Waste valorisation is an umbrella term to cover any industrial processing activity that aims to reuse, recycle or compost waste materials so that they are transformed into useful products or sources of energy.
There are many ways to give waste value. You may process a discarded product, byproduct or residue into a raw material, use waste materials to enhance a manufacturing process or add waste materials to finished products to alter or enhance their properties.
You can also extract energy from waste, which is normally done by combusting waste material to generate heat. This is perhaps the simplest way to acquire value from waste, but also the least efficient. Properly processing waste to extract valuable compounds will generally provide more profits and less environmental damage than burning waste in a furnace. Even if energy is the desired product from valorising waste, the production of biofuels as a renewable energy source provides many advantages over raw combustion, and is one of the prime avenues for waste valorisation that multiple industries can take advantage of.
Incineration is best seen as a last resort for waste valorisation. Although it is preferable to landfill, it doesn’t generate significant value from waste and is far from being environmentally friendly. Therefore, the focus for this paper is on the valuable materials and compounds that can be economically extracted and repurposed from waste.
How can we define “value”?
Valorisation processes can be broadly split into two categories: low-value valorisation and high-value valorisation. Low-value processes generate less valuable end-products, but generally require less work to produce, while the opposite is true for high-value processes.
An example of low-value valorisation is that of a farmer using the waste stalks from his wheat harvest as straw for his livestock. This straw helps remove manure from an animal’s environment, which can then be used as fertiliser to grow more wheat. In this example, the waste from the farmer’s crop is valorised for his livestock, and the waste from his livestock is valorised for his crop.
High-value valorisation typically requires waste material to be processed before its true worth can be acquired. The farmer in the above example receives minimal value from using his wheat stalks as animal bedding. If those wheat stalks could be converted into a more valuable substance, such as fuel for his tractor, the efficiency and profitability of his business could significantly increase.
High value valorisation is, of course, preferable to low value alternatives, although this avenue is often not practically or financially viable. Unfortunately, much technology still needs meaningful advancement until valuable materials can be valorised from the majority of waste that is produced.
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