass and lipid accumulation when they are inoculated in photobioreactors for lipid production as compared to the cells originally grown under photoautotrophic conditions. Technoeconomic analysis based on the pilot-scale data indicated that the cost of heterotrophic cultivation of microalgae for biomass production is comparable with that of the open-pond system and much lower than that of tubular PBR, if the biomass yield was higher than 200 g/L. This study demonstrated the economic viability of heterotrophic cultivation on large-scale microalgal inocula production, but ultrahigh-productivity fermentation is a prerequisite. Moreover, the advantages of the combined heterotrophic and photoautotrophic cultivation of microalgae for biofuels production were also verified in the pilot-scale.
Jan Vymazal
Land · 2022
Constructed wetlands (CWs) for wastewater treatment are engineered systems that are designed and operated in order to use all natural processes involved in the removal of pollutants from wastewaters. CWs are designed to take advantage of many of the same processes that occur in natural wetlands, but do so within a more controlled environment. The basic classification is based on the presence/absence of wastewater on the wetland surface. The subsurface flow of CWs can be classified according to the direction of the flow to horizontal and vertical. The combination of various types of CWs is called hybrid CW. The CWs technology began in the 1950s in Germany, but the major extension across the world occurred during the 1990s and early 2000s. The early CWs in Germany were designed as hybrid CWs; however, during the 1970s and 1980s, horizontal subsurface flow CWs were mostly designed. The stricter limits for nitrogen, and especially ammonia, applied in Europe during the 1990s, brought more attention to vertical subsurface flow and hybrid systems. Constructed wetlands have been used to treat various types of wastewater, including sewage, industrial and agricultural wastewaters, various drainage and runoff waters and landfill leachate. Recently, more attention has also been paid to constructed treatment wetlands as part of a circular economy in the urban environments: it is clear that CWs are a good fit for the new concept of sponge cities.
S. R. Sen Gupta, Annabel Fernandes, Ana Lopes et al.
Applied Sciences · 2024
Photo-fermentation is an efficient hydrogen production pathway in which purple non-sulfur bacteria (PNSB) play an active role and produce hydrogen as a part of their metabolism under optimal conditions. These bacteria work under the influence of light to advance their metabolism and use various substrates, such as simple sugars and volatile fatty acids, to produce hydrogen. This article presents a comparative review of several bacterial strains that have been efficiently used to produce hydrogen by photo-fermentation under different optimized conditions, including the substrate, its concentration, type and capacity of the bioreactor, light sources and intensities, and process conditions to achieve the maximum biohydrogen production rate. The analysis showed that the Rhodopseudomonas palustris is the main bacterium used for hydrogen production, with a maximum hydrogen production rate of 3.2 mM/h using 27.8 mM of glucose in a 165 mL serum bottle and 3.23 mM/h using 50 mM of glycerol at pH 7, followed by Rhodobacter sphaeroides, which gave a hydrogen production rate as high as 8.7 mM/h, using 40 mM of lactic acid, pH 7, and 30 °C temperature in a single-walled glass bioreactor. However, it is not preferred over R. palustris due to its versatile metabolism and ability to use an alternative mode if the conditions are not carefully adjusted, which can be a problem in hydrogen production.
Dimitris Sarris, Nikolaos G. Stoforos, Athanasios Mallouchos et al.
Engineering in Life Sciences · 2017
Yarrowia lipolytica ACA-YC 5033 was grown on glucose-based media in which high amounts of olive mill wastewaters (OMWs) had been added. Besides shake-flask aseptic cultures, trials were also performed in previously pasteurized media while batch bioreactor experiments were also done. Significant decolorization (∼58%) and remarkable removal of phenolic compounds (∼51% w/w ) occurred, with the latter being amongst the highest ones reported in the international literature, as far as yeasts were concerned during their growth on phenol-containing media. In nitrogen-limited flask fermentations the microorganism produced maximum citric acid quantity ≈19.0 g/L [simultaneous yield of citric acid produced per unit of glucose consumed (Y Cit/Glc )≈0.74 g/g]. Dry cell weight (DCW) values decreased at high phenol-containing media, but, on the other hand, the addition of OMWs induced reserve lipid accumulation. Maximum citric acid concentration achieved (≈52.0 g/L; Y Cit/Glc ≈0.64 g/g) occurred in OMW-based high sugar content media (initial glucose added at ≈80.0 g/L). The bioprocess was successfully simulated by a modified logistic growth equation. A satisfactory fitting on the experimental data occurred while the optimized parameter values were found to be similar to those experimentally measured. Finally, a non-aseptic (previously pasteurized) trial was performed and its comparison with the equivalent aseptic experiment revealed no significant differences. Yarrowia lipolytica hence can be considered as a satisfactory candidate for simultaneous OMWs bioremediation and the production of added-value compounds useful for the food industry.
