This paper deals with the comprehensive analysis for the removal of silver nanoparticles (AgNPs) from water environment. A new activated carbon derived from an agricultural waste, water lily mango seed shells, was proposed as a low-cost adsorbent to remove AgNPs. In addition, a new simple kinetic model was mathematically formulated and then tested using primary and secondary experimental AgNP adsorption data on different adsorbents. Moreover, cost analysis for the activated carbon production and removal of AgNPs was also estimated. Fourier-transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDX), and inductively coupled plasma mass spectroscopy (ICPMS) analyses were employed for the characterization. The proposed model evaluation was carried out using six statistical indicators, which are the coefficient of determination (R²), root mean squared error (RMSE), percentage of error in maximum estimated value (Eₘₐₓ), percentage of error in minimum estimated value (Eₘᵢₙ), mean absolute percent error (MAPE), and mean absolute deviation (MAD). This study found that the proposed activated carbon performed a rapid removal with a maximum percentage of up to 97%. It was also interesting to note that the proposed model outperformed existing kinetic models having the same number of parameters. Cost analysis carried out in this study exhibited that the activated carbon was highly economical compared with other water treatment technologies reported elsewhere.

The contamination of the environment by potentially toxic metals is highlighted by possible impacts of their high availability. Thus, the development of alternative absorbents that can be used in the remediation of contaminated areas, systems that are able to interact with these metals and affect their disposal, transportation, and bioavailability, is of great interest. Natural organic residue (NOR), often discarded as waste, is a promising alternative because it is capable of affecting the bioavailability of potentially toxic metals in the environment. This study assessed the interaction between NOR and NOR ashes (inorganic constituents) and lead ion (Pb²⁺), and its potential of adsorption, in order to analyze their use in contaminated areas. Two different NOR were evaluated and its structural characteristics presented differences in their organic material content and in its complexing capacity. NOR2 presented better capacity of complexing and adsorption of Pb²⁺ ions, performance that must be associated to the higher amount of organic matter present in the soil of this residue. In addition, the adsorption at pH 7.0 occurred through specific interactions with certain functional groups on the surface of NOR and NOR ashes. Besides that, the retention capacity of the Pb²⁺ ions was concentration dependent, in which the highest amount of mass will be the adsorbent retention. In light of this, the results obtained in this work highlight the importance of natural organic residues as a natural adsorbent material to lead removal.

This study aims to evaluate the practical potential of using constructed wetlands (CWs) for treating saline wastewater containing various heavy metals. The results demonstrated that CWs growing Canna indica with porous slag as substrate could efficiently remove heavy metals (Cu, Zn, Cd, and Pb) from saline wastewater at an electrical conductivity (EC) of 7 mS/cm, especially under low influent load. Salts with salinity level (characterized as EC) of 30 mS/cm suppressed the removal of some heavy metals, dependent on heavy metal species and their influent concentrations. The presence of salts in CWs can improve the accumulation of Cu, Zn, and Pb in plant tissues as compared to control treatment, irrespective of metal concentrations in solution. The influence of salts on Cd accumulation depended on both salinity levels and Cd concentrations in solution. Although more heavy metals were accumulated in roots than in shoots, the harvesting of aboveground plant materials is still efficient addition for heavy metal removal due to the greater biomass and growth rate of aboveground plant material. Furthermore, replacing all plants instead of preserving roots from harvested plants in CWs over a period of time is essential for heavy metal removal, because the continued accumulation by roots can be inhibited by the increasing accumulated heavy metals from saline wastewater.

Effluents form the swine livestock industry contain a high concentration of pollutants and require complex treatment systems. The most recurrent form to treat Swine wastewater is by a conventional anaerobic–aerobic treatment. For example, an up-flow anaerobic blanket sludge reactor followed by an activated sludge reactor. However, in many countries, a high percentage of producers are small or medium-sized farms that can afford neither complex treatment systems nor specialized operations. The present study assessed the performance of a novel and different combinations of treatment processes, based on changing the anaerobic systems that require a specialized operation for one very simple to operate for farm owners. The assessed system is composed by a septic tank in combination with an up-flow anaerobic filter packed with volcanic rocks and an aerobic biofilter packed with waste wood chips. The effect of the hydraulic residence time and the volumetric organic loading in the septic tank and up-flow anaerobic filter and the effect of surface hydraulic loading in the aerobic biofilter were also evaluated. The system efficiently removed chemical oxygen demand (86–93%), total suspended solids (91–97%), volatile suspended solids (86–97%), and ammoniacal nitrogen (86–87%), showing a constant removal efficiency under a VOL of between 5 and 14.6 kg COD m⁻³ d⁻¹in the up-flow anaerobic filter. The advantages of this system are that the packing materials can be available in rural zones and are sustainable; the whole system is cost-effective and easy to handle; thus, farmers can operate and maintain it with their own means.

