Uganda’s sugar industry sets example for industrial waste circularity 

Although the discussion on waste circularity is now prominent in some African nations, there are also countries on the continent where industries are already reaping the rewards of implementing this concept. An example of this is the sugar industry in Uganda.

The industry operates a distillery plant that produces industrial alcohol from molasses, a byproduct of sugar, and includes an in-house bagasse-fired power plant and a manufacturing facility for food-grade carbon dioxide and dry ice. These operations use waste within the process, making the industry a zero-waste discharge entity.

Sugar Corporation of Uganda Limited (SCOUL), operational since 1926, is one of the key sugar manufacturers of Uganda under the brand name Lugazi sugar, with production capacity of 100,000 tonnes per year. The industry, apart from being the largest employer in the country, plays a crucial role in country’s economy.

Sugar manufacturing involves crushing of sugarcane to produce juice and sugar through a series of steps. The process, along with sugar, generates bagasse, filtermud, molasses as by-products. A considerable amount of bagasse and molasses is produced during sugar manufacturing, and has to be managed well to avoid environmental pollution.

SCOUL, in order to manage this waste, has installed a 30 MW power plant that uses generated bagasse as fuel to generate steam and electricity. While the industry uses only 6 megawatts of electricity internally, remaining is sold to the national grid. This has become a source of additional income for the industry. 

Similarly, molasses is handled by converting it into alcohol through an in-house distillery. This alcohol is sold and adds to the revenue. The alcohol-producing process requires dilution of molasses, for which the industry initially was using freshwater.

Currently, a new intervention has been implemented where the spent wash from the fermentation process, previously discarded as waste, is now used to dilute molasses, thereby reducing the use of fresh water.

The final and concentrated spent wash, which is highly organic and harmful to the environment, is also not discharged. Instead, it is treated anaerobically to produce methane gas, which in turn is burnt in the boiler to generate steam.

Another initiative that the industry boasts about is the installation of 3,000 tonnes of food-grade carbon dioxide manufacturing plant. During the fermentation process in alcohol production, carbon dioxide, a greenhouse gas, was released.

With the installation of this plant, the carbon dioxide released during the process is captured and purified to make food-grade CO2 and dry ice.

This CO2 is sold to the beverage industries and for storage in the transport sector. This exemplifies industrial symbiosis, where the waste from one sector serves as raw material for another.

After incorporating sufficient measures of circularity, some waste consisting of boiler ash, spentwash and filtermud still remains unused. These waste products are combined to produce bio-compost and is fed back to the industry’s sugarcane fields. 

The interventions exhibited by SCOUL demonstrates a great implementation of industrial waste circularity. This closed-loop cycle not only utilises the entire waste but also reduces consumption of natural resource, emissions of greenhouse gases and an additional avenue for income generation to the industry, along with benefits from earning carbon-credits. 

More such interventions and innovations are the need of the hour for the world to move from linear to circular economy. The countries should develop policies that supports and promotes industrial waste circularity along with incentivisation schemes to encourage such initiatives.