Disadvantages associated with chemical coagulants and goal of sustainable development have shifted the focus to natural plant-based coagulants. Raw and defatted soybean (Glycine max L.) seed powder, as innovative and eco-friendly coagulant, was appraised in detail for turbid water treatment and compared with alum in this study. Design of experiments was conducted by employing response surface method which lacks in past studies pertaining to plant-based coagulants. Experiments were conducted with lab prepared turbid water with initial turbidity of 200 NTU and wide range of pH (2–10) and dose (20–100 mg/L). Results revealed that raw and defatted soybean gave residual turbidities of 4 and 3 NTU at optimum conditions which were comparable to alum. Analysis of variance (ANOVA) identified that pH was more significant parameter as compared with dose for soybean and alum, while interaction of pH and dose was most significant in case of defatted soybean. Characterization of the coagulants and flocs, by Fourier transform infrared (FTIR) spectroscopy and scanning electron microscope (SEM), revealed that postulated mechanism of coagulation for plant-based coagulants is adsorption and charge neutralization. Cost of treating 1000 m³ of water by raw and defatted soybean is lower (US$12 and US$3.9 respectively) compared with alum (US$31.2).

A biosurfactant (BS) is a surface-active metabolite that is secreted by microbial metabolism, and can be used as a substitute for chemically synthesized surfactants. The first and most critical step to the successful application of BSs is to isolate bacterial strains with strong BS-producing capabilities. In this study, a BS-producing Serratia marcescens ZCF25 was isolated from the sludge of an oil tanker. Through polyphasic characterization using Fourier-transform infrared spectroscopy, thin layer chromatography, and gas chromatography-mass spectrometry, the produced BS was classified as a lipopeptide; it can decrease the water surface tension from 72.0 to 29.50 mN m⁻¹ and has a critical micelle concentration of 220 mg/L. The BS showed a high tolerance over a wide range of pH (2–12), temperature (50–100 °C), and salinity (10–100 g/L). Furthermore, the inoculation of S. marcescens ZCF25 with fracturing flowback fluids could significantly (P < 0.05) reduce the chemical oxygen demand, concentration of alkanes, and concentration of polycyclic aromatic hydrocarbons, with removal efficiencies of 48.9%, 65.57%, and 64%, respectively. This is the first study on the application of BS-producing S. marcescens to treat fracturing flowback fluids. S. marcescens ZCF25 is a promising candidate for use in various industrial and bioremediation applications. Graphical abstract

The aim of this study is to examine the relationship between ecological footprint, economic growth, renewable energy consumption, and innovation within the framework of the environmental Kuznets curve (EKC) hypothesis for the top 10 innovative economies, namely, Denmark, Finland, Germany, Israel, Korea, The Netherlands, Sweden, Switzerland, the UK, and the USA, in the period of 1990–2015. For this purpose, the long-term relationship between variables was examined with a panel cointegration test. The results show that the variables in the EKC model move together in the long run. According to the long-run estimation results, the EKC hypothesis is valid for Israel, but not for the other countries. The study also makes the following observations: (i) For Korea, the USA, Finland, and the whole panel, innovation appears to reduce environmental pollution. (ii) Renewable energy consumption reduces environmental pollution for Denmark, Germany, The Netherlands, and the USA. (iii) Globalization has an impact on the reduction of environmental pollution for Germany and Switzerland. As a result, developing policies on the use of more innovative technologies in the countries studied will have a positive impact on environmental pollution. Graphical abstract

Synthetic dyes, generally resistant, toxic and carcinogenic presents a substantial risk to the environment and health of human. The present study was aimed to decolourize a dye mixture (Evans blue and brilliant green) by selected bacterial strains cultivated at different growth conditions (e.g. unmodified, correction of pH value and supplementation with nutrients). The bacterial strains used as pure and mixed cultures include facultative anaerobes Aeromonas hydrophila (Abs37), Citrobacter sp. (Cbs50) and obligatory aerobe Pseudomonas putida (Pzr3). The efficiency of removal of all successive doses of dye mixture (4–5 doses, total load 170–200 mg/l) was tested in static conditions in fed-batch bioreactors. The modification of bacteria growth conditions influenced on decolourization efficiency: most advantageous was pH value correction combined with nutrient supplementation then pH correction alone and nutrient supplementation (final removal results 95.6–100%, 92.9–100% and 89.1–97.2%, respectively). The mixed bacterial cultures removed the total load of dyes with higher efficiency than pure strains (final removal 95.2–100% and 84.0–98.2%, respectively). The best results were obtained for the mixture of facultative anaerobe Citrobacter sp. and obligatory aerobe Pseudomonas putida which removed the highest load of dye mixture (200 mg/l introduced at five doses) in the shortest time (288 h), while the others pure and mixed cultures needed 425–529 h for removal four doses of dye mixture (total load 170 mg/l). The zoo- and phytotoxicity decreased after these processes (from V class of toxicity (extremely toxic) even to II class (low toxicity)). The main mechanisms of decolourization was biotransformation/biodegradation, supported by sorption.