Hyeonjung Yu, Jaai Kim, Changsoo Lee
Scientific Reports · 2019
Potential of microalgal cultivation as an alternative approach to the treatment of anaerobic digestion (AD) effluents was examined using two representative Chlorella species, Chlorella vulgaris (CV) and Chlorella protothecoides (CP). Both species effectively removed NH 4 + -N from the AD effluents from four digesters treating different wastes under different operating conditions. In all experimental cultures on the AD effluents, NH 4 + -N (initial concentration, 40 mg/L) was completely removed within 10 days without residual NO 3 - -N or NO 2 - -N in batch mode. Compared to CP, CV showed greater biomass and lipid yields (advantageous for biodiesel production), regardless of the media used. Prolonged nitrogen starvation significantly increased the lipid accumulation in all cultures on the AD effluents, and the effect was more pronounced in the CV than in the CP cultures. On the other hand, compared to CV, CP showed significantly faster settling (advantageous for biomass harvesting) in all media. Our results suggest that the Chlorella cultivation on AD effluents under non-sterile, mixed-culture conditions may provide a viable way to manage and valorize the problematic effluents. Diverse bacteria derived from the AD effluents co-existed and presumably interacted with the Chlorella species in the cultures.
Rafael R. Philippini, Sabrina Evelin Martiniano, Avinash P. Ingle et al.
Frontiers in Energy Research · 2020
The integrated approach in biorefinery mainly involves the utilization of various agroindustrial byproducts such as raw materials for the production of several biobased products like biofuels, bioenergy, and other high-value chemicals. Biofuels are the backbone of biorefineries, however, production of value-added biomolecules such as biopigments, biopolymers, biosurfactants, and nutritional yeast has been attracting great attention. The production of these biomolecules using traditional approaches has been extensively studied in the last few years owing to their promising application in different industries such as chemical, food/feed, and pharmaceuticals for the development of novel products for mankind. Moreover, the production of such biomolecules using lignocellulosic, starchy, and some other agroindustrial byproducts is still not fully explored. Hence, there is a huge scope in the development of sustainable biorefining approaches to make the technology cost-effective. The lignocellulosic biomasses usually used in biorefineries are mainly composed of cellulose, hemicellulose, and lignin, whereas starchy materials, besides starch, usually contain, protein, lipids, and some micronutrients. The processing of these biomasses through successive steps like pretreatments, enzymatic hydrolysis, and fermentation is essentially required to obtained final biobased products. Considering certain bottlenecks of above-mentioned conventional biorefineries approaches, new technologies have been proposed for the improved pretreatment of biomass and efficient enzymatic hydrolysis in order to minimize the concentration of toxic inhibitors in resulting hydrolysate. In this review, we highlighted the different agroindustrial byproducts and their applications for the production of valuable biorefinery products.
Jo De Vrieze, Marlies Christiaens, Diego Walraedt et al.
Water Research · 2016
Anaerobic digestion of high-salinity wastewaters often results in process inhibition due to the susceptibility of the methanogenic archaea. The ability of the microbial community to deal with increased salinity levels is of high importance to ensure process perseverance or recovery after failure. The exact strategy of the microbial community to ensure process endurance is, however, often unknown. In this study, we investigated how the microbial community is able to recover process performance following a disturbance through the application of high-salinity molasses wastewater. After a stable start-up, methane production quickly decreased from 625 ± 17 to 232 ± 35 mL CH 4 L -1 d -1 with a simultaneous accumulation in volatile fatty acids up to 20.5 ± 1.4 g COD L -1 , indicating severe process disturbance. A shift in feedstock from molasses wastewater to waste activated sludge resulted in complete process recovery. However, the bacterial and archaeal communities did not return to their original composition as before the disturbance, despite similar process conditions. Microbial community diversity was recovered to similar levels as before disturbance, which indicates that the metabolic potential of the community was maintained. A mild increase in ammonia concentration after process recovery did not influence methane production, indicating a well-balanced microbial community. Hence, given the change in community composition following recovery after salinity disturbance, it can be assumed that microbial community redundancy was the major strategy to ensure the continuation of methane production, without loss of functionality or metabolic flexibility.
