The degradation of organic contaminants in actual textile wastewater was carried out by iron carbon (Fe-C) micro-electrolysis. Different Fe-C micro-electrolysis systems (SIPA and SISA) were established by using scrap iron particle (SIP) and scrap iron shaving (SIS) as anode materials. The optimal condition of both systems was obtained at the initial pH of 3.0, dosage of 30 g/L and Fe/C mass ratio of 1:1. Commercial spherical Fe-C micro-electrolysis material (SFC) was used for comparison under the same condition. The results indicated that total organic carbon (TOC) and chroma removal efficiencies of SIPA and SISA were superior to that of SFC. Total iron concentration in solution and XRD analysis of electrode materials revealed that the former showed relatively high iron corrosion intensity and the physicochemical properties of scrap iron indeed affected the treatment capability. The UV-vis and 3DEEM analysis suggested that the pollutants degradation was mainly attributed to the combination of reduction and oxidation. Furthermore, the potential degradation pathways of actual textile wastewater were illustrated through the GC-MS analysis. Massive dyes, aliphatic acids, and textile auxiliaries were effectively degraded, and the SIPA and SISA exhibited higher performance on the degradation of benzene ring and dechlorination than that by SFC. In addition, SIPA and SISA exhibited high stability and excellent reusability at low cost. Graphical abstract

In light of growing concern and insufficient knowledge on the negative impact of aircraft emissions on environmental health, this study strives to investigate the air burden of major and trace elements caused by general aviation, piston-engine, and turboprop aircraft, within the vicinity of Eskisehir Hasan Polatkan Airport (Eskisehir, Turkey). The levels of 57 elements were investigated, based on moss bag biomonitoring using Sphagnum sp., along with chemical analyses of lubrication oil and aviation gasoline fuel used in the aircraft’s operations. Five sampling sites were selected within the vicinity of the airport area to capture spatial changes in the concentration of airborne elements. The study demonstrates that moss bag biomonitoring is a useful tool in the identification of differences in the air burden by major and trace elements that have concentrated downwind of the aircraft emission sources. Moreover, pollutant enrichment in the Sphagnum moss bags and elemental characterization of oil/fuel are in agreement suggesting that Pb, followed by Cd, Cu, Mo, Cr, Ni, Fe, Si, Zn, Na, P, Ca, Mg, and Al are dominant elements that shaped the general aviation aircraft emissions.

This paper deals with the adsorption of an anionic dye, Eriochrome Black T (EBT), from aqueous solutions onto sawdust, which is a natural, eco-friendly, widespread, and a low-cost bio sorbent. The aim of the work is to append values to the wood industry waste. Thus, sawdust was used as adsorbent in both batch reactor (BR) and fixed bed column (FBC), and various operating parameters influencing the adsorption process were investigated. The kinetic and the equilibrium adsorption results were found to agree with, respectively, the prediction of the pseudo-second-order equation and the Langmuir model. This latter allowed also the determination of the maximum EBT dye adsorbed amount, which was found to be about 40.96 mg EBT per gram of sawdust at pH = 4, corresponding to % dye removal of about 80%. In addition, the influence of various parameters on the dye adsorption, such as the adsorbent dose, the aqueous phase pH, and the initial dye concentration, was also examined. In batch experiments, The EBT adsorbed amount was found to increase either by increasing the amount of sawdust or by decreasing the aqueous phase pH, whereas, in the fixed bed column, the EBT retention was found to increase by decreasing the flow rate of the dye through the column. The overall data indicate that the EBT adsorption is mainly governed by the electrostatic interactions occurring between the adsorbent material and the dye.

The quantity, intensity, and quality of urban stormwater runoff are changing as a consequence of urbanization and climate change. Low impact development (LID) techniques (e.g., bioretention systems) are emerging to manage runoff quantity and quality. Street tree pits were used as bioretention units in Montreal, Canada. The concentration and mass flux of contaminants (Na, Cr, Ni, Cu, Zn, Cd, Pb) and dissolved organic carbon (DOC) were measured in soil solution samples from the tree pits. The soil organic matter (SOM) and the permeability of the area nearby the tree pit (sidewalk and front lawn) were tested. The SOM did not affect contaminant concentrations. However, tree pits with higher SOM reduced the mass flux of contaminants more than tree pits with lower SOM. Sidewalk permeability decreased the concentration and mass flux of contaminants observed (e.g., Na and Cr). The estimated water flux in the open part of the tree pit changed from 6.15 to 1.64 mm week⁻¹ from the less permeable units (absence of lawn + impermeable sidewalk) to the more permeable units (presence of lawn + permeable sidewalk). Urban runoff quality and quantity were locally affected by the tree pits. This indicates that the increase in surface permeability and SOM in street tree pits is advisable. Street tree pits have the potential as bioretention units to locally mitigate some of the impacts of urbanization. City planners could consider the use of street tree pits as bioretention units to help the management of urban runoff.

