We investigated the treatment efficiency of micro-polluted NO₃⁻-dominated river water with low C/N ratio by five parallel pilot-scale IVCWs with different plant and substrate collocation. When the mean concentration was 2.24 and 0.193 mg L⁻¹ in influent, IVCWs achieved an average (mass) removal rate of (0.09 g m⁻² day⁻¹) 46.8% and (0.77 g m⁻² day⁻¹) 62.3% for TN and TP, respectively, during 1 year of operation. Water quality was significantly improved from grade V to meet the criterion of grade IV of surface water. Through the comparison of removal rate by different IVCWs, we found that lack of carbon sources in influent limited the denitrification in the middle and bottom layers (ML, BL) of IVCW. Zeolites deployed in the upper layer (UL) of IVCW reduced the overall N removal efficiency compared with gravels, due to a stronger nitrification but weaker denitrification. Canna indica (C. indica) was superior to Arundo donax (A. donax) and Thalia dealbata (T. dealbata) for N removal in the UL of IVCW due to higher aboveground biomass accumulation and microbial removal during the first 10 months. Stronger nitrification and denitrification were simultaneously facilitated near the rhizosphere of C. indica. When entered into Dec., A. donax performed higher N removal efficiency than the other two species. The internal replenishment of peats in the ML as carbon sources significantly improved N and P removal efficiency. Zeolites with stronger capacity of ammonium (NH₄⁺) adsorption was more in favor of anammox in the BL, when compared with roseites, but both of them were not conducive to the growth of denitrifiers. However, the deployment of shale ceramisites obtained an opposite result. Gemmata and Pirellula as anammox bacteria were more enriched in the zeolite layer, whereas some anaerobic denitrifiers (Corynebacterium and Paludibacter) and heterotrophic denitrifiers including Bacillus, Geobacter, Pseudomonas, and Lactococcus were more found in shale ceramisite. Supply of peats as carbon sources in the ML was beneficial for the adhesion of anammox bacteria and denitrifiers in the BL of shale ceramisites. An ideal model composed of C. indica + A. donax (DFU)-gravel (UL)-anthracite+peat (ML)-zeolite+shale ceramsite (BL)-Acorus calamus (UFU) was proposed for treating this type of river water to achieve high efficiency.

Long-distance inter-basin water transfer solves the problem of unbalanced water resources in different regions. However, it also changes the natural water chemistry characteristics as well as the bioavailability of heavy metals in the receiving water. In this study, taking the South-to-North Water Transfer Project in China as an example, the basic physicochemical characteristics of the source water (in the Danjiangkou (DJK) Reservoir) and receiving water (in the Beitang (BT) Reservoir) were studied. The BLM (biotic ligand model) was used to study the effect of long-distance inter-basin water transfer on the bioavailability of Cu in receiving waters. The results showed that the TOC (total organic carbon) and TDS (total dissolved solids) in the BT Reservoir water were 10 times and 4.6 times greater than those of the DJK Reservoir water, respectively. The ions in the BT Reservoir were mainly (K⁺+Na⁺)–(SO₄²⁻+CI⁻), while the ions in the DJK Reservoir were mainly (Ca²⁺+Mg²⁺)–HCO₃⁻. The results from the BLM showed that the main species of Cu in the water was total organic Cu (Torg Cu), which accounted for 98.69% and 99.77% of the Cu in the DJK Reservoir and BT Reservoir, respectively. The LC50 of Cu for Daphnia magna was 1203.40 ± 57.70 μg/l in the BT Reservoir and only 101.93 ± 7.60 μg/l in the DJK Reservoir. The criteria maximum concentration value of the BT Reservoir was 13.75 times that of the DJK Reservoir, while the criteria continuous concentration value of the BT Reservoir was 13.76 times that of the DJK Reservoir. These results showed that the heavy metals content in water bodies should not be used as the only consideration for water ecological security in the inter-basin water transfer process, and that differences in water quality criteria values caused by differing water environmental qualities in the river basins must be taken into consideration.

Heavy metal lead poses a great threat to organisms and the environment; the removal of lead has drawn more and more attention in recent years. In this paper, the sulfur-containing functional group was grafted onto the walnut shell with xanthate to synthesize a low-cost biosorbent (SWM) for the removal of lead in water. The synthesized adsorbent was characterized by Fourier-transform infrared spectroscopy (FT-IR), X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM), and Brunner−Emmet−Teller (BET). The effects of pH, adsorbent dosage, contact time, initial Pb (II) concentration, and temperature on adsorption were investigated, and the adsorption properties of walnut shells before and after modification were compared. Moreover, adsorption kinetics, adsorption isotherms, and adsorption thermodynamics were studied. The sulfur-containing functional group was confirmed to be successfully grafted onto the walnut shell. The results showed that the adsorption performance of SWM was much better than the unmodified walnut shell due to complexation by sulfur-containing functional group and ion exchange. The Pb (II) adsorption onto SWM was found to follow Temkin isotherm model and has a good correlation with the pseudo-second-order kinetic model. In addition, the adsorption process was spontaneous and exothermic. All the results showed that the high adsorption performance and low cost of SWM make it a potential biosorbent in the treatment of lead-contaminated water.

