Carbon nanotubes (CNTs) synthesized by the catalytic decomposition of methane were used as the support for magnetic Fenton and photo-Fenton catalysts to treat real wastewater contaminated with dyes and Escherichia coli. The effect of methane flow, the use of diluent (N₂), and the reaction time in the production of CNTs were studied. An increase in the production of CNTs with increased CH₄ flow and a decrease over the reaction time were recorded. Catalysts with 1, 3, and 5% w/w Fe were obtained and characterized by several spectroscopic and microscopic techniques. Multi-walled CNTs and bamboo-like carbon nanofibers with average diameters of 44.0 nm and average lengths of 237.0 nm were obtained. The catalysts had Fe ₓ O y (oxide species) crystallite sizes between 10 and 18 nm and soft ferromagnetic properties. A factorial 3³ design was used for selecting variables for the catalytic tests, wherein the concentration of H₂O₂, the catalyst mass, and the percentage of iron were evaluated. Subsequently, kinetic experiments were performed. The photo-Fenton process (5% Fe, 200 mg, and 0.4 M H₂O₂) showed the best results in terms of total organic carbon (TOC) abatement, discoloration, and E. coli inactivation without leaching of Fe. Graphical Abstract ᅟ

This study compares the effect of heavy metals (Hg²⁺, Cu²⁺, and Pb²⁺) on the Rhodotorula mucilaginosa and Saccharomyces boulardii biofilm and planktonic cells. A MBECᵀᴹ-HTP assay was used to test the levels of tolerance to heavy metals. The minimum inhibitory concentration (MICp) and minimum lethal concentration (MLCp) of the R. mucilaginosa and S. boulardii planktonic cells were determined, as well as minimum biofilm eradication concentration (MBEC). Metal removal efficiency was determined by batch biosorption assay. Previous studies had focused on heavy metal tolerance and removal efficiency of planktonic cells from Rhodotorula species only. Hence, our study presents and compares results for metal tolerance and removal efficiency of the R. mucilaginosa planktonic cells and biofilm. Biofilm tolerance was higher than the planktonic cells. The R. mucilaginosa planktonic cells showed the tolerance in the presence of Hg²⁺ (MICp 0.08 mM), Cu²⁺ (MICp 6.40 mM), and Pb²⁺ (MICp 3.51 mM), while the S. boulardii planktonic cells only tolerated Pb²⁺ (MICp 0.43 mM). The R. mucilaginosa biofilm showed the highest tolerance in the presence of Hg²⁺ (MBEC >0.31 mM), Cu²⁺(MBEC >12.81 mM), Pb²⁺ (MBEC >7.12 mM), and obtained results were confirmed by fluorescence microscopy. S. boulardii did not show potential in biofilm formation. The R. mucilaginosa biofilm exhibited better efficiency in removal of all tested metals than the planktonic cells. Metal removal efficiency was in the range from 4.79–10.25% for planktonic cells and 91.71–95.39% for biofilm.

Although every year, thousands of people die from asbestos-related diseases, many people disregard things that are past. Meanwhile, a lot of people, in particular, in many Asia countries that have no guideline values for waterborne asbestos are currently in a fever of anxiety about the possibility of its health hazards. This study focused on a grasping the actual situation of asbestos in household tap water. An intensive collection of the tract drinking-water was conducted in Iksan, Korea (at six homes), and Fukuoka, Japan (at nine homes). After pretreatment, both morphological observation and elemental analysis were simultaneously carried out using a scanning electron microscopy (SEM) with an energy dispersive X-ray spectrometer (EDX). The concentrations of waterborne asbestos fiber varied from place to place in both local cities. Their average concentrations at all sites in Iksan and Fukuoka were 213.3 and 181.1 f/L, respectively. Although the measured values in this study were the sum of chrysotile, amosite, and crocidolite fibers with a high risk of cancer, they were found to be consistently below the MCL (the Maximum Contaminant Level recommended by the U.S. toxicological profile for Asbestos). A significant link was found between open water supply channels and waterborne asbestos. The backward wind trajectory projections indicated that the present water sampling sites might be affected by the airborne asbestos fiber in the upwind atmosphere.

