In order to enhance the removal of heavy metals such as Ni, Cu, Zn and Cd from wastewater, different cow dung/sewage sludge ratios were tested to assess the effect of these metals on the adaptability of Eisenia fetida earthworms to the treatment process carried out in a typical plant located in Tamaulipas, Mexico. Two experimental water treatment setups were proposed. The first set of experiments was planned to determine the adequate sewage sludge/cow dung ratio(s), whereas the second arrangement was designed to evaluate the growth performance and fecundity of the earthworms under high heavy metal concentrations. To achieve the objectives, the experiments were conducted for 90 days under controlled environmental conditions. Maximum worm biomass and growth rates were attained in samples containing 25 wt.% of sewage sludge. Weight and mortality of worms were significantly affected by the high levels of heavy metals, making difficult the metal accumulation in the worm tissues.

The aim of the present study was the estimation of changes in the phytotoxicity of soils amended with sewage sludge with relation to Lepidium sativum, Sinapis alba and Sorghum saccharatum. The study was realised in the system of a plot experiment for a period of 29 months. Samples for analyses were taken at the beginning of the experiment, and then after 5, 17 and 29 months. Two kinds of sewage sludge, with varying properties, were added to a sandy soil (soil S) or a loamy soil (soil L) at the dose of 90 t/ha. The addition of sewage sludge to the soils at the start of the experiment caused a significant reduction of both seed germination capacity and root length of the test plants, the toxic effect being distinctly related to the test plant species. With the passage of time the negative effect of sewage sludge weakened, the extent of its reduction depending both of the kind of sewage sludge applied and on the type of soil. Phytotoxicity of the soils amended with the sewage sludges was significantly lower at the end of the experiment than at the beginning. The species of the plants grown on the soils also had a significant effect on their phytotoxicity. The greatest reduction of toxicity was observed in the soil on which no plants were grown (sandy soil) and in the soil under a culture of willow (loamy soil). Solid phase of sewage sludge-amended soils was characterised by higher toxicity than their extracts.

The Loxahatchee National Wildlife Refuge (Refuge) is impacted by inflows containing elevated contaminant concentrations originating from agricultural and urban areas. Water quality was analyzed using the Enhanced Refuge (ERN), the four-part test (FPTN), and the Consent Decree (CDN) monitoring networks within four zones in the Refuge. The zones were defined as the canal surrounding the marsh, the perimeter, the transition, and the interior zones. Although regression coefficients for ALK and SpC, and Ca, Cl, and SO₄ concentrations with distance from the canal were lower using the FPTN than when using the ERN, using the FPTN to measure water quality parameters in the Refuge would give similar results as the ERN. Most of the ERN and FPTN sites are located in the northern and central areas of the Refuge. Water is deeper in the southern Refuge, and on an area basis contains a greater volume of water than the northern and central Refuge and therefore, water flow from the canal into the marsh in the northern and southern Refuge may differ. Numerous water quality monitoring sites must be added to the ERN and FPTN in the southern area to characterize water quality in the southern Refuge with confidence.

Lime was investigated as a soil amendment to decrease phosphorus (P) loss in runoff from two Delaware sandy loam soils, one high and one low in P. Soils were limed at three rates (control and target pH values of 6 and 6.8, respectively), packed into runoff boxes (2,000 cm²) and received simulated rainfall (80 mm h⁻¹ for 30 min). Lime showed potential to decrease P loss in runoff, but its effectiveness was soil specific and dependant on other management factors also. Lime decreased dissolved reactive P (DRP) and dissolved organic P (DOP) loss by 20–25 and 52–93 %, respectively, for the high-P soil and particulate P (PP) by 13 % for the low-P soil. The majority of P lost in runoff was DOP (3–29 %) or PP (64–96 %). Lime increased PP losses from the finer-textured soil following P application, indicating that increased P sorption can lead to increased losses if P is sorbed to more erodable particles. Initial soil P status was more important than liming in determining P loss. While amendments may decrease P losses in the short term, addressing nutrient imbalances at the field scale is clearly necessary in the long term. Losses increased significantly following inorganic P application. Although P was sorbed rapidly, with less than 2 % of added P removed in runoff, mean concentrations in excess of 700 μg l⁻¹ DRP, 2,500 μg l⁻¹ OP and 6,500 μg l⁻¹ PP were recorded for both soils immediately following P application.

In situ remediation with waste material is an inexpensive method to reduce contaminant availability in polluted soil. The experiments were done to investigate the effects of possible in situ application of two different amendments: inorganic material (marble sludge) and organic material (horticultural waste compost) on chemical and biological properties of abandoned metalliferous mine wastes. The results show that the application of inorganic material raises the pH above neutrality and the combination of inorganic and organic material would produce the highest ratio of biological activity. The reductions of available Zn, Pb and As in lime, organic and lime/organic amendments were favoured by incubation time. However, available Cd content increased after 275 days of incubation, except the treatment with inorganic amendment. This work denoted that the application of lime with organic amendments has a better effect than the lime alone because the addition of both amendments improves both soil chemical and biological properties.

