This study reports the production, purification and application of cellulases from Trichoderma viride under still culture liquid state fermentation technique using microcrystalline cellulose and cheap and easily available waste material, as growth supported substrate. Trichoderma viride was cultured in fermentation medium of cellulose under some previously optimized growth conditions. Cellulase was purified in comparison to crude enzyme extract using ammonium sulfate precipitation, dialysis and ion exchange column chromatography. The purified cellulase was compatible with four local detergent brands suggesting its potential as a detergent additive for improved washing therefore it is concluded that it may be potentially useful for industrial purposes especially for detergent and laundry industry. The purified cellulase enzyme was also used as an alternative to degrade the waste material (potato peel) for further production of alcohol, organic acid etc.