What is organic waste?
Organic waste is the broad term used to encompass any waste from a biological source including paper, pulp, fibre, food and animal waste, biosolids and sludge. While organic waste may seem like it requires less attention due to its biodegradable nature, this waste stream is often the single greatest source of landfill material. Organic wastes such as food scraps may decompose reasonably quickly, however products such as paper take far longer to break down, significantly adding to the volume of waste generated each year. This dumping and decomposition of organic waste not only place our approximately 1200 landfills under considerable strain but the by-product of decomposition, methane gas, contributes substantially to global warming if not correctly managed.
According to a CSIR study environmentally damaging emissions across the food Supply Chain within South Africa range between 2.8t and 4t carbon dioxide equivalent per tonne of food. The study further found that the key waste points within the process are in agricultural production, at process and packing and lastly during distribution. These waste points are intrinsic to any Supply Chain, which reiterates the importance of incorporating robust organic waste solutions at every point along the chain. A zero waste-to-landfill philosophy may sound noble, but through the adoption of innovative, fit-for-purpose waste management the disposal of organic waste can also be profitable. The very premise of a circular economy is a paradigm shift wherein traditional waste materials are re-imagined into raw materials for reinsertion into the economy.
Organic waste has reuse applications in food, feed, soil and energy. From a food perspective, consumers are becoming more aware of their environmental footprints, and as such, the so-called “ugly food’ trend is taking hold. This is simply the purchase of produce deemed too unattractive to be sold at traditional retailers. As much as 50% of produce can go unsold due to the items not meeting the industry cosmetic standards but there is a growing drive to turn this around. Another emerging trend is that of restaurateurs beginning to use every bit of the produce, rather than throwing away off-cuts and more non-traditional parts of fruit and vegetables. The root-to-stalk trend understands that for the most part the portions usually discarded taste the same as the part customarily eaten and indeed carry nutritional value.
The use of organic waste for animal feed is the process of sterilising and converting such waste into either protein or carbohydrate based additive or replacements for traditional feed sources. While perhaps rather unpleasant to imagine, the production of maggots, for example, is a viable and cost-effective method of utilising plant and animal-based waste in a way that bolsters, not detracts, the biosphere and circular economy. This process is gaining traction locally, with fly farms using organic waste to produce maggots as alternative protein sources for livestock and fish food within South Africa. Flies are fed a mixture of organic waste and as such, farms can convert 10 tonnes of waste into approximately 20 tonnes of larvae and 3.5 tonnes of organic compost per day. Another example would be the processing of past sell-by-date baked goods through a process of dehydration and crushing which renders the product down into sterile, dry powder rich in carbohydrates ready to be mixed with traditional feeds to bolster nutritional value.
Composting is perhaps the most traditional means of reusing organic waste. The return of waste to the soil is a process that closes the cycle by adding back parts of what was taken through farming and builds a more sustainable, cost-effective and healthy means of agriculture. Recently technology has enhanced the composting process, decreasing the time it takes for organic material to break down. Methods such as aerobic or anaerobic digestion compost waste by using either microorganism that requires oxygen, or not, depending on the facilities available. The resultant compost is nutrient rich and relatively low cost, accruing huge benefit to agriculture. “By providing local, SME (small, medium and micro enterprises) farmers access to high quality, cost-effective compost through the process of waste beneficiation, they can improve the quality of their yield. Furthermore, these farmers can do so with a margin that gives access to the economy in a way that traditionally manufactured products may not”, says Marilize Worst, MD SmartMatta. On-site composting allows organisations to close the loop in terms of organic waste, by reusing such directly on-site and adding the end-product straight back to their lands.
By-products of breaking down organic waste through processes of composting include methane, bio fuel or ethanol. As waste is broken down into compost through anaerobic digestion, the gas released is channelled through a valve and pipe system to be used as energy. Diverting organic waste into so-called W-T-E (waste to energy) systems not only support a zero-waste-to-landfill strategy but can power industry, vehicles and homes contributing to a significant decrease in carbon footprint. Biogas produced through a typical anaerobic digestion (AD) plant can generate as much as 900 cubic metres of biogas from 1 tonne of organic waste. Considering that such a plant will only use about 9% of the energy created to run, 90% of this energy can be put back into the grid. The biogas produced is enough to make approximately 1,800 kWh of renewable electricity. South Africans use between 230kWh and 340kWh per person per month so 1 tonne of organic waste could power a household of four for just over about two months. Considering the staggering volumes of organic waste created within the country every month, large-scale AD plants could substantially augment the local energy supply.
Not only does the reuse of organic waste create viable, nutrient and energy-rich materials for return into the biosphere decreasing the environmental impact of numerous products, but the on-selling or immediate utilisation of such materials create an economic benefit to organisations willing to engage in the smart use of matter.
Watch Marilize Worst talk about creating a circular economy…
Reference: Using flies and maggot protein as animal feed