Exposure to complex organic substances present in textile wastewater has been considered a threat to human health and aquatic organisms. Development of appropriate treatment mechanisms, as well as sensitive monitoring assays, is considered important in order to safeguard and protect the delicate natural equilibrium in the environment. In this study, combined coagulation/flocculation and electrohydraulic discharge (EHD) system were explored for treatment of textile wastewater. Pre- and post-treatment samples were used to evaluate process efficiencies. Process efficiencies were evaluated using physicochemical characteristics, and cytotoxicity and inflammatory activities induced in macrophage RAW264.7 cell line. The RAW264.7 cell line was evaluated as an alternative to animals and human blood culture models, whose routine applications are hindered by stern ethical requirements. The toxicity of effluent was evaluated using WST-1 assay. The inflammatory activities were evaluated in RAW264.7 cell culture supernatant using nitric oxide (NO) and interleukin 6 (IL-6) as biomarkers of inflammation. The levels of NO and IL-6 were determined using the Griess reaction assay and double-antibody sandwich enzyme-linked immunoassay (DAS ELISA), respectively. Overall, the results of this study show that combined approaches and not the single EHD system are sufficient for complete removal of chemical oxygen demand (COD) and total organic carbon (TOC), toxicity and inflammatory activities in textile wastewater. The study shows that induction of NO and IL-6 secretions in macrophage RAW264.7 cells is a very sensitive model system to monitor the efficiency of textile effluent treatment processes.

Fully stabilized FeS nanoparticles were prepared with water-soluble carboxymethyl cellulose (CMC) as a stabilizer, and investigated for adsorption of lead (Pb²⁺) ions from simulated drinking water. The optimum particle stabilization was achieved using 0.0025 wt.% of CMC for 50 mg/L FeS (i.e., CMC-to-FeS molar ratio of 0.0005). The particle stabilization technique increased lead removal from 78.1% to 90.3%. However, further increasing the CMC-to-FeS molar ratio to 0.0025 diminished the removal. Rapid adsorption kinetics of Pb by CMC-FeS was observed with an equilibrium time of 240 min. The kinetic data was adequately fitted by a pseudo-second-order kinetic model. The adsorption isotherm showed a sigmoidal S-shape due to complexation of Pb with soluble CMC molecules, and the Sigmoidal isotherm model well fitted the adsorption isotherm data with a maximum monolayer adsorption capacity of 77.0 mg/g. FTIR and XRD analyses indicated that both surface complexation and chemical precipitation (in the form of PbS) were the dominant adsorption mechanisms. Pb uptake was enhanced with increasing CMC-FeS dosage from 10 to 125 mg/L and increasing pH from 4.5 to 8.5. The material can perform well under typical concentrations of a model humic acid (HA) and salts. Yet, unusually high concentrations of HA or hardness ions may exerted elevated inhibitive effect. The findings indicated that CMC-stabilized FeS nanoparticles are promising for effective immobilization of lead in contaminated water and soil.

The plasma electrolytic oxidation (PEO) technique was used to prepare photocatalytic S-TiO₂ coatings on Ti sheets; the incorporation of the S ions was possible from the electrolyte for modifying the structural and optics characteristics of the material. In this work, substrates of Ti (ASME SB-265 of 20 × 20 × 1 mm) were used in a PEO process in 10 min, using constant voltage pulses of 340 V with frequency of 1 kHz and duty cycles of 10% and of 30%. Solutions with H₂SO₄ (0.1 M) and CH₄N₂S (52 and 79 mM) were used as electrolytes. X-ray diffraction, scanning electron microscopy, and energy dispersive spectroscopy (EDS) were utilized to analyze the surface morphology, crystalline phase, and chemical composition of the samples. According to the results, the catalyst coatings had microporous structure and contained anatase-rutile TiO₂ nanocrystalline mixture, until 73.2% rutile and 26.8% anatase in the samples grown with 30% duty cycle and the lowest concentration of CH₄N₂S. From the EDS measurements, the incorporation of sulfur ions to the coatings was 0.08 wt%. 99.5% reduction efficiency of Cr(VI)-EDTA with sunlight was observed after 2 h; it was determined by diphenyl carbazide spectrophotometric method. These coatings have potential for effective sunlight heterogeneous photoreduction of this toxic, cumulative, and non-biodegradable heavy metal that contaminates the soil and water and is a serious risk to sustainability, ecosystems, and human health.

