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A large amount of fruit waste is being a great environmental and social problem due to a lack of adequate storage. Among the most abundant waste is papaya, due to its high consumption in various varieties. These wastes can generate bioelectricity through organic waste, being an important parameter the pH. In this research, low-cost laboratory-scale microbial fuel cells were fabricated, using papaya waste as fuel at different pH (4, 5.73, 7, and 9) to obtain the optimum operating pH. It was possible to observe the maximum values ​​of electric current and voltage of 17.97 mA and 1.02 V on days 16 and 14, in the cell with pH 7; while the cell with pH was the one that showed the lowest values. The electrical conductivity values ​​increased from the first day, observing a maximum peak of 172.50 mS/cm for the cell with pH 7. However, the internal resistance values ​​were low, the maximum value being for the cell with pH 4 (234.61 ± 34 Ω) and the minimum for the cell with pH 7 (46.543 ± 3.6 Ω). In the same way, the maximum power density was for the cell with pH 7 of approximately 645.74 ± 33.64 mW/cm2 and a current density of 5.42 A/cm2.

Potential use of organic waste and microalgae generates bioelectricity and thereby reduces harmful effects on the environment. These residues are used due to their high content of electron-generating microorganisms. However, so far, they have not been used simultaneously. Therefore, this research uses mango waste and microalgae Spirulina sp. in double-chamber microbial fuel cells to generate bioelectricity. The cells were made at a laboratory scale using zinc and copper electrodes, achieving a maximum current and voltage of 7.5948 ± 0.3109 mA and 0.84546 ± 0.314 V, with maximum electrical conductivity of the substrate being 157.712 ± 4.56 mS/cm and an optimum operating pH being 5.016 ± 0.086. The cells showed a low internal resistance of approximately 205.056 ± 25 Ω, and a maximum power density of 657.958 ± 21.114 mW/cm2 at a current density of 4.484 A/cm2. This research provides an excellent opportunity for mango farmers and exporting and importing companies because they can use their own waste to reduce their electricity costs when this prototype is brought to a large scale.

Power generation and wastewater treatment are two great challenges for sustainable development. Microbial fuel cells (MFCs) are a sustainable alternative that can generate bioelectricity in the bioremediation process of wastewater. For this reason, the objective of this research was to generate bioelectricity through double-chamber microbial-combustion cell systems from wastewater from the Covicorti Wastewater Treatment Plant (PTARC) in the anodic chamber and electrogenic bacteria such as Stenotrophomonas maltophilia, Acinetobacter bereziniae, and Achromobacteria xylosoxidans in the cathode chamber, respectively. Measurements of the voltage, current, power density, current density, and optical density of the bacteria and biochemical oxygen demand (BOD) were made. In addition, a metagenomic analysis of the wastewater sample was performed. It was shown that the MFC with A. xylosoxidans generated the highest voltage peak (1.01 ± 0.06 V) on day 24, while the MFC with S. maltophilia generated the highest current value (0.71 ± 0.02 mA). The pH levels were slightly alkaline, and the maximum anodic conductivity value was presented by the MFC with A. cerevisiae, with a peak value of 81 ± 2 mS/cm on day 24. On the other hand, a maximum power density and current density of 195,493 ± 4717 mW/m2 and 4987 A/cm2, respectively, were obtained in the MFC with A. xylosoxidans. Finally, the metagenomic analysis identified the predominant phyla of Proteobacteria present in wastewater samples capable of generating electrical energy as Bacillota, Pseudomonadota, Bacteroidota, Actinomyketone, and Campylobacterota.

