Persistent environmental pollutants are a growing problem around the world. The effective control of the pollutants is of great significance for human health. Some microbes, especially Arthrobacter, can degrade pollutants into nontoxic substances in various ways. Here, we review the biological properties of Arthrobacter adapting to a variety of environmental stresses, including starvation, hypertonic and hypotonic condition, oxidative stress, heavy metal stress, and low-temperature stress. Furthermore, we categorized the Arthrobacter species that can degrade triazines, organophosphorus, alkaloids, benzene, and its derivatives. Metabolic pathways behind the various biodegradation processes are further discussed. This review will be a helpful reference for comprehensive utilization of Arthrobacter species to tackle environmental pollutants.

The investigation of municipal solid waste (MSW) treatment in China is rare due to its sensitivity and difficulty in terms of access. We chose Beijing, the capital of China, as an example to identify the characteristics of MSW landfill treatments using a 2-month investigation with 20 participants. MSW landfill treatments account for nearly 70% of the annual MSW disposal in Beijing; the landfill processes are equipped with many kinds of technologies and consume a large amount of energy and produce a variety of contaminants. The cover method (the most obvious difference in landfill tamping) mainly includes high-density polyethylene (HDPE) geomembranes with loess and soil alone (i.e., loess or sandy soil). We investigated the actual conditions of landfills and collected data on leachate and landfill gas (LFG) emissions and energy consumption during 2009–2011. The results indicated that the cover method employed by landfills was related to treatment quantity, operation, and especially landfill location. Early large-scale landfills located in plains were covered with HDPE geomembranes, and newly built landfills covered with soil tended to be equipped with HDPE covers. Using HDPE cover also contributed greatly to LFG production due to its impermeability but had no remarkable effect on leachate yield reduction due to the dry climate in Beijing. The potential was reinforced by the potentials of decrement and reuse. The disposal method of LFG can be optimized, and the power generated by the LFG process can meet the landfill demand. The gray water recycled from the leachate could be used in the landfill process.

This study examines the photocatalytic activity of titanium dioxide (TiO₂) semiconductor supported on borosilicate tubes (cut-off 290 nm) towards removal of a mix of persistent organic pollutants (POPs) from water. For this purpose, two widely used analgesic and anti-inflammatory drugs (NSAIDs), ibuprofen (IBU) and mefenamic acid, along with MCPA sodium monohydrate, which is a common herbicide frequently used in the agricultural activities, were selected as a case study. Borosilicate tubes were coated with titanium oxide through two different approaches: sol-gel dip-coating and a hybrid nanoparticle dip-coating and plasma-enhanced chemical vapour deposition (PECVD) process. The photochemical reactor that hosts the titania-coated tubes was designed to permit continuous throughput of liquid feed stream. The photodegradation experiments were performed in laboratory conditions under artificial irradiation simulating solar light. The efficiency of direct photolysis and heterogeneous photocatalysis (TiO₂) was investigated, and the performance of each coating method was evaluated. Kinetic studies for each experiment were accomplished, the overall results showed poor efficiency and insufficient removal for NSAIDs through direct photolysis, whereas applying heterogeneous photacatalysis with TiO₂ coated on borosilicate tubes was found to accelerate their degradation rate with complete decomposition. Concomitantly, kinetic experimental results showed a critical difference of performance for the two coating methods used; in particular, the degradation rates of pollutants by the sol-gel-coated tubes were much faster than the degradation by the nanoparticle/PECVD-coated tubes. Using TiO₂ supported on borosilicate tubes appears to be a promising alternative to conventional TiO₂ suspension and avoid post-separation stages. The results achieved in this study can be used to optimise large-scale applications, and expanding the study to cover a wide range of pollutants will lead to achieve more representative results.

