Waste valorisation

Waste valorisation is the process of converting waste materials into more useful products, thereby adding value. It is a crucial aspect of the transition from a linear economy to a circular economy and can significantly reduce the environmental impact of waste.

With increasing pressure on producers through policy and legislation to reduce waste and perform full life cycle analysis on products, recognising opportunities to manage waste is of key importance. Life cycle analysis is the act of measuring the environmental impact of a product or service throughout its life cycle, from the resources used to create the product or service, across its use by the user, to its end of life.

Waste valorisation opportunities include:

• Utilising waste to produce energy – Incineration of waste produces heat and electricity and microbial decomposition of organic waste can produce biogas
• Recycling to recover useful materials such as glass, metal, paper and plastic
• Decomposition of waste to produce composts and fertilizers
• Production of new construction materials
• Chemical and biological processing of waste to produce chemicals and materials such as bioplastics

Here are some examples of waste valorisation globally in natural products:

Waste valorisation of olive oil pomace

Olive oil production is a major industry in the Mediterranean basin that generates a large waste stream. Olive oil pomace is the solid waste that remains after extraction of oil from the fruit and consists of pulp, skins and pits. It is produced in large quantities, production of each ton of olive oil generating approximately four tons of by-product waste.

Handling of olive waste is an environmental challenge due to the quantity, its toxicity and low biodegradability. Direct release into the environment is not recommended. There are opportunities, however, for valorisation of olive oil pomace focused on converting this by-product into valuable products or extracting useful components from it, thereby reducing waste and adding economic value.

Bioactive compounds can be extracted and used in the pharmaceutical, nutraceutical and cosmetic industries. Volatile fatty acids from olive oil pomace can be useful building blocks in the chemical industry. When processed to reduce potential toxin content, olive oil pomace can be used as a fertilizer, providing nutrients and increasing water retention in the soil, or can be incorporated into animal feed as a source of fibre and nutrients.

Olive oil pomace is under research as a starting material for the development of new materials such as biodegradable plastics. It can also be used as a biofuel.

Waste valorisation of brewer’s spent grain

Brewer’s spent grain is a byproduct of the brewing industry that constitutes 85% of brewing waste.

It is an industry by-product that has achieved much attention as it is low cost, readily available and rich in lignocelluloses, protein and fibre. Brewer’s spent grain has been valorised as a food additive, livestock feed, fertilizer and mushroom substrate. It has also been used to make paper.

In addition to these two examples there is good opportunity to explore the potential of valorisation of fruit and vegetable waste and their by-products such as pomace, peels, seeds and husks for use as dyes and natural pigments, as actives in food additives, for incorporation into food supplements and for use in cosmetics.

Recently, material formed from banana skins has been effectively shown to remove toxic metals from wastewater. The use of banana peel waste in the construction industry is also showing promising results with an investigation underway into the use of banana peel-polystyrene composites as thermal insulation to reduce energy consumption.