This research used tomato waste as a substrate (fuel) in Single Chamber-Microbial Fuel Cells (scMFC) on a small scale. The electrochemical properties were monitored, the functional groups of the substrate were analyzed by Fourier Transform Infrared Spectrophotometry (FTIR) and a microbiological analysis was performed on the electrodes in order to identify the microorganisms responsible for the electrochemical process. The results show voltage peaks and an electrical current of 3.647 ± 0.157 mA and 0.957 ± 0.246 V. A pH of 5.32 ± 0.26 was measured in the substrate with an electrical current conductivity of 148,701 ± 5849 mS/cm and an internal resistance (Rint) of 77. 517 ± 8.541 Ω. The maximum power density (PD) displayed was 264.72 ± 3.54 mW/cm2 at a current density (CD) of 4.388 A/cm2. On the other hand, the FTIR spectrum showed a more intense decrease in its peaks, with the compound belonging to the phenolic groups being the most affected at 3361 cm−1. The micrographs show the formation of a porous biofilm where molecular identification allowed the identification of two bacteria (Proteus vulgaris and Proteus vulgaris) and a yeast (Yarrowia lipolytica) with 100% identity. The data found show the potential of this waste as a source of fuel for the generation of an electric current in a sustainable and environmentally friendly way, generating in the near future a mechanism for the reuse of waste in a beneficial way for farmers, communities and agro-industrial companies.

Agricultural waste negatively impacts the environment and generates economic difficulties for agro-industrial companies and farmers. As a result, it is necessary for an eco-friendly and sustainable alternative to managing this type of waste. Therefore, the research aimed to investigate lettuce waste as an alternative substrate to generate bioelectricity in single-chamber microbial fuel cells (scMFCs). It was possible to report voltage and electric current peaks of 0.959 ± 0.026 V and 5.697 ± 0.065 mA on the fourteenth day, values that were attained with an optimum pH of 7.867 ± 0.147 and with an electrical conductivity of 118.964 ± 8.888 mS/cm. Moreover, as time passed the values began to decline slowly. The calculated value of maximum power density was 378.145 ± 5.417 mW/cm2 whose current density was 5.965 A/cm2, while the internal resistance reported using Ohm’s Law was 87.594 ± 6.226 Ω. Finally, it was possible to identify the Stenotrophomonas maltophilia bacterium (99.59%) on a molecular scale, as one of the microorganisms present in the anodic biofilm. The three microbial fuel cells were connected in series and demonstrated that they were capable of lighting an LED bulb, with a voltage of 2.18 V.

In this study, we aimed to determine the in vitro activity of Leuconostoc mesenteroides var. mesenteroides isolated from sugar-industry effluents to produce a dextran bioflocculant from sucrose as a low-cost substrate. L. mesenteroides strains present in residual cane juice from a sugar factory were isolated and biochemically identified using Mayeux, Sandine, and Elliker agar (MSE) as a selective medium. The strain number 3 (LM03) was biochemically identified as L. mesenteroides var. mesenteroides, which was used for this study. The concentration of dextran was quantified by dry weight, the morphology and purity were evaluated using Fourier-transform infrared (FTIR) spectroscopy, scanning electron microscopy (SEM), and energy-dispersive X-ray spectroscopy (EDS). Flocculation was evaluated via turbidimetric assays in different pH ranges from sugar-industry effluents and doses of dextran. To evaluate the flocculant activity according to the effect of pH, a jar test kit from Phipps and Bird, USA, was used with the sample recollected from the effluent (sugar industry). The pH of the samples was adjusted to 7, 8, 9, 10 and 11, with a dose of 40 ppm (dextran dose) at a fast and slow speed of 150 and 50 rpm, respectively. To evaluate the influence of the dose of dextran, values of 5, 20 and 40 ppm were used with fast speeds of 180–150 rpm and slow speeds of 30–50 rpm, respectively. The strain (LM03) was able to produce the highest concentration of dextran (26.87 g/L) in 76 h of incubation. The presence of dextran was identified in the MSE agar after incubation and characterized by FTIR, SEM, and EDS. Besides that, we observed that the best flocculation activity was observed at a pH of 9 and a concentration of 40 ppm of dextran, with a fast agitation speed of 150 rpm for 5 min and a slow agitation speed of 50 rpm for 15 min, achieving 77.7% removal of turbidity from the sugar factory effluent. L. mesenteroides was responsible for the bioflocculation of dextran in different sugar-industry effluents.

