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• Overlooked SDP enables nitrate to bypass denitrification to produce 61.1 % ammonium. • A previously concealed nitrogen fate with novel implication for ammonium recovery. • Addition of organic matter inhibits DNRA and weakens the robust network. • Genome-level interspecific relationship of SDP-coupled DNRA was discussed. Sulfur-based denitrification is a promising technology in treatments of nitrate-contaminated wastewaters. However, due to weak bioavailability and electron-donating capability of elemental sulfur, its sulfur-to-nitrate ratio has long been low, limiting the support for dissimilatory nitrate reduction to ammonium (DNRA) process. Using a long-term sulfur-packed reactor, we demonstrate here for the first time that DNRA in sulfur-based system is not negligible, but rather contributes a remarkable 40.5 %–61.1 % of the total nitrate biotransformation for ammonium production. Through combination of kinetic experiments, electron flow analysis, 16S rRNA amplicon, and microbial network succession, we unveil a cryptic in-situ sulfur disproportionation (SDP) process which significantly facilitates DNRA via enhancing mass transfer and multiplying 86.7–210.9 % of bioavailable electrons. Metagenome assembly and single-copy gene phylogenetic analysis elucidate the abundant genomes, including uc_VadinHA17, PHOS-HE36, JALNZU01, Thiobacillus , and Rubrivivax , harboring complete genes for ammonification. Notably, a unique group of self-SDP-coupled DNRA microorganism was identified. This study unravels a previously concealed fate of DNRA, which highlights the tremendous potential for ammonium recovery and greenhouse gas mitigation. Discovery of a new coupling between nitrogen and sulfur cycles underscores great revision needs of sulfur-driven denitrification technology. [Display omitted] [ABSTRACT FROM AUTHOR]

Abstract: In this paper, both 1,4-dihydropyridinones (Hantzsch products) and 3,4-dihydropyrimidinones (Biginelli products) are synthesized in one-pot of aldehydes, β-dicarbonyl compounds and urea, catalyzing by non-toxic room temperature ionic liquid 1-n-butyl-3-methylimidazolium saccharinate (BMImSac). The ionic liquid (BMImSac) is environmentally benign associated with ionic liquid with F−. In order to improve the yield and selectivity, the effects of the mole proportion of reactants and solvents are investigated. Interestingly, by increasing the amount of ethyl acetoacetate or utilizing water as solvent, an unexpected by-product, Hantzsch product which is distinct from Biginelli product, is generated. All Biginelli and Hantzsch products are simultaneously purified and characterized by IR, 1H NMR and 13C NMR, of which one Biginelli product (4h) and one Hantzsch product (5b) are structurally determinated by X-ray single crystal diffraction. The crystal data for 4h: triclinic system, P-1 space group, a =7.515(3)Å, b =9.011(4)Å, c =11.218(5)Å, α =106.288(6)°, β =104.644(6)°, γ =100.234(6)°, Z =2, V =679.7(5)Å3, D c =1.36g/cm3, R 1 =0.0603. The crystal data for 5b: monoclinic system, P2(1)/c space group, a =9.765(3)Å, b =7.391(2)Å, c =24.795(7)Å, β =93.669(5)°, Z =4, V =1785.7(9)Å3, D c =1.292g/cm3, R 1 =0.0440. [Copyright &y& Elsevier]