Salt-based preservation is practiced for decades in the leather industry because of its versatility, cost-effectiveness, and availability. The salt removed from the soaking process causes significant pollution including organic and elevated total dissolved solids (TDS). Hence, a low-salt skin preservation method using commercial sodium polyacrylate with a reduced quantity of sodium chloride aiming to retain leather properties and pollution reduction was the principal focus of the study. Commercial sodium polyacrylate initially characterized for water absorption capacity along with structural and functional properties is confirmed by NMR and IR spectroscopic techniques. In preliminary experiments, the process parameters attained optimized conditions of sodium polyacrylate (SPA) quantity (5%), a minimal amount of salt (15%), and contact time (4 h) required for skin preservation. Besides, reusability studies after SPA recovery (95%) were applied to skins with an optimized quantity of SPA and salt subsequently stored for 15 days along with control (40% salt). The results revealed that SPA with low salt aided an adequate curing efficiency with a substantial reduction (> 65%) of TDS and comparable physical and organoleptic properties on par with the conventional method. Overall, SPA supported low-salt skin preservation reduces pollutant load (TDS) caused due to using of 40% sodium chloride in the conventional curing process.

Controlled-release fertilizers (CRFs) are an effective approach in providing essential nutrients for plant growth while minimizing the loss of nutrients in water and air, reducing contamination risks. However, commercial CRFs often release nutrients either too quickly or slowly due to the properties of their coating materials (polymer or sulfur). In this work, a novel CRF technology was developed using chitosan (CS) and graphene oxide (GO) nanocomposites as coating materials. CS and GO solutions were applied at varying ratios in preparing different nanocomposites. CS and GO formed homogeneous nanocomposite films through their interactions with each other. Fertilizer beads were successfully encapsulated by the CS-GO films using the simple dipping method. Resulting CRFs showed controlled-release behaviors, with nutrient release lasting for about a week. Although additional investigations are required for further evaluation and optimization, this method presents a promising concept for an alternative fertilizer-coating technology.

Indirect potable reuse systems, which consist of wastewater treatment (WWT) and soil aquifer treatment (SAT), offer advantages such as their low cost and the underground storage of reuse water. In this study, the dissolved organic matter (DOM) profile of a sequential treatment system (i.e. WWT followed by SAT) was investigated using a pilot-scale SAT reactor. In addition, the biological DOM removal characteristics in the vadose zone of the SAT, which were found to play an important role in DOM removal for the entire SAT, were investigated using lab-scale reactors (LSRs). Composition of the removed DOM by WWT and SAT showed that the majority fraction of the removed DOM was different for the WWT (hydrophobic neutral 27.9%) and SAT (hydrophobic acids (HoA) 29.1%), suggesting that SAT exhibits unique DOM removal characteristics that contribute to water reclamation. Biological DOM removal was confirmed using the LSRs, and changes in the DOM removal characteristics 10–20 cm from the top of the vadose zone in the LSRs were revealed on the basis of the DOM fractionation and a BIOLOG assay, suggesting that microbial activity in the lower layer of the vadose zone contributed to the unique removal of the HoA fraction in the SAT.

The aim of this paper is to select feasible agricultural straws as high-quality sustained-release carbon source and examine the effect of determined agricultural organic waste on improving denitrification efficiency. Five kinds of agricultural straws, i.e., the rice straw, the corn straw, the wheat straw, the broomcorn straw, and the reed straw, were evaluated in a self-designed drawer-type biological filter. Results showed that the contents of C, H, and N in the five straws were 34.0~41.0%, 4.9~5.4%, and 1.1~1.5% respectively. The highest TOC release capacity of the rice straw was 12.4 ± 1.3 mg g⁻¹ and the average TOC release of other waste straws ranged from 6.0 to 9.2 mg g⁻¹. The TN release capacities of all the five straws were at a low level, ranging from 0.2 to 1.4 mg g⁻¹. Preliminary denitrification studies showed that the corn and the rice straw could be used as high-quality carbon sources, achieving a COD removal rate of 47.3~50.2% and a TN removal rate of 21.8~24.8% for wastewater with low C/N ratio. The rice straw and the corn straw founctioned both as favorable solid carbon sources and biofilm carriers; the carbon source quality of the corn straw lixivium is more beneficial to microbial utilization. The drawer-type biological filter has showed a good efficiency of denitrification for nitrogen removal when using agricultural straws as biofilm carriers.

