Following are the challenges 

High calorific value waste, which may otherwise be processed in more sustainable processes, is required as feedstock.

Organics can be converted into compost in a much more cost-effective and environmentally safe process, as against using them as feedstock for these processes.

Pyrolysis and gasification processes require specific feedstock quality, which has a direct impact on the efficiency and commercial viability of the product. Pre-treatment of waste is a must. Specific size and consistency of solid waste should be achieved before MSW can be used as feed.

During gasification, tars, heavy metals, halogens, and alkaline compounds are released within the product gas and can cause environmental and operational problems.

Heavy metals are toxic and accumulate, if released into the environment. Halogens are corrosive and a cause of acid rain, if emitted to the environment.

The key to achieving cost efficient, clean energy recovery from MSW gasification will be overcoming problems associated with the release and formation of these contaminants.