Copper oxide nanoparticles were immobilized on quartz sand and their catalytic activity for the degradation of an organic dye was investigated. The use of nanoparticles as catalysts for non photo-induced oxidation of water contaminants is relatively new. The CuO catalyst has shown promising results when suspended in free form in batch systems. Because heterogeneous catalysis is often the preferred mode of operation for application of catalytic technology, we studied the effect of immobilization of the nanoparticles on quartz sand in a flow-through system and its implication for the catalytic process. The coated sand was packed in a column and its catalytic activity for the degradation of an organic dye was investigated in a series of flow-through experiments with hydrogen peroxide as the oxidant. Control experiments with uncoated sand were also performed for comparison. The coated sand demonstrated high catalytic ability, achieving complete oxidation of the dye. During the reaction, CO2 was produced, leading to a decrease in the water saturation in the column and reduced contact surface between the nano-CuO catalysts and the dye solution. The degradation was improved by enabling a longer residence time of the dye in the column, yielding up to 85% degradation of the dye. These results suggest that CuO nanoparticle-coated sand is an efficient catalyst for complete degradation of the organic dye.

The effectiveness of a novel and low-cost adsorbent, iron-modified bamboo charcoal (BC-Fe), for arsenic removal from aqueous systems was evaluated in this study. The BC-Fe was synthesized by loading iron onto bamboo charcoal via soaking in a ferric salt solution. The BC-Fe possessed a porous structure with a surface area of 277.895 m2/g. The adsorption characteristics of arsenic onto BC-Fe were further investigated at various pHs, contact times, arsenic concentrations, and adsorbent doses in batch tests. The corresponding optimum equilibrium pH ranges for As(III) and As(V) removal were 4–5 and 3–4, respectively. The equilibrium times for As(III) and As(V) adsorption were 30 and 35.5 h, respectively. The arsenic removal was strongly dependent on the initial adsorbate concentration and adsorbent dosage. The maximum arsenic removal capacities of BC-Fe under the experimental conditions were 7.237 and 19.771 mg/g for As(III) and As(V), respectively. The pseudo-second-order kinetic model and Freundlich isotherm explained the kinetic and equilibrium of both the As(III) and As(V) adsorbent processes, respectively. Based on these results, the BC-Fe developed in this study is a promising material for the treatment of arsenic-contaminated water.

The combination of chemical oxidation (Fenton reaction) and biological treatment processes is a promising technique aiming to reduce recalcitrant wastewater loads. Preliminary tests were carried out on two widely used toxic and non-biodegradable pesticides, namely, Dazomet and Fenamiphos. The chemical reaction was employed as a pre-treatment step for the conversion of the substrates into oxygenated intermediates that were easily removed by means of a final biological treatment. In the combined action, the mineralisation activity of a selected microbial consortium was used to degrade residual volatile and non-volatile organic compounds into CO₂ and biomass.

Phosphate removal from water is crucial to the prevention of eutrophication. The phosphate adsorption performance from aqueous solutions by using lanthanum-doped activated carbon fiber (ACF-La) was developed by batch and continuous column adsorption method. The batch sorption condition with respect to interfering ions was tested, and the pseudo second-order and intraparticle diffusion models were used to evaluate the adsorption kinetics of phosphate onto ACF-La in the presence of interfering ions, with the second-order model to fit the experimental data better. Moreover, three factors (phosphate concentration, flow rate, and interfering ions) were examined at column run method to evaluate the practical application of ACF-La to the continuous removal phosphate from solution. Furthermore, how the factors (eluted solution concentration, eluted time, and regeneration number) affect the regeneration efficiency of ACF-La was also investigated. These findings suggest that ACF-La has a considerable potential for the application of phosphate removal from contaminated waters.

Slaughterhouse waste water (SHW) is discarded as unused disposals into the environment every day. The objective of the present study is to explore the possibility on the utilization of SHW for the preparation of culture media to produce mosquitocidal bacterium (Bacillus thuringiensis subsp. israelensis). This would help to overcome the problem of dumping SHW in to environment. A judicial combination of SHW with a mineral salt (MnCl2) was made to produce an enhanced level of bacterial production when compared with other culture media including conventional medium (Luria Bertani, LB). A complete degradation of SHW by the bacteria was observed. The biomass yield, bacterial growth, toxin production, and larvicidal activity against mosquito vectors were satisfactory. Cell mass yield of 4.55 gm l−1 (dry wt) and larvicidal activity of 0.006 mg ml−1 and 0.026 mg ml−1 at LC50 and LC90 levels were observed, respectively, against the filarial vector of Culex quinquefasciatus with bacteria grown in SHW + MnCl2. The B. thuringiensis subsp. israelensis also controlled the larvae in the field significantly for three weeks (>90% mortality) and the effect was comparable with LB. Cost-analysis for production of B. thuringiensis subsp. israelensis showed that it is more economical. Thus, this study suggested the dual benefit of efficient production of mosquitocidal toxin and management of slaughterhouse wastewater.