This study investigated the growth-dependent role of algal organic matters (AOMs) to achieve high removal efficiency (R.E) of microalgae. The results showed that the microalgae cells produced 96 ± 2% of total AOMs as loose bound AOMSS (LB-AOMs) and 4 ± 1% as cell-bound (CB-AOMs) in exponential phase. In stationary phase, LB-AOMs and CB-AOMs were 46 ± 0.7percentage and 54 ± 0.2 percentage, respectively. The R.Es in exponential and stationary phase were 83 ± 2.6% and 66 ± 1.2%, respectively. It is found that the difference of biomass concentration (between exponential and stationary phase) had no significant impact on the R.E (P > 0.01). Further investigations revealed that LB-AOMs inhibit flocculation in exponential and CB-AOMs in stationary phase; however, CB-AOMs showed stronger inhibition than the LB-AOMs (P < 0.01). The provision of calcium (17 ± 0.9 mg/L) to the culture reduced the AOMs inhibition and improved the R.E from 66 ± 1.2% (in control) to 90 ± 4.2%. An increase in R.E was attributed to the interaction of calcium with AOMs and subsequently acting as a flocculant. The findings of this study can be valuable to improve the performance of auto-flocculation technology, which is mainly limited by the presence of AOMs. Graphical Abstract

The denitrifying anaerobic methane oxidation (DAMO) process can achieve methane oxidation and denitrification at the same time by using nitrate or nitrite as an electron acceptor. The short- and long-term effects of nitrite on DAMO organisms were studied from macro (such as denitrification) to micro (such as microbial structure and community) based on two types of DAMO microbial systems. The results showed that the inhibitory effects of nitrite on the two DAMO microbial systems increased with rising concentration and prolonged time. In the short-term inhibitory phase, nitrite with concentrations below 100 mg N L⁻¹ did not inhibit the two distinct DAMO enrichments. When nitrite concentration was increased to 950 mg N L⁻¹, the nitrogen removal performance was completely inhibited. However, in the long-term inhibition experiment, when nitrite concentration was increased to 650 mg N L⁻¹, the nitrogen removal performance was completely inhibited. In addition, in acidic conditions, the real inhibitor of nitrite is FNA (free nitrous acid), while in alkaline conditions, the real inhibitor is the ionized form of nitrite. By using high-throughput sequencing technology, the species abundance and diversity of the two DAMO microbial systems showed an apparent decrease after long-term inhibition, and the community structure also changed significantly. For the enrichment culture dominated by DAMO bacteria, the substantial drop of Methylomonas may be the internal cause of the decreased nitrogen removal rate, and for the coexistence system that hosted both DAMO bacteria and archaea, the reduction of Nitrospirae may be an internal reason for the decline of the denitrification rate.

In this study, a novel Fe–Mn–Ce oxide-modified biochar composite (FMCBC) was synthesized via pyrolysis to enhance the adsorption capacity of biochar (BC). Scanning electron microscopy-energy-dispersive X-ray spectroscopy confirmed that Fe, Mn, and Ce were successfully loaded onto the surface of the BC. A series of adsorption experiments showed that the FMCBC exhibited improved adsorption of As(III) in an aqueous environment. The adsorption process was well expressed by the pseudo-second-order kinetic model. The adsorption capacity of FMCBC reached 8.74 mg L⁻¹, which was 3.27 times greater than that of BC. The pH of the solution significantly influenced the adsorption of As(III), where the amount of As(III) adsorbed by FMCBC was maximized at pH 3. A high phosphate concentration inhibited adsorption, whereas nitrate and sulfate ions promoted As(III) adsorption and increased the FMCBC adsorption capacity. Similarly, with increasing humic acid concentration, the adsorption capacity of FMCBC for As(III) decreased; however, a low concentration of humic acid promoted adsorption. X-ray photoelectron spectroscopy analysis revealed that the adsorption of As(III) by FMCBC occurred through redox and surface complexation reactions. Therefore, FMCBC has excellent potential for purifying arsenic-contaminated water.

