Waste Treatment Methods Research Articles

Occupational health of drilling waste workers as related to microbial exposure and waste treatment methods.

Exposure to microorganisms is a known contributor to occupational disease. This study assessed drilling waste workers' health status and investigated the potential of inhalable bioaerosols to elicit an immune response in vitro and in vivo. Venous blood and self-reported health data were collected from 56 and 73 Norwegian drilling waste workers, respectively. Immunological effects were assessed as Toll-like receptor (TLR) activation potential of personal air samples in vitro and biomarker expression in workers' plasma samples in vivo. Parameters, such as BMI, sex, and smoking habits, were considered along with factors such as purification technology of drilling waste when biomarker expression was interpreted. Symptom prevalence among exposed workers was compared to an unexposed control group. Personal air samples activated TLR signalling in vitro in 90% of all cases. The activation potential correlated significantly with work exposure to microbial agents and total dust. Significant differences in biomarker expression and symptom prevalence were identified between purification technologies and exposure groups. Drilling waste workers had significantly increased OR of skin irritation and respiratory symptoms compared to the control group. Exposure to microorganisms during the treatment of offshore drilling waste is an occupational health concern.

Modelling and Analysis of Low and Medium-Temperature Pyrolysis of Plastics in a Fluidized Bed Reactor for Energy Recovery

With the growing demand for plastic production and the importance of plastic recycling, new approaches to plastic waste management are required. Most of the plastic waste is not biodegradable and requires remodeling treatment methods. Chemical recycling has great potential as a method of waste treatment. Plastic pyrolysis allows for the cracking of plastic polymers into monomers with heat in the absence of oxygen, allowing energy recovery from the waste. Fluidized bed reactors are commonly used in plastic pyrolysis; they have excellent heat and mass transfer. This study investigates the influence of low and medium process temperatures of pyrolysis on fluidized bed reactor parameters such as static pressure, fluidizing gas velocity, solid movement, and bubble formation. This set of parameters was analyzed using experimental methods and statistical analysis methods such as experimental correlations of changes in fluidized bed reactor velocities (minimal, terminal) due to temperature increases for different particle sizes; CFD software simulation of temperature impact was not found. In this study, computational fluid dynamics (CFD) analysis with Ansys Fluent was conducted for the fluidization regime with heat impact analysis in a fluidized bed reactor (FBR). FBR has excellent heat and mass transfer and can be used with a catalyst with low operating costs. A two-phase Eulerian–Eulerian model with transient analysis was conducted for a no-energy equation and at 100 °C, 500 °C, and 700 °C operating conditions. Fluidizing gas velocity increases the magnitude with an increase of the operating temperature. The point of fluidization could be determined at 1.1–1.2 s flow time at the maximum pressure drop point. With the increase of gas velocity (to 0.5 m/s from 0.25 m/s), fluidizing bed height expands but when the solid diameter is increased from 1.5 mm to 3 mm, the length of the fluidized region decreases. No pressure drop change was observed as the fluidized bed regime was maintained during all analyses. The fluidization regime depends on gas velocity and all the applied fluidization gas velocities were of a value in between the minimal fluidization velocity and the terminal velocity.

Quantitative determination of Penicillamine in pharmaceutical samples by Copper-Modified Drug-Based carbon dots utilizing a turn ON-OFF-ON strategy

In the present work, a sensitive and simple method is developed for sensing and quantifying Penicillamine (PA) in pharmaceutical samples utilizing a copper-conjugated carbon dots probe. The proposed method employed a turn ON-OFF-ON strategy with carbon dots fluorescence quenching by addition of copper and fluorescence recovery of up to 91 % by addition of PA. Expired moxifloxacin tablet powder was used as a novel carbon precursor during the synthesis of the carbon dots (MOX–CDs) which involved a single-step solvothermal procedure. The prepared MOX–CDs demonstrated excitation independent yellowish green fluorescence emission (Quantum yield ≈ 51 %) with the maximum excitation and emission wavelengths being observed at 410 nm and 510 nm respectively. The suggested strategy for assaying PA offered a detection limit of 0.14 µM (S/N = 3) and a linear response from 2.5 µM to 50 µM (R2 = 0.9987). In addition to offering merits like accuracy and sensitivity, the proposed probe also provides a method for solid waste treatment by reprocessing expired moxifloxacin powder.

