Filter-based toxicology studies are conducted to establish the biological plausibility of the well-established health impacts associated with fine particulate matter (PM₂.₅) exposure. Ambient PM₂.₅ collected on filters is extracted into solution for toxicology applications, but frequently, characterization is nonexistent or only performed on filter-based PM₂.₅, without consideration of compositional differences that occur during the extraction processes. To date, the impact of making associations to measured components in ambient instead of extracted PM₂.₅ has not been investigated. Filter-based PM₂.₅ was collected at locations (n = 5) and detailed characterization of both ambient and extracted PM₂.₅ was performed. Alveolar macrophages (AMJ2-C11) were exposed (3, 24, and 48 h) to PM₂.₅ and the pro-inflammatory cytokine interleukin (IL)-6 was measured. IL-6 release differed significantly between PM₂.₅ collected from different locations; surprisingly, IL-6 release was highest following treatment with PM₂.₅ from the lowest ambient concentration location. IL-6 was negatively correlated with the sum of ambient metals analyzed, as well as with concentrations of specific constituents which have been previously associated with respiratory health effects. However, positive correlations of IL-6 with extracted concentrations indicated that the negative associations between IL-6 and ambient concentrations do not accurately represent the relationship between inflammation and PM₂.₅ exposure. Additionally, seven organic compounds had significant associations with IL-6 release when considering ambient concentrations, but they were not detected in the extracted solution. Basing inflammatory associations on ambient concentrations that are not necessarily representative of in vitro exposures creates misleading results; this study highlights the importance of characterizing extraction solutions to conduct accurate health impact research.

Two soil amendments, KH₂PO₄ and sodium tetraethylenepentamine–multi dithiocarbamate (TEPA/CSSNa), were applied to heavy metal-contaminated sites, and their corresponding stabilization effects were compared. Three kinds of procedures, namely, sequential extraction procedure (SEP), toxicity characteristic leaching procedure (TCLP), and diethylenetriaminepentaacetic acid (DTPA) extraction procedure, were adopted to examine the potential of using TEPA/CSSNa to stabilize Cd and Pb in polluted sites. Simplified bioaccessibility extraction test (SBET) was used to investigate the bioaccessibility of Cd and Pb. TCLP and DTPA results showed that TEPA/CSSNa was more efficient than KH₂PO₄ in reducing the mobility of Cd and Pb. SBET results indicated that the bioaccessibility of Cd and Pb decreased with increasing dose of TEPA/CSSNa. The mobility rates of Cd and Pb decreased to 0.26 and 0 %, respectively, when using 3 % TEPA/CSSNa. The exchangeable and carbonate fractions of Cd and Pb were gradually converted into organic matter–sulfate compounds. After 1 year, natural aging tests revealed that organic matter–sulfate fractions of Cd and Pb increased and the labile fractions (exchangeable and carbonate fractions) decreased in the treated soil.

The main objective of the present paper is to evaluate the use of Moringa oleifera (MO) as a natural coagulant in coagulation/flocculation/sedimentation (CFS) followed by the microfiltration (MF) or nanofiltration (NF) process in dairy wastewater treatment, focusing on determining the best association of treatments that can generate wastewater for reuse purposes. The association of CFS-MF-NF treatments showed a high removal efficiency for chemical oxygen demand (COD) (mean of 96%), turbidity, and color (mean of 99%) meeting water reuse standards, allowing the reutilization of the wastewater, in relation to the analyzed parameters. The results indicate a lower membrane fouling rate (63%), an increase in permeate flow, and better quality of the permeate, proving that the CFS-MF-NF treatment is the most suitable among all the tested treatments. Finally, the treated wastewater obtained with this process presents better quality than the wastewater obtained with the conventional treatments.

