Zeolitic tuff constitutes a technical and economical feasible alternative to manage acidic waters in initial phases of generation. A study of cation exchange with two zeolitic tuffs from Ecuador and one from Cuba has been conducted using breakthrough curve methodology. Cations Mn²⁺, Cd²⁺, Cr³⁺, Zn²⁺, and Al³⁺ have been chosen owing to their presence in underground water in exploration activities (decline development) in Fruta del Norte (Ecuador). Zeolites characterized by X-ray diffraction and thermal stability after heating overnight as heulandites show a similar exchange behavior for the five cations studied. The clinoptilolite sample Tasajeras shows a relevant cation exchange performance expressed in the important increment of spatial time to reach the breakthrough point in comparison with heulandite samples. The maximum length of unused beds was found for Cr³⁺ and Zn²⁺ cations showing, therefore, a lower adsorption performance in relation with Mn²⁺ and Cd²⁺. A final disposal method of metal-loaded zeolites with cement is proposed.

Microbial desalination cell (MDC) is a new approach for the synergy in bioelectricity generation, desalination and organic waste treatment without additional power input. However, current MDC systems cause salt accumulation in anodic wastewater and sludge. A microbial capacitive desalination cell (MCDC) with dewatered sludge as anodic substrate was developed to address the salt migration problem and improve the sludge recycling value by special designed-membrane assemblies, which consisted of cation exchange membranes (CEMs), layers of activated carbon cloth (ACC), and nickel foam. Experimental results indicated that the maximum power output of 2.06 W/m³ with open circuit voltage (OCV) of 0.942 V was produced in 42 days. When initial NaCl concentration was 2 g/L, the desalinization rate was about 15.5 mg/(L·h) in the first 24 h, indicating that the MCDC reactor was suitable to desalinize the low concentration salt solution rapidly. The conductivity of the anodic substrate decreased during the 42-day operation; the CEM/ACC/Ni assemblies could effectively restrict the salt accumulation in MCDC anode and promote dewatered sludge effective use by optimizing the dewatered sludge properties, such as organic matter, C/N, pH value, and electric conductivity (EC).

The estimation and modeling of streambed hydraulic conductivity (K) is an emerging interest due to its connection to water quality, aquatic habitat, and groundwater recharge. Existing research has found ways to sample and measure K at specific sites and with laboratory tests. The challenge undertaken was to review progress, relevance, complexity in understanding and modeling via statistical and geostatistical approaches, literature gaps, and suggestions toward future needs. This article provides an overview of factors and processes influencing streambed hydraulic conductivity (K) and its role in the stream–aquifer interaction. During our synthesis, we discuss the influence of geological, hydrological, biological, and anthropogenic factors that lead to variability of streambed substrates. Literature examples document findings to specific sites that help to portray the role of streambed K and other interrelated factors in the modeling of hyporheic and groundwater flow systems. However, studies utilizing an integrated, comprehensive database are limited, restricting the ability of broader application and understanding. Examples of in situ and laboratory methods of estimating hydraulic conductivity suggest challenges in acquiring representative samples and comparing results, considering the anisotropy and heterogeneity of fluvial bed materials and geohydrological conditions. Arriving at realistic statistical and spatial inference based on field and lab data collected is challenging, considering the possible sediment sources, processes, and complexity. Recognizing that the K for a given particle size group includes several to many orders of magnitude, modeling of streambed K and groundwater interaction remain conceptual and experimental. Advanced geostatistical techniques offer a wide range of univariate or multi-variate interpolation procedures such as kriging and variogram analysis that can be applied to these complex systems. Research available from various studies has been instrumental in developing sampling options, recognizing the significance of fluvial dynamics, the potential for filtration, transfer, and storage of high-quality groundwater, and importance to aquatic habitat and refuge during extreme conditions. Efforts in the characterization of natural and anthropogenic conditions, substrate materials, sediment loading, colmation, and other details highlight the great complexity and perhaps need for a database to compile relevant data. The effects on streambed hydraulic conductivity due to anthropogenic disturbances (in-stream gravel mining, contaminant release, benthic activity, etc.) are the areas that still need focus. An interdisciplinary (hydro-geo-biological) approach may be necessary to characterize the magnitude and variability of streambed K and fluxes at local, regional scales.