Fruit waste has increased exponentially worldwide, within which tangerine is one of those that generates a greater amount of organic waste, which is currently not fully used. On the other hand, microbial fuel cells (MFCs) are presented as an opportunity to take advantage of organic waste to generate electricity, which is why the main objective of this research is to generate bioelectricity using tangerine waste as a substrate in microbial fuel cells using zinc and copper electrodes. It was possible to generate current and voltage peaks of 1.43973 ± 0.05568 mA and 1.191 ± 0.035 V on days eighteen and seventeen, respectively, operating with an optimum pH of 4.78 ± 0.46 and with electrical conductivity of the substrate of 140.07 ± 3.51 mS/cm, while the Brix degrees gradually decreased until the last day. The internal resistance determined was 65.378 ± 1.967 Ω, while the maximum power density was 475.32 ± 24.56 mW/cm2 at a current density of 5.539 A/cm2 with a peak voltage of 1024.12 ± 25.16 mV. The bacterium (Serratia fonticola) and yeasts (Rhodotorula mucilaginosa) were identified in the substrate with an identity of 99.57 and 99.50%, respectively. Finally, the cells were connected in series, managing to generate 3.15 V, which allowed the turning on of a red LED light.

The increase in the population and its need to produce food has caused the level of contamination by organic waste to increase exponentially in recent years. Innovative methods have been proposed for the use of this waste and thus to mitigate its impact. One of these is to use it as fuel in microbial fuel cells to generate electricity. This research aims to generate bioelectricity using coriander waste in microbial fuel cells. The maximum voltage and current observed were 0.882 ± 0.154 V and 2.287 ± 0.072 mA on the seventh and tenth day, respectively, these values were obtained working at an optimum operating pH of 3.9 ± 0.16 and with an electrical conductivity of 160.42 ± 4.54 mS/cm. The internal resistance observed in the cells was 75.581 ± 5.892 Ω, with a power density of 304.325 ± 16.51 mW/cm2 at 5.06 A/cm2 current density. While the intensity of the final FTIR (Fourier transform infrared spectroscopy) spectrum peaks decreased compared to the initial one, likewise, with a percentage of identity, it was possible to attribute 98.97, 99.39, and 100% to the species Alcaligenes faecalis, Alcaligenes faecali, and Pseudomonas aeruginosa. Finally, the cells were connected in series, managing to turn on an LED light (red) with the 2.61 V generated. This research provides an innovative and environmentally friendly way that companies and farmers can use to reuse their waste.

The effluents generated by the tannery industry have a high content of chromium and other toxic elements, representing a potential threat to ecosystems. An eco-friendly alternative to treat these effluents is the use of microorganisms, such as fungi, with the capacity to biosorb heavy metals. The present work aims to determine the effect of the molasses concentration, pH variation, and time on the removal of total chromium using the filamentous fungus Trichoderma spp. An experimental design was adopted using pH (4 and 6), concentrations of molasses (0.5 and 1%), and time (8 and 12 days) as independent variables. The Trichoderma inoculum was constant in all the treatments. The different treatments were evaluated after 0, 8, and 12 days by taking 50 mL of sample from each bioreactor. The chromium concentration was subsequently determined in each sample. The results show that treatment 3 (1% molasses and pH 4) showed higher chromium removal after both 8 and 12 days. The concentrations of total chromium decreased from 665 mg/mL to values of 568 mg/mL by day 8 and 486 mg/mL by day 12. These values are, however, still above the maximum threshold imposed by Peruvian law regarding the discharge of non-domestic effluents into the sewage system. The results show that Trichoderma spp. can increasingly remove chromium from the effluent with longer incubation periods. However, future studies are necessary to determine the mechanisms of chromium biosorption by the fungus and the influence of other physicochemical parameters.

