During this study, the effect of applying several types of treated domestic wastewater on the translocation and accumulation of organic and inorganic micropollutants in soil and radish plants (Raphanus sativus L.) was examined. Primary (PTW), secondary (STW) and tertiary (TTW) treated wastewater as well as tap water (TW) were used for the irrigation of radish plants for a period (transplantating and harvesting) of 67 days. Higher concentrations of polycyclic aromatic hydrocarbons (PAHs) were observed in soils irrigated with PTW. The concentration of PAHs in radish roots ranged between 107.6 ± 12.1 μg/kg for plants irrigated with TTW and 124.1 ± 17.7 μg/kg for plants irrigated with PTW. The root concentration factors (RCFs) expressed as the ratio of PAH concentration in the root mass (dry weight) to the residual concentration in the soil varied from 1.6 to 1.9 indicating a higher accumulation of PAHs in the edible part of radishes than soil. Heavy metals were not detected in the wastewaters utilised and, as a result, no accumulation was found in either the soil or plants in comparison with tap water. RCFs for heavy metals were calculated between 0.91 and 0.99, 0.49 and 0.66, 0.004 and 0.005 for Cu, Zn and Ni, respectively. The results showed that radishes have the ability to concentrate PAHs when they are present in the wastewater and this could have associated health risks.

The transformation of less toxic Cr(III) species to harmful Cr(VI) is worth concerning. Compared with free Cr(III), however, the photo-oxidation of Cr(III)–organic acid complexes is seldom reported. In this study, Cr(III)–malate complex was synthesized and purified, and its photo-oxidation was investigated to reveal the potential conversion pathway of Cr(III) to Cr(VI). The results indicated that Cr(III)–malate complex could be gradually photo-oxidized to Cr(VI) through a ligand–metal charge transfer path. Higher pH and stronger light intensity promoted the conversion process. A 50-μM Cr(III)–malate complex was almost completely oxidized to Cr(VI) within 420-min irradiation of 500 W medium-pressure mercury lamp at pH 12. The introduction of H₂O₂, considered as a direct source of hydroxyl radicals (·OH) in the presence of Cr(II), markedly enhanced the yield of Cr(VI), and a complete oxidation of Cr(III)–malate complex (50 μM ) was realized within 20 min. Under a weak acidic condition, the production of Cr(VI) was coupled with the reduction of Cr(VI) by malic acid and its free radical generated from Cr(III)–malate complex, leading a gradual decrease in Cr(VI) concentration with the reaction.

Microcystis aeruginosa, the most common toxic cyanobacterial bloom, could cause severe environmental problem by producing and releasing lethal cyanobacterial toxins to water body. This study investigated the electron beam irradiation for the inactivation of M. aeruginosa. The treatment process was monitored via the measurement of chlorophyll a concentration, optical density, photosynthesis, and antioxidant enzymes. At low electron beam irradiation dose (1.0 kGy), its performance is not desirable. High dosage of electron beam irradiation (2.0–5.0 kGy) can dramatically decrease chlorophyll a concentration, optical density, and photosynthesis rate and affect activities of antioxidant enzymes. The transmission electron microscopy measurement indicates that electron beam irradiation treatment cause significant damages on integrity and morphology. Our results demonstrate that electron beam irradiation is a promising technique for quick and efficient inactivation of M. aeruginosa in aqueous solution.

The aim of the present study was the decolourisation of mixture of two dyes belonging to different groups by two Pseudomonas fluorescens strains (Sz6 and SDz3). Influence of different incubation conditions on decolourisation effectiveness was evaluated. Dyes used in the experiment were diazo Evans blue (EB) and triphenylmethane brilliant green (BG). Another goal of the experiment was the estimation of toxicity of process by-products. Incubation conditions had a significant influence on the rate of decolourisation. The best results were reached in shaken and semistatic samples (exception Evans blue). After 24 h of experiment in semistatic conditions, BG removal reached up to 95.4 %, EB 72.8 % and dyes mixture 88.9 %. After 120 h, all tested dyes were completely removed. In most cases, dyes were removed faster and better by strain Sz6 than SDz3. At the end of the experiment, in majority of the samples, decrease of phyto- and zootoxicity was observed.

Cemented paste backfill has been proposed in the mining industry for managing metal mill tailings. Low sulfide tailing (0.49 wt%) samples were prepared into different cemented pastes that were mixed with flocculants (polymerized aluminum chloride). The best mixing proportions of tailings, binder, flocculant, and filling structure (containing 0.5 wt% of ordinary Portland cement in one paste layer, 100 g/L polymerization aluminum chloride) were determined through leaching experiment. The addition of polymerization aluminum chloride improved the mechanical property of the paste. The strength of the cemented pastes by adding 100 g/L flocculant met the requirement of mine backfill. The cemented paste could also fix heavy metals, as shown in the paste leachate analysis of copper (Cu, about 0.01–0.08 mg/L of concentration) and chromium (Cr, about 0.03 mg/L of concentration). In summary, results from this study demonstrate that tailings can be managed by cemented paste backfill technique, preventing its contamination of the environment.

