In order to assess correctly the gases emissions from oil/gas field water and its contributions to the source of greenhouse gases (GHG) at the atmospheric temperature and pressure, a simulation experiment was first developed to study the natural emissions of GHG into the atmosphere in the southern gas field, Sichuan Basin, China. The result showed that methane (CH₄) and carbon dioxide (CO₂) were the two gases that released from the gas field water. Time and temperature played important roles in GHG emissions, and the higher temperature was found to enhance carbon emissions. Under the lower/intermediate temperature conditions (5 and 15 °C), majority of gases were released from the gas field water during the first 2 h, whereas under the higher temperature conditions (30 °C), the majority of gas released from the gas field water continued for 12 h. By dividing the whole emission duration into six time durations (one time duration was 12 h), we calculated the fluxes of CH₄and CO₂. The substantial variation in the gas fluxes reflected that the cumulation of time also played a crucial role in the process of GHG emissions. In the first emission duration (0–12 h) at 30 °C, the maximum fluxes of CH₄and CO₂were 1.47 and 1.87 g/m³·h, respectively. The values were obviously higher than those in other durations, so were the fluxes shift in different durations at 5 and 15 °C. Additionally, we found that the emissions released from the gas field water which came from overpressure formation formed higher carbon emissions.

In this study, the adsorbent, magnetic NaY zeolite was synthesized for simultaneous removal of three toxic cationic dyes, methylene blue, crystal violet, and fuchsine, from aqueous solutions. The influences of five dominant parameters of pH, temperature, time, initial dyes concentration, and adsorbent mass on dyes adsorption were investigated. The percentage of dye removal was mathematically described as a function of experimental parameters and was modeled through central composite design (CCD). According to the predicted experiments, optimum conditions of 10.3, 50 °C, 45 min, 10 mg L⁻¹, and 46.2 mg, for pH, temperature, time, initial dyes concentration, and adsorbent mass were resulted, respectively. The maximum experimentally achieved dye removal percent of 98.4 ± 0.6, 98.1 ± 0.5, and 98.1 ± 0.3 were obtained, which were close to the percent of model dye removal prediction of 99.0, 98.6, and 98.4 for methylene blue, crystal violet, and fuchsine, respectively. This agreement showed that the central composite design model could ideally make an acceptable estimation of the process.

Textile industry is responsible for a large amount of wastewater inappropriate for both human consumption and aquatic species. Aquatic ecosystems are way more sensitive to the release of textile wastewater, and the usage of Winogradsky columns is interesting, once they are a simulated aquatic ecosystem in which the growth of algae and other microorganisms can be observed. In this research, simulated textile effluents with the dye Acid Blue 40 were treated with an electrolytic reactor, for a later ecotoxicological evaluation using Winogradsky columns. The algal and microbial population and primary production were measured. The results have shown that the electrolytic treatment was satisfactory when it comes to color removal, but the presence of the treated effluent in the Winogradsky columns changed the microecosystem. The number of algae identified decreased when exposed to certain effluents, and some algae groups even disappeared, while others such as Cyanophyceae were benefited.

From April 2006 to April 2007, the geographical and seasonal variation in nitrogen content in terricolous lichen (Cladonia portentosa) and atmospheric ammonia concentrations were measured at five heathland sites. The seasonal variation in the nitrogen content of the lichen was small, even though there was a large seasonal variation in the air concentration of ammonia. A sizable local variation in the nitrogen content of the lichen was found even at the scale of a few kilometres. The nitrogen content in the lichen showed a high correlation to the yearly mean value of the measured ammonia concentration in air at the different locations. This investigation is part of a larger attempt to incorporate effects of nitrogen in the conservation status of terrestrial habitat types.

Removal of hexavalent chromium by precipitation from wastewater has received increasing interest in recent years. This study described the behavior of chromium and iron coprecipitation mediated by Acidithiobacillus ferrooxidans DC in an artificial simulated acid environment. In four parallel groups with the different concentrations of chromium(VI) (30, 60, 90, 120 mg/L), the precipitation efficiencies of chromium were enhanced uniformly by A. ferrooxidans DC. But chromium coprecipitation efficiency reduced as the initial chromium concentration increasing at the early stage. Especially in the 30 and 60 mg/L chromium groups, the maximum precipitation efficiency of chromium was improved from 56.22, 55.01 to 75.72, 74.37 % on the fourth day. Additionally, the characteristics of the precipitates were analyzed by x-ray diffraction (XRD), scanning electron microscope (SEM), and Fourier transform infrared spectroscopy (FTIR). Results showed that the precipitates were mainly present as jarosites and A. ferrooxidans was conducive to producing precipitates with good crystalline form and uniform dispersion with pH decrease, redox potential (ORP) increase, and iron oxidation. It can be concluded that the chromium could be incorporated into the jarosites through a certain biochemical reaction such as structural substitution, which shows a potential to remove chromium from wastewater by the bio-coprecipitation.

