Rhodamine B (RhB) is one of synthetic dyes with good stability. Treatment of wastewater containing synthetic dyes has attracted much attention. Heterogeneous activation of peroxymonosulfate (PMS) has been found to be a promising wastewater treatment technology through the activation with metal oxides for the generation of sulfate radicals. In this study, α-MnO₂ was prepared by a simple hydrothermal method and used as the catalyst to activate PMS. The degradation of RhB was studied by the α-MnO₂/PMS system. It was found that the prepared α-MnO₂ exhibited high catalytic activity on the activation of PMS for the degradation of RhB. The degradation of RhB could be well described by the first-order kinetic model. Influences of PMS concentration and α-MnO₂ dose on the degradation of RhB were examined. The chemical oxygen demand (COD) was determined to evaluate the mineralization capability of the α-MnO₂/PMS system. The stability of α-MnO₂ was also investigated through reusability experiments. Quenching tests of radicals were applied to differentiate the contribution of major reactive species for the degradation of RhB by the α-MnO₂/PMS system.

Pentachlorobenzene is one new persistent organic pollutants (POPs) that has been recently added to the Stockholm Convention on Persistent Organic Pollutants. Based on this reason, one treatment having ability to degrade this compound is needed. The microbiological process by using white-rot fungus was used in this experiment. Free cell of Trametes versicolor U80 degraded pentachlorobenzene 43 % in liquid medium at 40 days incubation. The rapid initial uptake of pentachlorobenzene was obtained in the first 20 days. The results based on ionization potential and the partial least square function indicated that both enzymatic systems of lignin peroxidase and P-450 monooxygenase involved in the degradation of pentachlorobenzene. By using addition of Tween 80, MnSO₄, and veratryl alcohol, degradation of pentachlorobenzene could be improved. Based on kinetic study, the use of 1 % of Tween 80 showed the highest degradation rate (2.0619/day) and the degradation of pentachlorobenzene by 50 % can be shortened up to 24 days. Application of T. versicolor U80 in soil and bioreactor degraded pentachlorobenzene 43 and 50 % at 40 days, respectively. T. versicolor U80 shows good capability degrading pentachlorobenzene in soil and bioreactor although it is lower than in liquid due to the difference of pollutant accessibility and transfer oxygen. Finally, strain T. versicolor U80 can be proposed as an excellent candidate for remediation application in pentachlorobenzene pollution.

Adsorption of Reactive Orange 107 dye from aqueous solution was investigated using an activated carbon from Pinus elliottii sawdust chemically prepared with ZnCl₂. The optimum conditions for the adsorption of Reactive Orange 107 dye by the activated carbon, obtained by response surface methodology, were pH = 10, ionic strength = 0.4 mol L⁻¹, agitation rate = 200 rpm, and adsorbent dosage = 0.025 g. For the experimental data of the adsorption equilibrium, nonlinear models, i.e., the Langmuir, Freundlich, Dubinin-Radushkevich, and Temkin isotherms, were applied; the best correlation was found for the Langmuir model. The thermodynamic parameters were determined using the adsorption equilibrium constant of the Langmuir isotherm and the van ‘t Hoff equation. The parameters suggest an endothermic, ∆H°ₐdₛ = 16.97 kJ mol⁻¹, and spontaneous process, ∆G°ₐdₛ = −23.96, −25.23, −26.78, and −28.05 kJ mol⁻¹, at 298, 308, 318, and 328 K, respectively. The results indicate that the activated carbon was efficient for the adsorption of Reactive Orange 107 and has excellent potential for the treatment of colored effluents.

Insecticides are widely sprayed in modern agriculture for ensuring the crop yield, which could also lead to contamination and insecticide residue in soils. Paichongding (IPP) is a novel neonicotinoid insecticide and was developed recently in China. Soil bacterial community, diversity, and community composition vary widely depending on environmental factors. As for now, little is known about bacterial species thriving, bacterial community diversity, and structure in IPP-spraying soils. In present study, IPP degradation in yellow loam and Huangshi soils was investigated, and bacterial communities and diversity were examined in soil without IPP spray and with IPP spray through pyrosequencing of 16S ribosomal RNA (rRNA) gene amplicons. The degradation ratio of IPP at 60 days after treatment (DAT) reached 51.22 and 34.01 % in yellow loam and Huangshi soil, respectively. A higher richness of operational taxonomic units (OTUs) was found in yellow loam soil (867 OTUs) and Huangshi soil (762 OTUs) without IPP spray while OUTs were relatively low in IPP-spraying soils. The community composition also differed both in phyla and genus level between these two environmental conditions. Proteobacteria, Firmicutes, Planctomycetes, Chloroflexi, Armatimonadetes, and Chlorobi were stimulated to increase after IPP application, while IPP inhibited the phyla of Bacteroidetes, Actinobacteria, and Acidobacteria.

One potential way for organic matter recovering contained in paper mill effluents can be obtaining polyhydroxyalkanoate (PHA). The aim of this work was to evaluate PHA biosynthesis from paper mill effluents by moving bed biofilm reactor (MBBR) under different operational strategies of the BOD₅/nitrogen (N)/phosphorus (P) ratio. The operational strategies were evaluated in two phases. During phase I, organic loading rates (OLRs) were increased from 0.13 to 2.99 biological oxygen demand kg BOD₅ m⁻³ day⁻¹, and in phase II, kg BOD₅ m⁻³ day⁻¹ was increased from 0.81 to 2.83. In both phases, the BOD₅/N/P ratios were 100:5:1 and 100:1:0.3. The maximum percentages of PHA-accumulating cells and organic matter removal were 85.10 and 95.60 % for phase I, both with a BOD₅/N/P ratio of 100:5:1, while in phase II, PHA biosynthesis and organic removal were 89.41 and 97.10 % with 100:1:0.3 and 100:5:1, respectively.