Raúl Robles‐Iglesias, Cecilia Naveira‐Pazos, Carla Fernández‐Blanco et al.
Renewable and Sustainable Energy Reviews · 2022
The recent unprecedented increase in energy demand has led to a growing interest in emerging alternatives such as the production of microbial lipids with high energy density and environmentally-friendly characteristics. Oleaginous yeasts represent a versatile and attractive tool for the accumulation of such lipids, also known as single cell oils (SCOs), used to manufacture biofuels (e.g., biodiesel, aviation fuel) and bioproducts. This review provides an overview of the most common oleaginous species, analysing the viability of typical feedstocks and their effect on lipid accumulation. The best results in terms of lipid content using glucose, glycerol, lignocellulose, or acetic acid as substrates are 81.4, 70, 68.2 and 73.4% (w/w), respectively. Besides, an analysis of the parameters that can affect lipid production is also presented. For instance, the optimum conditions for lipid accumulation are usually a C/N ratio between 100 and 200, pH between 5 and 6 (being more alkaline if acids are used as substrates) and temperature around 30 °C. Besides, genetic modifications generally allow to increase the lipid yield, even by up to 400%. Finally, some cost analysis is provided for scaling-up, with feedstock costs estimated at 50–80%, followed by fermenter costs, and downstream costs estimated at around 13%.
Thorben Muddemann, Dennis Haupt, Michael Sievers et al.
ChemBioEng Reviews · 2019
Abstract Regarding the treatment of (waste)water, electrochemical processes have various advantages over other methods. They are robust, easy to operate and flexible in case of fluctuating wastewater streams. In addition, a relatively broad spectrum of organic and inorganic impurities can be removed. This contribution provides an overview of electrochemical reactors for water, process water, and wastewater treatment, which are already in technical‐scale operation or subject of research. Some essential basics of electrochemical processes for the treatment of water are presented and examples for applications are given. This is followed by a description of the reactors.
Waleed Jadaa, Hamad Mohammed
Journal of Ecological Engineering · 2023
The constant discharge of large quantities of toxic substances due to human activities has led to a global environmental issue. Numerous industrial sectors’ effluents, which include coal-based power plants, mineral extraction activities, electroplating processes, as well as battery manufacturing, release metallic ions towards different ecosystems, such as Cadmium (Cd), Mercury (Hg), and Chromium (Cr). Heavy metals pose a significant danger to living organisms, humans, and environments because of their properties, mainly severe toxicity, and strong accumulation ability. Metallic ions are not subject to breakdown towards final components when contrasted with organic contaminants, which are significantly impacted by biochemical and chemical decomposition. Consequently, eliminating these elements has been regarded as a significant task within the water treatment sector. The purpose of this article is to analyze the literature related to heavy metals in terms of different issues. The heavy metals expression is explained. The natural sources and human activities responsible for releasing metallic ions into the environment are comprehensively discussed. In addition, heavy metals toxicity and potential risks to humans and different ecosystems are included. Various approaches for removing heavy metals from industrial wastewater, along with their associated advantages and drawbacks, are further evaluated.
Marcin Dębowski, Marcin Zieliński, Joanna Kazimierowicz et al.
Sustainability · 2020
Microalgal biomass is currently considered as a sustainable and renewable feedstock for biofuel production (biohydrogen, biomethane, biodiesel) characterized by lower emissions of hazardous air pollutants than fossil fuels. Photobioreactors for microalgae growth can be exploited using many industrial and domestic wastes. It allows locating the commercial microalgal systems in areas that cannot be employed for agricultural purposes, i.e., near heating or wastewater treatment plants and other industrial facilities producing carbon dioxide and organic and nutrient compounds. Despite their high potential, the large-scale algal biomass production technologies are not popular because the systems for biomass production, separation, drainage, and conversion into energy carriers are difficult to explicitly assess and balance, considering the ecological and economical concerns. Most of the studies presented in the literature have been carried out on a small, laboratory scale. This significantly limits the possibility of obtaining reliable data for a comprehensive assessment of the efficiency of such solutions. Therefore, there is a need to verify the results in pilot-scale and the full technical-scale studies. This study summarizes the strengths and weaknesses of microalgal biomass production technologies for bioenergetic applications.
Li Sun, Tong Liu, Bettina Müller et al.
