Waste Sludge Research Articles

Adsorption of Cd and Mn from neutral mine effluents using bentonite, zeolite, and stabilized dewatered sludge

This study aimed to investigate the adsorption efficiency of Cd and Mn using natural sorbents—bentonite, zeolite and stabilized digested dewatered waste sludge. The main contributions of the scientific article are in adding to the scientific knowledge of the use of natural and waste sorbents in the removal of heavy metals from neutral mine effluents. Current studies mainly focus on metal removal by sorption using natural sorbents from acid mine drainage. This study investigates sorption in neutral mine drainage. The efficiency of the sorption process was evaluated using the following parameters: efficiency (%) of metal ion removal, Freudlich and Langmuir adsorption isotherm constant. The AES–ICP method (atomic emission spectrometry with inductively coupled plasma) was used for the initial metal analysis of the materials used. The atomic absorption spectrometry (AAS) method was used for the analysis of Cd and Mn in the sorption process. The maximum efficiency of Mn removal by bentonite at the end of the test was approximately 90%. The removal of Mn by zeolite was considerably lower—about 20% compared to the use of sludge—80%. Based on the sorption efficiency, the sludge was suitable for sorption. Much higher levels of Cd sorption were achieved using sludge compared to using natural bentonite and zeolite. The main novelty of the work lies in the sorption of metals using dewatered digested sludge. Previous studies have focused on metal sorption using activated sludge. Most previous studies focused on sorption from acid mine drainage. The novelty of this study is that we focused on the sorption of neutral mine drainages, which are typical for the location we are monitoring.

Distinguished denitrifying phosphorus removal in the high-rate anoxic/microaerobic system for sewage treatment

This study re-evaluated the role of anoxic and anaerobic zones during the enhanced biological phosphorus (P) removal process by investigating the potential effect of introducing an anoxic zone into a high-rate microaerobic activated sludge (MAS) system (1.60–1.70 kg chemical oxygen demand (COD) m−3 d−1), i.e., a high-rate anoxic/microaerobic (A/M) system for sewage treatment. In the absence of a pre-anaerobic zone, introducing an anoxic zone considerably reduced effluent NOx−-N concentrations (7.2 vs. 1.5 mg L−1) and remarkably enhanced total nitrogen (75% vs. 89%) and total P (18% vs. 60%) removal and sludge P content (1.48% vs. 1.77% (dry weight)) due to further anoxic denitrifying P removal in the anoxic zone (besides simultaneous nitrification and denitrification in the microaerobic zone). High-throughput pyrosequencing demonstrated the niche differentiation of different polyphosphate accumulating organism (PAO) clades (including denitrifying PAO [DPAO] and non-DPAO) in both systems. Introducing an anoxic zone considerably reduced the total PAO abundance in sludge samples by 42% and modified the PAO community structure, including 17–19 detected genera. The change was solely confined to non-DPAOs, as no obvious change in total abundance or community structure of DPAOs including 7 detected genera was observed. Additionally, introducing an anoxic zone increased the abundance of ammonia-oxidizing bacteria by 39%. The high-rate A/M process provided less aeration, higher treatment capacity, a lower COD requirement, and a 75% decrease in the production of waste sludge than the conventional biological nutrient removal process.

