Salinity effect on simultaneous nitrification and denitrification, microbial characteristics in a hybrid sequencing batch biofilm reactor

Abstract

The effect of increasing salinity on nitrogen removal via simultaneous nitrification and denitrification, microbial activities and extracellular polymeric substances (EPS) were investigated in a hybrid sequencing batch biofilm reactor filled with soft combination carriers. In the influent salinity range from 1.0 to 2.0%, average COD, NH-N and TN removal efficiencies were higher than 97.1, 97.8 and 86.4% at the steady state. When salinity was increased to 2.5 and 3.0%, ammonium oxidation was obviously inhibited in the reactor. For both suspended sludge (S-sludge) and biofilm, specific ammonium oxidation rate, specific nitrite oxidation rate, specific oxygen uptake rate and dehydrogenase activity reduced with the increase of salinity. The quantity of total EPS increased with the increase of salinity from 1.0 to 2.0%. Generally, humic substances were the dominant composition of EPS in both S-sludge and biofilm, with the percentages of 43.9-54.0 and 43.8-64.6% in total EPS.

Genome Sequencing and Analysis of Thraustochytriidae sp. SZU445 Provides Novel Insights into the Polyunsaturated Fatty Acid Biosynthesis Pathway

“…The second half of the FAS pathway can be divided into two subpathways. One subpathway starts with C18:3 (9,12,15), the biosynthesis of which involves the delta-6 desaturation of C18:3 (9,12,15) to C18:4 (6,9,12,15), the elongation of C18:4 (6,9,12,15) to C20:4 (8,11,14,17), and the delta-5 desaturation of C20:4 (8,11,14,17) to C20:5 (5,8,11,14,17) followed by another elongation of C20:5 (5,8,11,14,17) to C22:5 (7,10,13,16,19) and a final delta-4 desaturation of C22:5 (7,10,13,16,19) to C22:6 (4,7,10,13,16,19). The same enzymes are involved in both the first and second pathways.…”

“…Research has shown that some thraustochytrid strains can be cultivated to yield high biomasses containing substantial quantities of lipids abundant in PUFAs [8]. There is an abundance of research on the optimization of fermentation parameters in terms of salinity [9], pH, temperature [10], and cultivation medium [11] for high DHA production. Besides, metabolic engineering is also used as a promising approach to promote DHA productivity.…”

The effects of high salinity on nitrogen removal and the formation characteristics of aerobic granular sludge

“…In addition, nitrite reductase is more sensitive than nitrate reductase to environment changes [57], thus leading to NO 2 − -N accumulation. Table S2 compares the NH 4 + -N removal efficiency by salinity injection [19,34,48,[58][59][60][61][62][63]. [48].…”

Enhanced nitrogen removal and in situ microbial community in a two‐step feed oxic/anoxic/oxic‐membrane bioreactor (O/A/O‐MBR) process

“…12 In the biofilm-MBR process, the functional microorganisms are mostly attached to the carriers, resulting in reduced membrane fouling and higher membrane filtration performance than in the activated sludge-MBR reactor. 13 The complex biofilm structure facilitates the simultaneous nitrification and denitrification (SND), 14 but the nitrogen transforming mechanism, autotrophic pathways or heterotrophic pathways are not clearly depicted in the literature.…”

“…Distribution of the DNA concentration (a) and the relative abundance of AOB amoA genes (b) derived from CsCl gradients after ultracentrifugation over BD for unlabeled14 N-DNA and 15 N-labeled DNA, respectively.…”