Old Waste Allowance is a term used to describe the amount of waste that can be disposed of in an environmentally friendly manner. TRET is an acronym for 'Treatment, Recovery and Disposal of Waste', which is the process of managing waste in a way that minimizes its impact on the environment. This process includes recycling, composting, and other methods of waste management. Old Waste Allowance is the amount of waste that can be disposed of in an environmentally friendly manner without exceeding the limits set by environmental regulations.