This study evaluated, at laboratory scale, if the using iron naturally present (0.3 mg L⁻¹) and adding 10 mg L⁻¹ of hydrogen peroxide was effective to remove 24.3 mgL⁻¹ of 2,4-dichlorophenoxyacetic acid (2,4-D) from groundwater samples by simulated solar irradiation (global intensity = 300 W m⁻²). Under these conditions, the degradation of 2,4-D reached 75.2 % and the apparition of its main oxidation byproduct 2,4-dichlorophenol (DCP) was observed. On the other hand, pH exhibited an increasing from 7.0 to 8.3 during the experiment. Experiments using Milli-Q water at pH 7.0, iron, and H₂O₂ concentrations of 0.3 and 10 mg L⁻¹, respectively, were carried out in order to study the effect of ions such as carbonate species, phosphate, and fluoride in typical concentrations often found in groundwater. Ion concentrations were combined by using a factorial experimental design 2³. Results showed that carbonates and fluoride did not produce a detrimental effect on the 2,4-D degradation, while phosphate inhibited the process. In this case, the pH increased also from 7.0 to 7.95 and 8.99. Effect of parameters such as pH, iron concentration, and hydrogen peroxide concentration on the 2,4-D degradation by the photo-Fenton process in groundwater was evaluated by using a factorial experimental design 2³. Results showed that the pH was the main parameter affecting the process. This study shows for the first time that using the photo-Fenton process at circumneutral pH and iron naturally present seems to be a promising process to remove pesticides from groundwater.

A novel analytical-scale concept to improve reliability of detection and analysis of natural and processed wastewater samples from a purification plant was developed. A sequential sample clean-up system of polymer-based octadecyl and silane-based quaternary amine sorbents were used for concentrating human based steroid hormones and their metabolites and detecting them by UV absorption with capillary electrophoresis (CE). The water samples were collected from influent and effluent processes of the water purification plant in Helsinki, Finland.The CE methods were partial-filling micellar electrokinetic chromatography and capillary zone electrophoresis. The analysis times and method concentration levels were optimized with eight steroids at the range of 0.5–10 mg/L. Since in CE the detectable quantities were higher than the existing amounts in the process waters, the real samples needed matrix removal combined with steroid enrichment. After 20,000-fold concentration testosterone-glucoside, androstenedione, progesterone, and estradiol-glucoside could be determined in the process water samples. The amounts of individual steroids in influent and effluent waters were 0–429 and 0–207 ng/L, respectively. Correspondently, their total amounts were 735 and 212 ng/L with excellent in day and inter-day repeatability. The RSD values were less than 1, 9.7, and 19% in repeated analyses, calculated from 60 analyses during 24 h, and from 130 analyses during 15 months, respectively. The steroid removal in purification process was 65% on average. The solid particles separated in three steps during the water clean-up concept contained 9.8–45 ng/g steroids in combined dry precipitates.

In this study, the quick, easy, cheap, effective, rugged, and safe (QuEChERS) method was applied for the analysis of the multiclass pesticide residues of 12 organochlorines (OCs), 9 organophosphates (OPs), 11 synthetic pyrethroids (SPs), 4 herbicides, 6 phthalates in raw tea (loose tea, branded tea and herbal tea), and tea infusion in 4 different containers (glass cup, earthen cup, plastic bag and disposal cup). In loose tea and branded tea residues, malathion (0.257 and 0.118 mg kg⁻¹), cypermethrin (0.065 and 0.030 mg kg⁻¹), and fenvalerate (0.032 and 0.030 mg kg⁻¹) were detected, respectively. In herbal tea, residues of only cypermethrin (0.053 mg kg⁻¹) and fenvalerate (0.045 mg kg⁻¹) were detected. Tea infusion samples contained in a plastic bag were found to be contaminated with only dibutyl phthalate (DBP) (0.038 mg kg⁻¹). Disposable cup was found to be contaminated with DBP (0.026 mg kg⁻¹) and diethyl phthalate (DEP) (0.004 mg kg⁻¹). Further, to know the processing behavior of pesticides, the spiked raw tea was subjected to tea infusion at different brewing times (2, 5, 10 min). The analysis demonstrated that dimethoate, dichlorvos, and malathion had shown more than 10 % of translocation at 5 min of brewing time. Further brewing for 10 min revealed the reduction in concentration of pesticides. Leaching of phthalate residues from different plastic containers was also studied at 10, 30, and 60 min. DBP, benzyl butyl phthalate (BzBP), and di-2-(ethylhexyl) phthalate (DEHP) were leached in the tea infusion samples packed in plastic bags. On the other hand, in disposable cups, leaching of DBP, DEP, and dimethyl phthalate were found. The concentration of phthalate residues increased with retention time. Pesticide and phthalate contaminants were recorded at low quantities in few samples only.

