I had the pleasure to visit a large waste treatment plant before, unlike the dirty, dark place people may imagine, the waste treatment plant is almost clean unless the place is stacked the garbage. I remember one thing that the expert who leads our team emphasized, which is that make sure the purity of biodegradable waste, such as table scraps and grasses. If the purity of biodegradable waste is high, this waste can be treated and then used in agricultural farming. However, if the biodegradable waste contains above 20% of other garbage, such as plastic, this waste can only be treated in a landfill, and even the cost is higher than usual. It was very common to see plastic appear in biodegradable garbage.
I envision a future that plastic bags can be separated from biodegradable waste, to make sure all biodegradable waste can be valuable. Even though plastic is hard to be recycled, the mix of plastic and other waste is less valuable and harder to be treated. To achieve this, it required more garbage education to evoke citizens' responsibility, and strict laws to guide the actions. I heard that garbage education is mandatory in primary schools in Japan, maybe we need more similar lessons.