In this study, the content of U, Th, Pb, V, Rb, and Ag in 19 soil samples from unpolluted Goč Mountain area (Serbia) was determined. The same elements were determined in 19 Macrolepiota procera samples, separately for caps and stipes. Soil samples were subjected to the BCR sequential extraction procedure. Element contents were determined by inductively coupled plasma mass spectrometry (ICP-MS). Obtained soil values for U were in the range from 0.30 to 0.86 mg/kg and for Th from 1.7 to 13.2 mg/kg. These values are the first for background levels at unpolluted Goč area, and they are lower than the corresponding values for European unpolluted soil. The mean values in soil for Pb, V, Rb, and Ag were 27.6, 57.4, 15.8, and 0.76 mg/kg, respectively. PCA was applied to establish criteria for translocation of the analyzed elements between two parts of the mushroom. Efficient translocation for all elements except Ag as the main amount of the elements was found in caps. The mean content in the caps for U and Th was 4.3 and 63 μg/kg, respectively. Bioconcentration factors were much higher than 1 only for Rb and Ag. M. procera only weakly accumulates U and Th from soil in unpolluted areas. These findings indicate limited role of M. procera in the mycoremediation of the mentioned actinides.

To study the impact of leachate recirculation frequency on the transformation of carbon and nitrogen pollutants in a semi-aerobic bioreactor landfill (SABL), three laboratory-scale SABLs were investigated, each using a different leachate recirculation frequency (daily, once each 3 days, and once each 5 days). Results showed that degradation of total nitrogen (TN), ammonium nitrogen (NH₄⁺-N), chemical oxygen demand (COD), and total organic carbon (TOC) could be described using a quadratic polynomial-compound index model. Degradation rates of TN, NH₄⁺-N, COD, and TOC slightly increased from 0.01795, 0.01814, 0.01451, and 0.01166 day⁻¹ to 0.02054, 0.01903, 0.01488, and 0.01203 day⁻¹, respectively, when the recirculation frequency increased from once per 5 days to once per 3 days. When recirculation frequency was increased to daily, degradation rates of TN, NH₄⁺-N, COD, and TOC significantly increased to 0.03698, 0.02718, 0.02479, and 0.02872 day⁻¹, respectively. Moreover, when recirculation frequency increased from once per 5 days to once per 3 days, the gasification rate of nitrogenous and carbonaceous pollutants was enhanced between 20.38 and 8.17%, respectively. When the leachate recirculation rate further increased to daily, only a small amount of carbonaceous and nitrogenous pollutants was transformed to the liquid phase. Thus, increasing the leachate recirculation frequency in an SABL benefits the removal of carbonaceous and nitrogenous pollutants from the reactor. In addition, the greater is the recirculation frequency, the lower is the residual carbon and nitrogen in the solid phase, and the higher is the gasification rate. A proper recirculation frequency promotes the stabilization of landfill leachate. This study provides a theoretical reference and experimental evidence for accelerating the stabilization of MSW and contributes to the macro-control of landfills.

Polycyclic aromatic hydrocarbons (PAHs), polychlorinated biphenyls (PCBs) and organochlorine pesticides (OCPs) are ubiquitous and toxic contaminants. Their atmospheric deposition fluxes on the regional scale were quantified based on simultaneous sampling during 1 to 5 years at 1 to 6 background/rural sites in the Czech Republic and Austria. The samples were extracted and analysed by means of gas chromatography coupled to mass spectrometry. For all seasons and sites, total deposition fluxes for Σ₁₅PAHs ranged 23–1100 ng m⁻² d⁻¹, while those for Σ6PCBs and Σ12OCPs ranged 64–4400 and 410–7800 pg m⁻² d⁻¹, respectively. Fluoranthene and pyrene were the main contributors to the PAH deposition fluxes, accounting on average for 19% each, while deposition fluxes of PCBs and OCPs were dominated by PCB153 (26%) and γ-hexachlorobenzene (30%), respectively. The highest deposition flux of Σ₁₅PAHs was generally found in spring, while no seasonality was found for PCB deposition. For deposition fluxes for Σ₁₂OCPs, no clear spatial trend was found, confirming the perception of long-lived regional pollutants. Although most OCPs and PCBs hardly partition to the particulate phase in ambient air, on average, 42% of their deposition fluxes were found on filters, confirming the perception that particle deposition is more efficient than dry gaseous deposition. Due to methodological constraints, fluxes derived from bulk deposition samplers should be understood as lower estimates, in particular with regard to those substances which in ambient aerosols mostly partition to the particulate phase.

