Where the gross total income of an assessee includes any profits and gains derived from the business of collecting and processing or treating of bio-degradable waste for generating power or producing bio-fertilizers, bio-pesticides or other biological agents or for producing bio-gas or making pellets or briquettes for fuel or organic manure, there shall be allowed, in computing the total income of the assessee, a deduction of an amount equal to the whole of such profits and gains for a period of five consecutive assessment years beginning with the assessment year relevant to the previous year in which such business commences.