The purpose of this piece of work is to study the process of adsorption of paracetamol on activated carbon, silica and alumina and their degradation using UV radiation. The results demonstrate a higher adsorption of paracetamol on alumina and activated carbon, while a minor value was observed in the case of silica. The H-bonding and π-stacking interactions between paracetamol and supports can be explained by the variation in the adsorption capacity values. When the paracetamol adsorbed was irradiated with two different UV irradiance values (59.78 mW cm⁻² and 119.56 mW cm⁻²) for 120 min, the higher degradation percentage was observed on activated carbon with a value of 79%. In the case of alumina and silica, the maximum percentages obtained were 65% and 77%, respectively. The incorporation of H₂O₂ in the reaction medium increases the rate of degradation, mainly at higher irradiance, reaching the maximum values in less time.

Ester-functionalized pyridinium ionic liquids (ILs), 1-decyloxycarbonylmethylpyridinium chloride (PyrСOOC₁₀-Cl), and 1-dodecyloxycarbonylmethylpyridinium chloride (PyrСOOC₁₂-Cl) have been synthesized and studied for their environmental toxicity. Simple long-chain pyridinium ILs, 1-dodecylpyridinium chloride (PyrC₁₂-Cl), and commercial disinfectant cetylpyridinium chloride (CPC) were used as reference compounds. Both ester-functionalized ILs and CPC showed significantly reduced antibacterial activity compared to PyrC₁₂-Cl. However, ester-functionalized ILs were found to have excellent antifungal activity towards Candida albicans fungus strains, similar to PyrC₁₂-Cl and much higher than for CPC. The molecular docking of ILs in the active site of the known antifungal target N-myristoyltransferase (Nmt) C. albicans has been conducted. The obtained results indicate the possibility of ILs binding into the Nmt pocket. The high stability of the complexes, especially for PyrCOOC₁₀-Cl, is ensured by hydrogen bonding, electrostatic anion-pi interactions, as well as hydrophobic pi-alkyl and alkyl interactions that was confirmed by calculated binding energy values. The acute toxicity studies of ester-functionalized ILs on D. rerio (zebrafish) hydrobiont have shown their dramatically reduced ecotoxicity compared to PyrC₁₂-Cl and CPC. Thus, LD₅₀ values of 15.2 mg/L and 16.8 mg/L were obtained for PyrCOOC₁₀-Cl and PyrCOOC₁₂-Cl, respectively, whereas CPC had LD₅₀ value of 0.018 mg/L. The primary biodegradation test CEC L-33-A93 of ILs indicated an improved biodegradability of ester-functionalized compounds compared to simple long-chain ILs. Based on the obtained results, PyrCOOC₁₀-Cl may be considered as very promising cationic biocide due to the combination of soft antimicrobial activity and reduced ecotoxicity, as well as improved biodegradability.

In order to get insight into the impact of Three Gorges Dam construction on silicon distribution pattern due to the altered hydraulic and environmental conditions, the Xiangxi River was chosen as the delegate of the tributaries in the Three Gorges Reservoir; dissolved silica (DSi), biogenic silica (BSi), and lithogenic silica (LSi) were investigated monthly from November 2015 to October 2016 and the hydrodynamic conditions and environmental parameters were addressed synchronously. DSi, BSi, and LSi ranged from 56.07 to 106.07 μmol/L, 0 to 5.64 μmol/L, and 0.49 to 11.47 μmol/L, with the average concentration of 81.84 ± 14.65 μmol/L, 1.11 ± 0.69 μmol/L, and 2.68 ± 1.97 μmol/L, respectively. DSi was significantly lower in the wet season than the dry season (P < 0.05), but BSi and LSi showed a converse trend. DSi was the dominant component in the total silicon (> 90%) and it has a higher concentration in the midstream than other sites. While BSi and LSi exhibited a decrease trend from the upstream to the downstream. Statistical analysis showed that DSi and LSi was primarily controlled by discharge. BSi concentration was affected by algal growth since it was positively correlated with Chla. The backwater area retained 3.67% total silicon. It was concluded that the spatiotemporal heterogeneity of silicon distribution related to hydrodynamics was determined by the regulation of dam; permanent backwater area was the main deposition area for silicon.