Acute (24 h) and sublethal (35 days) effects of cadmium chloride (CdCl₂) were examined in Cirrhinus mrigala using various endpoints (accumulation pattern, thyroid hormones (THs), and antioxidants). The mean concentrations of CdCl₂ for 24 and 96 h were found to be 35.974 and 22.387 mg L⁻ˡ, respectively. LC50 concentration of CdCl₂ for 24 h (35.97 mg L⁻ˡ) was used for the acute study. For the sublethal studies, fish were exposed to 3.59 mg L⁻¹ (Treatment I) and 7.19 mg L⁻¹ (Treatment II) corresponding to 1/10th and 1/5th of 24 h LC50 of the CdCl₂. During acute exposure, higher accumulation of CdCl₂ was noticed in the gill, liver, and kidney of C. mrigala, which is found in the order gill > liver > kidney tissues. Similarly, in sublethal treatments (Treatment I and II), a concentration and time-dependent increase of CdCl₂ accumulation was noticed in the order of gill > liver > kidney. GSH, GST, and GPx activities were found to be relatively lower from the treated groups in both acute and sublethal treatments. However, LPO activity was significantly increased in CdCl₂-treated fish C. mrigala. Further, plasma T₃ reduction was more pronounced than T₄ in acute study. During sublethal treatments, both T₄ and T₃ levels showed a continuous decrease as the exposure period extended. All the values in this study were statically significant (P < 0.01 and P < 0.05).

The content of As and heavy metals (Pb, Cd, Ni, and Cu) in total suspended particulate (TSP) and PM₁₀ at 3 locations (Park, Institute, and Jugopetrol) near the copper smelter in Bor (Serbia) has been analyzed within the period 2004 to 2015 with the aim of investigating the seasonal and spatial changes of those pollutants in the suspended particles. The content of As in TSP and PM₁₀ was over the annual EU limit value at all measuring points during the entire period of observation, while contents of Cd and Pb were periodically above the annual EU limits. There were no statistically significant seasonal changes between mean levels of the observed elements in the cold (October–March) and warm (April–September) periods during the year. A strong and moderate positive correlation was detected between the concentrations of each particular element (except Ni) at all measuring points. Additionally, Cd was the most enriched element followed by Pb, As, and Cu, while Ni was low-enriched. The constant air pollution with As particles, sometimes in concentrations even 20 times higher than the permitted annual value, requires urgent undertaking of concrete actions in order to reduce anthropogenic emission of suspended particles in Bor.

This study investigates effects of fixed film surface area increment on removal efficacy and biofouling in membrane bioreactor (MBR). For this purpose, a lab-scale membrane bioreactor was used. Domestic wastewater was fed into it. Three different trials were conducted at different fluxes; 15, 20, and 25 L/m²/h (LMH). Every trial was conducted using four different scenarios by varying surface area of fixed media viz. 0, 100, 150, and 200 m²/m³. Removal of pollutants viz. chemical oxygen demand (COD), biochemical oxygen demand (BOD), total organic content (TOC), total Khjdel nitrogen (TKN), and phosphorous was studied. In addition, cake resistance, pore resistance, and total resistance were also observed for aforementioned scenarios. The results demonstrated that pollutant removal efficiencies increased as the surface area per unit volume of bioreactor was increased. Conversely, the removal efficiency decreased with increase in the fluxes. In the case of biofouling, it increased while increasing the surface area or flux. The fixed media surface area increments proved beneficial in terms of removal efficiencies but at the cost of reduced operation time of MBR.

The release of arsenic (As) from sediments poses a risk to human health especially at high pH levels. Despite this, the distribution and kinetic response of mobile As remains unclear under varying pH conditions. In this study, a microcosm incubation experiment was performed, using sediment cores in combination with dialysis (Peeper) and thin film diffusive gradients (DGT), to investigate the distributions of mobile As (soluble As in pore water and DGT-labile As) at high vertical resolutions (2–4 mm). Results show that the concentrations of soluble As present in the water column increased 1.5-fold with an increase in pH from 5.4 to 11.2. Both soluble As in pore water and DGT-labile As exhibited stable low-level distributions in the uppermost layer beneath the sediment-water interface, followed by increasing concentration distribution with decreasing layers to middle depths. The mean concentrations of mobile As species increased with increased water pH in both sediment profiles and with upward diffusion gradients, showing a 0.2-fold increase of soluble As in the top 20-mm layer and a 0.6-fold increase in deeper 20–52-mm layers, while DGT-labile As showed a 1.0- and 1.1-fold increase in these two layers, respectively. Modeling of DGT-induced flux in sediments (DIFS) showed that the desorption rate constant increased more rapidly than the absorption rate constant, resulting in the increased availability of solid As pools, therefore resupplying the soluble As in pore water from sediments.

