Deammonification process has been studied as an alternative technology for nitrogen removal. This process consists of the association between nitrifying and anammox bacteria, in which the process success is related to aeration, recirculation, and reactor configuration. Considering this, the present study aimed to evaluate the performance of an expanded granular sludge bed (EGSB) reactor on nitrogen removal by deammonification process. Established in a single reactor, it considered the effects of recirculation rate and variation of dissolved oxygen (DO) concentration in microbial community and nitrogen removal efficiency. Thus, two independent tests were conducted: (T1) high recirculation flow rate, performed at 43 L d⁻¹ (Qᵣ/Qᵢₙ = 16), aeration of 30 mLₐᵢᵣ min⁻¹ L⁻¹ ᵣₑₐcₜₒᵣ, and conducted during 16 days; (T2) low recirculation flow rate performed at 6.7 L d⁻¹ (Qᵣ/Qᵢₙ = 2.5), operated for 55 days, divided into three aeration phases: (T2a) 30 mLₐᵢᵣ min⁻¹ L⁻¹ ᵣₑₐcₜₒᵣ, (T2b) 20 mLₐᵢᵣ min⁻¹ L⁻¹ ᵣₑₐcₜₒᵣ, and (T2c) 30 mLₐᵢᵣ min⁻¹ L⁻¹ ᵣₑₐcₜₒᵣ. Results showed that in T1 the high recirculation rate favored nitrifying bacteria prevalence, intensified by reactor turbulence and anammox granules disintegration, changing activity from deammonification to a nitrification process. In addition, T1 reached up to 350 ± 100 mgN L⁻¹ d⁻¹ nitrogen removal rate (NRR). For T2, at low recirculation rate, deammonification process was successfully established with a NRR of 490 mgN L⁻¹ d⁻¹ at Qᵣ/Qᵢₙ = 2.5 and air flow rate of 20 mLₐᵢᵣ min⁻¹ L⁻¹ ᵣₑₐcₜₒᵣ.

Panax notoginseng (P. notoginseng) is a well-known traditional Chinese medicinal herb. Due to elevated arsenic (As) levels in some planting area, P. notoginseng and its derivatives are contaminated, and the As concentration in these products exceeds the standard limit (As concentration < 2 mg/kg). In this study, the effects of sulfate (S) application on As uptake and the physicological response of P. notoginseng were investigated in a pot-culture experiment. The results showed that the As concentration in the roots was significantly decreased by a maximum of 64.9 % in response to the application of 75 mg/kg S. The proportion of methylated arsenic, which is less toxic, in the roots was increased by 263.4 %. Moreover, the application of S alleviated the oxidative damage due to As stress, and the activities of superoxide dismutase (SOD) and peroxidase (POD) were improved by 26.2 and 29.4 %, respectively. Finally, the total saponin content in the roots increased by 26.0 % in response to a supply of 50 mg/kg S. These findings implied that the application of S fertilizer could effectively reduce As accumulation in P. notoginseng and promote the formation of pharmaceutical components.

Metal cations could enhance the sorption of tetracyclines but sometimes the effects are negligible. It is still not clear how these metals produce different effects. In this study, the sorption of chlortetracycline (CTC), tetracycline (TC), and oxytetracycline (OTC) was performed in the presence of Cd (II) to reveal the unknown mechanisms with two river sediments. It is found that Cd (II) could enhance the sorption of TCs on sediment SS, while it is negligible on sediment SY. For different tetracyclines, the enhancement effect by Cd (II) was more significant for CTC, while it is inferior for OTC and TC. Sorption isotherms of Cd (II) under strong and weak background electrolyte and pH decrease of sorption solutions indicate specific sorption is major on SY and cation exchange is significant on SS. Consequently, specific sorption is unfavorable for the enhanced sorption of TCs in the presence of Cd (II) because it is not favorable for the sorption of Cd-TCs by complexation and cation exchange. By the theoretical calculations, it is found that the significant enhancement of CTC is due to the higher electron affinity of Cd-CTC complex than the others to the surface groups. In conclusion, TCs sorption will not be affected by Cd (II) on sediments or soils with strong specific sorption characters of Cd (II).

