The present research investigates potential of microalgae isolated from sewage treatment plant to utilize sodium bicarbonate as carbon source for CO₂ sequestration and biodiesel production. Eight algal isolates were isolated from waste water of sewage treatment plant, Amity University Haryana, India. The most potent algal isolates were identified and characterized on the basis of growth and lipid content. The efficient isolates ASW1 and ASW2 were identified as Chlorella sp. and Arthronema sp. by 18srRNA and 16srRNA sequencing method. In both isolates, maximum growth was observed under 20-W fluorescent bulb (3500 flux light intensity) with continuous light cycle of 24 h at pH 9.0 and 25 °C on the 20th day of incubation period. CO₂ utilization efficiency of both algal isolates were observed in terms of total CO₂ consumption rate. Under optimized culture conditions, total lipid content and lipid yield was higher in Arthronema sp. (180 mg l⁻¹; 32.14%) as compared to Chlorella sp. (98 mg l⁻¹; 29.6%) in 50 mM NaHCO₃. Transesterified lipids were analysed by GC-MS. The fatty acid methyl ester profile of Arthronema sp. was 34.42% saturated and 65.58% unsaturated fatty acid. Chlorella sp. produces 29.80% saturated and 70.20% unsaturated fatty acid. In both isolates, C16 and C18 fatty acids dominated, which is a promising component for biodiesel. Graphical abstract

Atmospheric particulate matter has become a major issue in urban areas from both a health and an environmental perspective. In this context, biomonitoring methods are a potential complement to classical monitoring methods like impactor samplers, being spatially limited due to higher costs. Monitoring using spider webs is compared with the more common moss bag technique in this study, focusing on mass fractions and ratios of elements and the applicability for source identification. Spider webs and moss bags with Hypnum cupressiforme were sampled at the same 15 locations with different types of traffic in the city of Jena, Germany. In the samples, mass fractions of 35 elements, mainly trace metals, were determined using inductively coupled plasma-optical emission spectroscopy (ICP-OES) and inductively coupled plasma-mass spectrometry (ICP-MS) after aqua regia digestion. Significantly higher mass fractions in spider webs than in moss bags were found, even after a much shorter exposure period, and could not be ascribed completely to a diluting effect by the biological material in the samples. Different mechanisms of particle retention by the two materials are therefore assumed. More significant correlations between elements have been found for the spider web dataset. Those patterns allow for an identification of different sources of particulate matter (e.g. geogenic dust, brake wear), while correlations between elements in the moss bags show a rather general anthropogenic influence. Therefore, it is recommended to use spider webs for the short-term detection of local sources while moss bag biomonitoring is a good tool to show a broader, long-term anthropogenic influence.

Organic sorbents alter physicochemical soil properties and mitigate heavy metal (HM) bioavailability. However, some sorbents are labile and, therefore, introduce the risk of HM release into soil after mineralisation. Before field application, new stable organic sorbents such as woodchip biochar (BIO) and brown coal waste (BCW) need to be tested and compared with standard organic amendments like farmyard manure (FYM). An incubated pot experiment was conducted to investigate the efficacy of FYM, BIO and BCW (added to soil in pots at 5 and 10% w/w) to alter soil physicochemical properties and mitigate bioavailability of Cd, Pb and Zn spiked in treatments at different doses (in mg kg⁻¹); 0 (not spiked), 1 (1 Cd, 70 Pb, 100 Zn) and 2 (3 Cd, 500 Pb, 700 Zn), and incubated for 9 weeks. At the end of the experiment, the EDTA-extractable HM fractions, pH, cation exchange capacity (CEC) and specific surface area (SSA, to check trends) were determined in all treated soils. Results showed that FYM, BCW and BIO generally improved all soil properties (except reduced pH from BCW and apparent SSA reduction from FYM) and accounted for respective maximum abatements of Cd (50.2, 69.9 and 25.5%), Pb (34.2, 64.3 and 17.4%) and Zn (14.9, 17.7 and 11.8%) bioavailability in soil. FYM and BCW were more effective at 10% w/w especially in the low contaminated soil, whereas the highest efficacy for BIO was at 5% w/w and in the high contaminated soil. The efficacies of sorption by the organic sorbents varied for different HMs and were in the orders: BCW > FYM > BIO for Cd, FYM > BCW > BIO for Pb and BIO > BCW > FYM for Zn. Soil pH and CEC were strongly correlated with HM bioavailability in all treatments and implied that immobilisation of HMs occurred via complex formation, ion exchange and pH-dependent specific adsorption. All three sorbents were beneficial as soil amendments, and in terms of HM mitigation, BCW had the highest efficacy, followed by FYM and then BIO. Considering the documented high soil stability of BCW and BIO, these results are promising for further trialling at field scale.

