Project: Develop incineration technology, to dispose of vinasse

Site: Mauritius : Mauritius Sugar Industry Research Institute (MSIRI)

Rationale: After extraction of the sugar from the cane juice, the last product obtained from which sugar can no longer be extracted at an economic price, under the present conditions of the sugar market, is called molasses. Molasses is a heavy and viscous product with a low international market price, and usually it is not worthwhile exporting it when the sugar factories are located in remote areas. The valorisation of molasses with ethanol production is a common trend in the present sugar world, as ethanol has a far higher market value than molasses and is easier to transport.

However, there is still a by-product resulting from the fermentation of the residual sugar contained in molasses into ethanol, called vinasses.

Vinasses are a coloured liquid with a very high COD and high potash content, and they are relatively harmful to the environment.

Nevertheless, their content in potash and also to a lesser extent in nitrogen or phosphorus, would allow them once treated to be used as fertilisers.

There is no simple, existing way to get rid of vinasses ; treating them with digester is very expensive and not fully efficient, concentrating them and spread them on fields is also expensive due to the huge volumes involved, burning them in a classical boilers is harmful for the boiler’s factories.

Using incinerators would make it possible to burn them, and to recover on the one hand part of the heat, and on the other the ashes that could then be returned to the fields as a fertiliser at a small cost.

Objectives: Solving the environmental and cost problems of vinasses treatment and finding an easy, environmentally friendly way to get rid of vinasses.

Saving on fertiliser costs (80% of potash returned back to fields, etc.).

Assumptions/Risks: Assumption/risks are as follows:

• Capital flow for investment is available,
• The new incineration method is proven to be more interesting than other alternative methods.
• Incinerator manufacturers are ready to collaborate.
• No expensive additional cost is imposed/necessary to comply with environmental regulations such as incinerator smoke treatment.

Expected outputs: An efficient way of incinerating vinasses is available.

ACP countries concerned: Mauritius and all ACP countries, particularly islands with ethanol production and a fragile ecological environment.