A fast sol-dipping-gel method was applied to load Ag and TiO₂ nanoparticles on the surface of crayfish shell biochar to make an inexpensive and novel nanocomposite. Tetra-n-butyl titanate (Ti(OC₄H₉)₄) and silver nitrate (AgNO₃) were used as the nanoparticle precursors. Crayfish shell was pyrolyzed to produce the biochar host. Paper-disk diffusion method was applied to measure antibacterial activities of the nanocomposites to E. coli. The maximum loading rate of TiO₂ and Ag nanoparticles on the biochar reached 7.54% and 3.20%, respectively. Results of long-term antibacterial effect experiment showed that the Ag-TiO₂-biochar had robust antibacterial activity and could be reused for multiple times. The inactivation of E. coli of initial concentration of 10⁵ CFU/mL by Ag-TiO₂-biochar under solar light reached around 99% of sterilization ratio in 5 min. In addition, the antibacterial ability of the nanocomposite was better in light than that in dark due to the presence of TiO₂. Findings of this study suggest that the novel nanocomposite is a promising material for water treatment units and household water purifiers.

The aims of this study were to analyze biochemical and morphological responses (glutathione S-transferase activity and branchial lesions) in Ucides cordatus (crabs) and to verify how the species is responding to environmental contamination in a port (potentially contaminated area) and mangrove (reference area; Amazon Coast, Maranhão, Brazil). Adult males were captured bimonthly for a period of 1 year. Higher GST activity (1.03 ± 0.07 μmol min⁻¹ mg protein⁻¹) was observed in crabs in the port when compared with those in the reference area (p < 0.05). The greatest number of branchial lesions (serious alterations) was recorded in crabs only in the port area. The GST activity increased until serious lesions appeared; after this limit, GST activity decreased dramatically to very low levels, thus resulting in irreversible lesions (lamella collapse). The mathematical model based on the two parameters evaluated in U. cordatus showed that the port area experienced substantial contamination impact, while the mangroves (reference area) presented moderate environmental quality.

Brominated diphenyl ethers-209 (BDE-209), a toxic and stably retardant, is a ubiquitous environmental contaminant and commonly used in daily consumer products. The Cenococcum geophilum and Laccaria amethystina were used to inoculate Japanese black pine (Pinus thunbergii Parl) seedlings, using root chamber experiments to check their potential for improving host growth and the capacity in establishing in persistent organic pollutants (POPs)-contaminated environments. The results showed that the inoculation with ectomycorrhizal (ECM) fungi significantly (p < 0.01) improved the growth and reduced the concentrations of BDE-209 in needles and stems of pine seedlings planted in polluted soils. The transfer ratio (calculated as the ratio between the concentrations in needles and roots) and the root concentration factor (calculated as the ratio of the concentration in roots to soil) decreased significantly (p < 0.01), when inoculated with ectomycorrhizal (ECM) fungi compared to without. However, inoculated with ECM fungi (EMF) increased the concentration of BDE-209 in tube soil (soil collected from tube where seedlings were grown) significantly (p < 0.01), especially C. geophilum, which has a rich mycelium system. The capability of EMF accumulation and enrichment of BDE-209 in the contaminated soil, from distance to root zone, reduced the risks of the spread and leaching of organic pollutants to the crops around. The pine inoculated with EMF can be considered to have a potential in forestation and remediating BDE-209 contaminated areas by the way of phytostabilisation pollutants.

Acid rain is a global environmental problem that threatens agricultural production. Calcium (Ca), as a signal substance for physiological activities, has been known to regulate plant growth under abiotic stresses. To clarify whether calcium could be one of possible ways to alleviate the reduction caused by acid rain in agricultural production and investigate its regulating mechanism on adaptation of plants under acid rain stress, we studied the effect of exogenous Ca²⁺ (5 mM CaCl₂) on growth of soybean at different growth stages (seedling, flowering-podding, and filling stages) as well as yield and grain quality of soybean under simulated acid rain (pH 4.5 or pH 3.0) stress. We found that the application of Ca²⁺ could regulate the activity of plasma membrane H⁺-ATPase, for mitigating the increase of ammonium and the decrease of nitrate and phosphorus in soybean roots, which mitigated the inhibition on growth and improved the yield and grain quality of soybean under simulated acid rain stress. In addition, the alleviating effect of exogenous Ca²⁺ on soybean was the most significant at seedling stage. The results indicate that the exogenous Ca²⁺ could enhance the adaptation of soybean and facilitate the recovery of soybean productivity and grain quality under simulated acid rain stress by maintaining the uptake of nitrate, ammonium, and phosphorus.

This article identifies environmental factors that explain most of the dynamic year-to-year changes in mercury concentrations of young-of-year (YOY) yellow perch (Perca flavescens) in study reservoirs. Mercury concentrations in fish, collected each fall, were measured for 9 years in four reservoirs in northeastern Minnesota. Three to 4 years of data were also obtained for two natural lakes and one other reservoir. Average annual concentrations varied considerably from year to year with a mean change of 39% between consecutive years across all lakes. Those averages show a similar time trend for each lake over the years and suggest that important factors influencing mercury bioaccumulation change annually and are also experienced in common over the study region. Three factors satisfying that description are precipitation depth, water level, and average air temperature. This article reveals that all three have statistically significant correlations with observed mercury concentrations. Moreover, multiple regressions indicate that maximum water levels and average air temperatures explain most of the observed variations. Regressions employing precipitation depth and temperature are less significant.

