The mass concentration of diesel particulate matter (DPM) and its elemental constituents (twenty-four) emitted from stationary diesel engine exhaust at ten different sizes (56 nm to 18 µm) increased with rise in engine-operating load. The maximum value of DPM concentration varied from 10.3 ± 2.4 mg/Nm3 at 0 % load to 20.4 ± 6.5 mg/Nm3 at 100 % load at size-bin of 0.10–0.18 μm. The elements of S, Ca, K, Al, Na, Mg, Fe, and Zn contributed as the major components to DPM mass with more than 90 % to total elements at six engine-operating loads. Ca, K, Al, Na, and Mg also showed higher values of EFs compared to Fe, Zn, As, Cr and Ni. Compared to Cu, Mn, Co, Se, Pb, Ba, Sr, fuel-based emission factor (EF) of Ti, Ga, Cd, Bi, and Te showed lower side of the estimated values. The levels of hazardous particulate elements generated from stationary diesel engine exhausts was a matter of concern from human health point of view as these elements showed better potential in causing significant cancer and non-cancer diseases through long-term exposure. The elements in DPM revealed significant deposition in the pulmonary and alveolar region of the human respiratory tract.

The study aimed to assess the impact of wearing protective facial masks (PFMs) on various health parameters of hospital staff amidst the COVID-19 pandemic. The aim of this study was to investigate the effects of wearing a face mask on blood oxygen saturation, heart rate, headache, fatigue, and shortness of breath in hospital staff during routine work shifts and COVID-19. In this study, participants from various clinical, administrative, and hospital cleaning professions who had at least one month of work experience were enrolled and their oxygen saturation (SpO2), heart rate (HR), and headache were measured during routine shifts with normal daily activities. The fatigue severity scale (FSS) and the modified Borg dyspnea scale were used to assess the participants. The significance level was set at 0.05. SpO2 and HR were lower at the end of the work shift than at the beginning (93.96 ± 1.57 vs. 95.03 ± 1.7 and 82.1 ± 11.83 vs. 83.93 ± 12.31, respectively). According to the result of the Borg scale, 59.2 % of the participants did not feel short of breath and 34.3 % had “mild-moderate” shortness of breath. The total FSS (21.46 ± 2.31) showed that the participants did not fall into the “fatigued” category. The Kruskal-Wallis test showed no significant difference in Borg score, FSS, HR, and SpO2 participants with different mask types (P > 0.05). The result of the Kruskal-Wallis test also showed no significant difference in Borg score between the occupational groups (P = 0.073). The results showed that the frequency of pre-existing headaches had increased in 18.2 % of the respondents. The findings indicated that wearing PFMs did not have a notable impact on oxygen levels and heart rate during the regular tasks of hospital staff. However, the use of PFMs led to the development of new headaches associated with PFMs or worsened existing headaches.

The major issue associated with coal mine drainage is its contribution to river pollution, which occurs at the local, regional, and global levels. The pollution of surface sediment by heavy metals is a major environmental and health concern in coal mining and downstream areas. This study explored the concentrations of eight metal components in the sediments from the Shari-Goyain River of Bangladesh. The trend of decreasing metal concentration was identified as Fe > Mn > Ni > Zn > Cu > Cr > Pb > Cd in sediment. The level of metal pollution in the study area was assessed by using various indicators like geo-accumulation index (Igeo), pollution load index (PLI), contamination factor (CF), potential ecological risk factor, and risk index (RI). The sediment in the river exhibited PLI values ranging from 0.133 to 0.543, suggesting a low level of pollution from the evaluated heavy metals (PLI < 1). The mean Igeo showed that the study area was unpolluted whereas Ni showed unpolluted to moderately polluted status. For most of the metals, the sediment samples recorded a low degree of contamination (CF < 1) except Pb, Cd, and Ni which exhibited moderate degree of contamination (1 ≤ CF < 3). Through the application of various statistical analyses, coal mine drainage has been identified as the possible source of pollution of the analyzed metals in the Shari-Goyain River. However, the risk index and RI suggested a low risk of metal pollution in the studied areas. To improve the environmental conditions of the Shari-Goyain River, it is crucial to construct permanent sediment quality monitoring stations and conduct extensive ecological investigations.