The effects of crude ethanol derived leaf extract Trichodesma indicum (Linn) (Ex-Ti) and their chief derivatives were accessed on the survival and development of the dengue mosquito Ae. aegypti also their non-toxic activity against mosquito predator. T. indicum is recognized to be the vital weed plant and a promising herb in the traditional ayurvedic medicine. In this study, the GC-MS chromatogram of Ex-Ti showed higher peak area percentage for cis-10-Heptadecenoic acid (21.83%) followed by cycloheptadecanone (14.32%). The Ex-Ti displayed predominant mortality in larvae with 96.45 and 93.31% at the prominent dosage (200 ppm) against III and IV instar. Correspondingly, sub-lethal dosage against the enzymatic profile of III and IV instar showed downregulation of α,β-carboxylesterase and SOD protein profiles at the maximum concentration of 100 ppm. However, enzyme level of GST as well as CYP450 increased significantly dependent on sub-lethal concentration. Likewise, fecundity and hatchability of egg rate of dengue mosquito decreased to the sub-lethal concentration of Ex-Ti. Repellent assay illustrates that Ex-Ti concentration had greater protection time up to 210 min at 100 ppm. Also, activity of Ex-Ti on adult mosquito displayed 100% mortality at the maximum dosage of 600, 500 and 400 ppm within the period of 50, 60 and 70 min, respectively. Photomicrography screening showed that lethal dosage of Ex-Ti (100 ppm) produced severe morphological changes with dysregulation in their body parts as matched to the control. Effects of Ex-Ti on the Toxorhynchites splendens IV instar larvae showed less mortality (43.47%) even at the maximum dosage of 1500 ppm as matched to the chemical pesticide Temephos. Overall, the present research adds a toxicological valuation on the Ex-Ti and their active constituents as a larvicidal, repellent and adulticidal agents against the global burdening dengue mosquito.

2-Propanol (IPA) is a highly water-soluble volatile organic compound that is used in the cleaning and drying processes during semiconductor fabrication. IPA is also used as a disinfectant in the pharmacy field. Water scrubber processing is one of the methods used for IPA collection. However, water scrubbing requires wastewater treatment. In this study, we propose a decomposition system for IPA in the liquid phase based on a TiO₂ photocatalyst immobilized on nonwoven fabric (TiO₂ nonwoven fabric) and ozone microbubbles (MBs). The thick nonwoven fabric with immobilized TiO₂ exhibits a higher IPA removal rate than that exhibited by the pleated fabric. IPA decomposes to produce acetone, which can be further decomposed and possibly undergo mineralization. The entire water tank can be supplied with ozone by introducing the MB-forming ozone, which considerably affects the decomposition of IPA. The efficient decomposition of IPA was achieved by combining ozone MBs, TiO₂ nonwoven fabric, and ultraviolet irradiation, presumably because the photocatalyst promotes the mineralization of the decomposition product. Thus, the OH radicals from the O₃ MBs competitively captured in the decomposition product strongly promote the decomposition of IPA, enhancing the IPA decomposition rate.

Chlorinated aromatic organic compounds are extremely toxic to the environment and cause cancer to the human body. Pentachlorophenol (PCP) is a hydrophobic and ionic organic compound that is employed as a production material in various industries. Although the Taiwanese government has banned the use of PCP for years, large PCP-contaminated areas remain in Southern Taiwan. Chemical oxidation, which has been proposed as a viable method for restoring PCP-contaminated areas, involves the use of micronanosize birnessite (δ-MnO₂), which is a type of manganese oxide and a natural mineral in soil environments. The goal of this study was to simulate the decontamination of the underlying soil of the PCP-contaminated areas, which is situated in anaerobic and lightless environment. Through the use of a self-developed gas release and absorption reaction flask, the oxidative mineral decarboxylation and dechlorination effects of δ-MnO₂ on PCP in aerobic and anaerobic (with oxygen removed through the use of nitrogen) environments without light were investigated. Results indicated that adding δ-MnO₂ facilitated the oxidative decarboxylation and dechlorination of PCP and the release of Cl⁻ in an aerobic, lightless environment without microbial activity. In the anaerobic environment, the oxidative decarboxylation effect of δ-MnO₂ on PCP decreased significantly, and the dechlorination effect was the primary reaction. Accordingly, adding δ-MnO₂ inorganically destroys aromatic benzene and releases CO₂ and Cl⁻. The molar ratio between CO₂ and Cl⁻ was calculated to assess the mechanisms of the distinct reaction systems. The parameters and data acquired from the experiment, which involved simulating the conditions of the contaminated areas, can be used in planning the on-site management of the PCP contamination; in particular, these parameters and data provide a reference for eliminating PCP from underlying soil—including groundwater-saturated layers.

