The combination of microalgae-based wastewater treatment with biomass production isrncurrently considered as a viable option for wastewater remediation and biofuel production.rnThe objective of this study was to evaluate the potential of Scenedesmus sp. for therntreatment of anaerobically digested brewery effluent and carbohydrate accumulation forrnbioethanol production. The Scenedesmus sp. was cultivated on unsterilized and sterilizedrnbrewery effluents under maximum light intensity of 5500 lux and a photoperiod of 12:12rnlight-dark cycle at room temperature to evaluate its growth, biomass production andrnnutrient removal. The microalgal biomass obtained from brewery wastewater was used forrnbioethanol production after pretreatment and optimization of carbohydrate and reducingrnsugar extraction. The concentrations of COD, NH4rn+-N, TN, PO4rn3--P, and TP in breweryrneffluent were found above the permissible discharge limit of brewery effluent set byrnEthiopian Environmental Protection Authority. The Scenedesmus sp. achieved a maximumrnbiomass production of 1.05 g/L and biomass productivity of 64.33 mg/L/d on unsterilizedrneffluent. The maximum removal efficiencies obtained were 99.89% NH4rn+-N, 96.14% TN,rnand 67.77% PO4rn3--P on sterilized effluent, and 69.32% TP and 77.78% COD onrnunsterilized effluent. The final effluent quality of COD and nitrogen nutrients were belowrnthe permissible discharge limit for Ethiopia brewery effluent standard, but phosphorusrnnutrient is above the permissible limit. Results showed that microwave pretreatment withrnHCl produced a higher total carbohydrate of 207.7 and 222.6 mg/g and reducing sugar ofrn146.8 and 159.2 mg/g compared to autoclave and oven pretreatments from the whole andrnlipid extracted microalgal biomasses, respectively. Optimizations of four independentrnvariables (HCl concentration, microwave power, temperature, and extraction time) werernperformed by response surface methodology (RSM) for the whole microalgae biomass andrnsingle-factor approach for lipid extracted biomass. The models derived from RSM for bothrnresponses were significant (P 0.9) to the experimental value. Thernpredicted values obtained at optimum conditions were 260.54 mg/g for carbohydrates andrn175.49 mg/g for reducing sugar. The experimental values under the optimum conditionsrnwere 259.9 mg/g for carbohydrate and 172.5 mg/g for reducing sugar, showing a goodrnagreement with the predicted values. The highest carbohydrate and reducing sugarrncontents achieved from lipid extracted biomass were 277.24 Â± 0.98 and 192.54 Â± 1.37rnmg/g, respectively, under optimum conditions. The maximum bioethanol yield wasrnobtained at 24 h fermentation time from both biomasses. However, the bioethanol yieldrnobtained from lipid extracted microalgal biomass was 0.1 g/g microalgae, which was 20%rnhigher than that found from the whole microalgal biomass. From this study, it can bernconcluded that the use of indigenous microalgae for wastewater treatment couple withrnbiomass production offer a promising results for wastewater remediation and bioethanolrnproduction.