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[Display omitted] • HA contributed a limited TC binding through intermolecular weak interactions. • Unique fluorescence induced by Al3+–TC coordination tracked TC migration. • Coordination with Al3+/Fe3+ immobilized over 90 % TC on HA flocs. • High binding energy from coordination drove superior interfacial binding. In environmental matrices, the migration and distribution of contaminants at water–solid interfaces play a crucial role in their capture or dissemination. Scientists working in environmental remediation and wastewater treatment are increasingly aware of metal–contaminant coordination; however, interfacial behaviors remain underexplored. Here, we show that trivalent metal ions (e.g. Al3+ and Fe3+) mediate the migration of pollutant ligands (e.g. tetracycline (TC) and ofloxacin) to the organic solid interface. In the absence of Al3+, humic acid (HA) colloids (50 mg/L) capture 26.1 % of the TC in water (initial concentration: 10 mg/L) via weak intermolecular interactions (binding energy: −5.71 kcal/mol). Adding Al3+ (2.5 mg/L) significantly enhances the binding of TC to an impressive 94.2 % via Al3+ mediated coordination (binding energy: −84.89 kcal/mol). The significant increase in binding energy results in superior interfacial immobilization. However, excess free Al3+ competes for TC binding via direct binary coordination, as confirmed based on the unique fluorescence of Al3+–TC complexes. Density functional theory calculations reveal the intricate process of HA–Al3+ binding via carboxyl and phenolic hydroxyl sites. The HA–Al3+ flocs then leverage the remaining coordination capacity of Al3+ to chelate with TC. As well as providing insights into the pivotal role of metal ion on the self-purification of natural water bodies, our findings on the interfacial behavior of metal–contaminant coordination will propel coagulation technology to the capture of microscale pollutants. [ABSTRACT FROM AUTHOR]

Proteins are the dominant organic component of extracellular polymeric substances (EPS) in waste activated sludge (WAS), and play an important role during sludge dewatering processes. Methanol is a polar hydrophilic reagent and can denature proteins, which suggested to us that the modification of protein configurations with methanol could improve sludge dewatering performance. In this study, methanol was used to precondition WAS prior to adding inorganic coagulants for dewatering enhancement. The morphology and EPS properties (especially of proteins) were investigated to analyze and explain the effects of methanol in the sludge conditioning process. The results show that methanol performed much better than traditional inorganic coagulants in improving sludge dewaterability in term of specific resistance to filtration (SRF) and cake solid content (CSC). Extractable proteins in EPS increased to a maximum when the concentration of methanol reached 40% (w/w) because cell membranes were destroyed and intracellular substances and water were released. Floc protein content was reduced with the further increase in methanol concentration due to protein precipitation. Confocal laser scanning microscopy analysis indicated that proteins precipitated and formed larger aggregates because methanol destroyed both the hydration shell and the hydrophobic clusters of proteins and expanded the protein tertiary structure to release interstitial water and bound water. The combination treatment of methanol and inorganic coagulants (PAC or FeCl 3 ) showed significant synergetic effects on enhancing sludge dewatering and cake drying. In practical applications, methanol from the dewatering sludge can be returned to the biochemical pool and used as the carbon source for nitrogen removal in the denitrification process. This integrated process is appropriate for sludge final disposal technologies that have high energy demands, such as incineration and pyrolysis. This paper describes a novel approach to improving sludge dewaterability through the alteration of protein properties by use of physiochemical techniques. [ABSTRACT FROM AUTHOR]

Parenting is a demanding task associated with parents' mental health, which is likely exacerbated by the COVID-19 pandemic lockdown. The present study investigated daily parenting hassles and their effects on parents' mental health during this period. A total of 7314 parents with children aged 3–14 years old completed a sociodemographic questionnaire and reported on their perceived daily parenting hassles, mental health, family support, and co-parenting during the COVID-19 school closure. Most parents (73.4%) showed different degrees of daily hassles, and a relatively higher prevalence of depression (18.7%), anxiety (22.4%), and stress (12.1%) were found. Motherhood, parents' younger ages, lower education parents, job loss, and having younger children, boys, and multiple children were associated with elevated daily parenting hassles and mental health issues. Importantly, daily parenting hassles were uniquely associated with mental health problems after controlling for various sociodemographic characteristics, family support, and co-parenting. Furthermore, family support and co-parenting can attenuate daily parenting hassles, which, in turn, protect parents' mental health. The findings of the present study underscore the critical need to consider daily parenting hassles and their effects on the mental health of parents during the COVID-19 lockdown. The present study also outlines potential factors (family support and co-parenting) that attenuate parents' daily parenting hassles and protect their mental health during the COVID-19 lockdown. • School closure during the pandemic changed daily family life routines. • Perceived daily parenting hassles increased during COVID-19 school closure. • Parenting daily hassles increased depressive, stress, and anxiety symptoms. • Family support and coparenting can attenuate daily parenting hassles. [ABSTRACT FROM AUTHOR]

