The sewage sludge contains abundant organic substances as well as a complex variety of inorganic substances (such as heavy metals). The extraction of protein from sludge is a new treatment approach to promote the utilization of sludge as a resource. However, heavy metals in sludge are extracted together with organic matter during the extraction process. In this study, the amounts of protein and heavy metal in the supernatant extracted from sewage sludge were investigated, and the effects of different passivator (modified fly ash and modified sepiolite) on the speciation of different heavy metals in the sludge were examined. Both materials reduced the contents of protein and heavy metal in the supernatant. When the dosage of sepiolite was 0.10 g/g total suspended solids of sludge, the content of heavy metals was the lowest and the protein content had little change. It can be deduced by analysis of specific area that sepiolite can complex with heavy metal ions and the fly ash adsorb the metals by physical adsorption. The modified sepiolite can be seen as an ideal passivator due to higher protein content and less heavy metals in the supernatant, as well as more stable heavy metals in the sediments.

The response of antioxidant enzymes to oxidative environmental stress was determined in 5th instar nymphs of Aiolopus thalassinus (Orthoptera: Acrididae) collected from sites with different level of pollution with heavy metals, PO₄³⁻, and SO₄²⁻. The high polluted site induced higher DNA damage to individuals compared to the control site. The highest values of tail length (TL), tail moment (TM), and percent of DNA in tail (TDNA) were found in the gut of 5th instar nymphs from a high polluted site. Also, protein carbonyls and lipid peroxide levels were significantly higher in insects collected from polluted sites compared to those from the control site. A strong positive correlation between both protein carbonyl and lipid peroxide concentration and the pollution level of the sites was found in all tissues of the insects. The activity of superoxide dismutase (SOD) in the brain of insects collected from the high polluted site was significantly higher than that in the thoracic muscles and gut. We observed strong inhibition of catalase (CAT) activity. This effect was apparently caused by pollutants present at the high polluted site. The level of pollution significantly influenced polyphenol oxidase (PPO) activity in A. thalassinus nymphs in all examined tissues. The highest values were observed in the brain. The relationship between pollution and ascorbate peroxidase (APOX) activity in the examined tissues had no clear tendency. However, the lowest APOX activity was observed in individuals from the low polluted site. Level of pollution of sampling sites, oxidative stress biomarkers, and enzymatic response in A. thalanthsis 5th instar were negatively or positively correlated. Oxidative damage parameters, especially the percent of severed cells, lipid peroxides, and the activity of APOX, can be perceived as good markers of environmental multistress.

In this study, thermochemical degradation of furfural by sulfate radical has been investigated to find the best-operating conditions. For this purpose, the response surface methodology (RSM) based on central composite design (CCD) was applied to optimize the five independent variables of thermally activated persulfate (TAP)/nZVI oxidation process including pH, PS concentration, furfural concentration, nZVI dosage, and heat. The ANOVA results (“P > F value” < 0.0001 and [Formula: see text] = 0.9701) showed the obtained quadratic model is acceptable to predict furfural removal. Based on the reduced quadratic model PS concentration, nZVI dosage, and heat revealed the positive effects on removal efficiency, while pH and furfural concentration had a negative effect. Accordingly, 98.4% of furfural could be removed within 60 min of reaction under the optimum conditions: pH 5.26, PS concentration of 20.52 mM, furfural concentration of 84.32 mg/L, nZVI dosage of 1.15 mg/L, and a temperature of 79 °C. In such circumstances, the furfural removal efficiency for TAP, PS/nZVI, PS, and nZVI was 94.5, 9, 3, and 2%, respectively. Therefore, based on the synergy index (SI) values, the combination of PS, nZVI, and heat can lead to a synergistic effect in the performance of the thermochemical process.

