This dissertation reports on culture- dependent and culture- independent characterization ofrnmicroorganisms of from tannery wastewater, with special reference to degradation of selectedrnretanning chemicals, In the culture- based study, four bacterial strains isolated ll'om a temporaryrnstorage site of composite tanncry wastewater were reported to grow and utilizc the retanningrnagcnts named as Basyantan AN and Retanal MD80 as their carbon and nitrogen sources. UltrarnPerformance Liquid Chromatography (UPLC) analysis of compounds in the retanning agentsrnfrom batch cultures over a period of 14 days revealed an average of 18, 26 and 33% degradntionrnof the three detected peaks of Basyantan by isolate B45. The same isolate also showed anrnaverage of 34% degradation of Retana!' Kinetic studies conducted on this isolnte showed therndependence of growth on the concentration of Retanal as a substrate, with a maximum grO1hrnrate (Jlma,)of 1450 cells mr'.hr" and a half saturation constant (Ks) of 10.16 mg.r'. On the basisrnof 16S rRNA gene amplification, sequencing and phylogenetic analysis, the four isolates wercrnidentified as Micrococcus luleus strain B lR, Brevibacleriulll pilyocalllpae strain B4500R,rnLysinibacillus sphaericlls strain R 1902R and Enlerococcus gallina/'lllJl Strain R280 I R.rnBench- scale study involving a sequencing batch reactor (SBR) run for 42 days for studying thernbiodegradation of Basyantan and Retanal revealed a pronounced degradation up to 100%rnregarding peak 2 of Basyantan. Dynamics of sludge microbial sub- communities as followed byrnT-RFLP showed the dominance of membcrs of the class Burkholderaceae and a less diverserncommunity in the first five batches of the SBR run; which was then succeeded by membersrnbelonging to the phylum Bacteroidetes and classes Rhodocycalaceae, Rhodobacteraceae,rnPseudomonadaceae and Bradyrhizobiaceae; with increased diversity towards the end of the run.rnFlow cytometric analysis of bacterial cells in the sludge was used to create pattcrns mirroringrndynamics of bacterial community over the period of SBR run. The patterns were resolved in 30rnsub, clusters eight of which wcre sOlicd and members identified. Correlation of the bacterialrnabundancc in thc sortcd sub- clusters with the measured abiotic data showed the prcsence of arnstrong (p< 0.0 I) positive correlation bctween degradation of Basyantan and Retanal withrnmcmbers of Bacteroidetes and Protcobactcria, indicating the key degradation role played byrnthesc members.rnFicld- scale study on the structure and diversity of the microbial community in the sludge of thernAnaerobic- aerobic reactors as well as the root area of a constructed wetland treating tanneryrneffluent located in Modjo tannery was conducted using the 16S ribosomal RNA gene scquencingrnperformcd for cach of the reactors. The results revealed a total of 31 different phylotypes withrnthe dominant members belonging to FirllliclIIes, Bacleroidia, Proleobacleria, Sphingobacleriarnand S)'Ilergislia in the anaerobic and aerobic reactors. In the constructcd wetland, members ofrnthc group C)'({l1obaCleria were also identified in addition to Firmicules, 13acleroidia andrnProleobaclel'ia. Thc presence of members of groups that arc associated with reduction of sulfate and removal of chromium, nitrate and degradation of synthetic aromatic compounds indicatesrntheir implication in the current performance of the treatment system. Furthermore, physicochemicalrndata (total Nitrogen, total Carbon, pH, Sulphate, Nitrate) have been recorded in thernanaerobic, aerobic and constructed wetlands and analyses of these data elucidate the key factorrnstructuring the observed microbial communities.