Climate change is expected to affect the groundwater quality by altering recharge, water table elevation, groundwater flow, and land use. In fractured bedrock aquifers, the quality of groundwater is a sensitive issue, particularly in areas affected by geogenic arsenic contamination. Understanding how climate change will affect the geochemistry of naturally occurring arsenic in groundwater is crucial to ensure sustainable use of this resource, particularly as a source of drinking water. This paper presents a review of the potential impacts of climate change on arsenic concentration in bedrock aquifers and identifies issues that remain unresolved. During intense and prolonged low flow, the decline in the water table is expected to increase the oxidation of arsenic-bearing sulfides in the unsaturated zone. In addition, reduced groundwater flow may increase the occurrence of geochemically evolved arsenic-rich groundwater and enhance arsenic mobilization by reductive dissolution and alkali desorption. In contrast, the occurrence of extreme recharge events is expected to further decrease arsenic concentrations because of the greater dilution by oxygenated, low-pH water. In some cases, arsenic mobilization could be indirectly induced by climate change through changes in land use, particularly those causing increased groundwater withdrawals and pollution. The overall impact of climate change on dissolved arsenic will vary greatly according to the bedrock aquifer properties that influence the sensitivity of the groundwater system to climate change. To date, the scarcity of data related to the temporal variability of arsenic in fractured bedrock groundwater is a major obstacle in evaluating the future evolution of the resource quality.

Spatial and temporal variation of rotifers in Lake Sattal of Western Himalaya was studied from January 2011 to December 2012. A total of 22 rotifer species could be identified in the lake with a biannual mean abundance of 2.07 × 10⁶ individuals/m³ in eastern basin and 1.92 × 10⁶ individuals/m³ in western basin having maximum abundance during summer season. The main factors regulating distribution patterns of rotifers are nutrients, viz. NH₄-N, PO₄-P, NO₂-N, and NO₃-N, and turbidity, pH, and transparency. Six species of rotifers were deliberated as important species based on importance value index. Keratella quadrata, Colurella obtusa, and Asplanchna priodonta flourish under low turbid conditions. Philodina roseola demonstrated as a phosphorous-tolerant species, whereas K. quadrata and C. obtusa are thermophilous and their distributions are highly influenced by pH and transparency. The total organic matter (TOM) of the sediment has a significant positive correlation with species richness and diversity. The hierarchical environmental descriptor suggests water chemistry has a greater significant role in assemblages of rotifers as compared to sediment characteristics.

The degradation of two pesticides, carbofuran (CBF) and ioprodine (IPR), was studied by the photolytic decomposition of hydrogen peroxide (UV/H₂O₂). The influence of two experimental parameters, H₂O₂ concentration and initial pH, as well as their interactions, was investigated. Optimization was carried out where experimental parameters were determined for the treatment of each pesticide. Both pesticides were totally eliminated by UV/H₂O₂ system under optimal conditions. However, significant differences were found: CBF degradation was influenced by both parameters and their interactions, while IPR degradation was not statistically affected by initial pH. Interestingly, analysis of degradation pathways showed a major influence of photolysis process and oxidation due to hydrogen peroxide for the CBF degradation, while the synergistic combination between both of them played the most relevant role during IPR degradation. A mixture of both pesticides was also submitted to UV/H₂O₂ action in which a lower rate was observed for IPR elimination while CBF was not affected. A 90 % of chemical oxygen demand (COD) was removed and 75 % of mineralization was achieved after the treatment of the mixture. Almost 92 % of the toxicity was eliminated making this technique a promising process to treat toxic mixtures of these pesticides.

Soil microbial communities play an important role in the biodegradation of different petroleum derivates, including hydrocarbons. Also other biological factors such as enzyme and respiration activities and microbial abundance are sensitive to contamination with petroleum derivates. The aim of this study was to evaluate the response of autochthonic microbial community and biological parameters (respiration, dehydrogenase and catalase activities, total microorganisms count) on contamination with car fuels and engine oils. The surface layer (0–20 cm) of Mollic Gleysol was used for the experiment. In laboratory conditions, soil was contaminated with the following petroleum substances: car fuels (petrol, diesel) and car engine oils (new and waste—after 10,000 km). The results demonstrated that, among the investigated hydrocarbon substances, petrol addition seemed to be the most toxic for the microbial activity of the investigated soil. The toxicity of the used hydrocarbon substances to microorganisms might be summarized as follows: diesel > new oil > waste oil > petrol. Species belonging to the genera Micrococcus and Rhodococcus were noted as the major autochthonic bacteria being present in soil contaminated with new automobile oil, whereas species of the genera Bacillus sp. and Paenibacillus sp. were identified in the combination treated with waste oil.

