The date palm has been cultivated in dry and hot areas of the planet for much of human history. In the Kingdom of Saudi Arabia, dates are the main crop used as a source of food. Among several species of date fruits, the Ajwa AL-Madinah date is unique, growing only in Al-Madinah geographical region. The Ajwa date is used in traditional medicine due to its abundant active components and therapeutic properties. This study investigates the structural properties and the antioxidant effects of water-soluble polysaccharides extracted from Ajwa flesh and seed. The polysaccharides were isolated by two techniques including hot water and ultrasonic extraction. After isolation and partial purification, the physicochemical properties of four samples of polysaccharides extracted from flesh and seed were studied by several techniques including FTIR, solid-state NMR, elemental analysis, and mass spectrometry. Several radical scavenging experiments were combined to study the antioxidant activity of the polysaccharide compounds. FTIR and NMR results showed a structure typical of heterogeneous polysaccharides. Mass spectrometry revealed that the polysaccharide samples were composed mainly of mannose, glucose, galactose, xylose, arabinose, galacturonic acid, and fucose. In addition, the physicochemical properties and composition of polysaccharides extracted from flesh and seed were compared. The extracted polysaccharides showed antioxidant activity, with 2, 2′-azinobis (3-ethylbenzothiazoline-6-sulfonic acid) (ABTS) radical scavenging, Fe chelating ability, hydroxyl free radical scavenging ability, and 2, 2-diphenyl-1-picrylhydrazyl (DPPH) radical scavenging. These results highlight their potential to be a useful nutritional element or supplemental medication.

Here, we explore the potential of a hybrid membrane aerated biofilm reactor (MABR), where suspended biomass and a biofilm co-occur, to remove remnant concentrations of dissolved methane and ammonium in anaerobic effluents. A combination of long-term reactor operation, in situ batch tests, and 16S rRNA gene amplicon sequencing confirmed the coexistence and spatial arrangement of three microbial populations in this hybrid system. These three microbial populations include the coupling of aerobic methane-oxidizing bacteria, nitrifying bacteria, and denitrifying bacteria, which collectively were able to promote the removal of dissolved methane, a greenhouse gas, and the removal of ammonium present in anaerobically treated wastewater. Once steady-state operation was reached, the system demonstrated dissolved methane removal efficiency of 99% and simultaneous nitrification and denitrification with ammonium and total nitrogen removal efficiencies of 90 and 65%, respectively. Similarly, metaproteomics analysis under steady-state conditions showed expression patterns of key nitrogen- and methane-related enzymes at different zones of the hybrid MABR. Additionally, ¹⁵N tracer experiments revealed the production of ²⁹N₂, suggesting that nitrosation or nitrifier-denitrification processes may play an important role in the nitrogen loss when methane is the only organic carbon source added to the system. These results are useful for developing and optimizing strategies to mitigate greenhouse gas emissions and nitrogen-related issues in reclaimed water.