END-OF-LIFE PHOTOVOLTAIC MODULES: LIFE CYCLE ASSESSMENT AND SENSIBILITY ANALYSIS

The use of photovoltaic (PV) systems in energy generation has been grown worldwide. In Brazil, this continuous growth is seen in the increase in the number of consumer units. The expected useful life of PV modules is estimated to be between 25 and 30 years. Therefore, most of these units will be deinstalled in the near future. It is important to evaluate the environmental impacts of the technology in order to safely adopt the use of PV energy. The environmental impact of PV modules is a widely studied topic, often using life cycle analysis (LCA). However, these studies emphasize the production phase and exclude or fail to analyze in detail the uninstallation and disposal phase of PV modules. The use of precious metals and components that contain materials classified as hazardous waste has sparked recent interest in highlighting the impacts and likely benefits related to the end-of-life management of PV modules. In this context, the purpose of work is to analyze the environmental impacts of the phase of uninstallation and disposal of photovoltaic (PV) system for Brazil waste management technologies: Recycling, incineration and landfill. The life cycle assessment (LCA) was applied in three scenarios for disposal of modules: Recycling, incineration and landfill. ReCiPe 2008 method was useful to calculating the environmental impacts, with assistance of SimaPro 8.3 software. The results showed that the recycling scenario had a lower environmental performance compared to the other scenarios. The main cause is the high consumption of electricity in metal recovery stage. Besides, this scenario produces a high amount of waste (residual liquid and sludge). The scenario of recycling will be attractive with technological investment in energy efficiency. The advantage of this scenario is the material recovery (precious metal and materials classified as hazardous waste), as consequence will bring environmental benefits.

Effect of Biochar on Anaerobic Co-Digestion of Untreated Sewage Sludge with Municipal Organic Waste under Mesophilic Conditions

Anaerobic digestion (AD) is a biological process that occurs in the limited presence of oxygen. This process involves various difficulties during the operation, such as acidification and increased concentration of volatile fatty acids, which can inhibit methane production. Therefore, in this work, the impact of biochar on the co-digestion of untreated sludge and residual biomass under mesophilic conditions was studied. For the production of biochar, the gasification process was used at different temperatures: 759 °C (BL), 798 °C (BM), and 888 °C (BH). This biochar was added in concentrations of 0 g/L, 3.33 g/L, and 6.67 g/L at the beginning of the co-digestion process. The results showed that a concentration of 6.67 g/L with BH biochar increased the PBM by 18% compared to the control sample and reduced the chemical oxygen demand (COD) by 88%. In addition, there was a reduction of volatile fatty acids (VFA) of 42.75%. Furthermore, FTIR analysis demonstrated that biochar has appropriate functional groups for this process. These data suggest a good interaction of biochar with the mixture of sludge and municipal waste, indicating that biochar can improve the anaerobic co-digestion of untreated sludge and municipal waste.

Preparation of egg-structured ceramsites from molybdenum tailings with improved properties

Conversion of solid waste tailings into building materials is an effective way to turn waste into resources as well as resolve the problems of their accumulation and pollution. Herein, in this paper, light-weight and high strength molybdenum tailings ceramsites (LHMCs) were prepared using molybdenum tailings as the main raw material supplemented with fly ash, sludge, steel slag and other solid wastes by egg-structure (three-layer structure) design and high-temperature sintering. The effects of raw material ratio, amount of carbon powder agent, sintering temperature, and sintering time on the properties of LHMCs were investigated, and the optimal preparation process was proposed to be preheating at 400 °C for 60 min and sintering at 1150 °C for 40 min. The results of the physicochemical properties, morphology, and component analysis of LHMCs show that the LHMCs with egg-structure including porous core, reinforced middle layer, and dense outer layer can significantly increase the strength of the ceramsites under the premise of ensuring the low density of the ceramsites. Meanwhile, the doping of molybdenum tailings improves the physical properties of the ceramsites and achieves the reuse of waste tailings. Importantly, the optimized LHMCs can meet the performance requirements of 900-grade ceramsites. This paper proposes a strategy for the preparation of tailings-doped light-weight and high-strength ceramic building materials, which provides a new idea for the recycling of solid waste.