Bangladesh is one of the hubs of the textile industry in the world; consequently, microfibers are an emerging threat to the aquatic ecosystem. Traditional effluent treatment plants (ETPs) might not be capable of removing most emerging pollutants like surfactants, dyes, and additives, including microfibers, and the textile industry may be a major source of microfiber pollution through products and ETPs. This study investigated the eleven woven, knit, and denim industries' ETP microfiber abundance and removal efficiency. The average (range) of microfibers found in influent, effluent, and sludge samples was 615.45 ± 377.52 particles/L (170−1460), 212.72 ± 80.14 particles/L (130−380), and 10545.45 ± 7989.54 particles/kg (4400−31000), respectively. The abundant shape was fiber, and most microfibres had sizes between 0 and 100 μm. Eight distinct colors of microfibers were found in the samples; black was the most abundant color among all the samples, followed by brown and blue. The studied ETPs showed a 23.52 % to 82.19 % microfiber removal rate, which is not satisfactory for minimizing pollution. The Fourier transform infrared (FTIR) analysis revealed that the main polymers in the samples were nylon, ethylene-vinyl acetate (EVA), polyethylene terephthalate (PETE), acrylonitrile butadiene styrene (ABS), cellulose acetate (CA), low-density polyethylene (LDPE or linear LDPE), and high-density polyethylene (HDPE). The contamination factor (CF) and pollution load index (PLI), which assess ecological risks, showed that samples were moderately to very highly contaminated by microfiber and could pose a threat to the aquatic ecosystem. The findings would help identify transformative challenges required for minimizing microfiber pollution from industrial sectors and improving ETP systems.

We present a methodology and the first tests to estimate the settling velocity of airborne microplastics based on wind tunnel experiments. A novel approach and original perspective are proposed, discussing in detail challenges and faced problems, both on the theoretical and experimental sides. Several experiments were performed, releasing fragments of different microplastic types, PET, PVC and LPDE. A statistical analysis was applied to the measurements and the values of the settling velocities were estimated to range between 0.1 and 0.2 ms−1, in agreement with most values found in the related literature. Based on the observed velocities, the applicability of the Stokes’ law, which is often used also for airborne microplastics, is then addressed, highlighting its potential limitations in the context of the microplastic dynamics in the atmosphere. We confirm that using the Stokes’ law may lead to a substantial overestimation of the settling velocity for the airborne microplastics. We also recommend to consider moving to the concept of ‘effective deposition velocity’, to account for the turbulent processes characterising the real atmosphere.

The development and widespread use of biomining are the result of the rising demand for metals. The depletion of organic resources, the abundance of low-grade metallic ores, and the vast production of metallic waste during mining and beneficiation processes have enhanced the need for biomining. Compared to high-energy-demanding and environmentally unsafe traditional mining techniques, the biomining approach is a revolutionary biotechnological technique. It is a sustainable alternative for extracting valuable metals from low-grade ores and waste materials by using microbes. Microbes have the capacity to catalyze biochemical processes, making it easier to solubilize and extract target metals from complicated mineral matrices. Notably, the redox processes, creation of organic or inorganic acids, and the release of complex agents are all necessary for biomining metals. Metal recovery is achieved from metallic grade ores, mine tailings, municipal solid waste disposal sites, incinerator ash, electronic wastes, tars, etc., all effectively processed via biomining. Biomining is also advantageous as it prevents the emission of harmful gases released from e-waste dump sites, including sulfur dioxides, nitrogen oxides, and carbon dioxide, which are of major concern. These gases may be released into the environment when open-air burning and acid baths are used for the recovery of valuable metals. Nowadays, both base metals (copper, and to a lesser extent, nickel and zinc) and precious metals (mainly gold) are extracted from ores and mineral concentrates in heaps, stirred-tank bioreactors, dumps, and other locations via microbial processing, or biomining. In the ongoing boom of the electronics industry, there is increasing pressure to handle huge amounts of electronic waste. This is also important considering the use of precious metals in the electronics sector and the need to extract them. The present review discusses biomining and bioleaching principles, methods, and also talks about e-waste in general, providing a worldwide overview. The review primarily concentrates on the use of biomining to recover valuable metals from electronic waste.

Microplastics (MPs) are an increasingly concerning type of environmental pollutant due to their abundance and the potential for bioaccumulation in aquatic food organisms. The presence of MPs in the natural waters is a clear indication of the incorrect disposal of plastic debris and the rapid growth of synthetic plastic production. An inclusive understanding of the sources, transportation, fate, and consequences of plastic waste is crucial for accurately estimating the global transit of plastic pollution and reducing its sources and hazards. Bangladesh is a significant contributor to global plastic pollution, and this review aims to summarize the existing knowledge and research gap on MP pollution in aquatic ecosystems in Bangladesh over the past five years. This article discusses the features, occurrence, and potential hazardous effects of MPs on aquatic organisms and humans to provide innovative approaches for sustainable remediation. It emphasizes the importance of a multidisciplinary approach to reducing plastic inputs into the aquatic environment, including regulation on production and consumption of plastics, using bio-based and biodegradable plastics, improving plastics life cycle, eco-friendly design for production, extended producer accountability over waste management, prioritizing recycling, creating demand for recycled plastics, and improving waste collection and management systems. The study purposes further research into plastic pollution in Bangladesh, explore environmentally friendly plastic substitutes, and provide decision-makers with effective strategies to address the plastic pollution problem in Bangladesh.

