For every litre of ethanol produced by the Ethanol Company Limited (ETHCO), thirteen (13) litres of effluent are discharged for evaporation in the effluent ponds. This has led to a dynamic project with exciting innovations in dealing with the sludge created in the ethanol production process. Besides the effluent discharged there is 1 tonne of sludge sediment left everyday at the bottom of the mash clarifier, a sludge sedimentation tank installed between the fermenters and the beer holding tank. Removing this sludge before distillation implies that there will be less scaling in the distillation column and less clogging in the effluent lines to the evaporation ponds. However, another disposal burden is yet again created after the sludge is discharged from the clarifier.
Because of these two issues, the Sludge Manure Project initiative came about in 2003. It has been found that distillery effluent, including sludge, has a high nutrient potential and hence the realization of this valuable resource by farmers and all concerned agencies to use this sludge for fertilizing agricultural crops. Distillery effluent or sludge application will reduce the nutrient requirement farms have from fertilizers. The company decided it could deliver the sludge to farmers within a 12 km radius from the factory. This distance was later extended to a 20 km radius. This initiative was introduced as an idea to evaluate the effect of sludge in the agronomic performance of maize production compared to inorganic fertilizer. This move would supply the company with substantive research to encourage farmers in the future to use the sludge in their maize gardens.
Chitedze research station was therefore engaged to conduct the necessary studies for evaluating the effects of sludge as an organic fertilizer on maize yields. Results from the three year study indicated that sludge as an organic fertilizer has a positive effect on maize crop yields and in some places is equally effective as inorganic fertilizer in supplying nitrogen to the maize crop. However its efficiency in supplying soil nutrients is highly moisture dependant. The results further revealed that sludge has positive effects on soil properties. It is able to neutralize acidic soils, and increase and maintain the nutrient levels of soil nutrients. The project was entered in 2004 to the IDESA awards for innovation and was awarded the 3rd position.
The Beneficiaries of the Sludge for Manure Project
Mr Bernard Nkhoma (insert) is one of the lucky farmers who in 2005 proudly reported that he has used ETHCO sludge in his 1 acre garden. Mr Nkhoma’s garden had a vibrant maize crop after applying ETHCO sludge as manure. The garden was prepared and planted in the same way as any other fertiliser-applied garden. By using ETHCO sludge, he had saved around MK4,000, which he would have spent on artificial fertilisers for basal and top dressing.
The Development Officer at Nkhunga Extension Planning Area (E.P.A), Mr Samuel Saka, proudly showed ETHCO Management the various farmers’ gardens that had used ETHCO sludge manure. Mr Saka expressed that a lot of farmers had benefited from the free sludge delivered to them.
Ethanol Company management is proud to note that while it extends its efforts to protect the environment, it is helping in reducing hunger and poverty among the rural masses of Dwangwa.