Three-dimensional numerical simulation of coal and papermaking trash co-combustion in a circulating fluidized bed

Circulating fluidized bed (CFB) combustion is a important method of waste treatment with the benefits of harmlessness, recycling, and energy recovery. Using the existing co-firing CFB boiler to dispose of waste can reduce investment in boilers and environmental protection equipment. However, there is currently limited research available on the co-combustion of coal and waste (especially for papermaking trash), and the mechanism of pollutant emissions during unit operation remains unclear. In this work, the co-combustion of coal and papermaking trash in a three-dimensional industrial-scale CFB are investigated by using the Dense Discrete Phase Model (DDPM) method. Both homogeneous reactions (such as fuel particle pyrolysis, combustion, and surface reaction) and non-homogeneous reactions (such as gas combustion and pollutant generation) are considered. The co-combustion characteristics are comprehensively analyzed in terms of gas distribution, chemical reaction rates, and bed temperature under various operating conditions, including fuel mixing ratio, secondary air arrangement, and excess air coefficient. The results are obtained by comparing the distribution profile along the height. By reducing the mixing ratio of papermaking trash, the excess air coefficient, and adjusting the secondary air arrangement in the lower region, an expanding, reducing atmosphere is observed in the vicinity of the fuel feeding point. This, in turn, leads to an increase in CO concentration and a decrease in NO emissions, which is attributable to the interplay of gas distribution, chemical reaction rates, and bed temperature. A reduction in NO gas emissions was achieved by adjusting the secondary air arrangement and the excess air coefficient. Overall, this work provides valuable insights into the co-combustion characteristics of coal and papermaking trash in an industrial-scale circulating fluidized bed boilers.

Comparative Life Cycle Assessment of Landfilling with Sustainable Waste Management Methods for Municipal Solid Wastes

Municipal solid waste (MSW) generation continues to increase exponentially, leading to the need for better disposal methods. Approximately 50% of the MSW is landfilled in the United States (US). Landfilling is known for its negative effects on the environment and human health. The objective of this study was to conduct a life cycle assessment (LCA) of some of the most common waste treatment methods and propose an alternative and environmentally friendly integrated waste management method (IWM). The LCA was conducted using OpenLCA. Replacing landfilling, incineration, and composting with recycling, gasification, and anaerobic digestion (IWM) reduced the global warming potential from 899 kg CO2 eq to −14.6 kg CO2 eq. The same trend was observed for acidification (from 0.21 kg SO2 eq to −1.1 kg SO2 eq), ecotoxicity (from 2363.8 CTUe to 1.22 CTUe), eutrophication (from 0.5 kg N eq to 0.3 kg N eq), smog formation (from 4.4 kg O3 eq to 1.85 kg O3 eq), ozone depletion (from 2.1 × 10−5 kg CFC-11 eq to 0 kg CFC-11 eq), respiratory effects (from 2.8 × 10−3 kg PM2.5 eq to −7.25 × 10−3 kg PM2.5 eq), cancer (from 2 × 10−5 CTUh to 1.2 × 10−7 CTUh), and non-cancer effects (from 6 × 10−5 to 1.4 × 10−5 CTUh). The results show that an integrated waste management approach with recycling, gasification, and anaerobic digestion can dramatically reduce the environmental and health impacts of municipal solid waste disposal. Policy reforms, technical innovation, economic investment, and social engagement are needed to change waste management paradigm.

Experimental Study on Optimizing Hydrogen Production from Sludge by Microwave Catalytic Pyrolysis Using Response Surface Methodology.