In this study, an alternative method is proposed for producing electricity using microbial fuel cells (MFCs) and fruit waste in case of industries and farmers. Herein, MFCs were manufactured using zinc and copper electrodes and three types of organic waste (R. ulmifolius, H. undatus, and M. citrifolia) as the substrate. The results revealed that the H. undatus waste generated the highest voltage and current values, i.e., 1.17 ± 0.12 V and 25.78 ± 0.89 mA, respectively, in an open circuit. However, all the substrates exhibited acidic pH values. The H. undatus substrate reported the highest voltage, power density (PD), and current density (CD) values at a V max value of 1.11 ± 0.25 V, a PD max value of 0.0719 ± 0.0012 W/cm2, and a CD max value of 0.051 A/cm2. Conversely, the R. ulmifolius substrate exhibited the lowest values at a V max value of 0.96 ± 0.13 V, a PD max value of 0.0668 ± 0.0013 W/cm2, and a CD max value of 0.025 A/cm2. The micrographs denote that the Cu anode porosity of H. undatus is higher when compared with those of the remaining two substrates, and the Pichia guilliermondii, Candida boidinii, and Brevibacillus laterosporus microorganisms were observed in its anodic biofilm.

Microbial fuel cells have undergone several modifications since their creation, mainly due to the different substrates that can be used as fuel for the generation of electrical energy. In this research, a deep and updated analysis of the characteristics of the literature published in the Scopus database from 1990 to 30 December 2022 has been carried out, finding 7055 documents indexed. The most used keywords are microbial fuel cells, performance, and electricity generation. From 2011 to the present, 5289 article-type documents were published; the article entitled “Microbial Fuel Cells: Methodology and Technology” by Logan B. E. et al., 2006 from Pennsylvania State University, USA in the Environmental Science and Technology journal of the ACS publisher was the most cited (4496 citations). On the other hand, in recent years, Chinese universities have begun to produce and highlight a number of documents positioning in the top ten, with six universities having the greatest presence in publications and as the country with the highest number of published and indexed documents (2773) in Scopus. Research on microbial fuel cells tends to grow, with China as a leading country on the subject, written by the author Wang X. It is observed that the new cell research trends deal with the modification and fabrication of electrodes with nanomaterials in order to improve their power and reduce costs to show their viability on a larger scale.

The objective was to determine the effect of inoculum concentration on the degradation of Diesel 2 by a microbial consortium called BIOT.PD001. For this, five systems were designed (in triplicate), which Contained Davis Minimum Medium, 5% Diesel 2 as a carbon source, and a suspension of the microbial consortium BIOT.PD001 (9 × 108 cells/mL) in concentrations of 2, 4, 6, 8, and 10% of the final volume. The monitoring of the degradation of Diesel 2 was carried out indirectly through the bacterial counts by the plate count method, the Biochemical Oxygen Demand (BOD5) by the Winkler Method modified according to Alsterberg, and the concentration of total fats by Gerber’s method. The retention time was 15 days. It was observed that the percentage of efficiency of the process increases as the concentration of inoculum increases, obtaining the highest percentage of efficiency (94.77%) when using 10% of inoculum (v/v), while when using inoculum concentrations of 2 and 4% (v/v), the efficiency percentages are the lowest, (68.4 and 66.6%, respectively). On the other hand, the variance analysis indicated that there is a significant difference between the averages of these values. The regression analysis indicated that the inoculum concentration significantly affects the efficiency of Diesel 2 degradation and that this is 86% explained by a linear regression model. There is a linear relationship between the inoculum concentration of the BIOT.PD001 microbial consortium and the BOD5 tend to decrease as a function of time. It is concluded that the inoculum concentration significantly affects the efficiency of the degradation of Diesel 2 by the BIOT.PD001 consortium.