The increased use of heavy metals in process industries often results in the generation of large quantities of wastewater (WW) and aqueous waste (AW) containing mixtures of heavy metals such as copper and nickel. This research focuses on the electrochemical recovery of copper and nickel from acid pickling solutions used to treat metal surfaces. Using hull cells, beaker plating, and electrolytic cells in pilot scale (capacity 30 L), the most important parameters influencing the process have been identified (temperature, contact time, and current density). In total, about 60 tests were carried out on AW containing nickel and copper. The results of the tests carried out with copper-containing AW shows that removal yields are often higher than 50%; while the energy consumption is less than 15 kWh kg⁻¹ of metal deposited. The best removal efficiency (100%) was achieved by applying a current density of 6 A dm⁻² and the energy consumption was 2 kWh kg⁻¹. The tests carried out with AW containing nickel point out very low removal yields (< 20%) and very high energy consumption (even exceeding 300 kWh kg⁻¹). The best removal yield obtained, applying a current density of 3 A dm⁻², is 6.7% with an energy consumption of 40 kWh kg⁻¹ of metal removed. A costs analysis based on Metal Exchange value was carried out. The cost analysis suggests that the results, in terms of removal and recovery, obtained for these metals, in particular for copper, are very promising for an industrial application.

Urbanization development plays a vital role in the health of modern residents; however, there have been very limited researches to specifically and comprehensively explore the relationship between urbanization level evaluating indicators (ULEIs) and female health outcomes. The mortality rate of breast cancer (BC), cervical cancer (CC), and ovarian cancer (OC) and classified urbanization factor are collected at provincial level. Stepwise regression model (SRM) and geographically weighted regression model (GWRM) are conducted to obtain spatial relationship between the mortality rate of those cancer and ULEI. Our results show that there is remarkable difference of mortality rate of BC, CC, and OC in different provinces as well as higher BC, CC, and OC distributed in northern regions. The increase of value added of primary industry (VAPI), taxi, and coal consumption has detrimental effect on BC and CC. Fuel oil consumption (FOC) ultimately results in increase of mortality rate of BC and OC, and urban fixed asset investment (UFAI) poses a risk to increase the mortality rate of OC. Contrarily, natural gas consumption (NGC) appear to mitigate mortality rate of BC. In particular, our findings demonstrate that there exist spatial differences for VAPI, FOC, NGC, taxi, and coal consumption influencing BC, CC, and OC. It is suggested that policy makers should take account of regional discrepancy and implement a sustainable urbanization development considering female health.

Given the prevalence of nitrate and phosphate in surface and groundwater, it is important to develop technology for the simultaneous removal of nitrate and phosphate. In this study, we prepared the bimetallic nanoparticles of Fe coupled with copper or nickel supported on chelating resin DOW 3N (D-Fe/Ni and D-Fe/Cu) for removing nitrate and phosphate simultaneously. XPS profiles revealed that Cu has better ability than Ni to increase the stability of Fe nanoparticles and prevent nZVI from oxidation. The results showed that nitrate removal efficiencies by D-Fe/Ni and D-Fe/Cu were 98.7% and 95.5%, respectively and the phosphate removal efficiencies of D-Fe/Cu and D-Fe/Ni were 99.0% and 93.0%, respectively. Besides adsorption and coprecipitation as reported in previous studies, the mechanism of phosphate removal also includes the adsorption of the newly formed polymeric ligand exchanger (PLE). Moreover, in previous studies, the presence of phosphate had significant negative effects on the reduction of nitrate. However, in this study, the removal efficiency of nitrate was less affected with the increasing concentration of phosphate for D-Fe/Cu. This was mainly because D-Fe/Cu had higher adsorption capacity of phosphate due to the newly formed PLE according to the XPS depth profile analysis.