Catalytic pyrolysis technology is a harmless and useful solid waste treatment method. Studying the catalytic pyrolysis of sludge for hydrogen production is of practical significance. Therefore, this paper prepared a bifunctional catalyst with both microwave absorption and catalytic properties from electroplating sludge through carbonization and acid modification processes and then was characterized by XRD, BET, SEM, XPS, and FTIR. An experimental study employed a conventional-then-microwave pyrolysis method to investigate the catalytic pyrolysis process of municipal sludge. Combining central composite design (CCD) and response surface methodology (RSM) with three factors and five levels, this paper investigated the interactive effects of the conventional pyrolysis temperature, microwave irradiation time, and catalyst addition ratio on the unit hydrogen production (UHP) of sludge. A predictive model based on a second-order polynomial regression equation was developed. The results revealed that the catalyst possesses a specific surface area and pore structure and that the second-order polynomial model fits well. The conventional pyrolysis temperature, microwave irradiation time, catalyst addition ratio, and interaction between the latter two significantly affected the UHP of sludge. The optimal operation conditions of conventional pyrolysis temperature, microwave irradiation time, and catalyst addition ratio were 462.7 °C, 8.8 min, and 12.4%, respectively. Under these optimal conditions, the UHP was 13.22 mmol/g, with a relative error of only 1.12% compared to the predicted model value of 13.37 mmol/g.

Energy and Economic Analysis of a New Combination Cascade Waste Heat Recovery System of a Waste-to-Energy Plant

Waste incineration has become the main treatment method for urban household waste, and it can produce a large amount of electricity. The efficiency of waste incineration plants is reduced due to the large amount of waste heat carried away by the flue gas. Recycling and utilizing the waste heat from flue gas are important in improving the economic benefits of waste incineration, which is necessary for energy conservation and emission reduction. Based on the principle of cascade waste heat recovery from waste incineration flue gas whilst considering system safety and efficiency, this study proposed a new combination cascade waste heat recovery system consisting of a Rankine cycle, an organic Rankine cycle and a heat pump cycle. Thermodynamic and economic analyses of the combined system were conducted in detail. The results indicated that the energy efficiency of the combined system could reach up to 73%. The maximum net present value of the system was million USD 1.59 million, and the dynamic investment payback period was about 6.5 years. The isentropic efficiency of the combined system’s pumps and turbines had a significant impact on the system’s performance. A higher isentropic efficiency resulted in better system performance. The exergy analysis showed that the evaporator of the heat pump system had the highest irreversible loss.

Priority Organic Pollutant Monitoring Inventory and Relative Risk Reduction Potential for Solid Waste Incineration.

Incineration is a promising sustainable treatment method for solid waste. However, the ongoing revelation of new toxic pollutants in this process has become a controversial issue impeding its development. Thus, identifying and regulating high-risk pollutants emerge as pivotal strides toward reconciling this debate. In this study, we proposed a workflow aimed at establishing priority monitoring inventories for organic compounds emitted by industries involving full-component structural recognition, environmental behavior prediction, and emission risk assessment, specifically focusing on solid waste incineration (SWI). A total of 174 stack gas samples from 29 incinerators were first collected. Nontarget full organic recognition technology was then deployed to analyze these samples, and 646 organic compounds were identified. The characteristics, i.e., toxicity effects, toxicity concentrations, persistence, and bioaccumulation potential, of these compounds were assessed and ranked based on the TOXCAST database from the US Environmental Protection Agency and structural effect models. Combined with consideration of changes in seasons and waste types, a priority control inventory consisting of 28 organic pollutants was finally proposed. The risks associated with SWI across different regions in China and various countries were assessed, and results pinpointed that by controlling the priority pollutants, the average global emission risk attributed to SWI was anticipated to be reduced by 71.4%. These findings offer significant guidance for decision-making in industrial pollutant management, emphasizing the importance of targeted regulation and monitoring to enhance the sustainability and safety of incineration processes.

