Tracing microplastic (MP)-derived dissolved organic matter in the infiltration of MP-contaminated sand system and its disinfection byproducts formation.

Microplastic (MP) pollution in soil/subsurface environments has been increasingly researched, given the uncertainties associated with the heterogeneous matrix of these systems. In this study, we tracked the spectroscopic signatures of MP-derived dissolved organic matter (MP-DOM) in infiltrated water from MP contaminated sandy subsurface systems and examined their potential to form trihalomethanes (THMs) and haloacetic acids (HAAs) by chlorination. Sand-packed columns with commercial MPs (expanded polystyrene and polyvinylchloride) on the upper layer were used as the model systems. Regardless of the plastic type, the addition of MPs resulted in a higher amount of DOM during infiltration compared with the clean sand system. This enhancement was more pronounced when the added MPs were UV-irradiated for 14 days. The infiltration was further characterized using FT-IR and fluorescence spectroscopy, which identified two fluorescent components (humic-like C1 and protein/phenol-like C2). Compared with pure MP-DOM, C1 was more predominant in sand infiltration than C2. Further studies have established that C2 may be more labile in terms of biodegradation and mineral adsorption that may occur within the sand column. However, both these environmental interferences were inadequate for entirely expanding the spectroscopic signatures of MP-DOM in sand infiltration. The infiltration also exhibited a higher potential in generating carbonaceous disinfection byproducts than natural groundwater and riverside bank filtrates. A significant correlation between the generated THMs and decreased C1 suggests the possibility of using humic-like components as optical precursors of carbonaceous DBPs in MP-contaminated subsurface systems. This study highlighted an overlooked contribution of MPs in terms of the infiltration of DOM levels in sandy subsurface systems and the potential environmental risk when used as drinking water sources.

Sequential Combination of Electro-Fenton and Electrochemical Chlorination Processes for the Treatment of Anaerobically-Digested Food Wastewater.

A two-stage sequential electro-Fenton (E-Fenton) oxidation followed by electrochemical chlorination (EC) was demonstrated to concomitantly treat high concentrations of organic carbon and ammonium nitrogen (NH4+-N) in real anaerobically digested food wastewater (ADFW). The anodic Fenton process caused the rapid mineralization of phenol as a model substrate through the production of hydroxyl radical as the main oxidant. The electrochemical oxidation of NH4+ by a dimensionally stable anode (DSA) resulted in temporal concentration profiles of combined and free chlorine species that were analogous to those during the conventional breakpoint chlorination of NH4+. Together with the minimal production of nitrate, this confirmed that the conversion of NH4+ to nitrogen gas was electrochemically achievable. The monitoring of treatment performance with varying key parameters (e.g., current density, H2O2 feeding rate, pH, NaCl loading, and DSA type) led to the optimization of two component systems. The comparative evaluation of two sequentially combined systems (i.e., the E-Fenton-EC system versus the EC-E-Fenton system) using the mixture of phenol and NH4+ under the predetermined optimal conditions suggested the superiority of the E-Fenton-EC system in terms of treatment efficiency and energy consumption. Finally, the sequential E-Fenton-EC process effectively mineralized organic carbon and decomposed NH4+-N in the real ADFW without external supply of NaCl.

Exploring the Role of Persulfate in the Activation Process: Radical Precursor Versus Electron Acceptor.

This study elucidates the mechanism behind persulfate activation by exploring the role of various oxyanions (e.g., peroxymonosulfate, periodate, and peracetate) in two activation systems utilizing iron nanoparticle (nFe0) as the reducing agent and single-wall carbon nanotubes (CNTs) as electron transfer mediators. Since the tested oxyanions serve as both electron acceptors and radical precursors in most cases, oxidative degradation of organics was achievable through one-electron reduction of oxyanions on nFe0 (leading to radical-induced oxidation) and electron transfer mediation from organics to oxyanions on CNTs (leading to oxidative decomposition involving no radical formation). A distinction between degradative reaction mechanisms of the nFe0/oxyanion and CNT/oxyanion systems was made in terms of the oxyanion consumption efficacy, radical scavenging effect, and EPR spectral analysis. Statistical study of substrate-specificity and product distribution implied that the reaction route induced on nFe0 varies depending on the oxyanion (i.e., oxyanion-derived radical), whereas the similar reaction pathway initiates organic oxidation in the CNT/oxyanion system irrespective of the oxyanion type. Chronoamperometric measurements further confirmed electron transfer from organics to oxyanions in the presence of CNTs, which was not observed when applying nFe0 instead.

Regression and progression of microalbuminuria in adolescents with childhood onset diabetes mellitus.

PURPOSE: Although microalbuminuria is considered as an early marker of nephropathy in diabetic adults, available information in diabetic adolescents is limited. The aim of this study was to investigate prevalence and frequency of regression of microalbuminuria in type 1 (T1DM) and type 2 diabetes mellitus (T2DM) patients with childhood onset. METHODS: One hundred and nine adolescents (median, 18.9 years; interquartile range (IQR), 16.5-21.0 years) with T1DM and 18 T2DM adolescents (median, 17.9 years; IQR, 16.8-18.4 years) with repeated measurements of microalbuminuria (first morning urine microalbumin/creatinine ratios) were included. The median duration of diabetes was 10.1 (7.8-14.0) years and 5.0 (3.5-5.6) years, respectively, and follow-up period ranged 0.5-7.0 years. Growth parameters, estimated glomerular filtration rate, glycosylated hemoglobin (HbA1c) and lipid profiles were obtained after reviewing medical record in each subject. RESULTS: The prevalence of microalbuminuria at baseline and evaluation were 21.1% and 17.4% in T1DM, and 44.4% and 38.9% in T2DM. Regression of microalbuminuria was observed in 13 T1DM patients (56.5%) and 3 T2DM patients (37.5%), and progression rate was 10.5% and 20% in T1DM and T2DM respectively. In regression T1DM group, HbA1c at baseline and follow-up was lower, and C-peptide at baseline was higher compared to persistent or progression groups. In T2DM, higher triglyceride was observed in persistent group. CONCLUSION: Considerable regression of microalbuminuria more than progression in diabetes adolescents indicates elevated urinary microalbumin excretion in a single test does not imply irreversible diabetic nephropathy. Careful monitoring and adequate intervention should be emphasized in adolescents with microalbuminuria to prevent rapid progression toward diabetic nephropathy.

Oxidizing capacity of periodate activated with iron-based bimetallic nanoparticles.

Nanosized zerovalent iron (nFe0) loaded with a secondary metal such as Ni or Cu on its surface was demonstrated to effectively activate periodate (IO4-) and degrade selected organic compounds at neutral pH. The degradation was accompanied by a stoichiometric conversion of IO4- to iodate (IO3-). nFe0 without bimetallic loading led to similar IO4- reduction but no organic degradation, suggesting the production of reactive iodine intermediate only when IO4- is activated by bimetallic nFe0 (e.g., nFe0-Ni and nFe0-Cu). The organic degradation kinetics in the nFe0-Ni(or Cu)/IO4- system was substrate dependent: 4-chlorophenol, phenol, and bisphenol A were effectively degraded, whereas little or no degradation was observed with benzoic acid, carbamazepine, and 2,4,6-trichlorophenol. The substrate specificity, further confirmed by little kinetic inhibition with background organic matter, implies the selective nature of oxidant in the nFe0-Ni(or Cu)/IO4- system. The comparison with the photoactivated IO4- system, in which iodyl radical (IO3•) is a predominant oxidant in the presence of methanol, suggests IO3• also as primary oxidant in the nFe0-Ni(or Cu)/IO4- system.