Deciphering the role of microplastic size on anaerobic sludge digestion: Changes of dissolved organic matter, leaching compounds and microbial community.

Here the role of microplastic size on dissolved organic matter, leaching compounds and microbial community during anaerobic sludge digestion was evaluated. Compared to that without the addition of polyvinyl chloride (PVC), during the 30 days' incubation, the anaerobic sludge digestion by adding PVC at the size of 75 µm and the concentration of 2.4 g/g volatile solids (VS) showed a 8.5% lower cumulative methane production, while a 17.9% higher cumulative methane production was noted by adding PVC at the size of 3000 µm and the concentration of 2.4 g/g VS. A long-term fed-batch laboratory-scale fermenter test for 147 days further testified, that higher removal efficiencies of total solids, volatile solids, and total chemical oxygen demand, and higher methane production were noted by adding PVC (2.4 g/g VS, 3000 µm) into the fermenter. More interestingly, higher concentrations of proteins, polysaccharides, volatile fatty acids, and soluble microbial by-products component were noted in the liquid phase of sludge drawn from the fermenter added with PVC since the biomass therein showed higher efficiencies of solubilization, hydrolysis, acidification, and methanogenesis. Moreover, as identified from the fermenter added with PVC, dibutyl phthalate (DBP) was the most predominant leaching phthalates compound, although the biomass therein showed a 93.4% anaerobic biodegradability of DBP. The leaching of DBP drove the predominance of microbial community towards Synergistota and Methanosaeta. More irregular elliptical shallow dimples were noted on the PVC surface after 147 days' incubation, accompanied with abundances of Proteobacteria, Actinobacteriota, Chloroflexi, Methanosaeta and Methanobacterium. The results from this study showed that the size of microplastic was a crucial factor in evaluating its impact on anaerobic sludge digestion.

Molecularly Imprinted Polymer as an Antibody Substitution in Pseudo-immunoassays for Chemical Contaminants in Food and Environmental Samples.

The chemical contaminants in food and the environment are quite harmful to food safety and human health. Rapid, accurate, and cheap detection can effectively control the potential risks derived from these chemical contaminants. Among all detection methods, the immunoassay based on the specific interaction of antibody-analyte is one of the most widely used techniques in the field. However, biological antibodies employed in the immunoassay usually cannot tolerate extreme conditions, resulting in an unstable state in both physical and chemical profiles. Molecularly imprinted polymers (MIPs) are a class of polymers with specific molecular recognition abilities, which are highly robust, showing excellent operational stability under a wide variety of conditions. Recently, MIPs have been used in biomimetic immunoassays for chemical contaminants as an antibody substitute in food and the environment. Here, we reviewed these applications of MIPs incorporated in different analytical platforms, such as enzyme-linked immunosorbent assay, fluorescent immunoassay, chemiluminescent immunoassay, electrochemical immunoassay, microfluidic paper-based immunoassay, and homogeneous immunoassay, and discussed current challenges and future trends in the use of MIPs in biomimetic immunoassays.

Citric acid assisted Fenton-like process for enhanced dewaterability of waste activated sludge with in-situ generation of hydrogen peroxide.

Fenton's reagent has been widely used to enhance sludge dewaterability. However, drawbacks associated with hydrogen peroxide (H2O2) in Fenton's reagents exist, since it is a hazardous chemical and shows carcinogenicity, explosivity, instability, and corrosivity. Moreover, initial acidification and subsequent neutralization are needed as optimal conditions for homogeneous Fenton conditioning and final filtrate discharge. In this study, a Fenton-like process for the enhanced dewaterability of waste activated sludge with in-situ generation of H2O2 and without extra pH adjustment was firstly proposed, namely citric acid (CA)-assisted oxygen activation in an air/nano zero-valent iron (nZVI) system and chemical re-coagulation with polydiallyldimethylammonium chloride (PDMDAAC). Using the response surface methodology (RSM), the optimal doses of CA, nZVI, and PDMDAAC were determined to be 13, 33, and 9 mg g-1 dry solids (DS), respectively. This composite conditioner showed a good dewatering capability compared with the raw sludge, e.g. the capillary suction time decreased from 130.0 to 9.5 s. The enhanced sludge dewaterability was further confirmed by laboratory-scale diaphragm filter press dewatering tests, which produced a lower cake moisture content compared with the raw sludge, and the final pH of the filtrate was close to neutrality. The citric acid promoted the production of H2O2 and Fe(II)/Fe(III) species, the degradation of protein in tightly-bound extracellular polymeric substances, and the decomposition of protein-N in the solid phase of sludge, resulting a greater conversion of bound water to free water. The results of electron spin resonance indicated that the hydroxyl radicals were mainly responsible for the decomposition of proteinaceous compounds. The subsequent chemical re-coagulation with PDMDAAC can make the zeta potential of sludge samples less negative, reduce the repulsive electrostatic interactions, and agglomerate the smaller particles into larger aggregates, thus enhancing sludge dewaterability.

Biomimetic nanofibers can construct effective tissue-engineered intervertebral discs for therapeutic implantation.

We present a total tissue engineered (TE) intervertebral disc (IVD) to address IVD degradation, which is a major cause of chronic neck and back pain. The TE IVD is comprised of an alginate hydrogel-based nucleus pulposus (NP) and hierarchically organized, concentric ring-aligned electrospun (ES) polycaprolactone (PCL)/poly (d,l-lactide-co-glycolide) (PLGA)/Collagen type I (PPC)-based annulus fibrosus (AF). The TE IVD exhibits excellent hydrophilicity to simulate highly hydrated native IVD. Long-term in vivo implantation assays demonstrate the excellent structural (shape maintenance, hydration, and integration with surrounding tissues) and functional (mechanical supporting and flexibility) performances of the TE IVD. Our study provides a novel approach for treating IVD degeneration.