Co-pyrolysis of sewage sludge with hydrogen-rich polythene: Effects on synergistic promotion and bio-oil quality

Co-pyrolysis of biomass with hydrogen-rich feedstock is a promising technology to improve bio-oil quality, in which understanding the synergistic effects and product of sewage sludge (SS) with two types of plastic waste (HDPE, LDPE) is essential to develop co-pyrolysis technology. This work used in situ tracking to detect co-pyrolysis promotion/inhibition effects with different mixed feedstocks and mixing ratios, and analyzed volatile and bio-oils in detail. The results show that co-pyrolysis synergistic promotion was mainly created by the release of a large amounts of free radicals, and the largest promotion occurred near the maximum mass loss rate (DTGmax). The synergistic promotion effect was 190 % higher for SS mixed with HDPE (S–H) than for SS mixed with LDPE (S-L). Co-pyrolysis reduced polluting gases (e.g., NO2, and SO2), enhanced the degradation of oxygenated functional groups, contains 2.7 times of hydrocarbons in bio-oil than SS mono-pyrolysis. S-L promoted short-chain generation and produced more naphthalene compounds (e.g., methylnaphthalene and 2-methylnaphthalene) in hydrocarbons. However, S–H tends to produce longer chains and more monocyclic aromatic hydrocarbons (e.g., alkylbenzenes). The gasoline fraction in bio-oil could reach 89.7 % (S7L3) and 55.8 % (S5H5). This information helps to promote clean disposal and resource utilization of sewage sludge and plastic waste through co-pyrolysis.

Studies on agar salt bridge based dual chamber microbial fuel cells using sludge and dustbin waste

Studies on agar salt bridge based dual chamber microbial fuel cells using sludge and dustbin waste

Removal of Dyes from Water Using Aluminum-Based Water Treatment Sludge as a Low-Cost Coagulant: Use of Response Surface Methodology

The aim of this research was to valorize waste (sludge) from a drinking water treatment plant as a coagulant in the removal of dyes (methylene blue and crystal violet) from water and to prevent environmental issues associated with sludge storage. To accomplish this purpose, the response surface methodology based on a central composite design with five levels was implemented. In order to enhance the efficacy of the coagulation–flocculation process, three key operational variables were considered for optimization: the pH, coagulant dosage (mg/L), and initial dye concentration (mg/L). To achieve this, a quadratic polynomial model was established. According to the mathematical model that has been developed, it is predicted that the highest efficiency for removing dyes is 94.44%. This maximum effectiveness is reached when the pH is adjusted to 12.04, the coagulant dose is set at 87.044 mg/L, and the dye concentration of MB is maintained at 2.955 mg/L. Conversely, the best dye removal of CV was attained at 100% under the following conditions: pH = 12.045, a coagulant dosage of 2.955 mg/L, and a dye concentration of 2.955 mg/L. The R2 (98.44% and 95.80% for MB and CV, respectively) validated both models. In this work, the coagulant was characterized by the surface charge, FTIR, BET, and SEM analysis.

Sewage sludge co-gasification in a pilot-scale two-stage fluidized bed gasifier for improved hydrogen production: Effects on sewage sludge moisture, metal species, and metal loading amount

Theabundant mineral olivine was applied as second-stage-gasifier bed materials to increase the H2 content in the syngas produced during the co-gasification of the sewage sludge and the simulated municipal solid waste. Regardless of the second-stage bed material used, the hydrogen-to-syngas ratio in the syngas output from the second stage increased when the S/B ratio increased from 0.02 to 0.13. This demonstrates that adding steam enhances the hydrogen-to-syngas ratio in the second-stage syngas. Under the same S/B conditions, the H2 content in the syngas varied when the original and modified olivine were separately used as bed materials in the second-stage gasifier. The H2 content was 23.12 mol.% when the original olivine was used and increased to 25.27 and 26.99 % mol.% when the olivine was respectively impregnated with 1 wt% Ni and 1 wt% Fe. These results evidenced that Ni and Fe could efficiently catalyzed the co-gasification of sludge and simulated municipal solid waste and improved the hydrogen production efficiency.

Study on the Environmental Impact and Benefits of Incorporating Humus Composites in Anaerobic Co-Digestion Treatment.

