This dissertation reports on developing and optimizing processes for SBR technologies for treatingrntannery wastewater, with special reference to degradation/removal of nutrients from tanningrnindustries and to identify the most efficient nitrifying and denitrifying organisms in tanneryrnwastewaters laden with toxic substances. Tannery wastewater is one of the most hazardousrnwastewater for the environment when discharged without any treatment. Biological treatmentrntechnologies have shown encouraging results in the treatment of toxic compounds containingrnwastewaters. In this study, real tannery wastewater (RTW) was treated in a pilot scale aerobicrnsequencing batch reactor (SBR).The main aim of this study was to investigate the effect of cyclerntime length, organic loading rate and sludge retention time on the performance of SequentialrnBatch Reactor for treating a high strength tannery wastewater. For this purpose, pilot-scalernsequencing batch reactor of 50m3 volume was operated under different phases with the samernconditions at different four cycle time length i.e.,6,12,24 and 48 days, five organic loadingrnratei.e.,0.5,1.04,2.1,3.1 and 4.2 kg COD /m3.day and five sludge retention times (SRT) i.e.,rn5,10,20,25 and 30 days for treating tannery wastewater. For single aerobic time SBR processes,rnthe maximum COD (82.26%) and TKN (71.59%) removal efficiencies were obtained at the cyclerntime and aerobic time of 24 h and 12h, respectively. While the maximum TN (68.18%) andrn14rnphosphorus (58.29%) removal efficiencies were obtained at a cycle time of 24 h and aerationrntime of 12 h/cycle.rnConsidering biochemical processes the volumetric loading rate for tannery wastewater shouldrnbe higher than 1.5 kgCOD/ (m3*d). Higher COD input load with a COD-based volumetricrnloading rate of 3.1 kgCOD/(m3*d) nearly led to complete nitrogen removal. Under differentrnoperational conditions average nitrification rates up to 5.2 gNH/(m3*h) and denitrification ratesrnup to 3.4 gNO/(m3*h) was achieved. Cycle time is another parameter that shows the effect onrnconcentration profiles. The increasing of reacting time provides more time for biomass to reactrnand makes the BOD effluent and ammonium concentration decrease. When cycle period decreases,rnnitrate has less time to transform to nitrogen gas. Total SBR-cycle times should be in between 20-rn24 hours. Reduction of the cycle time from 24h to 360 minutes resulted in an increase of peakrnnitrogen effluent concentrations by 88 %.The results at optimum cycle length, OLR and SRTrnshowed that over the experimental feeding phases ranged from 82-98% for the total nitrogen, 95-rn98% for COD, 96-98% for BOD5, 46-95% for ammonia nitrogen, 95-99% for sulphide and 93-rn99% for trivalent chromium. As a result, high cycle time (24 h), moderate aeration time asrnintermittently aerated SBR (12h/cycle), 3.1 kgCOD/(m3*d) and 25 -day SRT were found to bernthe optimal region for maximum tannery waste water carbon and nitrogen removal efficienciesrnusing SBR. Nitrogen removal in an aerobic SBR through simultaneous nitrification-â€“rndenitrification could be a good option for tannery wastewater. SBR is a viable option for tanneryrnwastewater compared to the conventional aerobic systems provided pollution control measuresrnare conducted at the source level through the use of eco-friendly chemicals and cleanerrnprocessing methods to avoid nitrification inhibiting compounds in the effluent. Ammonia of therninfluent and effluent and MLSS of aeration tank were determined at various detention times torn15rngenerate data for kinetic coefficients. The kinetic coefficients k (maximum substrate utilizationrnrate), Ks (half velocity constant), Y (cell yield coefficient) and Kd (decay coefficient) were found tornbe 29.41 12.24, day-1, 0.298 mg/L, and 0.058 day-1, respectively. These coefficients may bernutilized for the design of activated sludge process facilities for tannery wastewater. Overallrnammonia removal rate constant â€˜Kâ€™ was found to be 29.41 day-1.The result of pilot scale study onrnthe structure and diversity of microbial community in the sludges of SBR-wetland system revealedrnthat most dominant phylum, class, order, family, genuses and species in SBR were proteobacteriarn(40.11%),Gammaproteobacteria (39.07), Pseudomonadales (39.04), Moraxellaceae (39.03),rnPsychrobacter (32.98) and pulmonis(31.89). while the most dominant phylum, class, order, family,rngenuses and species in wetland were proteobacteria (35.72), Gammaproteobacteria (31.81),rnPseudomonadales (30.60), Pseudomonadaceae (15.58),Pseudomonas (15.55) and unclassifiedrnspecies from Pseudomonas genus (15.55) respectively. Therefore the prototype is now not onlyrnturning the industrial wastes into value-added products (clean water) but is also serving forrnuniversity- industry linkage in developing scalable innovations for the sustainable management ofrnall other agro-processing wastewaters in the country.