The herbicide terbuthylazine is widely used within the EU; however, its frequent detection in surface and groundwater, together with its intrinsic toxicological properties, may pose a risk both for human and environmental health. Organic amendments have recently been proposed as a possible herbicide sorbent in soil, in order to limit herbicide movement from soil to water. The environmental fate of terbuthylazine depends not only in its mobility but also in its persistence. The latter is directly dependent on microbial degradation. For this reason, the effects of pine and oak residues on terbuthylazine soil microbial community functioning and on the potential of this community for terbuthylazine degradation were studied. For this purpose, degradation kinetics, soil dehydrogenase activity and the number of live bacteria were assessed in a clay loam soil treated with terbuthylazine and either amended with pine or oak wood or unamended (sterilised and non-sterilised). At day 65, 85 % of the herbicide applied still persisted in the sterile soil, 73 % in the pine-amended one and 63 % in the oak-amended and unamended ones. Pine residues increased the sorption of terbuthylazine to soil and hampered microbial degradation owing to its high terbuthylazine sorption capacity and a decrease in the bioavailability of the herbicide. On the contrary, in the presence of oak residues, the herbicide sorption did not increase significantly. The overall results confirm the active role of the soil microbial community in terbuthylazine degradation in amended and unamended soils and in a liquid enrichment culture performed using an aliquot of the same soil as the inoculum. In this clay loam soil, in the absence of amendments, the herbicide was found to be quite persistent (t ₁/₂ > 95 days), while in the enrichment culture, the same natural soil bacterial community was able to halve terbuthylazine in 24 days. The high terbuthylazine persistence in this soil was presumably ascribable to its texture and in particular to the mineralogy of the clay fraction.

The mechanisms for translocation of heavy metals from soil to epigeal mosses were investigated. The first mechanism was demonstrated for 137Cs and involved the uplifting of the pollutant-containing dust from the soil, followed by the local secondary deposition on surfaces of epigeal mosses and epiphytic lichens. The second mechanism involved the diffusion of metal cations from the soil through water wetting the moss into the gametophyte. The mechanism was demonstrated by measuring the electric conductance of wetted gametophytes with single ends immersed in solutions of Cu and Na salts. In addition, the concentrations of Cu and Cd were compared in moss samples exposed to the natural soil and to the soil contaminated with the metals. The exposition to the contaminated soil resulted in the statistically significant increase of metal concentrations in the gametophytes.

The modification effects of hematite with aluminum hydroxide were investigated on the removal of fluoride ions from water using batch experiments. The effects of pH, contact time, fluoride concentration, and the dose of sorbent on the sorption of fluoride ions by a modified hematite were studied. Characterization of hematite before and after the modification with aluminum hydroxide was studied by X-ray diffraction, scanning electron microscope, and Brunauer–Emmett–Teller. Equilibrium was reached in 48 h of contact time and the maximum sorption of fluoride was found in the pHeq range between 2.34 and 6.26. The Elovich model described the kinetic sorption processes and the Langmuir–Freundlich model, the sorption isotherm process. These results indicated that the sorption mechanism was chemisorption on a heterogeneous material.

The aim was to study the influence of soil properties on the leaching of nitrate, phosphate and organic matter (OM) following the application of sewage sludge to contrasting soils. Seventy agricultural soils from different parts of Spain were amended with sewage sludge (50 t dry weight ha−1), and a controlled column study was developed. After 2, 4 and 6 months of incubation, distilled water, equivalent to an autumn rainfall event of 25 l m−2 in Mediterranean environments, was applied and leachates collected and analysed: pH, electrical conductivity (EC), chemical oxygen demand (COD), phosphate and nitrate. The mean values of pH in the leachates after 2, 4 and 6 months were similar and close to the neutrality. The highest concentrations for the rest of the parameters analysed were found after 2 months of incubation and diminished for 4 and 6 months, especially COD. Soil pH and texture were the most relevant soil properties controlling the leaching of the analysed parameters. The OM mineralization seemed to be enhanced at high values of soil pH, thus increasing the nitrate and reducing the COD leaching. However, phosphate levels were reduced at high values of soil pH. In addition, leaching was promoted in sandy soils. Other soil properties influenced phosphate leaching being the equivalent calcium carbonate soil content as the most relevant. Soil organic carbon was negatively related to the EC and nitrate concentration in the leachates but resulting in a weak contribution compared with soil pH and texture. Concerns about nitrate pollution have been confirmed.

The effects of a five-pesticide mixture on pesticide accumulation, phytohormone levels (indole-3-acetic acid, gibberellic acid, jasmonic acid, and salicylic acid), pigment contents (total chlorophyll and carotenoid), antioxidant enzyme (catalase and guaiacol peroxidase) activities, lipid peroxidation product (malondialdehyde), and DNA profiles were investigated in the leaves of Veronica beccabunga. Laboratory-acclimatized plants were treated with a mix of five pesticides (atrazine, disulfoton, chlorpyrifos, metalaxyl, and ethion) in doses of 50 ppt, 1 ppb, 100 ppb, and 1 ppm for 1, 3, and 6 days. The accumulation of each pesticide, from highest to lowest, was as follows: chlorpyrifos, atrazine, metalaxyl, disulfoton, and ethion. The amounts of total chlorophyll and protein decreased with increased pesticide concentration. Antioxidant enzyme activities and malondialdehyde amount increased linearly with increasing pesticide exposure. However, the highest pesticide concentration caused decreases in guaiacol peroxidase (POD) activity and malondialdehyde (MDA) content at all treatment times. Both jasmonic and salicylic acid levels increased with pesticide exposure and decreased gradually after. It was also determined that application of the pesticide mixture affected the DNA profiles of V. beccabunga. The most band changes were detected on the sixth day of treatment.