Rapid tests provide an inexpensive, desirable alternative to standard laboratory analyses for testing advanced onsite wastewater treatment system (OWTS) effluent in the field. Despite their potential utility, their accuracy for analysis of effluent from advanced OWTS has not been assessed. We evaluated the accuracy of an initial suite of rapid tests commonly used to analyze wastewater (test strips for ammonium, pH, nitrate, and alkalinity; pH pocket meter; titration kit for dissolved oxygen (DO)) by comparing values obtained in the field to values obtained using standard laboratory methods. We tested final effluent from three different advanced nitrogen removal OWTS technologies sampled monthly for 7 months at 42 different sites within the greater Narragansett Bay watershed in Rhode Island, USA. Significant differences between values obtained using field and standard methods were found only for nitrate and pH test strips when the data were analyzed using ANOVA on ranks. However, regression analysis indicated that all test strip-based rapid methods and the DO titration kit produced values that deviated significantly from correspondence with standard analyses. When effluent samples were analyzed in the laboratory (to minimize sources of variability) using the same rapid tests, significant differences between rapid tests and standard analysis disappeared for all the tests. Evaluation of a suite of alternative rapid tests for ammonium, nitrate, pH, and alkalinity indicated that test kits for NH₄ ⁺ and multi-analysis test strips for pH provide accurate results in the field. Our results indicate that the accuracy of rapid tests needs to be evaluated under field conditions before they are used to assess effluent from advanced N-removing OWTS.

Because of the increasing frequency and intensity of unexpected natural disasters, providing safe drinking water for the affected population following a disaster has become a global challenge of growing concern. An onsite water supply technology that is portable, mobile, or modular is a more suitable and sustainable solution for the victims than transporting bottled water. In recent years, various water techniques, such as membrane-assisted technologies, have been proposed and successfully implemented in many places. Given the diversity of techniques available, the current challenge is how to scientifically identify the optimum options for different disaster scenarios. Hence, a fuzzy triangular-based multi-criteria, group decision-making tool was developed in this research. The approach was then applied to the selection of the most appropriate water technologies corresponding to the different emergency water supply scenarios. The results show this tool capable of facilitating scientific analysis in the evaluation and selection of emergency water technologies for enduring security drinking water supply in disaster relief.

Photolysis or photocatalysis may provide a process for mitigating ecological risks of naphthenic acids (NAs) contained in energy-derived waters such as refinery effluents and process waters. If effective, fixed-film TiO₂ photocatalysis of NAs could decrease operational expenses as well as capital costs for water treatment. The overall objective of this study was to measure rates and extents of photolysis and photocatalytic degradation of commercial NAs using bench-scale fixed-film TiO₂ and confirm changes in NA concentrations using sensitive vertebrate (fish = Pimephales promelas) and invertebrate (Daphnia magna) species. Specific objectives were to (1) measure rates and extents of degradation of commercial (Fluka) NAs throughout an 8-h duration of natural sunlight (“photolysis”) and natural sunlight in the presence of fixed-film TiO₂ (“photocatalysis”) and (2) measure changes in toxicity in terms of mortality with sentinel fish and microinvertebrate species. Bench-scale chambers using thin-film TiO₂ irradiated with natural sunlight were used to measure photocatalysis, and HPLC was used to quantify NAs. After 4 h in photocatalysis treatments, >92 % decline was observed with an average removal rate of 15.5 mg/L/h and half-life of 2 h. After 5 h of photocatalysis, there was no measurable NA toxicity for fish (P. promelas) or microinvertebrates (D. magna). Photocatalytic degradation achieved efficacious rates and extents of removal of Fluka NAs and eliminated acute toxicity to sentinel aquatic organisms, indicating the potential for application of this technology for mitigating ecological risks. Coupled with existing treatment processes (i.e., aerobic biodegradation), photocatalysis can augment rates and extents of NA removal from impacted waters.