Biotechnology for Biofuels · 2016
The degradation rate of cellulose and straw varied in the batch tests dependent on the origin of the inoculum and was negatively correlated with the ammonia level. The cellulose-degrading community, targeted by analysis of the glycoside hydrolase families 5 (cel5) and 48 (cel48), showed a dominance of bacteria belonging the Firmicutes and Bacteriodetes, and a positive correlation was found between the cellulose degradation rate of wheat straw with the level of C. cellulolyticum.
Yang Tan, Ramesh Adhikari, Nikhil S. Malvankar et al.
Frontiers in Microbiology · 2016
Studies on the mechanisms for extracellular electron transfer in Geobacter species have primarily focused on Geobacter sulfurreducens, but the poor conservation of genes for some electron transfer components within the Geobacter genus suggests that there may be a diversity of extracellular electron transport strategies among Geobacter species. Examination of the gene sequences for PilA, the type IV pilus monomer, in Geobacter species revealed that the PilA sequence of Geobacter uraniireducens was much longer than that of G. sulfurreducens. This is of interest because it has been proposed that the relatively short PilA sequence of G. sulfurreducens is an important feature conferring conductivity to G. sulfurreducens pili. In order to investigate the properties of the G. uraniireducens pili in more detail, a strain of G. sulfurreducens that expressed pili comprised the PilA of G. uraniireducens was constructed. This strain, designated strain GUP, produced abundant pili, but generated low current densities and reduced Fe(III) very poorly. At pH 7, the conductivity of the G. uraniireducens pili was 3 × 10(-4) S/cm, much lower than the previously reported 5 × 10(-2) S/cm conductivity of G. sulfurreducens pili at the same pH. Consideration of the likely voltage difference across pili during Fe(III) oxide reduction suggested that G. sulfurreducens pili can readily accommodate maximum reported rates of respiration, but that G. uraniireducens pili are not sufficiently conductive to be an effective mediator of long-range electron transfer. In contrast to G. sulfurreducens and G. metallireducens, which require direct contact with Fe(III) oxides in order to reduce them, G. uraniireducens reduced Fe(III) oxides occluded within microporous beads, demonstrating that G. uraniireducens produces a soluble electron shuttle to facilitate Fe(III) oxide reduction. The results demonstrate that Geobacter species may differ substantially in their mechanisms for long-range electron transport and that it is important to have information beyond a phylogenetic affiliation in order to make conclusions about the mechanisms by which Geobacter species are transferring electrons to extracellular electron acceptors.
G. Venkatesh
Circular Economy and Sustainability · 2021
Abstract While ‘renewable’ is the keyword in a bioeconomy and resource conservation is the motivation behind a circular economy, a circular bioeconomy is one in which waste streams from renewable bio-resources are looped back into the technosphere—open-loop or closed-loop recycling or conversion from matter to energy. This systematic review brings together 385 publications from 2015 to 2021, originating from 50 countries and appearing in 150 journals, into a coherent account of the status quo of published research on circular bioeconomy. The numbers bear testimony to the growing interest in this field of research. Germany is the leading contributor to the scientific literature base (10%), while the Journal of Cleaner Production (9%) tops the list of journals in the fray. The methodology adopted has been clearly explained, and the discussion has been segmented into sub-sections and sub-sub-sections to do justice to the diversity of the nature of the publications. A little flexibility in organisation of the flow of the text has been availed of, to improve readability. The circular bioeconomy can be visualised as a set of ‘many through many to many’ relationships, enabling both economies of scale and scope in the longer run. This calls for extensive collaboration and cooperation among the numerous stakeholders involved. Several barriers will have to be overcome. Technology impact assessments and sustainability risk appraisals need to be carried out in order to ensure and convince stakeholders that they are on the right path. But as one knows and will appreciate, challenges lurk where there exist opportunities to be availed of, to replace the take-make-use-dispose paradigm of a linear economy to the grow-make-use-restore alternative. Graphical abstract
Md. Maniruzzaman A. Aziz, Khairul Anuar Kassim, Moetaz Elsergany et al.