Study on use of recycled waste materials on the performance of asphalt binder and mixes: A comprehensive review

All aspects of daily living frequently involve the use of plastics. Due to the lack of effective waste treatment methods, massive global environmental problems will be caused by the accumulation of waste plastics. The use of waste materials in road building is of tremendous interest since it has the potential to reduce hazards and pollution while conserving natural resources. High-density polyethylene (HDPE), low-density polyethylene (LDPE), polypropylene (PP), polystyrene (PS), polyethylene terephthalate (PET), ethyl vinyl acetate (EVA), and polyvinyl chloride are the most appropriate and relevant of waste plastics. There are other types of waste materials used in the asphalt such as reclaimed asphalt pavement (RAP), crumb rubber (CR), steel slag, glass powder etc. These all-waste materials have been briefly discussed. In this review article several concerns have been raised about the physical and chemical qualities, of asphalt pavements that have been mixed with waste materials. Using waste materials in asphalt pavements can raise several concerns regarding the physical and chemical qualities of the resulting mixtures. These concerns typically revolve around factors such as durability, performance, environmental impact, and overall sustainability. This research article provides a thorough analysis of the wet and dry procedures used to mix different types of waste plastics. Overall, including waste plastics into asphalt mix improved rutting, fatigue, and moisture resistance. Additionally, recycling waste plastics in this manner helps in reducing environmental pollution and conserving natural resources. Overall, the inclusion of waste plastics in asphalt mixtures can contribute to the development of more sustainable and durable pavements with improved performance in terms of rutting, fatigue, and moisture resistance. There are still certain issues like compatibility and low temperature performances that need to be addressed. To overcome the aforementioned issues, many strategies are used, including the use of nanomaterials, chemical additives, and polymer additives. Additional research should be conducted to investigate the ageing effect, pavement performance monitoring, polymer stability, and the economic and environmental considerations associated with the usage of plastics in asphalt pavements.

Pengurangan Nilai COD pada Effluent Fermentor Biogas UASB-HCPB dengan Memanfaatkan Mikroalga Chlorella vulgaris

Palm oil mill effluent (POME) is the main waste generated from the palm oil industry. LCPKS has a COD level of 57,000-60,400 mg/L. High levels of COD can harm the environment. LCPKS treatment techniques generally use a combination of anaerobic and aerobic waste treatment methods. The anaerobic process has been conducted using a UASB-HCPB reactor. But, the COD levels of anaerobic results have not reached the quality standards so that further processing is needed. Microalgae have the potential to reduce contaminant levels in wastewater. Chlorella vulgaris microalgae is a microalgae that is widely used in wastewater treatment. This study utilized Chorella vulgaris in reducing the COD levels of the effluent of the UASB-HCPB biogas fermentor with variations in lighting intensity and variations in the ratio of effluent to microalgae. It was found that the lighting intensity of light:dark (24:0) hours provided optimal microalgae growth so as to provide the best COD reduction with a COD reduction efficiency of 87.5%. The ratio of microalgae to effluent of 1000 mL: 500 mL showed the best COD reduction with an efficiency of 93.75%.

Targeting carbon-neutral waste reduction: Novel process design, modelling and optimization for converting medical waste into hydrogen

This study proposes a novel system designed to turn waste masks (WM) into hydrogen while aiming at carbon neutrality. The system utilizes plasma gasification to primarily convert WM into syngas, which is subsequently upgraded through water gas shift to enhance hydrogen fraction. To mitigate carbon emissions, carbon capture techniques including monoethanolamine-based carbon absorption and oxy-fuel combustion are incorporated into the system. A high-fidelity model of the designed process is developed in Aspen Plus. Machine learning-driven optimization is applied to identify the optimal operating conditions. Utilizing Gaussian process regression-based surrogate optimization, the system achieves around 0.5 kg CO2 eq/kg H2 of levelized emissions per unit hydrogen (LEH) in the reaction stage and the execution time required for optimization is only 4 s, outperforming detailed process models-based optimization. Energy assessment highlights plasma gasification and CO2 absorption as the primary sources of energy loss. Furthermore, life cycle analysis indicates that CO2 absorption is the primary contributor to carbon emissions, accounting for approximately 60% of the total emissions. With levelized emissions of 1.27 kg CO2 eq/kg WM and 5.18 CO2 eq/kg H2, the designed system demonstrates superiority over conventional medical waste treatment and hydrogen production methods.