• The presence of MRPs significantly inhibited the activity of extracellular lysozyme. • The MRPs-lysozyme interaction is a spontaneous exothermic process. • Aromatic structures with polar N atoms in MRPs interacted strongly with proteins. • H-bond and aromatic stacking occurred simultaneously in MRPs-Lysozyme complex. • The changes in protein secondary structure mainly contributed to enzyme activity decrease. Thermal hydrolysis pretreatment (THP) is often used to improve the anaerobic digestion performance of waste activated sludge (WAS) in wastewater treatment plants (WWTPs). During the THP process, the proteins and polysaccharides in the biomass will undergo hydrolysis and Maillard reaction, producing biorefractory organic substances, such as recalcitrant dissolved organic nitrogen (rDON) and melanoidins. In this study, a series of spectroscopy methods were used to quantitatively analyze the Maillard reaction of glucose and lysine, and the interaction mechanisms of the Maillard reaction products (MRPs) and lysozyme were investigated. Results showed that the typical aromatic heterocyclic structures in MRPs, such as pyrazine and furan, were found to quench molecular fluorescence of lysozyme, resulting in an unfolding of standard protein structure and increase in lysozyme hydrophobicity. Significant loss of enzyme activity was detected during this process. Thermodynamic parameters obtained from isothermal titration calorimetry (ITC) confirmed that the interaction between MRPs and lysozyme occurred both exothermically and spontaneously. Density functional theory (DFT) calculations suggested that the molecular interactions of MRPs and protein included parallel dislocation aromatic stacking, T-shaped vertical aromatic stacking, H-bond and H-bond coupled to aromatic stacking. [Display omitted] [ABSTRACT FROM AUTHOR]

• The interaction between EPS and TC was related to π–π stacking reaction and electrostatic interaction. • The presence of EPS could enhance the TC removal efficiency in PACl coagulation. • NH 2 in EPS and C O in TC were bridged by Al3+ responsible for TC coagulation. • Conjugated system of aromatic proteins and TC was coordinated with Al3+, which also contributed to TC removal. In this study, the effect of extracellular polymer substances on the tetracycline removal under hydroxyl aluminium treatment was investigated, and the molecular mechanisms of extracellular polymeric substances mediated coagulation of tetracycline were also explored. The results show that the presence of extracellular polymeric substances could significantly enhance the removal efficiency of tetracycline in hydroxyl aluminium coagulation. Findings suggest that tyrosine and tryptophan in extracellular proteins acted as binding sites to capture tetracycline. Evidences provided by the density functional theory calculations in combination with spectroscopy analysis indicated that two main mechanisms accounted for tetracycline removal in the presence of extracellular polymeric substances and polyaluminum chloride: (1) amino group in proteins and carbonyl in tetracycline were bridged by Al3+; (2) benzene rings in tryptophan and tyrosine were π–π stacked with tetracycline, and the amino group in complexes were further coordinated with Al3+. [ABSTRACT FROM AUTHOR]

• TCE sensitization mediated kidney disfunction and local renal pathological injury. • The complement was activated locally in kidney after TCE sensitization. • Local renal complement activation induces ET-1 signalling and ET-1-mediated inflammation. • Local renal complement activation affected NF-κBp65 and p38MAPK pathway activity. Trichloroethylene (TCE) is a widely used industrial solvent that causes trichloroethylene hypersensitivity syndrome (THS) with multi-system damage, including kidney injury. Clinical studies have shown that the complement system is important for TCE-induced kidney injury. Our previous study found excessive deposition of complement C3, mainly on the glomerulus, indicating that local renal complement is activated after TCE sensitisation. However, whether local renal complement activation mediates TCE-induced immune kidney injury and the underlying mechanisms remain unknown. Therefore, we established a TCE percutaneous sensitisation BALB/c mouse model to explore the mechanisms by pretreating with or without the complement activation antagonist, cathepsin L inhibitor (CatLi). As expected, more C3 and C3a were detected mainly on glomerulus of TCE positive sensitisation (TCE+) mice. Renal dysfunction and pathological damage were also clearly observed in TCE+ mice. Moreover, the mRNA and protein expression of ET-1 increased significantly with local renal complement activation after TCE sensitisation, leading to cytokines release and inflammation. In addition, activation of p38MAPK and NF-κBp65 pathways were detected in kidneys of TCE+ mice, and CatLi pretreatment decreased these changes through complement activation antagonisation. Our research uncovered a novel role of local renal complement activation during immune kidney injury after TCE sensitisation through induction of ET-1 signalling and inflammation. [ABSTRACT FROM AUTHOR]

Abstract Anaerobic digestion (AD) has been widely used in sludge treatment for biogas recovery, organic fraction stabilization, and sludge reduction. However, after AD, sludge filterability is extremely deteriorated due to the release of biopolymers and the formation of fine particles. AD sludge is generally rich in nutrients, mainly ammonium nitrogen and phosphates, that result from biopolymer degradation. We designed a conditioning process that combines the in-situ crystallization of magnesium ammonium phosphate (MAP), as a skeleton builder, with organic polymer flocculation. We show that crystallized MAP can bind with extracellular polymeric substance fractions to increase sludge floc density. The molecular structure and electrical charge of organic polymers importantly influence sludge particle flocculation and aggregation. We found that cationic polyacrylamides form flocs that aggregate with branching structures which are characterized by a larger size and a more compact structure. Simultaneous crystallization and flocculation produced by a magnesium–organic polymer gel improved AD dewaterability more than the separate addition of magnesium ions and organic polymers. The method of sludge conditioning that we propose was tested by extensive use in different AD sludge conditioning protocols. The method reduces the ammonium nitrogen load in AD liquor and increases the suitability of the biosolids for use as land fertilizer. Graphical abstract Image 1 Highlights • A novel AD sludge dewatering improvement process was proposed. • In-situ formed struvite could function as skeleton builders. • Molecular structure and charge property of PAM had important effects on sludge conditioning. • Mg-CPAM gel exhibited a synergistic effect in improving AD sludge dewaterability. [ABSTRACT FROM AUTHOR]