The objective of this research is to examine the effects of stock market on air pollution in Malaysia during the period 1980–2017. To realize this aim, a nonlinear autoregressive distributed lag (ARDL) model is constructed. The short results in general revealed that the increase in stock markets will increase CO₂ emissions and its significance increases in the long run. Moreover, the decline in stock market will reduce Malaysia’s CO₂ emissions but only in the long run. From the outcomes obtained, a number of policy recommendations were provided for the investigated country.

It was the aim of this work to evaluate the adsorptive performance of the biochar obtained from the gasification of wood residues onto a solution of Indosol Black NF1200 dye. The study was performed by means of factorial design 2², having as control variables: pH and adsorbent’s granulometry. Batch tests were carried out at 200 rpm for 3 h (T = 28 °C). As output variable, the percentage removal of dye was determined. The best operating conditions were pH = 2 and 100 mesh granulometry. Also, adsorbent dosage studies were carried out, as well as equilibrium and adsorption kinetics. Both kinetics and equilibrium of adsorption tests were proceeded in basic and acid medium. For a basic pH value (pH = 12), it was concluded the equilibrium was reached in about 3 h of experiment, the experimental qₘₐₓ value was near 12 mg g⁻¹, and the equilibrium data fitted the Langmuir model. On the other hand, for tests with pH = 2, the equilibrium was reached after 5 min of experiment, the experimental qₘₐₓ value was over 185 mg g⁻¹, and the equilibrium data fitted both the Langmuir and Freundlich models. Thus, the biochar produced via gasification of wood wastes appears to be a promising adsorbent for the removal of azo dyes from textile wastewater, especially when working at lower pH values. Also, for a 10-kg/h consumption of wood residue, approximately 10 kW of energy is generated and 1 kg of biochar is produced, which represents another advantage from the environmentally friendly point of view. Graphical abstract

In this study, health risk of human exposure to organohalogenated pollutants (OHPs) through milk consumption was determined. Conventionally produced, unprocessed cow’s milk samples taken from Konya District, in Turkey, and 15 different brand ultra-high-temperature (UHT) processed cow’s milk samples taken from supermarkets of Turkey were analyzed for organochlorine pesticides (OCPs, α-, β-, γ-, and δ-HCHs, p,p’-DDE, p,p’-DDD, and p,p’-DDT, heptachlor, heptachlor epoxide, endosulfan I, endosulfan II, endosulfan sulfate, endrin, endrin aldehyde, endrin ketone, aldrin + dieldrin, methoxychlor), polychlorinated biphenyls (PCBs, PCB 28, 52, 101, 153, 138, and 180), and polybrominated diphenyl ethers (PBDEs, PBDE 47, 99, 100, 153, and 154 congeners). Estimated daily intake (EDI) values calculated for both adults and children consuming raw or UHT milk were determined to exceed maximum residue limits (MRLs) set for γ-HCH, ∑Heptachlor, and endrin. EDI values also exceeded admissible daily intake (ADI) values given for ∑HCH, ∑Heptachlor, ∑Endrin aldrin + dieldrin, and ∑PCBs. p,p’-DDT/p,p’-DDE ratio was 1 or higher for 66% of the milk samples, which is an indication of sustaining illegal use of DDT. A health risk is determined for dietary intake of OHPs via consumption of milk.

Since anaerobic wastewater treatment is a nonlinear and complex biochemical process, reasonable monitoring and control are needed to keep it operating stably and efficiently. In this paper, a least-square support-vector machine (LS-SVM) was employed to construct models for the prediction of effluent chemical oxygen demand (COD) in an anaerobic wastewater treatment system. The result revealed that the performance of the steady-state model based on LS-SVM for predicting effluent COD was acceptable, with the maximum relative error (RE) of 11.45%, the mean average percentage error (MAPE) of 0.79% and the root mean square error (RMSE) of 3.08 when training, and the performance fell slightly when testing. Even though, the correlation coefficient value (R) between the predicted value and the actual value of 0.9752 could be achieved, which means this model can predict the variation of effluent COD in general. The dynamic-state models under three kinds of shock loads, which were concentration, hydraulic, and bicarbonate buffer absent, showed good forecasting performance, the correlation coefficient values (R) all excelled 0.99. Among these three shocks, the dynamic LS-SVM model under bicarbonate buffer absent shock achieved the optimal performance and followed by the dynamic-state model under hydraulic shock. This paper provides a meaningful reference to improve the monitoring level of the anaerobic wastewater treatment process.