This study evaluated the environmental impact and overall benefits of incorporating humus composites in the anaerobic co-digestion of kitchen waste and residual sludge. The life cycle assessment method was used to quantitatively analyze the environmental impact of the entire anaerobic co-digestion treatment process of waste, including garbage collection, transportation, and final product utilization. Moreover, the comprehensive assessment of the environmental impact, energy-saving and emission-reduction abilities, and economic cost of using humus composites in the anaerobic co-digestion treatment process was conducted using a benefit analysis method. The results showed that the anaerobic co-digestion of kitchen waste and residual sludge significantly contributed to the mitigation of global warming potential (GWP), reaching -19.76 kgCO2-eq, but had the least impact on the mitigation of acidification potential (AP), reaching -0.10 kgSO2-eq. In addition, the addition of humus composites significantly increased the production of biogas. At a concentration of 5 g/L, the biogas yield of the anaerobic co-digestion process was 70.76 m3, which increased by 50.62% compared with the blank group. This amount of biogas replaces ~50.52 kg of standard coal, reducing CO2 emissions by 13.74 kg compared with burning the same amount of standard coal. Therefore, the anaerobic co-digestion treatment of kitchen waste and residual sludge brings considerable environmental benefits.

Per- and polyfluoroalkyl substances (PFAS) in construction and demolition debris (CDD): discerning sources and fate during waste management

As regulatory frameworks for per- and polyfluoroalkyl substances (PFAS) evolve, the solid waste community seeks to manage PFAS risks effectively. Despite extensive research on PFAS in municipal solid waste (MSW) and wastewater sludge, there is limited information on a major global waste stream which seldom gleans regulatory oversight — construction and demolition debris (CDD). This study sampled a CDD processing facility to provide material-specific information on the PFAS profile within CDD. The bulk CDD accepted by this facility was separated into major categories, representatively sampled, then characterized for total available PFAS (∑92PFAS). As reprocessed CDD is ultimately recycled or landfilled, often unencapsulated or in unlined landfills, the PFAS leaching potential was also examined using two leaching procedures. Among the categories assessed for total PFAS, carpeting, carpet padding, and gypsum drywall showed elevated concentrations compared to other components, with most of the PFAS mass contributed by precursor species. However, materials with the highest total PFAS, such as carpeting, did not necessarily exhibit the highest leaching, and leachate was predominantly composed of terminal species rather than precursors. Extrapolating these findings with national CDD generation and management data inventories suggests that despite MSW having higher total available PFAS concentrations, the leachability of PFAS from landfilled CDD is comparable, raising legitimate concerns with CDD disposal practices, particularly in unlined CDD landfills.

Utilizing magnetic nanoparticles embedded into polyvinyl alcohol and sodium alginate for the absorption of arsenic

Arsenic is an extremely toxic metalloid. The majority of arsenic water pollution originates from industrial activities such as mining, smelting, and utilization of arsenic compounds in glass, pigment, semiconductor, and other industries. Arsenic-containing wastewater poses a threat to groundwater, freshwater, seawater, and soil. Bioaccumulation of arsenic as a result of accidental ingestion may have a harmful effect on the skin and cardiovascular, respiratory, and nervous systems, thereby posing a major health risk. Chemical coagulation, membrane filtration, and adsorption can be used to treat arsenic-containing wastewater. However, chemical coagulation produces a large amount of waste sludge, which is harmful and incurs high processing costs. Membrane filtration is difficult to adopt because of its high operation and maintenance costs. Adsorption is an inexpensive, easy-to-use, sludge-free water treatment method that enables adsorbent recycling. These characteristics make adsorption an economically feasible technique for water treatment. Magnetic nanoparticles (MNPs) are small particles with a high surface area to volume ratio. Their strong magnetic properties enable them to absorb specific water pollutants. MNPs are currently used as water treatment adsorbents. However, they have several drawbacks, including low acid and alkali buffer capacity and water oxidation. In this study, MNPs immobilized with polyvinyl alcohol (PVA) and sodium alginate (SA) were used to enhance the efficacy of wastewater treatment with magnetic materials. These modified MNPs exhibited magnetic characteristics and improved acid resistance. When 100 g/L PVA/SA-MNPs (pH 1–6) were stirred at 120 rpm for 30 min, the resulting iron concentration of the water was 16 mg/L. By contrast, the MNPs released iron in levels ranging from 18 to 4045 mg/L. The PVA/SA–MNPs efficiently adsorbed arsenic in the pH range 3–6, with a high removal efficiency of 76%–82%. At pH 5, the average adsorption capacity was 382 ± 27 μg/g. To recover the MNPs, they were rinsed with deionized water and immersed in acid three times, after which their adsorption capacity was 300 μg/g or higher. By contrast, the PVA/SA-MNPs could be recovered through spontaneous sedimentation, eliminating the need for a magnetic field and simplifying the collection process. In addition, iron dissolution in acidic solutions was minimized for the PVA/SA-MNPs, contributing to environmental protection.