Since the introduction of environmental legislations and directives, the impact of combined sewer overflows (CSO) on receiving water bodies has become a priority concern in water and wastewater treatment industry. Time-consuming and expensive local sampling and monitoring campaigns are usually carried out to estimate the characteristic flow and pollutant concentrations of CSO water. This study focuses on estimating the frequency and duration of wet-weather events and their impacts on influent flow and wastewater characteristics of the largest Italian wastewater treatment plant (WWTP) located in Castiglione Torinese. Eight years (viz. 2009–2016) of historical data in addition to arithmetic mean daily precipitation rates (PI) of the plant catchment area are elaborated. Relationships between PI and volumetric influent flow rate (Qᵢₙ), chemical oxygen demand (COD), ammonium (N-NH₄), and total suspended solids (TSS) are investigated. A time series data mining (TSDM) method is implemented with MATLAB computing package for segmentation of time series by use of a sliding window algorithm (SWA) to partition the available records associated with wet and dry weather events. According to the TSDM results, a case-specific wet-weather definition is proposed for the Castiglione Torinese WWTP. Two significant weather-based influent scenarios are assessed by kernel density estimation. The results confirm that the method suggested within this study based on plant routinely collected data can be used for planning the emergency response and long-term preparedness for extreme climate conditions in a WWTP. Implementing the obtained results in dynamic process simulation models can improve the plant operational efficiency in managing the fluctuating loads.

In this paper, we present a characterization of the optical properties of the aerosols emitted during biomass burning (BB) season in the period 2005–2009. Trends of aerosol optical depth (AOD), Angstrom exponent (α), and precipitable water (PW) were analyzed using a 5-year dataset from AErosol RObotic NETwork (AERONET) observations over Tuxtla Gutierrez (TG), Chiapas. The overall mean AOD (500 nm) during the 2005–2009 period was 0.26 ± 0.18. However, monthly mean values of AOD > 0.5 during the spring months (April and May) would indicate the high load of particles emitted by fires. The overall mean of α (440–870 nm) was 1.40 ± 0.21, which confirms the presence of fine aerosols. Additionally, the combined analysis of the α with its spectral curvature δα, and the results from the spectral de-convolution algorithm (SDA) shows that fine-mode aerosols dominated AOD variability in TG. In this paper, the trajectories of air masses (400 and 1500 m, a.s.l.) arriving at the TG site were classified by using backward trajectory cluster analysis. Trajectory clustering results indicate a BB regional transport from Central America that affects the atmosphere in southeastern Mexico. We use observations of fire radiative power (FRP) from the Moderate Resolution Imaging Spectroradiometer (MODIS) to study the incidence of wildfires and to estimate the BB emissions from 2005 to 2009 in southeastern Mexico. The results indicated a gradual decrease in fires throughout the years. Campeche and Yucatan are the states in southeastern Mexico where BB produces the highest emissions of carbon dioxide (CO₂), carbon monoxide (CO), black carbon (BC), and particulate material PM₂.₅. However, the largest emissions come from wildfires in Guatemala. Finally, to put in context the aerosol optical properties over southeastern Mexico, the sun photometric measurements in TG are compared with those retrieved from AERONET stations located in other tropical biomass burning regions (Brazil and Zambia).

Cobalt (Co) adsorption onto saline soil was investigated in this study. The effect of pH, interaction time, and initial concentration of Co on adsorption were evaluated empirically to screen the appropriate operating conditions. Three biosurfactant products (i.e., surfactin, trehalose lipids, rhamnolipid) each at two concentrations (1 and 2 critical micelle concentrations (CMCs)) were applied during Co adsorption. The adsorption kinetic models were explored and results indicated that the pseudo-second-order kinetic model fit the experimental data the best. Four isotherms, including Langmuir, Freundlich, Temkin, and Redlich-Peterson were used for regulating the Co adsorption with and without the addition of each biosurfactant. The research results show that Co has low mobility even with the existence of a biosurfactant. The findings help to better understand the adsorption behaviour of Co in saline soil so as to develop applicable remediation options.