Assessment of Veterinary Antibiotic Use and Occurrence of Veterinary Antibiotics in Livestock Manure from Farms in Rongai Sub-County, Kenya

Veterinary antibiotics are commonly used in livestock rearing to prevent diseases and stimulate growth. The release of antibiotics into the environment has become a significant environmental and public health concern. This research evaluated antibiotic use, livestock treatment, manure utilization, livestock waste treatment methods and antibiotic residues in livestock manure. Questionnaires were administered to 170 farmers rearing both cattle and poultry. Subsequently, 28 livestock manure samples from 15 cattle and 13 poultry rearing farms were collected from various farms to assess concentrations of tetracyclines (Tetracycline, Oxytetracycline) and sulfonamides (Sulfadiazine, Sulfamethoxazole) residues. Residues analysis was done using High Performance Liquid Chromatography-Diode Array Detector (HPLC-DAD). Veterinarians were the most preferred in treating both cattle and poultry in farms. Tetracyclines and sulfonamides were the most consumed class of antibiotics among both poultry and cattle rearing farmers. Compost manure and Biogas were the most preferred use of animal waste within farms. Antibiotic presence in samples was detected in 80% and 93% of cattle and poultry manure respectively. Maximum antibiotic concentrations of 16.24 and 15.18 (mg/kg) were recorded in poultry and cattle manure, respectively. There was a statistically significant difference in antibiotic concentrations in poultry and cattle manure (P<0.05). The results of this research are important in monitoring rising concerns about veterinary antibiotics on environmental and public health.

Study on the Preparation and Performance of Lightweight Wallboards from MSWIBA Foam Concrete.

To reduce land use and avoid further pollution, incineration for power generation has become the main method for municipal solid waste treatment. This research focused on the potential for transforming Municipal Solid Waste Incineration Bottom Ash (MSWIBA) into a finely ground powder. The impact of the powder's fineness and the amount of water used on its effectiveness was analyzed using a method called grey theory. MSWIBA was used as a partial substitute for cement in making MSWIBA foam concrete and lightweight wall panels. By modifying the fineness and water utilization of the recycled micro-powder, its maximum activity index can be increased to 90.1. This study determined the influence of factors including apparent dry density, water-cement ratio, foaming agent dilution ratio, and admixture dosage on the strength of the recycled foam concrete, and established the optimal mix ratio. This study employed a combination of physical experiments and numerical simulations to elucidate the impact of panel material, core layer thickness, and layer sequence on sound insulation performance. The simulation results were in close agreement with the experimental findings.

Synthesis of mixed-base active material from drilling fluid solid waste and biomass for oil wastewater adsorption and its mechanism

To address the issues of high energy consumption, high cost and the risk of secondary pollution in drilling fluid solid waste treatment methods, this study prepared a mixed-based active material using drilling fluid solid waste and biomass materials as raw materials. The mixed-based active material is characterized by its abundant pore structure and high pore volume, demonstrating excellent adsorption performance for heavy metal ions and residual oil in industrial wastewater. Thermogravimetric and basic physical property analyses indicated a synergistic effect between drilling fluid solid waste and biomass materials, showing that joint pyrolysis of the two can enhance the yield of active materials. The adsorption performance of mixed-base active materials for heavy metal ions and residual oil were was tested. It was found that the removal rate of four heavy metal ions (Cr6+, Mn2+, Cu2+, and Zn2+) from the solution could reached 57.1 %, 96.3 %, 99.0 % and 94.1 %, respectively, at a concentration of 0.5 g/L of mixed-base active materials. Characterization revealed that the mixed-base activated carbon has a well-developed pore structure and numerous types of functional groups. The isothermal adsorption process of heavy metal ions by the active material is consistent with the Langmuir model and belongs to the monomolecular layer adsorption. The adsorption rate model of residual oil in wastewater by active materials conforms to the pseudo-second-order equation. The adsorption performance of mixed-base active materials primarily stems from physical adsorption enabled by their well-developed internal pore structure, along with chemical adsorption facilitated by oxygen- and nitrogen-containing functional groups on the surface.