Papaya (Carica papaya) waste cause significant commercial and environmental damage, mainly due to the economic losses and foul odours they emit when decomposing. Therefore, this work provides an innovative way to generate electricity for the benefit of society and companies dedicated to the import and export of this fruit. Microbial fuel cells are a technology that allows electricity generation. These cells were produced with low-cost materials using zinc and copper electrodes, while a 150 mL polymethylmethacrylate tube was used as a substrate collection chamber (papaya waste). Maximum values of 0.736 ± 0.204 V and 5.57 ± 0.45 mA were generated, while pH values increased from 3.848 to 8.227 ± 0.35 and Brix decreased slowly from the first day. The maximum power density value was 878.38 mW/cm2 at a current density of 7.245 A/cm2 at a maximum voltage of 1072.77 mV. The bacteria were identified with an identity percentage of 99.32% for Achromobacter xylosoxidans species, 99.93% for Acinetobacter bereziniae, and 100.00% for Stenotrophomonas maltophilia. This research gives a new way for the use of papaya waste for bioelectricity generation.

Research on the use of microbial biosensors for monitoring wastewater contaminants is a topic that covers few publications compared to their applicability in other fields, such as biomedical research. For this reason, a systematic analysis of the topic was carried out, for which research-type articles were reviewed during the period 2012 to September 2022. For this, different search platforms were used, including PubMed, ScienceDirect, Springer Link, and Scopus, and through the use of search equations a relevant bibliography was located. After that, the research articles were selected based on exclusion criteria. As a result, it was found that, of the 126 articles, only 16 articles were strictly related to the topic, since there was a duplication of articles among the different databases. It was possible to demonstrate the usefulness of microorganisms as components of biosensors to monitor BOD, heavy metals, and inorganic contaminants in wastewater that also had a high sensitivity. Additionally, recombinant DNA techniques were shown to improve the performance of this type of biosensor and can finally be coupled to other emerging technologies, such as microbial fuel cells (MFCs). In conclusion, it was established that microbial biosensors have high acceptability and monitoring characteristics that make them a useful tool to detect low concentrations of pollutants in wastewater that can also provide results in real-time, thus generating forms of ecological safety and social responsibility in companies where wastewater is generated.

The biosorption of arsenic (As) with macroalgae has aroused much interest as a clean and low-cost technology. To evaluate arsenic biosorption by Chondracanthus chamissoi and Cladophora sp., approximately 5 kg of algae was collected from Huanchaco’s beach and Sausacocha lake (Huamachuco), La Libertad. As biosorption was carried out in four column systems, with 2 g of algae pellets each, circulating As solutions of 0.25 and 1.25 ppm, respectively, at 300 mL/min cm2. As concentration was determined at 3 and 6 h of treatment by flame atomic absorption spectrophotometry. Data were analyzed using Student’s t-test with 95% confidence. At 6 h, Chondracanthus chamissoi presented an As biosorption of 95.76% in a 0.25 ppm mg/L solution and 85.33% in a 1.25 mg/L solution. Cladophora sp., at 6 h, presented an As biosorption of 95.76% in a 0.25 mg/L solution and 42.03% in a 1.25 mg/L solution. It was concluded that Chondracanthus chamissoi achieves higher percentages of biosorption than Cladophora sp. in solutions of 1.25 mg/L As (p < 0.05), and that there is no significant difference between the biosorption percentages of Chondracanthus chamissoi and Cladophora sp. in a 0.25 mg/L solution of As at 6 h of treatment (p > 0.05).

Global warming and the increase in organic waste from agro-industries create a major problem for the environment. In this sense, microbial fuel cells (MFC) have great potential for the generation of bioelectricity by using organic waste as fuel. This research produced low-cost MFC by using zinc and copper electrodes and taking blueberry waste as fuel. A peak current and voltage of 1.130 ± 0.018 mA and 1.127 ± 0.096 V, respectively, were generated. The pH levels were acid, with peak conductivity values of 233. 94 ± 0.345 mS/cm and the degrees Brix were descending from the first day. The maximum power density was 3.155 ± 0.24 W/cm2 at 374.4 mA/cm2 current density, and Cándida boidinii was identified by means of molecular biology and bioinformatics techniques. This research gives a new way to generate electricity with this type of waste, generating added value for the companies in this area and helping to reduce global warming.