Groundwater studies often involve using any one of geophysical, geological, geochemical, or chemical data in the assessment of its characteristics. An integrated method in using all the above had been carried out for more comprehensive and confirmative assessments along the Thandava River basin, India. The geophysical data included the recording of the vertical electrical soundings by Schlumberger array configuration in 50 stations along the basin. Thirty soil samples and rainfall data of 5 years included the geological data. Chemical characterizations for 117 groundwater water samples were carried for two seasons. This study proposes the advantages besides delineating the approach in carrying integrated rather than mere single parameter-based speculative study. This correlative and computer modeling aided study led to an in-depth along with confirmative assessments on various geological, geophysical, and chemical characteristics of the groundwater along with the pollution status. Comprehensive details of groundwater like geomorphology, potential water zones, flow pattern, soil types, geochemical evolution of ions, chemical status, and suitability can be accessed by applying this type of integrated study. Graphical Abstract ᅟ

TiO₂-graphene (TiO₂-GR) composites were successfully prepared by a two-step solvothermal method using titanium dioxide and natural graphite powder. X-ray diffraction (XRD) patterns showed that graphene oxide (GO) was prepared from natural flake graphite by a modified hydrothermal pressurized oxidation method. The results of Fourier transform infrared spectroscopy (FTIR) proved that TiO₂-GR composites were synthesized during the process of hydrothermal reaction while GO was changed into graphene. X-ray photoelectron spectroscopy (XPS) demonstrated that TiO₂ particles contacted closely with graphene via Ti–O–C bonds. The results of Raman spectra confirmed the existence of graphene in the TiO₂-GR composite. Scanning electron microscopy (SEM) images showed that TiO₂ particles were oval and grafted on the graphene sheet which was smooth with ripples. UV-visible diffuse reflectance spectra demonstrated that there was a red shift in the absorption edge of TiO₂-GR composite. The experimental results indicated that the TiO₂-GR composite had significantly adsorption-photocatalytic activity for the degradation of methylene blue (MB) dyes. The adsorption capacity (q ₘₐₓ) of TiO₂-6%GR-4h for MB was 41.32 mg ⋅ g⁻ ¹ calculated based on the Langmuir adsorption model, which was about 3.3 times the adsorption capacity of TiO₂. Adsorption kinetics studies showed that the adsorption process fit well with the pseudo-second-order model. It proved that the TiO₂-GR composites were more efficient than the pure TiO₂ in the field of environmental protection.

Polyether trisiloxane surfactants are widespread used as agricultural adjuvants because they increase the activity and the rainfastness of pesticides. On the contrary to pesticides, the environmental fate of agricultural adjuvants has not been much investigated, yet. Especially for trisiloxane surfactants, the knowledge on their environmental fate is scarce. To fill this gap, the mobility of a polyether trisiloxane surfactant on soil was studied. With a sorption batch equilibrium method, distribution coefficients between water and soil (K d, K ₒc, and K cₗₐy) were estimated for two standard soils (loam and sandy loam) and for every homologue of the trisiloxane surfactant. The obtained values for K d were between 15 and 135 cm³ g⁻¹, indicating that the trisiloxane surfactant is only slightly mobile in soil. The leaching in soil column was studied in a worst case scenario where the application of the trisiloxane surfactant was done on quartz sand and was immediately followed by a heavy rainfall. Less than 0.01 % of the initially applied trisiloxane surfactant had leached through 20 cm of quartz sand. Based on the K d values and the leaching in a soil column, the studied trisiloxane surfactant seems to be unlikely to leach through soil after application as agricultural adjuvant.