Copper (Cu) and cadmium (Cd) are ordinary heavy metals. Unreasonable development and utilization of these heavy metals will cause severe pollution to the soils and consequently bring damage to human health. Therefore, recovering soils polluted by heavy metals is crucial. An indoor pot experiment was carried out involving seven treatments, namely, low-concentration Cu stress (Cu1), high-concentration Cu stress (Cu2), low-concentration Cd stress (Cd1), high-concentration Cd stress (Cd2), low-concentration Cu–Cd combined stress (Cu1Cd1), and high-concentration Cu–Cd combined stress (Cu2Cd2), and an uncontaminated soil as a control. Results demonstrated that the net photosynthetic rate and chlorophyll content are approximately 8.36–72.51% and 7.22–36.50%, respectively, lower under the Cu, Cd, and Cu–Cd combined stresses than under the control. The net photosynthetic rates are higher under Cu2 and Cd2 than under Cu1 and Cd1; by contrast, the net photosynthetic rate of leaves is lower under Cu2Cd2 than under Cu1Cd1. The net photosynthesis rate of Cinnamomum camphora is significantly positively correlated with superoxide dismutase activity but is significantly negatively correlated with the total chlorophyll, malondialdehyde, soluble sugar, and proline contents. Young Cinnamomum camphora grows well under Cu, Cd, and Cu–Cd combined stresses and is applicable in ecologically restoring heavy metal–contaminated soils.

The immobilized algae Sargassum vulgare was used as biosorbent for Fe³⁺ removal through a batch and continuous system in order to study the biosorption capacity and to establish a new method of the valorization of this waste. The kinetic data could be described by the pseudo first-order and pseudo second-order kinetic models. The batch equilibrium was fitted by the Langmuir model with a value of correlation coefficient (R² = 0.98) higher than that of the Freundlich (R² = 0.89). The process was exothermic and spontaneous and the biomass was successfully desorbed using 0.1 M HCl. Furthermore, the Thomas model, Bohart-Adams model, and Yoon-Nelson model were successfully applied to evaluate the dynamic behavior of Fe³⁺ biosorption in a fixed-bed column. The lower flow rate of 1.04 ml/min showed the greater performance of the process. Fourier transform infrared spectroscopy revealed the presence of several active binding sites, and scanning electron microscopy micrograph confirmed the metal adsorption on the surface. The results reveal that the immobilized algae have a potential removal for Fe³⁺ in a batch and continuous system.

The integrated algal pond system (IAPS) is a passive wastewater treatment technology that can be used to remediate liquid waste from domestic, industrial and agricultural sources. The system exploits the mutualistic interaction between microalgae and bacteria to generate water of a quality suitable for discharge and/or reuse. During the treatment process, biomass in the form of microalgal–bacterial flocs (MaB-flocs) is generated, and this can be harvested and beneficiated in downstream processing. Here, we review literature on MaB-floc and extracellular polymeric substance (EPS) formation and discuss how essential microalgal–bacterial mutualism is at effecting IAPS-based wastewater treatment. Aggregation of microalgae and bacteria into MaB-flocs is clearly an outcome of EPS production by these microorganisms and arises for purposes of chemical and developmental interaction, protection, communication, aggregation and adhesion. The polymeric compounds which form the scaffold of this extracellular matrix comprise polysaccharides, proteins, uronic acid and nucleic acid. Natural EPS can be used as bioflocculant in water purification and in the dewatering and settling of sludge and is therefore an ideal natural replacement for commercially available synthetic polymers. Additionally, EPS are considered high value and can be used in many commercial applications. Thus, and to ensure sustained MaB-floc production in IAPS-based wastewater treatment plants, it is important that correct levels of EPS are maintained to facilitate settling and biomass recovery. Furthermore, it is the associated environmental and operational conditions that most impact EPS production and in turn, MaB-floc formation, and quality of the final IAPS-treated water.

The aim of this work is to evaluate the application of a steel waste, basic oxygen furnace sludge (BOFS), rich in iron, to treat water contaminated with elevated arsenic and sulfate concentrations. In the first step, three doses (10, 60, and 80 g L⁻¹) of BOFS were tested to investigate the removal of As(III) and As(V) (67 mg L⁻¹) and sulfate (3700 mg L⁻¹) separately from an aqueous solution. In the second step, the efficacies of BOFS (10 g L⁻¹) and commercial ZVI (5 g L⁻¹) were compared to simultaneously remove arsenic and sulfate. The pH of the feed solution was adjusted to 2.5 and monitored during the experiment. The use of BOFS achieved arsenic removal up to 92% and sulfate removal of nearly 40% after 72 h of contact time. Use of BOFS also increased the solution pH to 12. Similar removal levels were achieved with both BOFS and ZVI. These results confirm the potential application of BOFS to remove high arsenic and sulfate concentrations from acidic solutions. The data obtained here should be used as a basis for further studies on the remediation of acid mine drainage with high concentrations of arsenic and sulfate using an abundant and low-cost steel waste.

The purpose of this study was the identification of the major factor for sustainable development in textile industries and preferred textile wastewater management practices for environmental protection. Moreover, a structural framework for sustainable textile wastewater management concept in the textile industry was developed, and further, the proposed model was examined based on the effect of economic performance, environmental impact, and operational performance in textile sectors. Therefore, to achieve the above issues, major factors were identified through exhaustive literature, and then a test was conducted for the reliability of the proposed constructs for validation. However, there was no specific study on the sustainability of textile wastewater management principle by using exploratory structural equation modeling (SEM). Finally, the proposed structural model was validated by confirmatory factor analysis (CFA) and structural equation modeling with the help of the SPSS software package.