Renewable and Sustainable Energy Reviews · 2019
Yogita Basene, Ragini Gothalwal
International Journal of All Research Education & Scientific Methods · 2022
The different types of organic waste/ pollutants are mainly generated from the various industries, specifically in the sectors of paper, fertilizer, silk, textiles, food processing, pharmaceuticals, oil refineries, sugar, distillers, brewery, cotton etc. The main pollutants from such industries are particulate matter, waste water, which contains carbohydrates, protein, lipids and oxides of Sulphur, nitrogen, carbon, which are continuously raising soil, water and air pollution index of state. Such type of pollution can be reduced by the proper utilization of organic waste/pollutants for the purpose of energy generation; due to the organic matter has immense potential for energy recovery. One of the latest technologies is microbial fuel cell technology (MFC). MFC is a modern alternative renewable energy resource for wastewater treatment and contaminants reduction. The mechanisms of MFC are based on oxidation – reduction, where microbes like bacteria, fungi and cynobacteria will catalyze oxidation of organic substrate and electron donor at the anode or removed at the cathode as electron acceptor through reduction. It is a device that converts chemical energy to electrical energy during conversion of complex organic matter, which is used as substrate by microorganism, where bioelectricity can be produced, under low cost and in ecofriendly manner which can be beneficial to reduce the carbon footprint in future.
Qiang Fei, Marykate O’Brien, Robert Nelson et al.
Biotechnology for Biofuels · 2016
Our results suggest that the fed-batch feeding strategy can strongly influence the lipid production. The online sugar control feeding mode was the most appealing strategy for high cell density, lipid yield, and lipid productivity using lignocellulosic hydrolysates as the sole carbon source.
Nirav P. Raval, Prapti U. Shah, Nisha K. Shah
Applied Water Science · 2016
Adsorption can be efficiently employed for the removal of various toxic dyes from water and wastewater. In this article, the authors reviewed variety of adsorbents used by various researchers for the removal of malachite green (MG) dye from an aqueous environment. The main motto of this review article was to assemble the scattered available information of adsorbents used for the removal of MG to enlighten their wide potential. In addition to this, various optimal experimental conditions (solution pH, equilibrium contact time, amount of adsorbent and temperature) as well as adsorption isotherms, kinetics and thermodynamics data of different adsorbents towards MG were also analyzed and tabulated. Finally, it was concluded that the agricultural solid wastes and biosorbents such as biopolymers and biomass adsorbents have demonstrated outstanding adsorption capabilities for removal of MG dye.
Xing Liu, Shiyan Zhuo, Christopher Rensing et al.
The ISME Journal · 2018
Direct interspecies electron transfer (DIET) may prevail in microbial communities that show methanogenesis and anaerobic methane oxidation and can be an electron source to support anaerobic photosynthesis. Previous mutagenic studies on cocultures of defined Geobacter species indicate that both conductive pili and extracellular cytochromes are essential for DIET. However, the actual functional role of the pili in DIET is uncertain, as the pilus mutation strategy used in these studies affected the extracellular cytochrome profile. Here we repressed the function of pili by deleting the pilus polymerization motor PilB in both Geobacter species. The PilB mutation inhibited the pilus assembly but did not alter the pattern of extracellular cytochromes. We report that the two pilus-free Geobacter species can form aggregates and grow syntrophically with DIET. The results demonstrate that the Gmet_2896 cytochrome of Geobacter metallireducens plays a key role in DIET and that conductive pili are not necessary to facilitate DIET in cocultures of Geobacter species, and they suggest cytochromes by themselves can meditate DIET, deepening the understanding of DIET.
David J. F. Walker, Kelly P. Nevin, Dawn E. Holmes et al.
The ISME Journal · 2020
Syntrophic interspecies electron exchange is essential for the stable functioning of diverse anaerobic microbial communities. Hydrogen/formate interspecies electron transfer (HFIT), in which H 2 and/or formate function as diffusible electron carriers, has been considered to be the primary mechanism for electron transfer because most common syntrophs were thought to lack biochemical components, such as electrically conductive pili (e-pili), necessary for direct interspecies electron transfer (DIET). Here we report that Syntrophus aciditrophicus, one of the most intensively studied microbial models for HFIT, produces e-pili and can grow via DIET. Heterologous expression of the putative S. aciditrophicus type IV pilin gene in Geobacter sulfurreducens yielded conductive pili of the same diameter (4 nm) and conductance of the native S. aciditrophicus pili and enabled long-range electron transport in G. sulfurreducens. S. aciditrophicus lacked abundant c-type cytochromes often associated with DIET. Pilin genes likely to yield e-pili were found in other genera of hydrogen/formate-producing syntrophs. The finding that DIET is a likely option for diverse syntrophs that are abundant in many anaerobic environments necessitates a reexamination of the paradigm that HFIT is the predominant mechanism for syntrophic electron exchange within anaerobic microbial communities of biogeochemical and practical significance.
Alessandro Blasi, Alessandra Verardi, Catia Giovanna Lopresto et al.