Transformation of phosphorus speciation during hydrothermal treatment of digestate of rural animal manure

Digestate of rural animal manures (DM) contain valuable P resource, but when they are directly used on land, they can cause soil and water pollution. Hydrothermal treatment (HT) has been widely applied as an effective method of waste treatment and P recycling. This study aims to realize the P recovery in DM by illustrating the migration and transformation of phosphorus (P) species during HT process of DM. Two acids (e.g., hydrochloric acid and oxalic acid) were compared in terms of their abilities to extract P from solid products after HT process. The results revealed that organic phosphorus (OP) was converted into inorganic phosphorus (IP), whereas non-apatite phosphorus (NAIP, mainly AlPO4) was transformed to apatite phosphorus (AP, Ca3(PO4)2) during HT at different temperatures. Specifically, the percentage of IP increased from 30.4% in DDM to 90.6% after HT process at 220 °C (HT220). The P leaching efficiency of HT220 reached 94.8% during HCl extraction. The study indicated that P bioavailability and solubility could be improved by HT process. This study would provide deeper insights into the application of HT technology for recovery of P in DM, as well as provide guidance for P recovery and recycling from P containing wastes.

Assessing the Economic and Environmental Impacts of Anaerobic Digestion for Municipal Organic Waste: A Case Study of Minamisanriku Town, Japan

Anaerobic digestion (AD), or biogas technology, is an optimal method for municipal organic waste (MOW) treatment, recovering both material and energy. This study takes a life cycle assessment perspective and examines the economic and environmental impacts of a BIO facility in Minamisanriku Town, Japan, which has utilized MOW (kitchen/food waste and surplus sludge from sewage) as local biomass resources since 2012. Stakeholder interviews were conducted to gather data on material flows and impacts. Scenario analysis considered various conditions, such as pre- and post-operation of the BIO facility, the use and non-use of digestate as liquid fertilizer, and the facility’s 100% operational efficiency. The results indicate that full operation of the BIO facility and marketing of value-added products, such as branded rice grown using liquid fertilizer, could significantly reduce greenhouse gas (GHG) emissions, lower integrated environmental costs, improve the regional economy, and increase net income. In the business as usual (BAU) scenario with a 56% operation rate of the BIO facility, there is an over 10% improvement in economic and environmental impacts compared to the pre-operation baseline. This study underscores the importance of maximizing biomass utilization to develop value-added uses by enhancing, extending, and expending stakeholder collaboration.

Solid waste management and resource recovery during the 4-crew 180-day CELSS integrated experiment

In order to explore the management and treatment methods of solid waste in the Controlled Ecological Life Support System (CELSS) of future lunar bases, during the 4-crew 180-day integrated experiment, the Solid Waste Management and Treatment System (SWMTS) was built, in which the treatment of recyclable solid waste such as inedible plant parts and human excrement was completed through a combination of biological aerobic composting and high-temperature oxidation. Basic data on the types and amounts of solid waste generated during the 4-crew 180-day experiment mission were obtained. There were six types of solid wastes, including the work support wastes, the household support wastes, the plant cultivation wastes, the plant-based wastes, and crew feces. The daily average production was 0.67, 1.4, 0.32, 8.48, 0.534 kg/d, respectively. The proportion of plant-based wastes was high as 74.3 %, indicating that it was the most important part. By closed-loop air drying and graded crushing, all 1526.97 kg of plant-based waste was treated, with water recovery (about 1163.87 kg), as well as volume reduction and stabilization treatment. By incineration and aerobic composting treatment, 67.3 % (244.4 kg) of the plant-based wastes (dry weight) and all of the feces (96.26 kg) were converted, providing 339.54 kg carbon dioxide for plant growth. And 90.6 kg organic fertilizer was obtained. The fertilizer was highly mature, met safety requirements, and effectively improved lettuce yield. The recycling rate of renewable solid waste during the experiment reached 89.8 %. The efficient circulation of solid waste had been achieved during the 4-crew 180-day integrated experiment. The long-time experimental results have shown that the established solid wastes management and treatment system can timely treat biomass solid waste such as inedible parts of plants and crew feces, achieve timely recovery of water in such solid waste, and recycle carbon and other elements, which effectively improved the material closure of the system and ensured the successful 4-crew 180-day experiment. This work also maybe lay the foundation for the construction and operation of an ecological life support system for future lunar bases.