The reduction of nitrous oxide (N₂O) emission during nitrogen removal process in municipal wastewater treatment is of great urgency. Sequencing batch biofilm reactor (SBBR) system could be a promising and efficient way to solve the problem. In order to get the high chemical oxygen demand (COD) and nitrogen removal efficiency and low nitrous oxide emission, the influence of biofilm density on SBBR was investigated. When the biofilm density changed from 15 to 30 %, the effluent COD, total nitrogen (TN) and ammonia nitrogen decreased, but the effluent TN concentration did not meet the class I-B standard of the Discharge Standard of Pollutants for Municipal Wastewater Treatment Plant in China. COD, TN, and ammonia nitrogen concentration was 42.34, 19.14 and 2.97 mg/L at 50 % biofilm density. When the density turned from 50 to 70 %, although the effluent COD, TN, and ammonia nitrogen were still decreased, N₂O emission increased from 0.45 to 0.77 %. Considering the effluent quality and N₂O emission, the optimal biofilm density in SBBR was 50 %.

A biogeochemical investigation was carried out on Origanum majorana grown on limestone substrate in Greece. Possible health risks from consumption of dried herbs and infusions were assessed. Macronutrients and essential and toxic metals were determined in the leaves of O. majorana plants and in their soil substrates. Toxic metals were measured in the herbal infusions. Macroelements were found generally in low concentrations for normally developing plants, except for Ca. The ratios N/P and N/K were found lower than the optimum range for normal growth, while the values of K/(Ca + Mg) ratio prevent the development of grass tetany. Manganese and arsenic were enriched in distinct samples. O. majorana plants can be used as indicators for soil environmental assessment. They can also be applied in phytoremediation methods in metal-polluted soils. Hazard indices were far below 1. Carcinogenic risks were found to be within the acceptable range. No health risk is anticipated by the consumption of the specific plants investigated in the present study.

Phosphogypsum (PG) is an industrial waste composed mainly by sulfate, turning it a suitable sulfate source for sulfate-reducing bacteria (SRB). In the present work, the capability of two SRB communities, one enriched from Portuguese PG (culture PG) and the other from sludge from a wastewater treatment plant (culture WWT-1), to use sulfate from PG was compared. In addition, the impact of this sulfate-rich waste in the microbial community was assessed. The highest efficiency in terms of sulfate reduction was observed with culture WWT-1. The bacterial composition of this culture was not significantly affected when sodium sulfate from the nutrient medium was replaced by PG as a sulfate source. Next generation sequencing (NGS) showed that this community was phylogenetically diverse, composed by bacteria affiliated to Clostridium, Arcobacter, and Sulfurospirillum genera and by SRB belonging to Desulfovibrio, Desulfomicrobium, and Desulfobulbus genera. In contrast, the bacterial structure of the community enriched from PG was modified when sodium sulfate was replaced by PG as the sulfate source. This culture, which showed the poorest performance in the use of sulfate from PG, was mainly composed by SRB related to Desulfosporosinus genus. The present work provides new information regarding the phylogenetic characterization of anaerobic bacterial communities with the ability to use PG as sulfate donor, thus, contributing to improve the knowledge of microorganisms suitable to be used in PG bioremediation. Additionally, this paper demonstrates that an alternative to lactate and low-cost carbon source (wine wastes) can be used efficiently for that purpose.

Polyether trisiloxane surfactants are widespread used as agricultural adjuvants because they increase the activity and the rainfastness of pesticides. On the contrary to pesticides, the environmental fate of agricultural adjuvants has not been much investigated, yet. Especially for trisiloxane surfactants, the knowledge on their environmental fate is scarce. To fill this gap, the mobility of a polyether trisiloxane surfactant on soil was studied. With a sorption batch equilibrium method, distribution coefficients between water and soil (K d, K ₒc, and K cₗₐy) were estimated for two standard soils (loam and sandy loam) and for every homologue of the trisiloxane surfactant. The obtained values for K d were between 15 and 135 cm³ g⁻¹, indicating that the trisiloxane surfactant is only slightly mobile in soil. The leaching in soil column was studied in a worst case scenario where the application of the trisiloxane surfactant was done on quartz sand and was immediately followed by a heavy rainfall. Less than 0.01 % of the initially applied trisiloxane surfactant had leached through 20 cm of quartz sand. Based on the K d values and the leaching in a soil column, the studied trisiloxane surfactant seems to be unlikely to leach through soil after application as agricultural adjuvant.

Natural volcanic tuff was used for the synthesis of geopolymer and then for the removal of Zn⁺². The characteristics of the natural volcanic tuff and the synthesized geopolymer were determined by X-ray diffraction (XRD), X-ray fluorescence (XRF), Fourier transform infrared (FTIR), and scanning electron microscopy (SEM). Results referred that the synthesized geopolymer had a higher efficiency uptake of 97.7 % as against 78.5 % for the natural volcanic tuff. The uptake capacity of geopolymer for Zn⁺² adsorption increased with increasing temperature in the studied range of 25–45 °C, contact time up to 30 min, pH up to 7, and initial concentration up to 160 ppm, while it decreased with an increase in geopolymer dosage. The isotherm study showed best fit on Langmuir and Radlich-Peterson models. The maximum uptake capacity obtained from Langmuir model increased from 14.7 to 17.63 mg/g as the temperature increased from 25 to 45 °C. The pseudo-second-order model showed the best fitness for the experimental data followed by intraparticle diffusion model. The adsorption process can be characterized as endothermic, homogeneous, spontaneous, irreversible, physical, and a high adhesion of the ions to the geopolymer surface. The results obtained buttressed the feasibility and applicability of producing geopolymer from natural volcanic tuff for the removal of heavy metals.