Reactive extraction of phenol (0.053 mol kg⁻¹) from aqueous solution is carried out using two aminic extractants, trioctylmethylammoniumchloride (TOMAC) and trioctylamine (TOA) considering four concentrations (0.023 to 0.091 mol kg⁻¹) and dissolving them in solvents like nonane and isoamyl alcohol (IAA) at 298 K. The effects of extract type (TOMAC and TOA), their concentrations, and type of diluent on the separation efficiency of extraction have been determined. Data show that the neutral phenol molecule is more effectively extracted by TOA than TOMAC into the organic phase. Increase in the extractant concentration from 0.023 to 0.091 mol kg⁻¹ obviously enhances the recovery of phenol (2.3 times with nonane + TOMAC or TOA; 2.97 times with IAA + TOMAC; and 4.83 times with IAA + TOA). The equilibrium extraction results are presented in terms of distribution coefficient (D), degree of extraction (%E), and loading ratio (Z). Maximum value of D (=12.25) is obtained with TOA + IAA (0.091 mol kg⁻¹) which could extract 92.45 % of phenol from the water phase. A suitable mathematical model for the determination of equilibrium D is expressed by employing the mass action law. The equilibrium constant (K E) and the stoichiometric coefficient (n) of extraction are determined graphically. Also, the individual equilibrium constants (K ₁₁, K ₂₁, and K ₁₂) for the phenol-extractant complexes formed are estimated from the regression of the experimental values. The better extraction power of the TOA + IAA extract system is also shown from the estimated value of complexation constant (K E = 164.44). Phenol molecules form 1:1 and 2:1 and 1:1 and 1:2 solvates with nonane and IAA, respectively, with both the extractants.

This study focused on the treatment of effluent contaminated with chromium, being driven by the application of magnetic field studies in living cells and organisms. The objective was to quantify the removal of chromium(VI), total chromium, and total organic carbon (TOC) by applying a magnetic field generated by permanent magnets of neodymium in mixed culture. The resistance of microorganisms was evaluated for 4 h and 17 min against the application of a magnetic field at frequencies of 3, 5, and 10 Hz, which correspond to flow rates of 3.93, 7.07, and 14.92 cm³ s⁻¹ in the system loop, respectively. The initial concentration of Cr(VI) was 100 mg L⁻¹. The magnetic field frequency of 5 Hz showed a higher removal of Cr(VI) (100 %), total chromium (82 %), and TOC (34 %) compared with frequencies of 3 and 10 Hz and the absence of magnetic field exposure.

In this study, column leaching experiments were used to evaluate the leachability, distribution and bioavailability of phenanthrene and pyrene by root exudates from contaminated mangrove sediments. We observed that root exudates significantly promoted the release and enhanced the bioavailability of phenanthrene and pyrene from sediment columns. The concentration of phenanthrene and pyrene and cumulative content released from the analyzed sediment samples following root exudate rinsing decreased in the following order: citric acid > oxalic acid > malic acid. After elution, the total concentrations of phenanthrene and pyrene in sediment layers followed a descending order of bottom (9–12 cm) > middle (5–7 cm) > top (0–3 cm). Furthermore, a positive correlation between leachate pH values and PAH concentrations of the leachate was found. Consequently, the addition of root exudates can increase the leachability and bioavailability of phenanthrene and pyrene.

Ivermectin (IVM) is a broad-spectrum antiparasitic drug that is regularly employed in veterinary medicine. In this work, the sorption and desorption of IVM in two Brazilian soils (N1-sand and S2-clay) as well as its leaching capacity, dissipation under aerobic conditions, and degradation in aqueous solution by photocatalysis with TiO₂ in suspension were evaluated. The kinetic sorption curves of IVM were adjusted to a pseudo-second-order model. The sorption and desorption data were well fitted with the Freundlich isotherms in the log form (r > 0.96). The Freundlich sorption coefficient (K F ᵃᵈˢ) and the Freundlich desorption coefficient (K F ᵈᵉˢ) were 77.7 and 120 μg¹⁻¹/ⁿ (cm³)¹/ⁿ g⁻¹ and 74.5 and 138 μg¹⁻¹/ⁿ (cm³)¹/ⁿ g⁻¹, for soils N1 and S2, respectively. A greater leaching capacity of IVM was observed for the sandy soil N1 than for the clay soil S2. Under aerobic conditions, the dissipation (DT₅₀) at 19.3 °C was 15.5 days (soil N1) and 11.5 days (soil S2). Photocatalysis with UVC and TiO₂ in suspension resulted in the degradation of 98 % of IVM (500 μg L⁻¹) in water in 600 s. The toxicity (Daphnia similis) of the solutions submitted to the photocatalytic process was completely eliminated after 10 min.