Recycling · 2023
The sustainable management of lignocellulosic agricultural waste has gained significant attention due to its potential for the production of valuable products. This paper provides an extensive overview of the valorization strategies employed to convert lignocellulosic agricultural waste into economically and environmentally valuable products. The manuscript examines the conversion routes employed for the production of valuable products from lignocellulosic agricultural waste. These include the production of biofuels, such as bioethanol and biodiesel, via biochemical and thermochemical processes. Additionally, the synthesis of platform chemicals, such as furfural, levulinic acid, and xylose, is explored, which serve as building blocks for the manufacturing of polymers, resins, and other high-value chemicals. Moreover, this overview highlights the potential of lignocellulosic agricultural waste in generating bio-based materials, including bio-based composites, bio-based plastics, and bio-based adsorbents. The utilization of lignocellulosic waste as feedstock for the production of enzymes, organic acids, and bioactive compounds is also discussed. The challenges and opportunities associated with lignocellulosic agricultural waste valorization are addressed, encompassing technological, economic, and environmental aspects. Overall, this paper provides a comprehensive overview of the valorization potential of lignocellulosic agricultural waste, highlighting its significance in transitioning towards a sustainable and circular bioeconomy. The insights presented here aim to inspire further research and development in the field of lignocellulosic waste valorization, fostering innovative approaches and promoting the utilization of this abundant resource for the production of valuable products.
Xianbo Su, Weizhong Zhao, Daping Xia
Biotechnology for Biofuels · 2018
Traces of hydrogen-producing bacteria and methanogens were detected in both biogenic and non-biogenic CBM areas. The diversity and abundance of bacteria in the biogenic CBM areas are relatively higher than in the areas without biogenic CBM. The community structure and distribution characteristics depend on coal rank, trace metal elements, temperature, depth and groundwater dynamic conditions. Biogenic gas was mainly composed of hydrogen and methane, the difference and diversity were caused by microbe-specific fermentation of substrates; as well as by the environmental conditions. This discovery is a significant contribution to extreme microbiology, and thus lays the foundation for research on biogenic CBM.
Marco Martino, Concetta Ruocco, Eugenio Meloni et al.
Catalysts · 2021
Due to its characteristics, hydrogen is considered the energy carrier of the future. Its use as a fuel generates reduced pollution, as if burned it almost exclusively produces water vapor. Hydrogen can be produced from numerous sources, both of fossil and renewable origin, and with as many production processes, which can use renewable or non-renewable energy sources. To achieve carbon neutrality, the sources must necessarily be renewable, and the production processes themselves must use renewable energy sources. In this review article the main characteristics of the most used hydrogen production methods are summarized, mainly focusing on renewable feedstocks, furthermore a series of relevant articles published in the last year, are reviewed. The production methods are grouped according to the type of energy they use; and at the end of each section the strengths and limitations of the processes are highlighted. The conclusions compare the main characteristics of the production processes studied and contextualize their possible use.
Robert Hren, Annamaria Vujanović, Yee Van Fan et al.
Renewable and Sustainable Energy Reviews · 2022
Hydrogen applications range from an energy carrier to a feedstock producing bulk and other chemicals and as an essential reactant in various industrial applications. However, the sustainability of hydrogen production, storage and transport are neither unquestionable nor equal. Hydrogen is produced from natural gas, biogas, aluminium, acid gas, biomass, electrolytic water splitting and others; a total of eleven sources were investigated in this work. The environmental impact of hydrogen production, storage and transport is evaluated in terms of greenhouse gas and energy footprints, acidification, eutrophication, human toxicity potential, and eco-cost. Different electricity mixes and energy footprint accounting approaches, supported by sensitivity analysis, are conducted for a comprehensive overview. H2 produced from acid gas is identified as the production route with the highest eco-benefit (−41,188 €/t H2), while the biomass gasification method incurred the highest eco-cost (11,259 €/t H2). The water electrolysis method shows a net positive energy footprint (60.32 GJ/t H2), suggesting that more energy is used than produced. Considering the operating footprint of storage, and transportation, gaseous hydrogen transported via a pipeline is a better alternative from an environmental point of view, and with a lower energy footprint (38 %–85%) than the other options. Storage and transport (without construction) could have accounted for around 35.5% of the total GHG footprint of a hydrogen value chain (production, storage, transportation and losses) if liquefied and transported via road transport instead of a pipeline. The identified results propose which technologies are less burdensome to the environment.