The purpose of the study was to determine the role of land use, seasonality, and hydrometeorological conditions on the relationship between stream water potassium (K⁺) concentration and discharge during different types of floods—short- and long-duration rainfall floods as well as snowmelt floods on frozen and thawed soils. The research was conducted in small catchments (agricultural, woodland, mixed-use) in the Carpathian Foothills (Poland). In the woodland catchment, lower K⁺ concentrations were noted for each given specific runoff value for summer rainfall floods versus snowmelt floods (seasonal effect). In the agricultural and mixed-use catchments, the opposite was true due to their greater ability to flush K⁺ out of the soil in the summer. In the stream draining woodland catchment, higher K⁺ concentrations occurred during the rising limb than during the falling limb of the hydrograph (clockwise hysteresis) for all flood types, except for snowmelt floods with the ground not frozen. In the agricultural catchment, clockwise hystereses were produced for short- and long-duration rainfall floods caused by high-intensity, high-volume rainfall, while anticlockwise hystereses were produced for short- and long-duration rainfall floods caused by low-intensity, low-volume rainfall as well as during snowmelt floods with the soil frozen and not frozen. In the mixed-use catchment, the hysteresis direction was also affected by different lag times for water reaching stream channels from areas with different land use. K⁺ hystereses for the woodland catchment were more narrow than those for the agricultural and mixed-use catchments due to a smaller pool of K⁺ in the woodland catchment. In all streams, the widest hystereses were produced for rainfall floods preceded by a long period without rainfall.

The mechanisms by which complex products released from the organic matrix of cattle manure impact phosphorus (P) behavior and transport are largely undefined. Effects of a dairy slurry isolate on sorption characteristics of three benchmark soils and the breakthrough of phytate-P were determined in short soil columns of Mattapex loam (fine-silty, mixed, active, mesic Aquic Hapludults) under saturated flow conditions. The manure liquid isolate was obtained after a 7-day incubation of reconstituted dairy manure (1.6:1, feces-to-urine) at 37 °C and centrifugation at 16,000×g. The liquid isolate, at dilutions of 20:1 to 4:1 water-to-isolate, decreased soil sorption of phytate-P, with reduction in logₑ K averaging 30%. Whether the influent contained artificial rainwater or the manure isolate at a water-to-isolate ratio of 20:1, P retention and breakthrough curves were differentially impacted. Only inorganic phosphate-P was eluted in a multiple-stage process, and breakthrough occurred after 16 pore volumes of rainwater. Both inorganic- and enzyme-labile P (TBIOP) appeared in the effluent when either a dilute solution of 0.05 M EDTA (ethylenediamine-N, N, N′, N′-tetraacetate) or one containing 5% of manure liquid isolate was used as influent. The polydentate ligand-like substances reduced (i) the soil’s affinity for phytate and (ii) the hydrolysis rate in soil, allowing phytate to be eluted. Therefore, dissolved components of the manure matrix played critical roles in controlling transport and dispersion of phytate-derived P forms in soil and may hold the key to the understanding of biogeochemical bases of persistent effects of legacy P in agricultural watersheds.

Dynamics of chemical characteristics and hygienic quality, particularly nutrients, heavy metals, and bacterial pathogens, were investigated along the storage of anaerobically digested slurry derived from chicken and pig manure. The average total solid (TS) content decreased by 3.6 and 24.1%, while soluble chemical oxygen demand (SCOD) decreased by 23.7 and 31.4%, in chicken manure- and pig manure-digested slurries storage, respectively. A rapid increase in NH₄ ⁺-N concentration from 1600 to 4800 mg/L in chicken manure-digested slurry and from 1200 to 1700 mg/L in pig manure-digested slurry was noted, particularly during the first 10 days of storage. A positive correlation between TS and content of heavy metals (Cu, Zn, Cr, and Pb) in the digested slurry was clearly shown. These metals are mainly associated with suspended particles and tend to be settled in the bottom during the storage process. Increasing attention should be paid to the land application of these bottom-settled digestates with higher TS content. The number of total coliforms and Escherichia coli in the both digested slurries decreased continuously during the whole storage period. The higher reduction rate observed during the storage of chicken manure-digested slurry may be due to the higher content of NH₄ ⁺-N, which may cause the inhibition of gram-negative bacteria. The results of this study provides a better understanding of the storage process of anaerobically digested slurry, which could benefit the digested slurry further utilization as agriculture fertilizer.

Activated carbon has widespread application in antibiotic-loaded wastewater treatment in recent years, owing to its developed pore structure, high superficies reactivity, and excellent mechanical and chemical stability. In this work, sorption experiments of four representative antibiotics, including sulfadiazine (SDZ), norfloxacin (NOR), metronidazole (MDE), and tetracycline (TC), over granular activated carbon (GAC), which was made from maize straw, were firstly studied. Kinetics, mechanism, and isotherm models related to the sorption process were employed. Results revealed that the sorption capacity by GAC followed the order SDZ > NOR > MDE > TC. The sorption kinetics of the four antibiotics well conformed to the pseudo-second-order model. Both the Weber-Morris intraparticle diffusion and Boyd kinetic models conveyed the information that film diffusion was dominant in the sorption process. The sorption isotherm was better fitted to the Langmuir model. This research may pave a basic way for removing antibiotics in municipal and industrial wastewater by activated carbon.

