Governments and industries across the world are raising the standard of recycling. Massive amounts of collected waste require precise material sorting, from small sized light objects such as bottle caps, to complex material mixtures like paper, plastics and metals. There are also essential sorting considerations for domestic hazardous materials. But, with accurate waste categorizations and separation, we can prolong the lifespans of incinerators, reuse valuable materials, and reduce greenhouse gas emissions. Moreover, billions of dollars worth of recyclable materials goes unrecovered annually. Therefore, how to mitigate the impact to the environment is an important issue for government and industry to focus on.