Organic waste can be a contributor to pollution if not treated in a good matter. In Brazil, the majority of the organic waste ends up at the landfill where it contributes to the formation of methane gas, a greenhouse gas much stronger than carbon dioxide. If your country or municipal do not have a proper treatment system for organic waste, composting is a less polluting and sustainable option.
We have visited many hostels that use a composting system. Aju Hostel in Aracaju for example gathers all their left over foods from the breakfast they serve and puts in a bin. They have a complete collection of bins that are being circulated over time. When a bin is full of left over foods it will be stored and treated for some months until it has become fertilizer, which they use in their own garden.
If you do not have a garden or space to store a composting system like this, you can search for alternatives in your community. Praia do Forte Hostel in Praia do Forte for example, has made an agreement with a local farmer that collects their organic waste and uses it as fertilizer. In return the hostel gets back some of the vegetables the farmer is growing.