Anaerobic fermentation of waste activated sludge (WAS) for recycling valuable volatile fatty acids (VFAs) is economically valuable. However, the fermentation of protein is the rate-limiting step of VFA production with WAS as a substrate. In this study, the effect of redox mediators (RMs, i.e., riboflavin and lawsone) on the enhanced production of VFAs from WAS was investigated. The results indicate that both RMs can promote protein-dependent fermentation, increasing maximum VFA accumulation by 43.9% and 42.5% respectively. In cultures supplemented with riboflavin and lawsone, VFA production was highly correlated with protease activities, but not with α-glucosidase activities. This implies that RMs affected the redox reaction of amino acids degradation, resulting in an increased release of ammonia. Sequencing results showed that RMs significantly increased the abundance of bacteria related to VFA fermentation and protein/amino acid degradation at the levels of phylum, class, order, family, and even genus.

The freezing process consists of dissipating heat from the product until the final temperature is lower than the temperature of crystallisation of that product. Freezing can be used for numerous applications, including for disruption of waste-activated sludge (WAS). The aim of this study was to calculate the estimated amount of heat conveyed between the solidified carbon dioxide and the WAS, in the following ratios: 0.25:1; 0.5:1; 0.75:1 and 1:1. In heat of phase transformations, dry ice sublimation, water solidification, the amount of heat transferred by other substances and heat transferred from the sludge (dry sludge) were taken into account during the process of WAS freezing. Heat changes on the surface of WAS were registered using a thermovision camera. The effectiveness of WAS disintegration was confirmed by several biochemical parameters such as soluble chemical oxygen demand (increase over 14 times), degree of disintegration (48%), proteins (increase over 5 times), carbohydrates (increase almost 7 times), RNA (increase by 2.23 mg L⁻¹), ammonia nitrogen (increase over 23 times), phosphates (increase almost 27 times) and turbidity (increased over 7 times). It was found that dry ice pretreatment of WAS can be an intriguing alternative for the conventional methods used.

Pesticides are used worldwide in farming activities to guarantee crop yields. In southeastern Mexico, groundwater is the primary source of water for humankind. However, because of the soil characteristics and of intensive agricultural practices, the aquifer is vulnerable to pollution as shown by the regular detection of pesticide residues in groundwater. Within this context, the dissipation and adsorption of four of most used pesticides (2,4-D, atrazine, diazinon, and glyphosate) by farmers in southeastern Mexico were studied to determine their fate in agricultural soil and estimate their risk for the aquifer. Forty-one days after their application, the four pesticides were entirely dissipated from the soil. 2,4-D and glyphosate were the most persistent according to DT₅₀. Diazinon was the most adsorbed to the soil at equilibrium time. All pesticides were volatilized in substantial amounts, reaching 10.1, 22.3, 22.4, and 43.4% of initial amount 72 h after application of glyphosate, atrazine, 2,4-D, and diazinon, respectively. Volatilization was dependent on time and pesticide type (P < 0.05). Following their KOC, diazinon and glyphosate were found to be the most prone to leach. Therefore, in the absence of mitigation measures, their use represents a significant threat for the groundwater in Southeastern Mexico.

Huge amounts of natural bischofite (MgCl₂∙6H₂O) resulting from the mining process of salt lakes often cannot be utilized effectively and are discarded; techniques for reutilization of the discarded bischofite as magnesium resources are limited. The nano-magnesium hydroxide (nano-Mg(OH)₂) synthesized from natural bischofite was firstly used as catalyst for ozonation of antibiotics including sulfathiazole (ST), ofloxacin (OFL), and tetracycline (TC). Rapid ozonation of ST, OFL, and TC was achieved using nano-Mg(OH)₂ as catalyst. The removal rate constant of OFL in the catalytic ozonation treatment (kOFL = 0.512 min⁻¹) was nearly 2.1 times higher than the single ozonation (kOFL = 0.249 min⁻¹). The removal rate constant of ST and TC increased by 23.5% and 32.8% from 0.298 min⁻¹ and 0.384 min⁻¹ to 0.368 min⁻¹ and 0.510 min⁻¹, respectively, when the catalyst was added into the reaction system. The removal rate constant of ST sharply increased from 0.259 to 0.604 min⁻¹ when the reaction temperature increased from 15 to 35 °C while those of OFL and TC changes slightly. The removal efficiency sharply decreased when the initial concentration of ST, OFL, and TC increased from 10 to 500 mg L⁻¹. Both anions and cations could inhibit the removal of ST, OFL, and TC at relatively higher concentrations. The prepared nano-Mg(OH)₂ catalyst could maintain its catalytic activity in the repeated use process. High removal efficiency of typical antibiotics and heavy metals free indicated that nano-Mg(OH)₂ from natural bischofite is a promising ozonation catalyst in terms of antibiotics removal.

