Sustained-release nitrate combined with microbial fuel cell: A novel strategy for PAHs and odor removal from sediment.

Nitrate addition is a biostimulation technique that can improve both the oxidation of acid volatile sulfide (AVS) through autotrophic denitrification and the biodegradation of polycyclic aromatic hydrocarbons (PAHs) via heterotrophic denitrification. However, during the remediation, parts of the dissolved nitrate in the sediment migrates from the sediment to the overlying water, leading to the loss of effective electron acceptor. To overcome this limitation, a combined approached was proposed, which involved nitrocellulose addition and a microbial fuel cell (MFC). Results indicated the nitrate could be slowly released and maintained at a higher concentration over long term. In the combined system, the removal efficiencies of PAHs and AVS were 71.56% and 89.76%, respectively. Furthermore, the voltage attained for the MFC-nitrocellulose treatment was maintained at 146.1 mV on Day 70, which was 5.37 times higher than that of the MFC-calcium nitrate treatment. Sediments with nitrocellulose resulted in lower levels of nitrate and ammonium in the overlying water. Metagenomic results revealed that the combined technology improved the expression of nitrogen-cycling genes. The introduction of MFC inhibited sulfide regeneration during incubation by suppressing the enzyme activity like EC4.4.1.2. The enhanced biostimulation provided potential for in-situ bioremediation utilizing MFC coupled with slow-released nitrate (i.e., nitrocellulose) treatment.

Comparative study on the digestion and absorption characteristics of n-3 LCPUFA-enriched phospholipids in the form of liposomes and emulsions.

Previous studies have reported that phospholipids rich in n-3 long-chain polyunsaturated fatty acids (n-3 LCPUFA) in the form of liposome exhibited superior bioactivities than other formulation. However, the digestion and absorption characteristics of n-3 LCPUFA-enriched phospholipids were still unclear, restricting the molecular mechanism analysis related to their distinctive activities. The aim of the present study was to compare the digestion and absorption characteristics of DHA/EPA-PC in the forms of liposome and emulsion. The fatty acid composition and lipid species in serum, intestinal wall and content of healthy mice were determined after oral administration with DHA/EPA-PC. Results showed that the peak value of serum DHA/EPA level in the liposome group was significantly higher than that of the emulsion group (p < 0.05), although the peak in the liposome group appeared at 3 h and the peak time was 2 h in the emulsion group. Lipidomics analysis indicated that the high levels of total PL and PL-DHA could be retained in serum for a substantial period after administration of the DHA/EPA-PC liposome, which might be attributed to that the DHA/EPA-PC in the form of liposomes was hydrolyzed slower by pancreatic phospholipase A2 than the emulsion form in small intestinal content. The obtained results might provide theoretical basis for the development and utilization of marine-derived phospholipids.