Nowadays, most of mineral-based adsorbents are powder form, which makes them inconvenient to collect and always easy to cause secondary pollution. In this work, an organic rectorite composite nanofiber membrane (SRt-PAN) was designed and prepared by electrospinning technique. The as-received composite nanofiber membranes were characterized by XRD and SEM analysis, proving the homodisperse and existence of SRt in PAN nanofiber membrane. A series of batch experiments for BPA adsorption were carried out to investigate the effect of different adsorption parameters, including initial concentration, pH, and temperature of pollutant solution. The influences of modifier dosage and adsorbent dosage on the adsorption performance were investigated as well. On the basis of the experiment results, the adsorption process could be well described by the pseudo-second-order model and the Langmuir isotherm. In addition, the thermodynamic parameters indicate that this adsorption process is exothermic and spontaneous. Moreover, compared with pure nanofiber membranes and organic rectorite powders, the resultant SRt-PAN adsorbents exhibited higher adsorption capacity, superior reusability, and adsorption stability. It is indicated that the hydrophobicity surface of organic rectorite should be the key factor to not only the intimate interfacial combination between the mineral and PAN, but also the enhancement of BPA adsorption capacity.

Organic micropollutants in rivers are emitted via diffuse and point sources like from agricultural practice or wastewater treatment plants (WWTP). Extensive laboratory and field experiments have been conducted to understand emissions and fate of these pollutants in freshwaters. Nevertheless, data is often difficult to compare since common protocols for appropriate approaches are largely missing. Thus, interpretation of the observed changes in substance concentrations and of the underlying fate of these compounds downstream of the chemical input into the river is still challenging. To narrow this research gap, (1) process understanding and (2) measurement approaches for field-based investigations are critically reviewed in this article. The review includes, on the one hand, processes that change the volume of the water (hydrological processes) and, on the other hand, processes that affect the substance mass within the water (distribution and transformation). Environmental boundary conditions for the purpose of better comparability of different attenuation studies, as well as promising state-of-the-art measurement approaches from different disciplines, are presented. This overview helps to develop a tailored procedure to assess turnover mechanisms of organic micropollutants under field conditions. In this respect, further research needs to standardize interdisciplinary approaches to increase the informative value of collected data.

This study investigated the protective effects of melatonin (MLT), a potent antioxidant, in male Wistar rats exposed to environmentally relevant doses of bisphenol A (BPA) in utero. Pregnant Wistar rats were randomly assigned into five groups. Group 1 (control) received 0.2 mL 1% dimethyl sulfoxide (DMSO)/99% canola oil as vehicle; group 2 received BPA at 25 μg/kg/day; group 3 received BPA at 250 μg/kg/day; group 4 received BPA at 25 μg/kg/day with concurrent MLT 1 mg/kg/day while group 5 received BPA at 250 μg/kg/day with concurrent MLT 1 mg/kg/day. Treatments were by gavage from gestational day (GD) 10–21. The BPA-treated rats showed dose-dependent significant reduction in body weight, gonosomatic index, sperm motility, livability and count. Also, BPA caused significant reduction in the levels of serum testosterone and luteinizing hormone while it caused significant increases in the levels of follicle stimulating hormone as well as estradiol. Furthermore, BPA induced testicular oxidative stress including significant decreases in the activities of testicular SOD, GSH and GPx as well as GST, increasing the levels of testicular MDA and H₂O₂. It further induced interstitial necrosis and germinal cell degeneration in the testis with a subsequent diminution of the tubular and luminal diameter. However, co-treatment with MLT offered protection against testicular damage induced by BPA. Melatonin is likely to protect against alterations of the male reproductive system caused by BPA through a direct action on the mechanism of anti-oxidants as well as through the inhibition of necrosis.

Despite attempts to enhance the recycling of waste printed circuit boards (WPCBs), the simultaneous recovery of major metals of WPCBs using an efficient approach is still a great challenge. This study mainly concerned with applying an effective statistical tool to optimize the recovery of metal content (i.e., Cu, Fe, Zn, Pb, Ni, Sn, and Al) embedded in WPCBs using a leaching agent without any additive or oxidative agent. Another target was to optimize a multi-response recovery process by minimizing time, energy, and acid consumption during the leaching. Effective parameters and their levels, including leaching time (20–60 min), temperature (25–45 °C), solid to liquid (S/L) ratio (1/8–1/20 g/ml), and acid molarity (1–2.7 M), were optimized. A well-established statistical approach (i.e., response surface methodology (RSM)) was applied to precisely quantify and interpret the effects. General optimum conditions for nine responses were introduced with the desirability of ≈ 85%. Finally, the solid residue of leaching was characterized and results showed the morphology, structure, and composition of the residue content (i.e., polymers and ceramics) remained the same after the leaching, indicating the neutral behavior of the leaching process on these two materials. Also, thermal behavior and phase analysis of the original WPCBs and leaching residue were compared and analyzed. Graphical abstract