Co-hydrothermal carbonization of municipal sludge and agricultural waste to reduce plant growth inhibition by aqueous phase products: Molecular level analysis of organic matter

The organic matter molecular mechanism by which combined hydrothermal carbonization (co-HTC) of municipal sludge (MS) and agricultural wastes (rice husk, spent mushroom substrate, and wheat straw) reduces the inhibitory effects of aqueous phase (AP) products on pak choi (Brassica campestris L.) growth compared to HTC of MS alone is not clear. Fourier-transform ion cyclotron resonance mass spectrometry was used to characterize the differences in organic matter at the molecular level between AP from MS HTC alone (AP-MS) and AP from co-HTC of MS and agricultural waste (co-Aps). The results showed that N-bearing molecules of AP-MS and co-Aps account for 70.6 % and 54.2 %–64.1 % of all molecules, respectively. Lignins were present in the highest proportion (56.3 %–78.5 %) in all APs, followed by proteins and lipids. The dry weight of co-APs hydroponically grown pak choi was 31.6 %–47.6 % higher than that of the AP-MS. Molecules that were poorly saturated and with low aromaticity were preferentially consumed during hydroponic treatment. Molecules present before and after hydroponics were defined as resistant molecules; molecules present before hydroponics but absent after hydroponics were defined as removed molecules; and molecules absent before hydroponics but present after hydroponics were defined as produced molecules. Large lignin molecules were broken down into more unsaturated molecules, but lignins were the most commonly resistant, removed, and produced molecules. Correlation analysis revealed that N- or S-bearing molecules were phytotoxic in the AP. Tannins positively influenced the growth of pak choi. These results provide new insights into potential implementation strategies for liquid fertilizers produced from AP arising from HTC of MS and agricultural wastes.

Impacts of free nitrous acid on stabilizing food waste and sewage sludge for anaerobic digestion

This work investigated the effectiveness of free nitrous acid (FNA) in enhancing organic waste solubilization to improve biogas production in anaerobic digestion (AD). The results indicated that FNA pretreatment can enhance soluble organic content and control H2S odor in tested organic wastes, including food waste, sewage sludge, and their combination. However, a significant decrease (>50 %) in FNA concentration was found in the reactors, possibly due to denitrifier-driven NO2– consumption. Biochemical methane potential (BMP) tests showed a 25 ± 8 % enhancement in CH4 production in the reactors fed with mixed substrate pretreated with 2.9 mg FNA-N/L. However, the presence of NO2– (325.6–2368.0 mg N/L) in some BMP reactors, due to carryover from FNA pretreatment, adversely affected CH4 production (>55 %) and prolonged lag time (>4.2 times). These findings are valuable for researchers and practitioners in waste management, offering insights for implementing FNA pretreatment to enhance the biodegradability of organic wastes in AD.