Frequent heavy air pollution occurred during the winter heating season of northern China. In this study, PM₂.₅ (particles with an aerodynamic diameter less than 2.5 μm) was collected from a coastal city of China during the winter heating season from January 1 to March 31, 2018, and the soluble ions, organic carbon (OC), elemental carbon (EC), bacterial, endotoxin, and fungal concentration in PM₂.₅ were analyzed. During the winter heating season, PM₂.₅ and bioaerosols increased on polluted days, and the secondary inorganic ions, including NO₃⁻, NH₄⁺, and SO₄²⁻, increased significantly. Meteorological factors, such as wind direction and wind speed, had major impacts on the distributions of PM₂.₅ and bioaerosols. Pollutant concentration was high when there was a westerly wind with the speed of 3–6 m/s from inland area. Using the air mass backward trajectories and principal component analysis, we elucidate the potential origins of bioaerosol in PM₂.₅. The backward trajectory suggested that air mass for polluted samples (PM₂.₅ > 75 μg/m³) commonly originated from continent (9.62%), whereas air masses for clean samples (PM₂.₅ < 35 μg/m³) were mainly from marine (56.73%). The interregional transport of pollutants from continental area contributed most to PM₂.₅. Principal component analysis of the water-soluble ions and bioaerosol indicated that air pollution of the coastal city was greatly affected by coal combustion, biomass burning, and regional transmission of high-intensity pollutants from continent. Among that, interregional transport, biomass burning, and dust from soil and plants were main sources of bioaerosol. Our findings provide important insights into the origins and characteristics of bioaerosol in PM₂.₅ during the winter heating season of the coastal city in northern China.

Magnetic NiₓMgyZn₍₁₋ₓ₋y₎Fe₂O₄ nanoparticles were fabricated via the ethanol-assisted combustion process. The characterizations of the nanoparticles were illuminated by SEM, EDS, XRD, and VSM. The specific surface area and pore diameter distribution were measured by the Brunauer–Emmett–Teller (BET) measurement. Magnetic Ni₀.₄Mg₀.₃Zn₀.₃Fe₂O₄ nanoparticles calcined at 400 °C for 2 h with anhydrous ethanol of 20 mL were chosen to remove methyl blue (MB), and their adsorption performances for removal of MB from water environment were evaluated. Adsorption kinetics and adsorption isotherm experiments had been carried out; the adsorption mechanisms were well demonstrated by the pseudo-second-order kinetics model and Temkin isotherm model, respectively, which indicated that the removal of MB by Ni₀.₄Mg₀.₃Zn₀.₃Fe₂O₄ adsorbent was multimolecular layer chemisorption mechanism. The pH effect of the dye solutions was explored to reveal that the adsorption capacity remained a solidly high level when pH was above 5. After three times of recycling, the relative removal activity of MB onto the nanoparticles remained above 97.6% of its original removal activity. The adsorption process of MB removed by Ni₀.₄Mg₀.₃Zn₀.₃Fe₂O₄ adsorbent was further illuminated by cyclic voltammetry (CV) and electrochemical impedance spectra (EIS). Graphical Abstract Magnetic Ni₀.₄Mg₀.₃Zn₀.₃Fe₂O₄ nanoparticles were fabricated by the ethanol-assisted combustion method, and they were chosen to remove methyl blue. Adsorption experiments were performed, and the pseudo-second-order kinetics model and the Temkin isotherm model fitted well with the experimental data. When pH was above 5, the adsorption capacity remained at a solidly high level. After three times of recycling, the relative removal activity of the nanoparticles remained above 97.6% of its original removal activity. The adsorption process was further illuminated by CV and EIS.

This study investigated the potential of horizontal subsurface flow constructed wetlands (HSSF-CWs) and open raceway ponds (RWPs) operated under different regimes (plants, impregnated activated charcoal (IAC), and algae) for long-term nitrogen removal to control eutrophication problems. For experimental purposes, five mesocosms HSSF-CWs and two RWPs were set up in Wuxi, China, a temperate climate zone. Three HSSF-CW units were cultivated with different regions’ plant species including Nasturtium officinale, Juncus effusus, and Brassica juncea, whereas the one unit packed with IAC and the fifth was left as a control, while two species of algae (Spirogyra and C. pyrenoidosa) were cultured in RWPs. All the amendments tested in this study were almost equally effective for long-term nitrogen removal. The results demonstrated that more than 75.7, 88, and 66%, removal of TN, [Formula: see text]–N, and [Formula: see text]–N was achieved by the HSSF-CWs, packed with IAC and N. officinale. Concerning RWPs, both algal species showed almost similar results but slightly lower than others, which may be attributed to the less compatibility with the environment. It was observed that nitrogen removal performance was higher in the winter-spring (March–April) season as compared with winter (January–February). Moreover, all plants, particularly N. officinale growth, were quite steadier than others. The present study validates the impression that both treatment systems were potentially effective in long-term nitrogen removal from sewage and could be considered beneficial to control the eutrophication. Graphical Abstract