Based on the quasi-natural experiment of the establishment of the Yangtze River economic belt, this paper uses a difference-in-difference-in-differences model (DDD) to test the impact of regional integration on transboundary pollution. The results show that regional integration can significantly reduce transboundary water pollution. Regional integration reduces chemical oxygen demand (COD) by 0.357, ammonia nitrogen content (NH₃-N) by 0.155, and dissolved oxygen content (DO) by 0.088 in the downstream of the provincial boundary. And regional integration has a long-term inhibitory effect on transboundary pollution. The heterogeneity results show that the regional integration has a stronger inhibition effect on the transboundary pollution of the middle and lower reaches of the Yangtze River economic belt and the tributaries. At the government level, regional integration can reduce transboundary pollution by strengthening the government’s environmental regulation and collaborative governance. At the industry level, it can inhibit transboundary pollution by promoting industrial structure optimization and green technology innovation. At the market level, regional integration can promote market competition to reduce transboundary pollution and expand market scale to intensify transboundary pollution. At the society level, regional integration can intensify transboundary pollution by promoting population agglomeration and effectively alleviate transboundary pollution by enhancing public environmental supervision.

DEHP is a wildly used plasticizer. Maternal DEHP exposure induced fetal growth restriction (FGR) and behavioral abnormalities in adolescence and adulthood mouse. The effect of low birth weight induced by DEHP on behaviors after growing up is not certain. In this study, the ICR pregnant mice were exposed to 200 mg/kg DEHP during gestation 6–12 days or 13–17 days, which can create FGR model. The F1 offspring were performed three ethological experiments at puberty (6 weeks postpartum) and adult period (8 weeks postpartum). The open field test was performed to detect the locomotor activity and anxiety, the elevated plus maze to test anxiety-like behavior, and the Morris water maze assay to measure the spatial learning and memory capability of male and female offspring. The results showed that spatial memory ability was dramatically impaired for male rather than female offspring in gestation 13–17 days’ group. Other behaviors had no statistically different between groups. These findings suggest that prenatal DEHP exposure disturbed mouse offspring spatial memory ability in a phase- and gender-dependent manner.

In this study, several immobilized ionic liquid adsorbents on carbon materials were synthesized with impregnation method. The carrier materials were activated carbon and three kinds of multi-walled carbon nanotubes. And the synthetic adsorbents immobilized different kinds of ionic liquids were characterized by Boehm titration, FT-IR, XPS, TG, and BET analysis, respectively. Finally, carbon materials after [C4mim]HSO₄ immobilization were selected as adsorbent to remove Hg²⁺ from water phase. The optimum conditions of adsorption test of ionic liquid immobilized by multi-walled carbon nanotubes were as follows: the initial concentration of Hg²⁺ was 400 mg/L, the adsorbent addition amount was 40 mg, the temperature was 20 °C, the reaction time was 200 min, the removal rate of Hg²⁺ peaked at 62.95%, the adsorption capacity was reached 79.00 mg/g. The optimum conditions of adsorption test of ionic liquid immobilized by activated carbon were as follows: the initial concentration of Hg²⁺ was 300 mg/L, the adsorbent addition amount was 0.2 g, the temperature was 20 °C, pH was 2.0, the reaction time was 100 min, the removal rate of Hg²⁺ was more than 99%, the adsorption capacity was 118.65 mg/g. The adsorption isotherm fitting study found that the adsorption of adsorbent on Hg²⁺ was more in line with the Langmuir model, and the adsorption kinetics study shows that the adsorption process is consistent with the pseudo-second-order kinetic equation. The results of kinetic analysis are further verified by thermodynamic analysis.

