Redox conditions play an outstanding role in controlling the behaviour of trace elements in soil environments. They are not only sensitive to water saturation but also to soil temperature because many redox reactions are mediated by microorganisms. In this study, we investigated the influence of oxidising (oxygen predominant), weakly reducing (Mnᴵᴵᴵ,ᴵⱽreduction) and moderately reducing (Feᴵᴵᴵreduction) conditions at three temperature regimes (7, 15 and 25 °C) on the solubility of ten trace elements. Multimetal-contaminated topsoil (pH 5.8) from a floodplain in Germany was investigated with the following aqua regia-soluble concentrations: Zn 903, Cu 551, Cr 488, Pb 354, Ni 93.5, As 35.7, Co 22.4, Sb 20.5, Cd 8.3 and Mo 6.5 mg kg⁻¹. Soil suspensions were held at fixed redox potential in microcosm experiments, sampled at every third day and analysed for trace elements. Time to achieve weakly and particularly moderately reducing conditions was temperature dependent and increased in the order 25 °C < 15 °C < 7 °C. Under oxidising conditions, the solubility of the trace elements was low. Reductive dissolution of Mn oxides under weakly reducing conditions was accompanied by a release of Co and Mo. Reductive dissolution of Fe oxides (and of remaining Mn oxides) under moderately reducing conditions additionally led to a release of As, Cd, Cr, Ni and Pb, whereas Cu and Zn were hardly affected. Antimony revealed a different behaviour because, after a first increase, a continuous decrease in its concentration was observed soon after the onset of weakly reducing conditions. We conclude that soil temperature should be considered as a master variable, to distinguish between weakly and moderately reducing soil conditions, and that it is necessary to keep element-specific behaviour in mind when dealing with the effects of redox conditions in soils on trace element solubility.

The effect of anaerobic digestion (AD), coarse solids removal, and a manure additive More Than Manureᵀᴹ (MTMᵀᴹ) on ammonia (NH₃) emission from raw (Non AD) dairy manure and AD manure was studied during 110 days of storage. The study consisted of eight treatments in duplicate: AD manure and non AD manure, with and without coarse solids, and with and without MTMᵀᴹ additive. These studies were conducted in a naturally ventilated barn. The nitrogen content of manure, especially the ammoniacal nitrogen, played an important role in NH₃ emission. During the first 11 weeks of the storage, AD manure had significantly greater peak (33 to 38 ppm) concentrations of NH₃, and NH₃ fluxes (94 to 130 μg min⁻¹ m⁻²) compared to raw manure (14 to 25 ppm and 55 to 81 μg min⁻¹ m⁻², respectively). From the 11th week until the end of storage, there was no significant difference in NH₃ emissions across the manure treatments. The presence of course solids resulted in significanlty less peak NH₃ for non AD manure when data were evaluated for the whole storage period. The manure additive MTMᵀᴹ did not have a significant effect on NH₃ emissions during storage, however, temperature was positively related to NH₃ emissions. Total ammoniacal nitrogen and solids concentration in manure was the most important factors affecting NH₃ emissions during storage.

Many of municipal wastewater treatment plants (WWTPs) are operated by biological process with their excellent performances. However, the early warning system in the influent line is required to avoid the process malfunction because the biological wastewater treatment system has serious drawback to toxic chemicals in the influent. In order to develop a new type of biosensor using anaerobic granules in an online device for rapid detection of toxic inhibitory to the biological process, a porous pot reactor and an anaerobic granule biosensor (AGB) were demonstrated as an upset early warning device (UEWD) in this study. In the first group of toxic loading tests, the prepared cupric chloride solutions were separately injected into both the porous pot and AGB systems at six different concentrations, and phenol solutions were used at three different concentrations in the second group of tests. The results showed the chemical oxygen demand (COD) and ammonia nitrogen (ammonia-N) removal efficiency from porous pot reactor decreased dramatically in response to the addition of Cu²⁺and phenol with the variation of the oxidation-reduction potential (ORP) in AGB. The response of AGB system was 6 to 20 h in advance of porous pot reactor performance response, which suggests that the AGB could potentially be used as an online UEWD.

Pirina, a waste of olive oil factory, was used as an adsorbent for the removal of remazol brilliant blue R (RBBR) from aqueous solution by adsorption process. The pirina was pretreated with HNO₃before batch adsorption experiments. The effects of contact time, initial concentration, pH, temperature, and ionic strength on dye removal were investigated. While the amount of the dye removed by the pirina was increasing with increasing initial concentration and temperature, it decreased with an increase in pH. Moreover, commercial activated carbon (CAC) was also used to compare with the pirina in removing the RBBR. The maximum amounts of the RBBR removed by the pirina and the CAC were 23.63 and 199.45 mg g⁻¹per unit mass of the adsorbents, and the removal efficiencies of them were found as 94.52 and 99.72 %, respectively. Ionic strength in the presence of NaCl and KCl had also a reducing effect on the removal efficiency. The adsorption isotherm was in the best harmony with Langmuir, Freundlich, and Temkin models. The adsorption kinetic obeyed the pseudo-second-order and the intra-particle diffusion models. The values of the r²from the pseudo-second-order kinetic and intra-particle diffusion were between 0.984–0.999 and 0.85–0.996, respectively. From thermodynamic studies, it was seen that the adsorption was of spontaneous and endothermic nature. The values of ΔG° of the adsorption were between −3,218 and −8,867 J mol⁻¹. The values of ΔH° and ΔS° were 50,134 J mol⁻¹and 179 J mol⁻¹ K⁻¹, respectively. Moreover, SEM and FT-IR studies were also performed.