Comparative analysis of biochar production methods and their impacts on biochar physico-chemical properties and adsorption of heavy metals

Rapid industrialization, urbanization, and population growth result in vast amounts of organic waste being produced, including agricultural waste, animal waste, industrial waste, sewage sludge, and municipal solid waste. Biochar production from solid waste has become a popular waste management method. However, in rural areas of developing nations, biomass is typically used for cooking without being charred. Urban biowaste-derived biochar may enhance soil fertility and overall soil health. However, large-scale biochar production from an electronic muffle furnace could be very expensive, and there is little information on the conversion of biowastes to biochar using traditional kilns or its effects on biochar characteristics, and farmers' biochar production methods are yet underdeveloped. Hence, this study provides biochar production from biowastes using two production methods: 1) a traditional kiln (a tin kiln) intended for use by small farmers and gardeners, and 2) a laboratory muffle furnace, with the aim of evaluating biochar characteristics. Biochar produced in a muffle furnace and tin kiln has found similar physicochemical and adsorption properties at the same pyrolysis conditions. They include high pH, EC, CEC, Pava, Ca, Mg, K, and carbon content. We expect these biochars to have larger long-term effects on agricultural characteristics and soil carbon sequestration. However, the present results might be utilized to drive cleaner biochar production for agricultural use in developing nations, which may multiply local producer benefits.

Isotherm-kinetic equilibrium investigations on absorption remediation potential for COD and ammoniacal nitrogen from leachate by the utilization of paper waste sludge as an eco-friendly composite filler

The paper industry is a major environmental polluter due to paper waste sludge (PWS), often disposed of in hazardous ways. The techniques are employed to disposing of PWS are posing significant environmental hazards and risks to well-being. This study aims to evaluate PWS as a potential replacement for commercial adsorbents like AC and ZEO in treating stabilized leachate. Contact angle analysis of PWS was 92.60°, reveals that PWS to be hydrophobic. Batch adsorption experiments were conducted with parameters set at 200 rpm stirring speed, 120 min contact time, and pH 7. Optimal conditions for COD and NH3–N removal were identified at 120 min contact time, 200 rpm stirring speed, pH 7, and 2.0 g PWS ratio. Removal percentages for COD and NH3–N were 62% and 52%, respectively. Based on the results of the isotherm and kinetic studies, it was observed that the Langmuir and Pseudo second order (PSO) model exhibited greater suitability compared to the Freundlich and Pseudo first order (PFO) model, as indicated by higher values of R-squared (R2). The R-squared of Langmuir for COD and NH3–N were 0.9949 and 0.9919 and for Freundlich model were 0.9855 and 0.9828 respectively. Whereas the R-squared of PFO for COD and NH3–N were 0.9875 and 0.8883 and for PSO were 0.9987 and 0.9909 respectively.

Experimental Investigation and Classification of Wastewater Treatment Sludge as Pozzolan for Cement

This paper presents an investigation conducted to evaluate wastewater treatment sludge for potential use as a cement extender or pozzolan. Two varieties comprising the digested wastewater sludge (DWWS) and activated wastewater sludge (AWWS) materials, were finely ground then calcined at 750 °C for 30 min. Subsequently, the calcined sludge waste materials were blended with ordinary Portland cement CEM I 52.5 N at 0, 10, 20, 30% DWWS or AWWS, and used to prepare mortar mixtures at proportions of 1:3:0.61 cement to sand to water. Various tests were conducted including workability, compressive strength, pozzolanic activity with lime, drying shrinkage and alkali-silica reaction. It was found that both varieties of the sludge waste materials, once blended with CEM I at 20% DWWS or 20% AWWS, satisfied the ASTM C618 criteria for Class C pozzolan, and may be classified as CEM II /A-P 32.5 N,R cement type of EN 197-1/SANS 50197-1. The overall performance of DWWS was relatively better than that of AWWS.