Biofumigation is considered a good alternative to chemical fumigation because it can control crop pathogens and diseases with lower health and environmental risks than chemical fumigants. Glucosinolates are volatile compounds found in most Brassica species, and when hydrolysed, it forms a range of natural toxins including isothiocyanates that act as biofumigants. However, the effect of glucosinolates and their breakdown products on non-target and beneficial soil organisms is not well documented. Three biofumigants, broccoli, mustard and oilseed radish, were evaluated for their effect on earthworms (Eisenia andrei) and the soil microbial community. Sub-lethal endpoints, including growth and reproductive success of the earthworms, were monitored. Genotoxicity of the biofumigants towards earthworms was evaluated by means of the comet assay. Broccoli reduced earthworm reproduction while mustard induced more DNA strand breaks in earthworm cells compared to the control. Soil microbial community function and structure were evaluated by means of community level physiological profiling and phospholipid fatty acid analyses. The effects exerted by the biofumigants on the microbial community were the most pronounced within the first 14 days after application. Carbon substrate utilisation was most affected by the oilseed radish treatment and microbial community structure by the mustard treatment.

Fe₂O₃ and CeO₂ modified activated coke (AC) synthesized by the equivalent-volume impregnation were employed to remove elemental mercury (Hg⁰) from simulated flue gas at a low temperature. Effects of the mass ratio of Fe₂O₃ and CeO₂, reaction temperature, and individual flue gas components including O₂, NO, SO₂, and H₂O (g) on Hg⁰ removal efficiency of impregnated AC were investigated. The samples were characterized by Brunauer–Emmett–Teller (BET), X-ray diffraction (XRD), scanning electron microscopy (SEM), and X-ray photoelectron spectroscopy (XPS). Results showed that with optimal mass percentage of 3 % Fe₂O₃ and 3 % CeO₂ on Fe3Ce3/AC, the Hg⁰ removal efficiency could reach an average of 88.29 % at 110 °C. Besides, it was observed that O₂ and NO exhibited a promotional effect on Hg⁰ removal, H₂O (g) exerted a suppressive effect, and SO₂ showed an insignificant inhibition without O₂ to some extent. The analysis of XPS indicated that the main species of mercury on used Fe3Ce3/AC was HgO, which implied that adsorption and catalytic oxidation were both included in Hg⁰ removal. Furthermore, the lattice oxygen, chemisorbed oxygen, and/or weakly bonded oxygen species made a contribution to Hg⁰ oxidation.

Denitrification coupled to anaerobic methane oxidation is a recently discovered process performed by bacteria affiliated to the NC10 phylum. These microorganisms could play important roles in the energy-efficient way of anaerobic wastewater treatment where residual dissolved methane might be removed at the expense of nitrate or nitrite. The difficulty to enrich these microorganisms due to a slow growth rate, especially at low temperatures, limited its application in engineering field. In this study, an NC10 bacteria community was enriched from Taihu sediments by a membrane biofilm bioreactor at ambient temperature of 10–25 °C. After 13 months enrichment, the maximum denitrification rate of the enriched culture reached 0.54 mM day⁻¹ for nitrate and 1.06 mM day⁻¹ for nitrite. Anaerobic methane oxidation coupled denitrification was estimated from the ¹³C-labeled CO₂ (¹³CO₂) production during batch incubations with ¹³CH₄. Furthermore, analysis of 16S rRNA genes clone library confirmed the presence of NC10 phylum bacteria and fluorescence in situ hybridization showed that NC10 bacteria dominated the reactor. All of the results indicated the NC10 bacteria community was competitive in terms of treating nitrate-contaminated water or wastewater under natural conditions.