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.

Natural resource habitats, which are isolated from the surface water bodies, are often unregulated and face a higher risk of degradation. Vernal pools, habitats for amphibians, are vulnerable to external stressors that often lead to decline in biodiversity. There is a need to protect these through conservation measures at a spatially targeted level. This study is conducted in the Middle Connecticut River Watershed of Massachusetts State. We evaluate the risk faced by isolated vernal pools at the subwatershed scale. The assessment involves the impact of agricultural intensity and vernal pool distribution in proximity to agriculture parcels. This is performed using geoprocessing techniques within a geographic information system (GIS). The spatial data are used in a nonlinear regression model to evaluate potential stressors to vernal pool existence. The model included land use, geographic features, and hydrographic factors. Agriculture and open land positively influence vernal pool existence, because of vernal pool association with low-lying areas. In addition, elevation showed a negative influence on the number of vernal pool habitats. The results of the spatial risk evaluation of habitat are helpful to target efforts on specific subwatersheds in conserving vernal pool habitats.

The nanoscale zero-valent iron supported on biochar (B-nZVI) was prepared by liquid-phase reduction method and used for the removal of acid orange 7 (AO₇). The structure of composited B-nZVI was characterized by transmission electron microscopy, scanning electron microscopy, X-ray diffraction analysis, X-ray photoelectron spectroscopy, and Brunauer-Emmett-Teller surface area analysis. nZVI was well dispersed on the surface of biochar with a specific surface area 52.21 m²/g, and no obvious aggregation was observed. Batch experiments demonstrated that the degradation of AO₇(20 mg/L) by B-nZVI (2 g/L) at initial pH 2 reached 98.3 % within 10 min. There was a good linearity (r² = 0.99) between kₒbₛand B-nZVI dosage. The reductive cleavage of the azo group in AO₇to amino group may be the dominant stage. This study demonstrated that B-nZVI has the potential to be a promising material for the removal of azo dyes.

Zn²⁺was added to one of the two identical bench-scale upflow anaerobic sludge blanket (UASB) reactors in steady-state period treating swine wastewater to evaluate the effects of Zn²⁺on performance and methanogenic population. Real-time quantitative PCR (QPCR) was used to quantify the 16S rRNA gene concentrations of the four methanogenic orders. In both reactors, the hydraulic retention time (HRT) was sustained at 48 h and the inner temperature was kept at 35 °C. Both promotion and inhibition of Zn²⁺on chemical oxygen demand (COD) removal, methane production and methanogens community were observed in accordance with different Zn²⁺dosages. COD removal rate and methane production reacted in the same way as methanogens, suggesting that the impact of Zn²⁺on the methanogenic community was the critical reason that caused the changes of UASB performance in treating swine wastewater with unstable Zn²⁺concentration. Among the methanogenic community, Methanomicrobiales (MMB) was the dominant group which got visibly impacted by the dosed Zn²⁺. Overall, lower concentration of Zn²⁺, e.g., less than 17.8 mg/L, was supposed to be advisable for a stable and high efficient treatment of swine wastewater by UASB reactor in practice.

This paper reports about the modification of sand and fumed silica with titania in order to obtain a photocatalytic active material for the degradation of pollutants. The coating process was performed based on the sol–gel method. Tetrapropylorthotitanate was used as the titania precursor to apply a nanoscaled layer on sand grains. For silica fume, the coating process was varied. Various amounts of tetrapropylorthotitanate were used to obtain different coating thicknesses and to identify the maximum amount of titania that could be loaded on the material. All samples showed high photonic efficiencies in the degradation of nitrogen monoxide despite their low titania quantities, which were identified via x-ray fluorescence analysis. Some samples showed higher photonic efficiencies than commercial Degussa P25. Due to the preparation method, calcination of the sand composites was not necessary to yield a crystalline coating which was responsible for the high photocatalytic activity. However, silica fume composites had to be calcined possibly due to variation in the preparation method. Scanning electron micrographs revealed the structured morphology of all specimens. Energy dispersive x-ray analysis identified nanoscaled titania particles on the sand surface that could not be observed only via SEM. The results of this research are especially interesting for large scale applications of photocatalysts. As industrial sand and silica fume used are low cost materials, this new kind of photocatalyst can be applied in higher quantities and distributed onto larger areas, while saving costs at the same time.