Passage: "Barangay Malinis began a waste segregation programme last year. Each household now separates biodegradable waste, recyclables and residual waste. Biodegradable waste goes to a community composting area, while recyclables are sold to junk shops, and the income funds the barangay's tree-planting drive. As a result, the amount of garbage collected by the municipal truck fell by almost half within six months. Barangay officials say the programme succeeded because volunteers visited every household to explain it, instead of simply posting a notice." Which law does the barangay's programme put into practice?