Constructed wetlands (CWs) and algae tanks are regarded as promising polishing steps to treat wastewaters for the removal of persistent organic pollutants, such as pharmaceuticals and personal care products (PPCPs). In this systematic review, we provide a synthesis of the relationship between the presence of the most widely studied PPCPs in domestic wastewater and the conformation of the CWs and algae tanks constructed to treat them. The six drugs most commonly found in the reviewed articles were caffeine, carbamazepine, diclofenac, ibuprofen, ketoprofen, and naproxen. Removal efficiency of the PPCPs was evaluated by means of the following selected parameters: hydraulic retention time (HRT), system flow rate, temperature, inflow concentration, and average removal rate. The average removal rate of PPCPs in CWs showed a positive and moderate relationship with the HRT (r = 0.346). A different flow configuration and plant species acted better for different target compounds. The average concentration reduction ranged from 80% for caffeine to zero reduction levels in some conformations for carbamazepine, diclofenac, and ketoprofen. There was a wide variation in the concentration reduction of different plant genera or unplanted tanks, ranging from 81% (caffeine using Phragmites sp.) to no reduction in an unplanted tank for diclofenac. The algae tanks were more efficient in removing most of the six target compounds than the wetlands. Removal rates ranged from 50% for ketoprofen to 16% for naproxen. According to our results, a combination of CW systems and algae tanks might be an effective alternative for the removal of PPCPs from domestic wastewater.

The degradation of organic contaminants in actual textile wastewater was carried out by iron carbon (Fe-C) micro-electrolysis. Different Fe-C micro-electrolysis systems (SIPA and SISA) were established by using scrap iron particle (SIP) and scrap iron shaving (SIS) as anode materials. The optimal condition of both systems was obtained at the initial pH of 3.0, dosage of 30 g/L and Fe/C mass ratio of 1:1. Commercial spherical Fe-C micro-electrolysis material (SFC) was used for comparison under the same condition. The results indicated that total organic carbon (TOC) and chroma removal efficiencies of SIPA and SISA were superior to that of SFC. Total iron concentration in solution and XRD analysis of electrode materials revealed that the former showed relatively high iron corrosion intensity and the physicochemical properties of scrap iron indeed affected the treatment capability. The UV-vis and 3DEEM analysis suggested that the pollutants degradation was mainly attributed to the combination of reduction and oxidation. Furthermore, the potential degradation pathways of actual textile wastewater were illustrated through the GC-MS analysis. Massive dyes, aliphatic acids, and textile auxiliaries were effectively degraded, and the SIPA and SISA exhibited higher performance on the degradation of benzene ring and dechlorination than that by SFC. In addition, SIPA and SISA exhibited high stability and excellent reusability at low cost. Graphical abstract

In light of growing concern and insufficient knowledge on the negative impact of aircraft emissions on environmental health, this study strives to investigate the air burden of major and trace elements caused by general aviation, piston-engine, and turboprop aircraft, within the vicinity of Eskisehir Hasan Polatkan Airport (Eskisehir, Turkey). The levels of 57 elements were investigated, based on moss bag biomonitoring using Sphagnum sp., along with chemical analyses of lubrication oil and aviation gasoline fuel used in the aircraft’s operations. Five sampling sites were selected within the vicinity of the airport area to capture spatial changes in the concentration of airborne elements. The study demonstrates that moss bag biomonitoring is a useful tool in the identification of differences in the air burden by major and trace elements that have concentrated downwind of the aircraft emission sources. Moreover, pollutant enrichment in the Sphagnum moss bags and elemental characterization of oil/fuel are in agreement suggesting that Pb, followed by Cd, Cu, Mo, Cr, Ni, Fe, Si, Zn, Na, P, Ca, Mg, and Al are dominant elements that shaped the general aviation aircraft emissions.