Myrto‐Panagiota Zacharof
Waste and Biomass Valorization · 2016
Grape wine is among the most important alcoholic beverages in the globe, with a continuously rising world demand, currently sizing at 25 billion litres. Such a large and heavily industrialised market calls for the maintenance of a steady production of raw materials to end products. Consequently, intensive cultivation of land, harvesting of the goods and manufacturing for the production of commercially available products are being implemented. Wine making is a timed, multistage process producing a large amount of organic and inorganic waste. It has been calculated that during cultivation and harvesting about 5 tonnes of solid waste are generated per hectare per year, while the winery wastewater varies according to the production size from 650,000 m3 (Greece) to over 18,000,000 m3 (Spain) per year. Conventional treatments of winery waste are becoming increasingly expensive, demanding significant amounts of effort, resources and energy for safe waste discharge. Therefore, the need to recycle, reuse and recover energy and valuable chemicals from winery waste and wastewater becomes apparent. Valorisation of winery waste is possible when introducing the concept of biorefinery, i.e. the use of winery waste as bioconversions feedstock in order to produce platform chemicals, biofuels, heat and energy.
Mebrahtu Hagos Kahsay
National Academic Digital Repository of Ethiopia · 2019
The release of brewery wastewater sludge with high pollutants and soluble organic contents can pose a significant threat to human health and environment due to their toxicity. The present study aims at investigating the potential of Microbial Fuel Cell (MFC) to utilize brewery wastewater sludge as feed stock of electricity generation. The characterization of the brewery wastewater sludge before and after it goes through the microbial fuel cell was analyzed using reactor digestion method, OxiTop BOD5, (HACH method DR890) molybdovanadate method, (HACH method DR 890) TNT per-sulfate digestion method for chemical oxygen demand (COD), biological oxygen demand (BOD), total nitrogen (TN), and total phosphorus (TP) respectively. The effect of varying salt concentrations (1 M, 2M, and 3M) of the salt bridge in MFC have been analyzed with different factors like temperature ranging 20 to 45 °C, and pH ranging from 4 to 10. Results were analyzed in terms of efficiency in chemical oxygen demand (COD), biological oxygen demand (BOD5), total nitrogen (TN), and total phosphorus (TP) removal and capability of energy generation. The optimum temperature was found 32.5 °C, with the optimum pH of 7 and 3 M salt bridge concentration in which the maximum removal percentage and power generation was observed. At the optimum condition the observed power output, removal percentage of chemical oxygen demand (COD), biological oxygen demand (BOD5), total nitrogen (TN), and total phosphorus (TP) were 0.88 V, 93.58%, 93.07%, 1.39%, and 1.19% respectively. Box-Behnken experimental design (BBD) has been used to find the optimum condition for voltage production, chemical oxygen demand (COD), biological oxygen demand (BOD5), total nitrogen (TN), and total phosphorus (TP) removal percentage.
Getachew Bantihun, Andualem Mekonnen, Seid Mohammed et al.
Environmental Technology & Innovation · 2025
Potentially useful species, electrogenicbacteria are used as sustainable anode biocatalysts to produce green energy and in wastewater management. Here, this study aims to identify and characterize electrogenic bacteria from six wastewater and one soil samples. Double chambered microbial fuel cell (MFC) system was designed to develop anode biofilm. Bio-electrochemical property of electrogenic bacteria isolates (EBIs) were characterized using cyclic voltammetry (CV), electrochemical impedance spectroscopy (EIS) and observation of biofilm on the anode using scanning electron microscope (SEM). Matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF-MS) and 16S rRNA gene sequencing was performed for identification. From a total of 72 biofilm forming EBIs, MALDI-TOF-MS identified 21 selected EBIS, including Aeromons, Bacillus, Citrobacter, Pseudomonas and Raoultella genus . This is the first study to characterize Enterococcus species from real brewery sludge waste, using the 16S rRNA sequencing. Evolutionary history analysis, GC content (53.72 %) and sequence alignment profiles infer this isolate as the first time report with biocatalyst potential. The evolutionary history for EBIs was found to be Enterococcus species and designated as E. faecium strain BSE14. The isolate showed biologically stable for long term operation of MFC (0.46 ± 0.038 V) with chemical oxygen demand (COD) (95.4 ± 0.82 %), biological oxygen demand (BOD) (53.3 ± 0.531 %), total nitrogen (TN) (73.1 ± 0.674) and total phosphorus (TP) (44.8 ± 0.281). Voltage generation among unknown mixed and pure EBIs exhibited significant variation (df=6, p < 0.05 and df=7, p < 0.05, respectively). Finally, the EBIs contribute as a potential biocatalyst in energy generation and wastewater treatment applications . • Wastewater was potential hosting environment for electrogenic bacteria. • 16S rRNA analysis revealed a biocatalyst Enterococcus species for MFC application. • Isolated spp. showed active metabolic process in electron transfer & biodegradation. • The electrogenic isolates showed 95.4 % of COD removal efficiency of wastewater. • Use of electrogenic bacteria for wastewater treatment is promising and low cost.
