Interactive effect of trivalent iron on activated sludge digestion and biofilm structure in attached growth reactor of waste tire rubber

Abstract

Waste tire rubber (WTR) has been introduced as an alternative, novel media for biofilm development in several experimental systems including attached growth bioreactors. In this context, four laboratory-scale static batch bioreactors containing WTR as a support material for biofilm development were run under anoxic condition for 90 days using waste activated sludge as an inoculum under the influence of different concentrations (2.5, 6.5, 8.5 mg/l) of trivalent ferric iron (Fe). The data revealed that activated sludge with a Fe concentration of 8.5 mg/l supported the maximum bacterial biomass [4.73E + 10 CFU/ml cm]; besides, it removed 38% more Chemical oxygen demand compared to Fe free condition from the reactor. Biochemical testing and 16S rDNA phylogenetic analysis of WTR-derived biofilm communities further suggested the role of varying concentrations of Fe on the density and diversity of members of Enterobacteria(ceae), ammonium (AOB) and nitrite oxidizing bacteria. Furthermore, Fluorescent in situ hybridization with phylogenetic oligonucleotide probes and confocal laser scanning microscopy of WTR biofilms indicated a significant increase in density of eubacteria (3.00E + 01 to.05E + 02 cells/cm) and beta proteobacteria (8.10E + 01 to 1.42E + 02 cells/cm), respectively, with an increase in Fe concentration in the reactors, whereas, the cell density of gamma proteobacteria in biofilms decreased.

Experimental investigation of biofilm carriers of varying shapes, sizes, and materials for wastewater treatment in fixed bed biofilm reactor: a qualitative study of biocarrier performance

“…Sharafat et al . used tire‐derived rubber media as a biofilm carrier for the growth of Pseudomonas aeruginosa 51 . Sharafat et al .…”

“…Sharafat et al used tire-derived rubber media as a biofilm carrier for the growth of Pseudomonas aeruginosa. 51 Sharafat et al reported the ability of P. aeruginosa to grow during the availability of Fe 3 + , which is supplied from the steel beltings attached to tire chips. Biochemical testing and 16S rDNA phylogenetic analysis showed a higher growth of ammonia-oxidizing bacteria and nitrite-oxidizing bacteria during the availability of Fe 3 + , and denser biofilms when the Fe 3 + concentration was increased.…”

Plant Secondary Metabolite-Derived Polymers: A Potential Approach to Develop Antimicrobial Films

“…Active biofilms are highly hydrated, with 50%–90% of the overall area at each sectioning depth comprising EPS and liquid [37]. Direct microscopic observation has shown that biofilm clusters accumulate a large quantity of pathogens within a small area, with microorganism cell densities on an infected surface reaching 10 6 cells/cm 2 [38]. Microorganisms communicate with each other inside a biofilm by producing chemotactic particles or pheromones, in a process called “quorum sensing” [39].…”