Assessing the Environmental and Health Impacts of Thermal Waste and Landfill-Based Waste Management

According to Presidential Regulation No. 35 of 2018, which focuses on accelerating the development of waste-to-energy projects, Denpasar City in Bali has been identified as one of the key Indonesian cities for implementing these projects. The daily waste generation in Denpasar City is estimated at 750 tons. The city's sanitation strategy outlines that 20% of this waste will be reduced at its source, while the remaining 80% is managed at the final treatment site. This study employs the Life Cycle Analysis (LCA) approach to evaluate the environmental impacts of traditional landfilling and various thermal waste treatment methods. The findings reveal that gasification (Scenario 2) has the lowest Global Warming Potential (GWP), with 779,759 kg CO2 equivalent emitted, indicating its superiority in reducing greenhouse gases. In contrast, landfilling (Scenario 1) is the least favorable, with a GWP of 2,885,770 kg CO2 equivalent and a significant cancer risk due to hexavalent chromium emissions estimated at 1,634,050 kg equivalent. These results underscore the health and environmental hazards of landfilling. Further, the study delves into each treatment scenario's impact on acidification, eutrophication, global warming potential, and photochemical oxidation.

Utilization of local corn (Zea Mays) wastes for bioethanol production by separate hydrolysis and fermentation

Maize is the second most-common crop globally. Thus, enormous maize cobs are generated annually from maize processing activities which could serve as a potential and non-edible source for biofuel production. The primary aim of this research was to assess the practicality of producing bioethanol from discarded maize cob through a distinct two-step process referred to as separate hydrolysis and co-fermentation. After a 72-hour fermentation period, the greatest ethanol yield of 66.23 ± 8.35 mL/kg was obtained. This was followed by 54.33 ± 7.27 35 mL/kg after 48 h, and 21.68 ± 2.97 35 mL/kg after 24 h. Importantly, all ethanol yields at different time points exhibited statistical significance at p < 0.05. Moreover, the study revealed a robust positive correlation (r = 0.99, p < 0.01) between glucose and Total reducing Sugars (TRS) yields, and negative correlations were observed between ethanol yield and glucose (r = -0.97, p < 0.05) as well as ethanol and TRS (r = -0.98, p < 0.05). The results indicate the potential of maize cob waste as a valuable resource for bioethanol production. Significant enhancements in operational processes are necessary to enhance the economic feasibility of producing ethanol from maize cobs. Nigeria's utilization of waste for biofuel production is bolstered by substantial policy and financial backing for renewable fuels. The economic viability of ethanol production from maize cobs relies heavily on its competitiveness relative to other waste treatment methods and the effectiveness of policy measures.

Utilization of fungal and bacterial bioremediation techniques for the treatment of toxic waste and biowaste

The escalating accumulation of toxic wastes and biowastes constitutes a critical environmental crisis that demands immediate and effective solutions. Traditional waste treatment methods, predominantly chemical and physical, are increasingly viewed as unsustainable, burdened by high operational costs and the risk of generating secondary pollutants. Against this backdrop, bioremediation emerges as a crucial and sustainable alternative, utilizing the natural detoxifying capabilities of microorganisms. This review article focuses on the use of fungal and bacterial strategies in bioremediation, emphasizing their vital role in the degradation, stabilization, or detoxification of pollutants. We provide an in-depth analysis of the mechanisms by which fungi and bacteria break down various contaminants, presenting a current snapshot of the field’s state of knowledge. The article highlights recent innovative advancements that improve the effectiveness and expand the applicability of bioremediation technologies. Moreover, it discusses the practical challenges of scaling these solutions to meet global environmental needs and suggests directions for future research and implementation. This synthesis not only underscores the significance of microbial bioremediation in addressing pressing environmental problems but also acts as a call to action for continued innovation in the sustainable management of hazardous wastes.