The role of salinity on the changes of the biomass characteristics and on the performance of an OMBR treating tannery wastewater

Abstract

Tannery wastewaters are difficult to treat biologically due to the high salinity and organic matter concentration. Conventional treatments, like sequential batch reactors (SBR) and membrane bioreactors (MBR), have showed settling problems, in the case of SBR, and ultrafiltration (UF) membrane fouling in the case of MBR, slowing their industrial application. In this work, the treatment of tannery wastewater with an osmotic membrane bioreactor (OMBR) is assessed. Forward osmosis (FO) membranes are characterized by a much lower fouling degree than UF membranes. The permeate passes through the membrane pores (practically only water by the high membrane rejection) from the feed solution to the draw solution, which is also an industrial wastewater (ammonia absorption effluent) in this work. Experiments were carried out at laboratory scale with a FO CTA-NW membrane from Hydration Technology Innovations (HTI). Tannery wastewater was treated by means of an OMBR using as DS an actual industrial wastewater mainly consisting of ammonium sulphate. The monitoring of the biological process was carried out with biological indicators like microbial hydrolytic enzymatic activities, dissolved and total adenosine triphosphate (ATP) in the mixed liquor and microbial population. Results indicated a limiting conductivity in the reactor of 35 mS cm (on the 43th operation day), from which process was deteriorated. This process performance diminution was associated by a high decrease of the dehydrogenase activity and a sudden increase of the protease and lipase activities. The increase of the bacterial stress index also described appropriately the process performance. Regarding the relative abundance of bacterial phylotypes, 37 phyla were identified in the biomass. Proteobacteria were the most abundant (varying the relative abundance between 50.29% and 34.78%) during the first 34 days of operation. From this day on, Bacteroidetes were detected in a greater extent varying the relative abundance of this phylum between 27.20% and 40.45%.

Effects of Hydraulic Retention Time and Influent Nitrate-N Concentration on Nitrogen Removal and the Microbial Community of an Aerobic Denitrification Reactor Treating Recirculating Marine Aquaculture System Effluent

“…Focusing on bacteria affecting nitrogen processing, Halomonas and Azoarcus were abundant and clustered in the community heatmap analysis across all phases. The genera most frequently identified among the 10 experimental phases were Cohaesibacter, Marinobacter, and Halomonas, which have been found in marine environments [61,62]. The most dominant genera in phase H4_N50 were Rhodobacteraceae (13.7%), Fusibacter (8.0%), and Halomonas (6.6%), while the dominant ones changed to Cohaesibacter (17.7%) and Labrenzia (7.1%) in H7_N150.…”

Lipid hydrolysis monitoring in wastewater treatment: proof-of-concept for a high throughput vegetable oil emulsion based assay

“…The underlying assumption that lipid hydrolysis is mediated mostly by microbial enzymes and not by physico-chemical processes in the wastewater treatment system, might be incorrect. However, an extensive body of research on aerobic municipal wastewater treatment (Molina-Muñoz et al 2010;Cortés-lorenzo et al 2012;Calderón et al 2013;Ferrer-polonio et al 2018), anaerobic municipal wastewater treatment (Petropoulos et al 2018) and industrial wastewater treatment (Silva-bedoya et al 2016;Luján-Facundo et al 2018) has been published to corroborate the assumption of enzymatic lipid hydrolysis. It should be noted that this prior research was most often conducted with p-nitrophenol synthetic substrates, which target both true lipases, hydrolyzing triacylglycerol lipids, and esterases, hydrolyzing several types of ester bonds.…”

State-of-the-Art and Opportunities for Forward Osmosis in Sewage Concentration and Wastewater Treatment

“…Their result indicated that the OMBR system showed low membrane fouling tendency and high water flux with this draw solution. In another study by Luján-Facundo et al [ 97 ], they used the same wastewater as the draw solution to treat tannery wastewater which contained high salinity and organic matter concentration in an OMBR system. Although the reverse salt flux was mitigated by using this new draw solution, the salt accumulation was also observed due to the dewatering process of the naturally high-salinity wastewater.…”