Graphene oxide-based nickel-iron superparamagnetic nanoadsorbent (GO/Ni-Fe) was synthesized from electronic waste to effectively remove doxycycline (DXC) in aqueous media. The GO/Ni-Fe nanoadsorbent has been characterized using a number of instrumental techniques, including X-ray diffractometer, Zeta potential, Fourier transform infrared spectroscopy, elemental analyzer, vibrating sample magnetometer, transmission electron microscopy, energy dispersive x-ray, and X-ray photoelectron spectroscopy. These techniques showed that nickel-iron (Ni-Fe) nanoparticles with an average size of 4.26 nm were successfully fabricated on GO surfaces. The batch experiments were conducted under different conditions, including contact time, adsorption dosage, pH, concentration, and temperature, to determine the optimal conditions of the adsorption process. The maximum adsorption (90% removal) was established within 20 min, while the adsorbent dose was only 0.1 g/L at pH 5. The adsorption process was best fitted with the pseudo-second-order model, which suggests the interaction of doxycycline with the GO/Ni-Fe nanoadsorbent is mainly controlled by the chemisorption process. This may be due to hydrogen bonding as well as electrostatic interaction and π-π interaction between adsorbates and adsorbents. The isotherm data of the adsorption process was best fitted with Langmuir isotherm model with a maximum adsorption capacity of 13.02 mg g−1 at 25 °C, indicating that the adsorption is a monolayer adsorption to heterogeneous surfaces with electrostatic interaction. The superparamagnetic properties of GO/Ni-Fe nanoadsorbent can be easily separated by external magnetic field and regenerated with methanol washing. The findings unambiguously demonstrated that magnetically separable GO/Ni-Fe nanoadsorbent could be a good choice to remove DXC from wastewater sources.

Microplastic surface properties are dynamic in the environment, as weathering, primarily through photooxidation due to ultraviolet light (UV) exposure, modifies surface chemistry and surface roughness, which can affect the fate, transport and reactivity of microplastics, and therefore any potential environmental risk they may pose. This study aims to investigate and characterise the effect of different UV radiation sources that are typically used in weathering studies (UVA-340 fluorescent lamps, xenon-arc lamps and natural sunlight) on two key properties of microplastics: surface roughness and oxidation level. High- and low-density polyethylene, polypropylene and polystyrene microplastic nurdles (<5 mm) were weathered and characterised using Atomic Force Microscopy and Fourier-Transform Infrared spectroscopy. After two weeks, UVA light was found to significantly increase the carbonyl index of the subject high-density polyethylene and decrease its surface roughness. The subject low-density polyethylene was found to increase in carbonyl index when exposed to all three light sources for two weeks, and reduced in surface roughness when exposed to both xenon-arc and UVA light. Xenon-arc light increased surface roughness on the subject polypropylene after two weeks exposure. The subject polystyrene significantly increased in carbonyl index when exposed to xenon-arc light for two weeks but decreased in surface roughness when exposed to UVA light. Surface oxidation was found to be dependent on polymer type, UV source and additive content, with the data showing a relationship between surface roughness, surface shading and additive content. The results from this study highlight the complexity of microplastic weathering processes and how metrics such as carbonyl index must be applied with caution when estimating how long a plastic has been in the environment.

Water pollution caused by chromium released from tannery is a serious concern to the environment and public health. Chromium removal from tannery effluent is a crying need before discharging to the surface water. In this study, acrylic acid-grafted sawdust was prepared by Tectona grandis sawdust grafting with acrylic acid employing gamma irradiation in the presence of air and Mohr's salt. It was treated with NaOH and the characterization of surface morphology and functional groups of modified sawdust was studied by SEM and FTIR.. The effects of solution pH, adsorbent dosage, adsorption time, and initial Cr(III) ion concentration were investigated by batch sorption studies. The process was found to be pH, temperature and concentration dependent. Langmuir and Freundlich isotherms were applied to realize the adsorption process in depth, and it was found that the Langmuir isotherm model fitted well with experimental data (R2 value of 0.983). The maximum monolayer adsorption capacity of acrylic acid-grafted sawdust for Cr(III) from aquous solution was found to be 21.55 mg g-1 at 25 °C. Pseudo-first-order and pseudo-second-order kinetic models were employed to analyze the kinetics of the process, and it was found that the experimental process followed the pseudo-second-order kinetic model, i.e. chemisorption. This study revealed that acrylic acid-grafted sawdust has a decent potential for the removal of Cr(III) from tannery effluents.