The present study was aimed to reveal the effect of cadmium (Cd)-polluted soil on the activation of antioxidant enzymes, photosynthesis, pigments, water relation, and other biochemical traits and comparative effect of synthetic and organic chelators. A pot experiment was conducted using two maize varieties grown in Cd-contaminated (15 and 30 mg kg⁻¹) soil and chelators (1 mM EDTA, and 1 mM citric acid). Cd decreased biomass and photosynthetic traits while increased malondialdehyde (MDA) contents, total proteins, and antioxidant enzyme activities. Addition of EDTA enhanced Cd uptake, antioxidative enzyme, and total proteins; however, it reduced the water, osmotic, and turgor potential as compared to Cd alone. Addition of citric acid has lessened the antioxidant enzyme activities and MDA contents and enhanced the plant biomass as compared to Cd alone. Increases in antioxidants and MDA content were found to be positively related to the Cd contents in shoot and root. The application of citric acid significantly alleviated the Cd-induced toxic effects, showing remarkable improvement in biomass. These results indicated that EDTA was more effective for mobilizing Cd from soil to the root and shoot than citric acid; however, the physiological traits and plant biomass were more strongly inhibited by EDTA than by the Cd. Our study implies that citric acid ameliorated the negative effect of Cd on physiological traits and biomass, and hence could be used effectively for Cd phytoextraction.

Phytoplankton assemblages were investigated in 2015 along the seasonal changes of the Genhe River in the Greater Hinggan Mountains. The survey was performed in June (spring), August (summer), and October (autumn) at nine sampling stations to study the community composition, abundance, and biodiversity. The results showed that 61 species belonging to 16 genera were identified, including Bacillariophyta of 31 species, Dinophyta 2 species, Cyanophyta 2 species, Chlorophyta 20 species, Chrysophyta 2 species, and Cryptophyta 1 species; Besides, Bacillariophyta are dominant species. Shannon-Wiener (H′) and Pielou (J′) indices indicated that phytoplankton community was stable. And these two indices were significantly lower in summer than in spring and autumn. Phytoplankton abundance and biomass show significant differences in each season. The total phytoplankton abundance (1122.3 × 104 ind/L) and biomass (6.5709 mg/L) in summer are much higher than that in spring and autumn. There were few species and low abundance and biomass in the upper reaches of Genhe River; this fact can be explained by the cold climate in the Greater Higgnan Mountains region. Canonical correspondence analysis (CCA) was used to analyze the data. It revealed that Fe³⁺, Cu²⁺, pH, and water temperature (WT) were responsible for most of the variation in space in the phytoplankton community. These environmental parameters play an essential role in the community structure variation of phytoplankton in the upper reaches of Genhe River, the strong association between phytoplankton community structure and ecological factors is varied in each season.

In this study, some different selected plant leaves grown in Jordan such as Citrus limon (Rutaceae), Ceratonia siliqua L., Olea europaea (Oleaceae), Washingtonia filifera, and Myoporum (Myoporaceae) were examined for removal of copper (Cu) and zinc (Zn) ions from aqueous solutions. Cu and Zn were analyzed by atomic absorption spectrometry. A pH S-2 acidometer was used for determining the acidity of leaves solution system. Our findings showed the plants leaves were relatively efficient for removal of Cu and Zn compared to activated carbon. Removal of a 5 mg/L aqueous metal solution of Cu and Zn was treated with 2.5 g oven-dried plant in a 50 mL deionized water. The removal of Cu and Zn was expressed in terms of a time function ranged between 0 and 192 hours of contact time. The uptake of Cu and Zn by plant leaves was arranged in the following order:(i)Cu: Activated carbon > Washingtonia filifera > Ceratonia siliqua L. > Olea europaea (Oleaceae) > Myoporum (Myoporaceae) > Citrus limon (Rutaceae)(ii)Zn: Activated carbon > Olea europaea (Oleaceae) > Citrus limon (Rutaceae) > Ceratonia siliqua L. > Washingtonia filifera > Myoporum (Myoporaceae)