Barbara Włodarczyk, Paweł P. Włodarczyk
Energies · 2026
The increasing generation of industrial wastewater necessitates sustainable treatment strategies combined with resource recovery. Brewery wastewater, characterized by high organic content and low toxicity, represents a promising substrate for bio-electrochemical systems such as microbial fuel cells (MFCs). This study evaluates the feasibility of electricity generation from wastewater originating from a small-scale research brewery using a dual-chamber glass MFC equipped with a carbon felt anode and a foamed-glass separator. The system was operated in a repeated fed-batch mode over six consecutive 100 h cycles, with fresh wastewater supplied when the cell voltage decreased to 60% of its maximum value. Stable electrochemical performance was observed, with an average cell voltage of 304 mV and a maximum power density of 24 mW·m−2. A consistent decrease in COD concentration of approximately 8.66% per 100 h operational cycle was recorded, along with a 4.93% reduction in NO3− concentration, while NH4+ levels remained largely unchanged. The results indicate that brewery wastewater from small-scale facilities can support sustained bio-electrochemical activity under simplified, non-optimized conditions. Although power output and contaminant concentration changes were limited, the study provides a laboratory-scale study and highlights the need for further optimization of reactor configuration and operational parameters.
Shaoqin Liu, Jinzhi Sun, Ruiwen Wang et al.
SSRN Electronic Journal · 2023
Dawn E. Holmes, Pravin Malla Shrestha, David J. F. Walker et al.
Applied and Environmental Microbiology · 2017
The possibility that Methanothrix (formerly Methanosaeta ) and Geobacter species cooperate via direct interspecies electron transfer (DIET) in terrestrial methanogenic environments was investigated in rice paddy soils. Genes with high sequence similarity to the gene for the PilA pilin monomer of the electrically conductive pili (e-pili) of Geobacter sulfurreducens accounted for over half of the PilA gene sequences in metagenomic libraries and 42% of the mRNA transcripts in RNA sequencing (RNA-seq) libraries. This abundance of e-pilin genes and transcripts is significant because e-pili can serve as conduits for DIET. Most of the e-pilin genes and transcripts were affiliated with Geobacter species, but sequences most closely related to putative e-pilin genes from genera such as Desulfobacterium , Deferribacter , Geoalkalibacter , and Desulfobacula , were also detected. Approximately 17% of all metagenomic and metatranscriptomic bacterial sequences clustered with Geobacter species, and the finding that Geobacter spp. were actively transcribing growth-related genes indicated that they were metabolically active in the soils. Genes coding for e-pilin were among the most highly transcribed Geobacter genes. In addition, homologs of genes encoding OmcS, a c -type cytochrome associated with the e-pili of G. sulfurreducens and required for DIET, were also highly expressed in the soils. Methanothrix species in the soils highly expressed genes for enzymes involved in the reduction of carbon dioxide to methane. DIET is the only electron donor known to support CO 2 reduction in Methanothrix Thus, these results are consistent with a model in which Geobacter species were providing electrons to Methanothrix species for methane production through electrical connections of e-pili. IMPORTANCE Methanothrix species are some of the most important microbial contributors to global methane production, but surprisingly little is known about their physiology and ecology. The possibility that DIET is a source of electrons for Methanothrix in methanogenic rice paddy soils is important because it demonstrates that the contribution that Methanothrix makes to methane production in terrestrial environments may extend beyond the conversion of acetate to methane. Furthermore, defined coculture studies have suggested that when Methanothrix species receive some of their energy from DIET, they grow faster than when acetate is their sole energy source. Thus, Methanothrix growth and metabolism in methanogenic soils may be faster and more robust than generally considered. The results also suggest that the reason that Geobacter species are repeatedly found to be among the most metabolically active microorganisms in methanogenic soils is that they grow syntrophically in cooperation with Methanothrix spp., and possibly other methanogens, via DIET.
Jinzhi Sun, Ruiwen Wang, Huidong Li et al.
Materials Today Energy · 2023