While interest in and adoption of graywater reuse for irrigation has rapidly grown in recent years, little is known about the long-term effects of graywater irrigation. Concerns exist in relation to the presence of pathogenic organisms, fate of personal care products, and accumulation of salts. The purpose of this research was to evaluate the long-term effects of graywater irrigation to soil quality under real conditions where homeowners may not always apply graywater in a highly controlled manner. Four households from different climatic and geological conditions were selected for sampling (AZ, CA, CO, and TX) where graywater was applied for irrigation for a minimum of 5 years. Soil samples were collected in areas irrigated with graywater and areas irrigated with freshwater within the same yard. Soil cores were taken at depths of 0–15, 15–30, and 30–100 cm and analyzed separately for surfactants, antimicrobials, sodium adsorption ratio (SAR), electrical conductivity (EC), extractable boron, fecal indicator organisms (E. coli, enterococci, and Clostridium perfringens), and soil dehydrogenase activity. In surface soil samples (0–15 cm), the average total surfactant concentration (over all sites) was higher in graywater-irrigated soil (0.078 ± 0.033) compared to freshwater-irrigated soil (0.030 ± 0.025 mg kg⁻¹). This difference was not found to be significant (P > 0.05). Triclosan and triclocarban were detected in surface soil samples at some locations (3.8–6.3 and 3.5–9.1 μg kg⁻¹, respectively), but not in samples deeper than 15 cm. Among the sampling locations, the TX household appeared to be most impacted by graywater, as evidenced by elevated SAR, potentially toxic levels of B, and relatively high numbers of E. coli and enterococci due to 30 years of graywater application for irrigation.

Gas dispersion in a set of three different porous materials with similar particle size, as a function of material tortuosity and anisotropy ratio, was investigated. The materials were packed with different spatial orientations of the individual particles so as to create media with different tortuosity and anisotropy ratios. Three different media (slate chips, wood chips, and pebbles) and four particle orientations have been used to generate a total of nine different porous media mimicking single porosity, dual porosity isotropic, anisotropic, aggregated, or granular materials. Resulting values of tortuosity and anisotropy ratio for each medium were determined via measurements of gas permeability and molecular gas diffusion coefficient. These values were then compared to measured values of gas dispersivity for each medium. The results showed that dispersivity is inversely proportional to tortuosity but directly proportional to anisotropy ratio and that the relations were approximately linear within the range of tortuosities and anisotropy ratios investigated. Wood chips (dual porosity material) yielded higher values of gas dispersivity compared to slate chips (single porosity material). A likely reason is in part the difference in pore structure between the materials and in part a difference in particle surface roughness (which was highest for wood chips) both of which affects dispersion.

A rapid, simple, sensitive and cost-effective analytical method has been standardised to determine the residues of imidacloprid and thiamethoxam in soil. This method does not require any cleanup with costly sorbents. The recoveries of imidacloprid and thiamethoxam obtained in this no-cleanup method were on par with the protocol involving primary–secondary amine-based cleanup. This method requires less volume of solvent (20 mL of acetonitrile/sample) and is suitable for high throughput analyses involving large number of samples. The limit of quantification of the method was 0.01 μg/g. Dissipation kinetics of imidacloprid and thiamethoxam in the soils of sugarcane ecosystem was studied by adopting this rapid method. The half-life of imidacloprid and thiamethoxam was 9.07 and 6.22 days when applied at 70 and 100 g a.i./ha, respectively. The dissipation of both the neonicotinoids followed first-order kinetics with good fit.

The sorption and desorption processes of Se(VI) onto non-living Eichhornia crassipes (E. crassipes) and Lemna minor (L. minor) were evaluated. Different pH values of the initial Se solution (20 μg L⁻¹) were tested at static conditions. At dynamic conditions of horizontal flow, biomass-packed columns (BPC) were estimated as prepared (pH 4) and unprepared (pH 6–7) and at different flow rates. The desorption process was tested using HCl (0.1 M) as the eluent. The maximum Se uptake took place at a pH of 4 for both biomasses. The lowest flow rate improves major Se removal due to the increase in contact time. The Se was desorbed from the biomass with elution efficiencies of 5 and 18 % for E. crassipes and L. minor, respectively. Nevertheless, more time was needed to increase these efficiencies and reach desaturation times. The breakthrough curves showed that unprepared E. crassipes and L. minor BPC at horizontal flow, with a flow rate of 6 and 4 mL min⁻¹ respectively, had a biomass removal capacity of 0.135 and 0.743 μg g⁻¹ correspondingly. The system of E. crassipes is more efficient, suggesting an ion exchange sorption mechanism. This demonstrates that non-living E. crassipes and L. minor have the capacity to remove Se from very dilute solutions.

Novel adsorption materials—Fe–Ni nanostructures and C/Fe–Ni composites—with the carbonaceous material coming from sewage sludge, have been developed and evaluated to remove indigo carmine from aqueous solution. The adsorbents were characterized by transmission and scanning electron microscopy, X-ray powder diffraction, IR spectroscopy and Brunauer–Emmett–Teller analysis. Sorption kinetics and isotherms were determined and the adsorption behaviours analysed. All adsorbents here studied have exhibited good efficiency to remove indigo carmine from aqueous solution. Pseudo-second-order kinetic and Langmuir–Freundlich isotherm models were successfully applied to the experimental data. Fe–Ni nanostructures adsorption capacity was 977.18 mg/g, followed by C/Fe–Ni 75/25% composite with 654.33 mg/g, and a lowest value, 486.41 mg/g, was obtained for C/Fe–Ni 95/5% composite. It can be suggested that the sorption mechanism of the dye is chemisorption on these heterogeneous novel, cheap and efficient functional materials. All materials provide the highest adsorption capacities in pH between 4 and 10. In addition, three sorption–desorption cycles using 30% H2O2 solution and distilled water were performed; sorption efficiencies of both composites (C/FeNi 75/25% and C/FeNi 95/5%) decreases in each cycle, but this behaviour is not observed for FeNi nanoscale oxides.