Single-stage autotrophic nitrogen removal offers advantages of low energy and carbon consumptions. Based on previous work about a novel composite membrane aerated biofilm (CMAB), two microbial entrapping patterns (mixed and stratified patterns) were evaluated for their applicability to artificially regulate the spatial distribution of distinct microbial aggregates for single-stage autotrophic nitrogen removal. Experimental results showed that the stratified pattern caused little accumulation of NO₂⁻ and NO₃⁻, which leads to a superior nitrogen removal performance compared with the mixed pattern. Candidatus Kuenenia was found to be the major anammox bacterium in the gel film of the mixed pattern and the outer film of the stratified pattern. In contrast, Nitrosomonas, as a representative genus of ammonia-oxidizing bacteria, was substantially enriched in the inner film of the stratified pattern and the gel film of the mixed pattern. Finally, modeling results further confirmed the advantages of the stratified pattern with respect to the formation of rational microbial and nutrient profiles in gel films. The ratio of partial nitrification and anammox film thicknesses should remain below 3:2 to obtain a high fraction of anammox bacteria and to avoid NO₂⁻ accumulation. Increasing O₂ surface loading does not affect microbial profiles, but can greatly promote the TN removal performance only in the stratified pattern. Overall, the stratified pattern should be employed to achieve optimal microbial profiles and nitrogen removal efficiency.

Rapid growth of vehicles in Medan, Indonesia, is one of the causes in the increasing of air pollution, in which approximately 85% is contributed merely by vehicles. On the other hand, the use of lead-based fuel in motor vehicle increases the air contamination in Medan. This study aimed to obtain an accumulation of lead (Pb) in the thallus of lichens in mahogany trees in four different locations in Medan, Sumatera Utara, Indonesia, in which the lichens act as a bioindicator of air contamination as well as measuring the lichen’s lead correlation and traffic densities. Purposive sampling location was determined based on the traffic density level with different air pollutions; the location which was far from traffic circulation was used as the control. The analysis of Pb was conducted using atomic absorption spectrophotometry (AAS). The data were analyzed descriptively to discover and compare Pb accumulation between each location with different traffic density levels. The result showed that there were 11 species of 7 genera and 7 families with two types of the thallus (foliose and crustose) in mahogany trees. The traffic density level influenced the diversity of lichens as the traffic density was quite significant with the number of lichen types. The levels of Pb and traffic density correlated very significantly at the level of α = 0.01 for Parmelia saxatilis, Lepraria incana, and Pertusaria amara type, while Opegrapha atra had a significant correlation. The accumulation of Pb in the thallus of Pertusaria amara ranged from 5.23 to 15.07 μg/g, whereas medium in Lepraria incana ranged from 1.19 to 4.88 μg/g. Thus, Pertusaria amara which had greater Pb level than Lepraria incana had the potential as a resistant bioindicator. The correlation analysis of Pb levels and traffic density showed that Pertusaria amara had a significantly high correlation compared with Parmelia plumbea, Parmelia glabratula, and Graphis scripta. Furthermore, Lecanora conizaeoides was a tolerant bioindicator of air pollution whereas Parmelia saxatilis had the potential to be a tolerant bioindicator.

A BiVO₄-WO₃ nano-composite (NC) was hydrothermally prepared and characterized by different techniques including X-ray diffraction (XRD), scanning electron microscope equipped with an energy-dispersive X-ray (EDX) analyzer, X-ray mapping, UV-Vis reflectance spectroscopy (DRS), and photoluminescence spectroscopy (PL). The average crystallite size of 8.5 nm was estimated for the composite by the Williamson–Hall equation. The band gap energies of 2.46, 3.02, and 2.95 eV were obtained for the direct electronic transitions of BiVO₄, WO₃, and the composite, respectively. The point of zero charges (pHpzc) of the composite was also estimated at 5. The composite was then used in the photodegradation of sulfasalazine (SSZ). When the moles of WO₃ was four times greater than BiVO₄, the best photocatalytic activity and the lowest PL intensity were obtained. The simultaneous effects of the experimental variables on the boosted photocatalytic activity of the composite (to the single semiconductors) were studied by the response surface methodology (RSM). A significant quadratic model was confirmed for processing the data based on the F value of a model F value of 63.55 > F₀.₀₅, ₁₄, ₁₃ = 2.55. This was also confirmed by LOF F value of 2.56 < F₀.₀₅, ₁₀, ₃ = 8.79. Besides, the multiple correlation coefficients R² (R² = 0.9856), adjusted R² (adj-R² = 0.9701), and predicted R² (pred-R² = 0.9098) confirm the goodness of the model. The optimal run included CSSZ 9 mg/L, pH 4, 40 min irradiation time, and 0.8 g/L of the composite under the visible light irradiation.