In this study, we report an effective degradation method for trace level beta-blockers (propranolol and acebutolol) in hospital wastewater using a new droplet flow-assisted heterogeneous electro-Fenton reactor (DFEF) system. Biogenic iron–carbon nanocomposites (RHS/C-x% Fe) as eco-friendly and low-cost heterogeneous Fenton catalysts were synthesized from rice husk via hydrolytic sol–gel routes. Here, we demonstrate the use of natural air as a nebulizing agent for fast and continuous catholyte air saturation and Fenton catalyst transfer to the cathode electrode. The effects of key operational parameters were evaluated and optimized using central composite design. Results clearly indicated that enhanced beta-blocker degradation was mainly dependent on the interactive effects of electrolysis time, current density, and catalyst dosage. Fast degradation efficiencies (≥ 99.9%) was recorded at neutral pH conditions. The decay followed pseudo-first-order kinetics with degradation rates of up to 2.72 × 10⁻² and 2.54 × 10⁻² min⁻¹ for acebutolol and propranolol, respectively. The synergistic contribution of •OHbᵤₗₖ attributable to DFEF process and •OHₐdₛₒᵣbₑd for anodic oxidation (AO) at the anode electrode significantly enhanced the degradation process. Compared to AO, the conventional flow-assisted electro-Fenton (FEF), and the batch electro-Fenton (BEF), DFEF degradation efficiency followed a decreasing order: DFEF ˃ FEF ˃ BEF˃ AO. This trend in performance was mainly due to the fast and continuous cathodic electro-generation of H₂O₂ and Fe²⁺ regeneration. Additionally, in order to elucidate degradation mechanism, we used a combination of DFEF approach with liquid chromatography-tandem mass spectrometry analysis. This approach demonstrates a simple, cleaner, and highly efficient degradation approach for trace level recalcitrant pollutants in a complex aquatic matrix, without the need for external chemical addition and pH adjustment.

The adsorption characteristics of C.I. basic blue 26 (BB26) from aqueous solutions onto H₃PO₄-activated carbons (ACs) produced from açai stones (Euterpe oleracea Martius) and Brazil nut shells (Bertholletia excelsa H. B. K) were investigated in a batch system. The ACs were characterized by XRD, FT-IR, N₂ adsorption at 77 K, mercury porosimetry, and acidity/basicity analysis. The pseudo-first-order, pseudo-second-order kinetic models and intraparticle diffusion model were used for the kinetic interpretations. The adsorption processes follow the pseudo-second-order kinetic model. The Boyd plots revealed that the adsorption processes were mainly controlled by film diffusion. Equilibrium data were analyzed by the Langmuir and Freundlich models, at different temperatures. The equilibrium data were best represented by the Langmuir isotherm. The adsorption processes were found to be favorable, exothermic, and spontaneous. The açai stones and Brazil nut shells-based ACs were shown to be effective adsorbents for removal of BB26 from aqueous solutions.

The aim of this study was to show the dynamics of changes in the activity of enzymes responsible for C, N, and S metabolism, i.e., cellulase, protease, urease, and arylsulfatase in two lignocellulosic composts as well as changes in the concentration of mineral forms important in plant nutrition (N-NH₄⁺, N-NO₃⁻, S-SO₄²⁻). Most of the enzyme activity was higher during 10 weeks of composting in compost I, containing higher amounts of easily available organic matter than in compost II. Enzymatic activities in compost II remained at a higher level for a longer time, but they increased at a slower rate. Mineral content changes in the compost mass consisted primarily of an increase in N-NO₃⁻ concentration and a decrease in N-NH₄⁺ and S-SO₄²⁻ levels, especially in compost I. The concentration of mineral nitrogen and sulfur forms in compost water extracts was about 10–100 times lower than in the compost mass. At the end of composting, the amount of sulfates in the compost mass was 30 and 150 mg kg⁻¹ dw in compost II and I, respectively. In this context, the composts obtained should be considered valuable for fertilizing soils poor in this component and for cultivating plants with high sulfate S demand.

The primary objective of this research was to investigate the cadmium (Cd) distribution in Pennisetum purpurem (Napier grass) in the presence of 30 mg/L of Cd and different types and concentrations of chelating agents (ethylenediaminetetraacetic acid disodium dihydrate (EDTA), nitrilotriacetic acid (NTA), and EDTA-NTA mixtures). Plant samples were collected every 15 d during a 105-d experimental period. Accumulation of Cd in each part of the plant was determined using atomic absorption spectrometer (AAS), and the distribution of Cd was determined by laser ablation inductively coupled plasma mass spectrometer (LA-ICP-MS) and synchrotron radiation micro X-ray fluorescence (SR-micro-XRF). The highest concentrations of Cd accumulation of 889 ± 53 mg kg⁻¹ in the underground part (roots) and 265 ± 26 mg kg⁻¹ in the aboveground part (stems and leaves) in the presence of 1:1 M ratio of Cd:EDTA after 30 d of exposure were observed. Plants grown in the presence of either NTA or EDTA-NTA mixtures showed significant lower Cd accumulation levels. The LA-ICP-MS analysis showed that Cd was primarily accumulated in the aboveground part (stems and leaves), especially in the xylem and intercalary meristem. In addition, translocation factor was very low. Thus, P. purpurem could be considered as a candidate plant for cadmium phytostabilization.

