The potential of osmolytes and their precursors to alleviate osmotic stress of anaerobic granular sludge.
Sudmalis, D. ; Millah, S.K. ; Gagliano, M.C. ; Butré, C.I. ; Plugge, C.M. ; Rijnaarts, H.H.M. ; Zeeman, G. ; Temmink, H. - \ 2018
Water Research 147 (2018). - ISSN 0043-1354 - p. 142 - 151.
Anaerobic granular sludge - Methanogenic activity - Osmolytes - Saline wastewater
Increasing amounts of saline (waste)water with high concentrations of organic pollutants are generated globally. In the anaerobic (waste)water treatment domain, high salt concentrations are repeatedly reported to inhibit methanogenic activity and strategies to overcome this toxicity are needed. Current research focuses on the use of potential osmolyte precursor compounds for osmotic stress alleviation in granular anaerobic sludges upon exposure to hypersalinity shocks. Glutamic acid, aspartic acid, lysine, potassium, gelatine, and tryptone were tested for their potential to alleviate osmotic stress in laboratory grown and full – scale granular sludge. The laboratory grown granular sludge was adapted to 5 (R5) and 20 (R20) g Na+/L. Full-scale granular sludge was obtained from internal circulation reactors treating tannery (waste)water with influent conductivity of 29.2 (Do) and 14.1 (Li) mS/cm. In batch experiments which focused on specific methanogenic activity (SMA), R5 granular sludge was exposed to a hypersalinity shock of 20 g Na+/L. The granular sludge of Do and Li was exposed to a hypersalinity shock of 10 g Na+/L with sodium acetate as the sole carbon source. The effects on R20 granular sludge were studied at the salinity level to which the sludge was already adapted, namely 20 g Na+/L. Dosing of glutamic acid, aspartic acid, gelatine, and tryptone resulted in increased SMA compared to only acetate fed batches. In batches with added glutamic acid, the SMA increased by 115% (Li), 35% (Do) and 9% (R20). With added aspartic acid, SMA increased by 72% (Li), 26% (Do), 12% (R5) and 7% (R20). The addition of tryptone resulted in SMA increases of 36% (R5), 17% (R20), 179% (Li), and 48% (Do), whereas added gelatine increased the SMA by 30% (R5), 14% (R20), 23% (Li), and 13% (Do). The addition of lysine, meanwhile, gave negative effects on SMA of all tested granular sludges. Potassium at sea water Na/K ratio (27.8 w/w) had a slight positive effect on SMA of Do (7.3%) and Li (10.1%), whereas at double the sea water ratio (13.9% w/w) had no pronounced positive effect. R20 granular sludge was also exposed to hyposalinity shock from 20 down to 5 g Na+/L. Glutamate and N-acetyl-β-lysine were excreted by microbial consortium in anaerobic granular sludge adapted to 20 g Na+/L upon this exposure to hyposalinity. A potential consequence when applying these results is that saline streams containing specific and hydrolysable proteins can be anaerobically treated without additional dosing of osmolytes.
Influence of salinity on fungal communities in a submerged fixed bed bioreactor for wastewater treatment
Cortés-Lorenzo, C. ; González-Martínez, A. ; Smidt, H. ; González-López, J. ; Rodelas, B. - \ 2016
Chemical Engineering Journal 285 (2016). - ISSN 1385-8947 - p. 562 - 572.
Fungal communities - Pyrosequencing - Saline wastewater - Submerged fixed bed bioreactor - Wastewater treatment
Salinity is known to influence the performance of biological wastewater treatment plants. While its impact on bacterial communities has been thoroughly studied, its influence on fungal communities has been largely overlooked. To address this knowledge gap, we assessed the effect of saline influents (0, 3.7, 24.1 and 44.1. g. NaCl/L) on the community structure and diversity of fungi in a submerged fixed bed bioreactor (SFBBR). For this purpose, denaturing gradient gel electrophoresis (DGGE) and 454-pyrosequencing of PCR-amplified fungal 18S rRNA gene fragments and ITS regions, respectively, were used. Significant differences in the fungal community structure were found in relation to the NaCl concentration. Fungal diversity increased as salinity increased to a concentration up to 24.1. g. NaCl/L, but was significantly reduced at 44.1. g. NaCl/L. Basidiomycota dominated the fungal community in the absence of NaCl but decreased in relative abundance with increasing salinity, being replaced progressively by Ascomycota.