Evaluating the efficacy of vermicomposted products in rain-fed wetland rice and predicting potential hazards from metal-contaminated tannery sludge using novel machine learning tactic

The study assessed the ecotoxicity and bioavailability of potential metals (PMs) from tannery waste sludge, alongside addressing the environmental concerns of overuse of chemical fertilizers, by comparing the impacts of organic vermicomposted tannery waste, chemical fertilizers, and sole application of tannery waste on soil and rice (Oryza sativa L.) plants. The results revealed that T3, which received high-quality vermicomposted tannery waste as an amendment, exhibited superior enzymatic characteristics compared to tannery sludge amended (TWS) treatments (T8, T9). After harvesting, vermicomposted tannery waste treatment (T3) showed a more significant decrease in PMs bioavailability. Accumulation of PMs in rice was minimal across all treatments except T8 and T9, where toxic tannery waste was present, resulting in a high-risk classification (class 5 < 0.01) according to the SAMOE risk assessment. Results from Fuzzy-TOPSIS, ANN, and Sobol sensitivity analyses (SSA) further indicated that elevated concentrations of PMs (Ni, Pb, Cr, Cu) adversely impacted soil-plant health synergy, with T3 showing a minimal risk in comparison to T8 and T9. According to SSA, microbial biomass carbon and acid phosphatase activity were the most sensitive factors affected by PMs concentrations in TWS. The results from the ANN assay revealed that the primary contributing factor of toxicity on the TWS was the exchangeable fraction of Cr. Correlation statistics underscored the significant detrimental effect of PMs' bioavailability on microbial and enzymatic parameters. Overall, the findings suggest that vermicomposting of tannery sludge waste shows potential as a viable organic amendment option in the near future.

Unlocking the potential of depleted dry batteries: A dual-purpose approach for waste mitigation and sustainable energy production

Electronic-waste (e-waste) poses a serious environmental challenge due to the increasing consumption and disposal of electronic devices. In the present work a novel method is proposed to repurpose e-waste and bio-waste into a single-chamber and mediator-less microbial fuel cells using dead, non-rechargeable D-type dry batteries. The carbonaceous material inside the dry batteries was replaced with kitchen waste sludge, which served as the substrate. The outer zinc casing was also reused as the anode and the carbon rod as the cathode. Treating the kitchen waste sludge with dilute nitric acid improved the performance of the microbial fuel cells by enhancing the biodegradability and conductivity of the substrate. The untreated microbial fuel cells produced a maximum power density of 15.0 mW/kg at a maximum current density of 50.0 mA/kg, while the treated microbial fuel cells achieved 67.0 mW/kg at 178.0 mA/kg. The main mechanism behind the working of the device is the combined action of galvanic and microbial processes, which synergistically generate electricity from e-waste and bio-waste. Moreover, when four treated microbial fuel cells were connected in series, a high open circuit voltage of 3.3 V was achieved. These microbial fuel cells stand out as eco-conscious and lightweight alternatives to conventional dry batteries, presenting an environmentally sustainable solution for waste management and clean energy production.

Taxonomic report of filamentous fungi presents in sewage waste sludge with biotechnologi-cal potential

There is few information regarding the identification of filamentous fungi present in sewage sludge, the importance of these microorganisms lies in the potential use they have in the food, pharmaceutical and agri-environmental industries as they are beneficial in the remediation of water, sludge and soil contaminated by Heavy metals and hydrocarbons also contribute to the adsorption of nutrients by crops. The use of residual sludge once decontaminated by these microorganisms can be used in agriculture as soil structure improvers, organic fertilizers and as an amendment to prevent soil erosion. The objective of this research was to characterize and identify fast and medium-growing filamentous fungi from sewage sludge. The residual sludge was collected directly from the thickness of the municipal water treatment plant of Cd. Victoria, Tamaulipas, Mexico. Subsequently, the fungi were isolated on agar plates and identified using morphological characters of the colonies and by PCR and diana sequences. The species identified were: Trichoderma longibrachiatum, Aspergillus terreus, Tylopilus porphyrosporus and Aspergillus fumigatus. Being the first report for Mexico of fungal species that grow in residual sludge from water treatment plants. The molecular characterization of the species of filamentous fungi found in sewage sludge will allow progress in research focused on knowing the advantages and biological and chemical mechanisms of these microorganisms for the development of biotechnological processes and products, with high agricultural potential and environmental.