The number of cytostatic drugs used in cancer treatments is wide and increases every year; therefore, tools have been developed to predict their concentration in the environment to prioritize those for monitoring studies. In the present study, the predicted environmental concentrations (PECs) were calculated according to consumption data in Catalonia (NE Spain) for 2014. According to PECs and to the most widely reported compounds, 19 cytostatics were monitored in two sampling campaigns performed along the Besòs River. A total of seven drugs were detected at levels between 0.5 and 656 ng L⁻¹. PEC and measured environmental concentrations (MECs) were compared in order to validate PECs. The PEC/MEC ratio presented a good agreement between predicted and measured concentrations confirming the PEC estimations. Mycophenolic acid, prioritized as the compound with the highest PEC, was detected at the highest concentrations (8.5–656 ng L⁻¹) but showed no risk for aquatic organisms (risk quotient <1) considering acute toxicity tests performed in Daphnia magna.

We report a pyrolysis–gas chromatography/mass spectrometry (Py-GC/MS) method capable of analyzing traditional East Asian papers. The method proposed is based on rapid and easy single step Py-GC/MS analysis that can be carried out with a minimum amount of matter, in the few microgram range. Three reference papers manufactured from kozo (Broussonetia kazinoki Siebold & Zucc.), mitsumata (Edgeworthia chrysantha Lindl.), and gampi (Wikstroemia sikokiana Franch. & Sav.) with the traditional hand paper making processes were examined. The method allows discrimination between terpenic and steroid compounds, which were revealed as chemical markers of origin of the plant fibers. Each paper investigated was found to have characteristic pyrolysis fingerprints that were unique to the traditional handmade paper, demonstrating the potential for differentiation of these biochemical components of fiber plants on East Asian papers towards identification and conservation of cultural heritage. The investigation on Py-GC/MS was extended to liquid extraction followed by GC/MS analysis to characterize the biochemical components of fiber plants. The main contribution of this study is to provide molecular criteria for discriminating plant species used for traditional East Asian hand papermaking. Py-GC/MS complements efficiently microscope identification especially for adverse cases. A case study of archaeological Chinese paper painting artefacts was thereafter successfully investigated to address informative potential and efficiency of the criteria of identification on ancient and degraded East Asian paperworks.

This paper presents a technology of releasing phosphate from activated sludge by using a combined process of microwave irradiation and anaerobic stirring, followed by phosphate recovery from the resulting supernatant via chemical precipitation without addition of chemicals, except for a pH regulator. A series of experiments was conducted to examine the effects of microwave irradiation time, sludge solution pH, sludge concentration, and anaerobic stirring time on the release of phosphate. The results revealed that all of these parameters had a significant effect on the release of phosphate via the proposed combined process, and the combination of 180 s of microwave irradiation and 1 h of anaerobic stirring was found to give optimal phosphate release. When the sludge solution was acidized before pretreatment, the phosphate concentration of the supernatant increased rapidly. A 25 g/L sludge concentration was found to be optimal for the release of phosphate, beyond this concentration, there was no increase in the phosphate release. Under the optimal conditions of phosphate release (irradiation time, 180 s; solution pH, 2; sludge concentration, 25 g/L; anaerobic stirring time, 1 h), the total orthophosphate (PT) concentration in the supernatant reached 396 mg/L, accompanied by high concentrations of metal cations such as Ca, Mg, K, Al, and Fe. When the pH of the supernatant was adjusted to 9–10, the recovery efficiency of phosphate reached approximately 95 %. The analysis results indicated that the main components of the collected precipitates were amorphous calcium phosphate and struvite, which can be used as alternate phosphate minerals.

Strain selected from mine tailings in Anshan for Pb bioremediation was characterized at the genetic level by internal transcribed spacer (ITS) sequencing. Results revealed that the strain belongs to Mucor circinelloides. Bioremediation of lead-contaminated soil was conducted using Solanum nigrum L. combined with M. circinelloides. The removal efficacy was in the order microbial/phytoremediation > phytoremediation > microbial remediation > control. The bioremediation rates were 58.6, 47.2, and 40.2% in microbial/phytoremediation, microbial remediation, and phytoremediation groups, respectively. Inoculating soil with M. circinelloides enhanced Pb removal and S. nigrum L. growth. The bioaccumulation factor (BF, 1.43), enrichment factor (EF, 1.56), and translocation factor (TF, 1.35) were higher than unit, suggesting an efficient ability of S. nigrum L. in Pb bioremediation. Soil fertility was increased after bioremediation according to change in enzyme activities. The results indicated that inoculating S. nigrum L. with M. circinelloides enhanced its efficiency for phytoremediation of soil contaminated with Pb.