Organophosphate esters (OPEs), as re-emerging contaminants considered to be a potential health concern, are ubiquitous in the environment and have been widely investigated. However, little is known on the safe OPE concentrations in the water quality criteria for the protection of the aquatic environment, which is an indispensable part of environmental management. In the present study, aquatic acute and chronic predicted no-effect concentrations (PNECs) of six frequently detected OPEs were derived from the hazardous concentrations for 5% of species (HC₅s), respectively. The acute PNECs for the selected OPEs ranged from 17.70 to 3562 μg/L, while the chronic PNECs ranged from 4.6 × 10⁻⁴ to 61.85 μg/L. Among these OPEs, tricresyl phosphate (TCrP) exhibited the lowest acute PNEC, while tris(1,3-dichloro-2-propyl) phosphate (TDCPP) presented chronic PNEC, which indicated that it has a higher toxicity effect on the aquatic environment. Furthermore, the aquatic ecological risks of individual OPEs (except for TDCPP) were deemed to be relatively low in Chinese surface water; however, the aquatic ecological risks of TDCPP and ΣOPEs indicated that they have potential adverse effects and should be considered as a potential health concern. The probability of 5% of aquatic organisms being affected by ΣOPEs was in the range of 0.21 to 17.39% based on the joint probability curve method.

Highly porous biochar (BC) structures have been prepared from inexpensive biomasses like rice straw, bamboo, sugarcane waste, and corn cob via a slow pyrolysis technique in nitrogenous atmosphere. A surface engineering technique has been applied to enhance the surface-to-volume ratio of each biochar sample and finally compared its characteristics through standard surface and elemental characterization techniques, viz. CHN (carbon, hydrogen, and nitrogen), FTIR (Fourier transform infrared spectroscopy), BET (Brunauer–Emmett–Teller), and SEM (scanning electron microscopy). All the biochar samples were observed to be highly carbonized and aromatized. Exfoliated structures were found to contain more elemental carbon (34.14–77.32%) than its native form (30.92–74.46%). Aromatic hydrocarbon, aromatic C=C, aromatics, aliphatic C–O, aliphatic hydrocarbon, and H-bonded OH groups were found to predominate in the surface of biochar structures independent of their precursor composition and extent of exfoliation. SEM micrographic images clearly ensured about the unoriented sheets like the morphology of different biochar samples. Although no significant structural difference was found to exist depending on their precursor compositions, quantitative enhancement of porosity was found to be observed after exfoliation. Both native (240.65 m²/g) and exfoliated (712.89 m²/g) biochars derived from sugarcane wastes were observed to have a maximum surface area in comparison to the biochars derived from rice straw (native, 22.08 m²/g; exfoliated, 29.92 m²/g), bamboo (native, 42.08 m²/g; exfoliated, 248.38 m²/g), and corn cob (native, 136.62 m²/g; exfoliated, 221.71 m²/g). Exfoliated biochars were found to be consistently more potent in comparison to its native form as per our comparative characterizations performed so far.

Petroleum hydrocarbons are potentially toxic for organisms due to the inherent properties, such as solubility, volatility, and biodegradability. The petroleum materials released from corroded old pipelines would pollute soils, shallow groundwater and air as a consequence, and threat the health of human and environment. Therefore, the removal of these compounds from environment is vital. The stability of these pollutants at the soil and their gradual accumulation over time would disrupt the normal function of the soil, such as reduced agricultural capability. In this research, the influence of two plant species (Bromus tectorum L. and Festuca arundinacea) with different amendments including arbuscular mycorrhizal fungi, alfalfa residues, and nutrient solution on the degradation rate of petroleum hydrocarbons in soil was studied. The results showed that the most effective treatment for petroleum remediation was related to B. tectorum L. plant when treated with mycorrhizal fungi and nutrient solution. The degradation rate during 40 days was about 83.27% when compared to the control. Arbuscular mycorrhizal associations are important in the restoration of degraded ecosystems because of the benefits to their symbiotic partners. This fungal phytotechnological mechanism is still in its infancy and there has been little research on aged-contaminated soils.