Environmental impact of livestock production has received a considerable public scrutiny because of the adverse effects of nutrient run-offs, primarily N and P, from agricultural land harboring intensive energy livestock operations. Hence, this study was designed to determine the efficacy of dietary phytase supplementation on fermentation of a sorghum grain–based total mixed ration (TMR) using a ruminal in vitro digestion approach. Phytase was supplemented at three doses: 0 (control), 540 (P540), and 720 (P720) g/t dry matter, equivalent to 0, 2.7 × 10⁶, and 3.6 × 10⁶ CFU/t DM, respectively. Compared to P720 and the control, gas production was higher for P540 after 12 h (P = 0.02) and 24 h (P = 0.03) of fermentation suggesting a higher microbial activity in response to phytase supplementation at lower phytase levels. Correspondingly, dry matter degradability was found to have improved in P540 and P720 compared to the control by 13 and 11% after 24 h of incubation (P = 0.05). For ammonia nitrogen (NH₃-N), a tendency towards lower values was only observed for P540 at 24 h of fermentation (P = 0.07), while minimal treatment effects were observed at other fermentation times. The concentrations of total volatile fatty acids (VFA) were higher (P < 0.05) after 48 h of fermentation for P540 and P720 compared to the control (P = 0.03) by 10% and 14%, respectively. Ruminal acetate tended towards higher values in the presence of phytase after 12 h of fermentation (P = 0.10), but towards lower values after 24 h of fermentation (P = 0.02), irrespective of the phytase dose applied. A trend towards lower ruminal propionate levels was observed in the presence of phytase after 6 h (P = 0.10) and 12 h (P = 0.06) of fermentation, while no effects were found at other fermentation times. In conclusion, phytase supplementation has the potential to improve metabolic energy activity of rumen microorganisms and the use of feed constituents. Thus, phytase supplementation could help to reduce environmental contamination in areas of ruminant production.

The purposes of this research are to quantify the concentration of heavy metals (Zn, Cu, As, Pb, Cd, and Hg) in the water and fish tissues of common carp (Cyprinus carpio) in the upper Mekong River and to thereby elucidate the potential dietary health risks from fish consumption of local residents. Surface water and fish tissues (gill, muscle, liver, and intestine) from four representative sample areas (influence by a cascade of four dams) along the river were analyzed for heavy metal concentrations. Results revealed that the levels of heavy metals in fish were tissue-dependent. The highest Cu and As levels were found in the liver; the highest Zn and Pb levels occurred in the intestine, and the highest Hg level was found in the muscle. The total target hazard quotient (THQ) value for residents is > 1 for long-term fish consumption, and local residents are, therefore, exposed to a significant health risk. Results from the current study provide an overall understanding of the spatial and tissue distribution of heavy metals in water and fish body along the upper Mekong River under the influence of cascade dams and highlight the potential health risk of As for the local residents of long-term fish consumption.

The study was conducted to evaluate the concentration of essential elements (Cu, Fe, Mn, Ni, Se, Zn, and B) and non-essential elements (Cd, Pb, Hg, Cr, As, and Ni) in muscle, liver, bone, and intestine of matured cattle egret (Bubulcus ibis). Sampling was carried out at two sites of Lahore, Pakistan—Havalian Karbath (site I) and Mehmood Booti (site II)—over a period of 1 month in the winter season. Metal analyses of samples were carried out using inductively coupled plasma mass spectroscopy (ICPMS). The trend of essential elements in liver and intestine of site I was noticed as Fe > Zn > Cu > B > Mn > Se > Ni and almost same for bone and muscle as Fe > Zn > B > Mn > Cu > Se > Ni. It was noticed that Cu was less deposited in bone and muscle tissues compared to liver and intestine from site I. The deposition of essential elements in liver and intestine from site II was noticed as Fe > Zn > Cu > Mn > B > Se > Ni. Similar trend was found for bone and muscle: Fe > Zn > B > Mn > Cu > Se > Ni with great deposition of B than Cu compared to liver and intestine. The findings of the present study revealed almost similar trend for essential elements deposition at both sites. However, a random trend was observed for deposition of non-essential elements (Ag, As, Ba, Cd, Cr, Hg, Pb) in organs from both sites. Moreover, data showed higher levels of non-essential elements accumulation (particularly As, Ba, and Pb) in the body tissues/organs of cattle egret in an urban area (site II) as compared to rural area (site I) of Lahore. Furthermore, non-essential elements were more in intestine, bone, and muscles from site II showing more exposure to some non-essential elements at urban site due to human and natural activities. However, higher concentration of non-essential elements in liver from site I as compared to other organs not only reflect the land exposure to plant growth promoting fertilizers and sewage water for irrigation purpose but also better detoxification abilities of the rural birds. The study gave a new insight to inform contamination levels in the rural and urban sites. Future implications of this study need remediation strategies to clean environment requisite for avian species.