The food industry is considered to be one of the greatest sources of environmental contamination produced by dyes. Moreover, a large number of commercial food dyes and their by-products have been shown to be toxic, having chronic effects on human health. The search for efficient processes with which to treat these compounds is, therefore, necessary. In this work, the photo-peroxidation and photo-Fenton processes using UV-C and sunlight radiations were evaluated in order to degrade two synthetic dyes commonly found in food industry wastewater, sunset yellow and tartrazine, in an aqueous mixture. The preliminary results showed that the photo-Fenton/UV-C system was the most efficient. The ANOVA analysis results indicated a good fit of the model. The higher degradations were obtained using 50 mg L⁻¹ of [H₂O₂], 1 mg L⁻¹ of [Fe], a pH of 3.5, and a lower surface area/volume ratio (0.02 cm² mL⁻¹). In the kinetic study, a good fit was found for the kinetic model proposed by Chan and Chu. Degradations higher than 99% and 78% were obtained for the chromophore and aromatic groups, respectively, in 180 min. Toxicity tests showed that post-treatment samples did not interfere in the development of Lactuca sativa seeds and Escherichia coli and Salmonella enteritidis bacteria strains. The photo-Fenton/UV-C system can, therefore, be considered an efficient treatment for the degradation of the mixture of sunset yellow and tartrazine dyes under the conditions evaluated.

Sulfadiazine (SDZ) was effectively removed by the heterogeneous catalytic sulfate radical (SO₄•⁻) oxidation using a novel composite material of mesoporous carbon (MC) loaded nano zero-valent iron (nZVI). Possessing larger specific area (433.3 m² g⁻¹) and high mesopores volume (2.537 cm³ g⁻¹), the composite material (nZVI/MC) was used as the activator to activate persulfate for the degradation of SDZ. The results of degradation experiments indicated that the removal efficiency of SDZ in nZVI/MC+ persulfate (PS) process reached the highest, due to good dispersing property of MC for nZVI. The removal of SDZ was further enhanced by the increase of nZVI loading as well as the nZVI/MC composite content. Quenching experiments showed that SO₄•⁻ acted a crucial role in the degradation process of SDZ. Both the FT-IR and XPS analyses showed that the FeO contents decreased after degradation reaction, which indicated the occurrence of active oxidation reaction between SO₄•⁻ and Fe²⁺ from the breakage of the Fe–O bond. The LC-MS analysis indicated that the cleavages of C–N bond in the heterocyclic ring and N–S bond were the major degradation pathway of SDZ, attributing to the attack of SO₄•⁻ and •OH. These results demonstrated that the novel nZVI/MC composite with excellent stability could be used for the effective degradation of SDZ through activating PS to produce SO₄•⁻. Graphical Abstract

In a context of scarcity of good quality water, reuse is a mandatory practice to increase water availability, thus allowing the exploitation of more cropland. Although several studies have evaluated the hydric potential of domestic gray water to promote the economic and environmental sustainability of agriculture, the focus of this study was to evaluate the application of this effluent on an ornamental plant, the sunflower. The experiment was conducted in a protected environment using a completely randomized block design with split plots and four replicates. Irrigation solutions containing different mixtures of treated gray water effluent (TGW) and drinking water (DW) (100% DW, 25% TGW + 75% DW, 50% TGW + 50% DW, 75% TGW + 25% DW, and 100% TGW) were arranged in the plots, while the ornamental sunflower cultivars (Bonito de Outono Sortido and Sol Vermelho) were arranged in the split plots. Irrigation with treated gray water did not affect the growth of the plants and the quality of the flowers until the dilution of 55% in drinking water. The cultivar Sol Vermelho showed better plant growth and flower quality when fertigated with dilutions of treated gray water. The principle of mixing fresh with gray water, applied to the production of ornamental sunflowers, allows obtaining flowers of good quality while saving drinking water and decreasing the deposition of effluents in the environment.

While foliar application of copper (Cu) containing fungicides can protect vines from fungal infections such as downy mildew (Plasmopara viticola), it can increase soil Cu content which increases disease susceptibility, especially in acidic soils. In this study, we hypothesized that lime (CaCO₃ + MgCO₃) addition may minimize Cu toxicity in vines by increasing pH and reducing Cu bioavailability. We applied two Cu (no Cu added, 50 mg Cu kg⁻¹) and three lime (no lime added, 1.5, 3.0 Mg ha⁻¹) quantities on a Typic Hapludalf soil. After 60 days, root, plant performance, and biochemistry were measured. As expected, high Cu content negatively affected growth, nutrient status, and metabolism of young vines. However, addition of 3.0 Mg ha⁻¹ lime raised the soil pH from 4.5 to 6.1, decreasing Cu toxicity effects in young vines. Thus, lime addition is an effective strategy in protecting young vines in soils with high levels of Cu. Graphical Abstract .