This paper presents a study of the combined process of adsorption and biodegradation in solid biologically activated carbon (AC) for the removal of salicylic acid aimed at determining the influence of the presence of biofilm on the process. Adsorption on AC and biodegradation of free cell cultures were studied separately so as to compare their performance with that of the combined biosorption system. The formation of bacterial biofilm on the surface of the carbon was investigated. The study was carried out using a range of synthetic solutions containing between 15 and 500 mg/L salicylic acid simulating an industrial effluent from the pharmaceutical industry. An individual bacterium, Pseudomonas putida (DSM 4478), was used to study the differentiated effects. Filtrasorb 400 and GAC 830 ACs were used in the adsorption processes and Filtrasorb 400 in the biofilm formation and combined biosorption processes. As regards, combined adsorption/biodegradation results indicated that the bioactivated carbon system outperformed the combination of conventional AC and biological water treatment processes when working with high pollutant concentrations.

A novel high-capacity phosphate removal adsorbent of graphene nanosheets (GNS) supported lanthanum hydroxide (LaOH) is prepared. The phosphate adsorption performance for GNS-LaOH is examined by a batch adsorption method from aqueous solutions. The Freundlich and Langmuir models are used to simulate the sorption equilibrium, which reveal that the Langmuir model has a better correlation with the experimental data. The maximum adsorption capacity is calculated to be 41.96 mg/g. The kinetic data from the adsorption of phosphate is suggested as the pseudo-second-order model, and the multi-linearity adsorption process is observed in the intraparticle diffusion model, indicating that a chemisorption process is dominant in the adsorption of phosphate. The phosphate adsorption mechanism is explored by analyzing the Fourier transform infrared spectroscopy (FT-IR) and the relationship between the adsorption amount and the pH value of phosphate solution. Ligand exchange and electrostatic and Lewis acid–base interactions are determined to be three main factors for phosphate adsorption.

This contribution is concerned with the comparison of the efficiency of the removal of four pure neonicotinoid active ingredients (AIs) and their commercial formulations (CFs) from aqueous solutions by using different advanced oxidation processes at the pH 2.8. The AIs of thiamethoxam and imidacloprid, and their CFs (Actara and Confidor), having a nitroguanidine functional group, exhibited low persistence to photolysis. In contrast to them, thiacloprid and acetamiprid and their CFs (Calypso and Mospilan), containing a cyanoimine functional group, were stable during the UV irradiation period. As expected, the degradation rate of the studied neonicotinoids increased significantly in the combined action of UV radiation and H₂O₂. In the case of thiacloprid and acetamiprid and their CFs, the reaction of the OH radicals formed and molecules of these insecticides was the major destruction pathway. The increased photodegradation efficiency of the UV/7.2Fe/TiO₂/H₂O₂ and vis/7.2Fe/TiO₂/H₂O₂ processes was attributed to the surface photoreduction of Fe³⁺ to Fe²⁺, which produces new OH radicals in the reaction with H₂O₂. In the presence of visible light, the efficiency may be partly due to the formation of the H₂O₂–TiO₂ complexes. For the 7.2Fe/TiO₂/H₂O₂ process in the presence of UV or visible radiation, no significant influence on the efficiency of photodegradation was observed in dependence of the structural differences of selected neonicotinoids. These results strongly suggest that highly reactive hydroxyl radicals, generated on the catalyst’s surface in the reaction involving H₂O₂, are responsible for this oxidation. In order to investigate degree of mineralization for all insecticides, TOC measurements were also conducted. Also, it was observed that the removal of pure AIs and their CFs by dark adsorption was almost negligible.

The aim of this study was to investigate the effect of pH 4 and 7 on the cellular toxicity impact of silver nanoparticles (AgNPs) on the green alga Chlamydomonas acidophila. Changes in chlorophyll content, cellular viability, and reactive oxygen species (ROS) formation were determined permitting the characterization of the toxicity of AgNPs. Chemical characterization of AgNPs in suspension showed that nanoparticle size distribution was dependent to the pH of the culture medium, and a higher solubility was observed at pH 4 compared to that at pH 7. After 24 h of exposure, results indicated that the chlorophyll content and cellular viability decreased significantly, while the intracellular ROS production increased significantly, in relation to the increasing concentration of AgNPs (0.1–100 mg/L). Therefore, our results demonstrated that AgNP-induced toxicity was pH dependent as indicated by the cytotoxicity mediated through the induction of oxidative stress. In conclusion, the characterization of the physicochemical properties of AgNPs in aqueous solution having different pH is essential for the understanding of their toxicity impact on algal cells.

The growing demand for new sources of water for irrigation has led to an increase in the practice of using treated wastewater in agricultural processes. Thus, in the present research, we have assessed the irrigation of a culture of eucalyptus with reclaimed wastewater. The sewage comes from domestic sources and was treated in a facultative lagoon. The culture of eucalyptus was assessed through plant diameter at breast height and total volume of wood produced. Soil contamination was determined through its salinization and the values of sodium adsorption ratio (SAR). The use of wastewater in irrigation has brought an increase of 82.9 % in productivity compared to traditional cultivation. This shows that in a same area of cultivation, practically double of the eucalyptus wood could be obtained and used in the most different industrial activities. In addition, it would prevent the entering of a large amount of nutrients in water bodies due to their recycling in the agricultural culture. In the period of 4 years of studies, SAR has always been below the values pointed by the literature as indicators of problems for the soil.