Phytoremediation using vetiver grass (Vetiveria zizanioides) has been regarded as an effective technique for removing contaminants in polluted water. This study was conducted to assess the removal efficiency of heavy metals (Cu, Fe, Mn, Pb, Zn) using vetiver grass (VG) at different root lengths and densities and to determine metals uptake rate by plant parts (root and shoot) between treatments (low and high concentration). Removal efficiency for heavy metals in water by VG is ranked in the order of Fe>Pb>Cu>Mn>Zn. Results showed that VG was effective in removing all the heavy metals, but removals greatly depend on root length, plant density and metal concentration. Longer root length and higher density showed greater removals of heavy metals due to increased surface area for metal absorption by plant roots. Results also demonstrated significant difference of heavy metals uptake in plant parts at different concentrations indicating that root has high tolerance towards elevated concentration of heavy metals. However, the effects were less significant in plant shoot suggesting that metals uptake were generally higher in root than in shoot. The findings have shown potential of VG in phytoremediation for heavy metals removal in water thus providing significant implication for treatment of metal-contaminated water.

The setting-up of anammox granules reactor is time-consuming and highly sensitive to the environment. Metal ions were reported to facilitate granulation; however, there is no report of a practical guide to metal ion application in anammox, especially relative to the effects of different ions at different concentrations on granulation. Adding recycle to reactors is important in treating industrial wastewater with high levels of NH₄ ⁺-N, but the optimum recycle ratio is still unclear. This study investigated the effect of Ca, Mg, Fe ions, their concentration, and recycle ratio of an upflow anaerobic sludge blanket reactor on anammox granulation as well as on reactor performance. The main physical properties of granules tested were sludge granulation rate, settling velocity, mixed liquor suspended solids (MLSS), mixed liquor volatile suspended solids/MLSS, and specific anammox activity (SAA)/nitrogen removal rate. The results demonstrated that introducing cations into cultivating mediums accelerates the anaerobic granulation process and improves specific anammox activity. In particular, Mg and Fe runs reached maximum SAAs with concentrations of 0.06 mmol/L and improved by ~ 25% of SAA compared with the control. SAAs of Ca runs were lower than those of Mg and Fe runs and showed a peak at a concentration of 0.03 mmol/L. In addition, recirculation enhanced the granulation. Granulation and retention of the anammox biomass were benefitted most when the recycle flow added was equal to the influent injection (noted as Q). Nitrogen removal also reached a maximum at Q, with removal efficiency of 97.3% with NH₄ ⁺-N and 98% with NO₂ ⁻-N. Thus, appropriately adding metal ions and recycle flow helped achieve quick setting-up and better performance. We also considered the relationship between four properties of granules tested and the performance of the reactor.

The effect of different Cr and Zn concentrations in the soil on the development of Albares wheat and Pedrezuela barley plants at the physiological, biochemical, and structural levels was evaluated during the crop cycle in a greenhouse assay, as well as their potential use in phytoremediation strategies. The accumulation of Cr and Zn in plants was dose-dependent for both cultivars. The highest contents were found in root and the lowest in grain. In the Cr treatments, the decrease with respect to the control in the biomass, relative water content (RWC), chlorophyll content (Chl), and chlorophyll fluorescence values (Fv/Fm) was more pronounced in wheat than in barley. For the Zn treatments, the behavior was the opposite. Barley showed less tolerance to Zn concentrations although its higher translocation factor (TF) and greater biomass make this plant adequate to use in phytoremediation process in soil contaminated with Zn. The electron microscopy studies showed evidence that treatment with both Cr and Zn produced alterations in the cellular ultrastructure of the plant leaves. Cr and Zn induced the production of malondialdehyde (MDA) in both cultivars; the highest concentrations were observed in barley leaves. In general, the ascorbate peroxidase activity (APX) was higher in the plants exposed to metal treatments. The catalase activity (CAT) showed a different behavior depending on the metal studied. These results highlight the potential capacity of Albares wheat for use in the phytoremediation of soils contaminated by Zn and of Pedrezuela barley for use in Cr- and Zn-contaminated soils.