Simultaneous power generation and fecal wastewater treatment were investigated using a combined ABR-MFC-MEC system (anaerobic baffled reactor-microbial fuel cell-microbial electrolysis cell). The installation of multi-stage baffles can benefit retaining the suspended solids in the system and help separate the hydrolysis-acidification and the methanogen processes. The efficiencies of the nitrification-denitrification process were improved because of the weak current generation by coupling the microbial electrochemical device (MFC-MEC) with the ABR unit. Maximum removal rates for chemical oxygen demand (COD) and ammonia nitrogen (NH₄ ⁺-N) were 1.35 ± 0.05 kg COD/m³/day and 85.0 ± 0.4 g NH₄ ⁺-N/m³/day, respectively, while 45% of methane (CH₄), 9% of carbon dioxide (CO₂), and 45% of nitrogen gas (N₂) contents in volume ratio were found in the collected gas phase. An average surplus output voltage of 452.5 ± 10.5 mV could be achieved from the combined system, when the initial COD concentration was 1500.0 ± 20.0 mg/L and the initial NH₄ ⁺-N concentration was 110.0 ± 5.0 mg/L, while the effluent COD could reach 50.0 mg/L with an HRT of 48 h. The combined process has the potential to treat fecal wastewater efficiently with nearly zero energy input and a fair bio-fuel production.

Spherical biochar derived from saccharides (glucose, sucrose, and xylose) was prepared through two steps: pre-hydrothermal carbonization at 190 °C and calcination at low temperatures (200–325 °C). The spherical biochar was characterized by Brunauer–Emmett–Teller (BET) surface area analysis, Fourier transform infrared spectroscopy, zeta potential, scanning and transmission electron microscopies, and X-ray diffraction. The result indicated that the spherical biochar exhibited low S BET (15–22 m²/g), but abundant superficial active oxygen-containing functional groups. The spherical biochar possessed a negatively charged surface within solution pH 2.0–11. The adsorption process of Pb²⁺, Cu²⁺, and methylene green 5 (MG5) was strongly dependent on the solution pH and reached fast equilibrium at approximately 60 min. The maximum Langmuir adsorption capacity (Q°ₘₐₓ) exhibited the following order: glucose-biochar > sucrose-biochar > xylose-biochar prepared at 300 °C. The selective adsorption order of glucose-biochar was Cu²⁺ (0.894 mmol/g) > Pb²⁺ (0.848 mmol/g) > MG5 (0.334 mmol/g). The electrostatic attraction played a determining role in the adsorption mechanism of pollutant cations. The adsorption of anionic dye (acid red 1) on the spherical biochar was negligible because of electrostatic repulsion. The spherical biochar can serve as a newer and promising adsorbent to remove toxic pollutant cations from water media.

Water contamination has reached an alarming state due to industrialization and urbanization and has become a worldwide issue. Dyes contaminate water and are addressed extensively by researchers. Various technologies and materials have been developed for the treatment of contaminated water. Among them, adsorption has attracted great attention due to its ease and cost-effective nature. In recent years, graphene-based composites have shown great potential for the removal of contaminants from water. The literature reveals the usefulness of composites of graphene with metal oxides, carbon derivatives, metal hybrids and polymers for the removal of organic dyes from contaminated water. In this review, efforts have been made to compile the studies on the removal of cationic and anionic dyes from water using graphene-based composites.