Analytical method for the determination of six flame retardants (FRs) from two groups was proposed. These groups included the brominated flame retardants (BFRs) 3,3′,5,5′-tetrabromobisphenol A (TBBPA), 1,2,5,6,9,10-hexabromocyclododecane (HBCD) and tetrabromophthalic anhydride (TBPA) and triester organophosphate flame retardants (OPFRs) tris(2,3-dibromopropyl) phosphate (TBPP), ethylhexyl diphenyl phosphate (EHDP) and triphenyl phosphate (TPhP). Reversed phase ultrahigh-performance liquid chromatography (UHPLC) with a UV detector, different chromatographic columns, different mobile phases and gradient elution programmes were used to obtain the best separations within the shortest possible time. Solid-phase extraction (SPE) was examined as a pre-concentration step from distilled water. The column with the highest recoveries (the Bond Elut ENV column gave recoveries over 70 % for all compounds) was then tested on 1-L blank surface water samples. The proposed analytical procedure was applied for the determination of FRs in surface water samples. The concentrations of FRs found in water samples ranged from 0.03 (TPhP) to 3.10 μg L⁻¹(HBCD). Method detection limits (MDLs) ranged from 0.008 to 0.518 μg L⁻¹, and method quantification limits (MQLs) ranged from 0.023 to 1.555 μg L⁻¹for all compounds.

The simultaneous removal of phenol and ammonium using heterotrophic nitrifying-denitrifying bacterium Serratia sp. LJ-1 was investigated. The maximum removal rates of ammonium nitrogen and phenol were 1.08 ± 0.05 and 2.14 ± 0.08 mg L⁻¹ h⁻¹, respectively. The ammonium oxidation had much higher tolerance to phenol toxicity than that of the autotrophic nitrifying bacteria. The increase in phenol concentration led to an increase in ammonium oxidation rate under the phenol concentration of 600 mg L⁻¹. The increase in ammonium concentration caused an increase in phenol biodegradation rate under the ammonium nitrogen concentration of 150 mg L⁻¹. Maximum rates of phenol biodegradation and total nitrogen removal in the treatments with nitrification metabolite (nitrate or nitrite) as the sole nitrogen source were more than 30 % lower than those of the treatment with ammonium as the sole nitrogen source. Ammonium was removed through nitrification and subsequent aerobic denitrification while phenol was biodegraded through the ortho-cleavage pathway and subsequently mineralized. Since phenol often coexists with nitrogen pollutants, these findings have significant environmental implications in terms of the simultaneous removal of these contaminants.

In this study, zinc oxide was immobilized on magnetite nanoparticles by chemical method and it was used as an adsorbent to remove reactive black 5 (RB5) dye from aqueous solution. The removal efficiency of RB5 was studied as the function of adsorbent dosage, pH, initial RB5 concentration, H₂O₂, and ionic strength (sodium carbonate, sodium bicarbonate, sodium sulfate, and sodium chloride). Removal efficiency of RB5 by ZnO–Fe₃O₄ was greater than that by ZnO and Fe₃O₄ in similar conditions. Maximum adsorption of ZnO–Fe₃O₄ was obtained at neutral pH, and adsorption capacity was estimated to be 22.1 mg/g. Adsorption kinetic study revealed that the pseudo-second-order model better described the removal rate than the pseudo-first-order model. Adsorption isotherm was analyzed by both Langmuir and Freundlich equations, and results showed that it was better described by the Langmuir equation. The removal efficiency of RB5 was increased with increasing initial H₂O₂ concentrations from 2 to 5 mM but was decreased above 5 mM. The adsorption capacities of RB5 was increased in the presence of NaCl but was greatly decreased in the presence of bicarbonate, carbonate, and sulfate ion. Adsorption activity of RB5 by ZnO–Fe₃O₄ composite was maintained even after five successive cycles, suggesting a promising adsorbent for wastewater-contaminated organic dyes.

In this study, the potential effects of three modified industrial by-products—modified low-grade phosphate rock with soda dregs (MP), modified flue gasses desulfurization residue (MF), and a mixture of MF and phosphoric acid (MFP)—were evaluated in the remediation of heavy metal-contaminated agricultural soil at four different treatment levels. The effects of the amendments on the extractability and phytoavailability of soil heavy metals were tested using a standardized sequential extraction test and a pakchoi pot experiment. The impacts of the three amendments on soil quality was investigated, including changes of soil pH, availability of K, Ca, Mg, Si and P, and the effects on pakchoi growth. The addition of these amendments resulted in a significant decrease of labile fraction of the heavy metals in soil (p < 0.05) and a marked decrease in heavy metal uptake by pakchoi (p < 0.05) in the pot experiment. All the amendments improved soil quality as measured by neutralization of soil acidity, increased content of mineral nutrients of soil (specifically, available K, Ca, Mg, Si, and/or P), and enhanced pakchoi growth when compared to the controls. Significant correlations (positive/negative) were observed among these factors, indicating multiple effects of the amendments on the remediation process. The increased soil pH and elevated mineral nutrients contributed to the stabilization of heavy metals, and the remediated soil conditions resulted in improved growth of pakchoi. These results suggest that all three of the modified industrial by-products could be used for the remediation and restoration of heavy metal-contaminated agricultural soil.

The remediation of dye-contaminated soil using silent discharge plasma in dielectric barrier discharge (DBD) reactor was reported in this study. Acid scarlet GR was selected as the representative of azo dye pollutants. Effects of applied voltage, discharge frequency, and gas flow rate on Acid scarlet GR treatment effect which were characterized by degradation efficiency and the change of chemical oxygen demand (COD) during the degradation were investigated. The decolorization rate of Acid scarlet GR in the soil increased with the applied voltage and discharge frequency, and the optimal gas flow rate was obtained at 1.0 L min⁻¹. The energy efficiency was clearly enhanced by way of increasing the amount of contaminated soil in the DBD reactor finitely. The degradation efficiency of Acid scarlet GR and the removal of COD value were achieved 93 % and 74 % after 25-min discharge treatment, respectively. The results indicated that the DBD remediation system was able to degrade Acid scarlet GR in the soil quickly and efficiently. This study is expected to provide a possible pathway of Acid scarlet GR degradation in soil.