The need of new sustainable sources of energy is on the top priority to fulfil the demand of energy atdifferent corners today. Biogas is one distinct source from other renewable energy providing sources because ofits environment friendly as well as economic characteristics. Biogas does not have any geographical limitationsnor it requires advancedtechnology for producing energy, it is also very simple to use and apply.Although, Biogasgenerated from anaerobic digestion process is a clean, carbon neutral and environmental friendly energyalternative, raw biogas needs to be purified necessarily before using. The removal of impurities from raw biogaswhich is referred as enrichment ensures its better applications and also enhances its calorific value. Fundamentalaspects of anaerobic digestion are briefly described in the paper. The paper mainly includes various biogasenrichment techniques and their comparative studies have been made. A novel technique of bio-electrochemicaltechnique has also been briefly discussed.