No 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.

No abstract

Enrichment of electricigens was carried out in double chamber Microbial fuel cells (MFCs) for synchronized organic waste treatment and bioenergy recovery. Activated sludge was inoculated in MFCs to measure the effect of two carbon sources (sucrose and acetate) on current output. MFCs operated with sucrose showed current generation of 5µA and 3µA with COD removal efficiency (86.04% and 77.85%) in two respective stages of enrichment. Whereas, the relative efficiency of MFCs run with acetate remained considerably low in the 1 st stage though it inclined to 4µA with 81.17% removal of COD after 2 nd stage of enrichment. Culture based analysis of anodic biofilms indicated the presence of different bacterial species i.e. Pseudomonas sp., Proteus sp., Citrobacter sp., with different biofilm forming capabilities (strong 5%, moderate 15% and weak 14.8%) in sucrose and acetate fed MFCs. 454 pyrosequencing of acetate-fed MFC indicated clear difference between established biofilm communities on anode and sludge sample. Anodic biofilm was covered with both culturable and un-culturable Pseudomonas species along with Nitrosomonas europaea and Massilia sp., etc. Principle component analysis also confirmed that major contributing classes were α-proteobacteria (48.51%), β-proteobacteria (31.48%) and γ-proteobacteria (16.16%). The results of current study implied that enrichment technique resulted in better selection of electricigens along with waste water treatment.