POTASSIUM REMOVAL FROM DISTILLERY SLOPS BY CANDIDA UTILISPROPAGATION

By
M.A. OTERO-RAMBLA, O.A. ALMAZAN-DEL OLMO, DANIEL BELLO-GIL, 
GUSTAVO SAURA-LARIA and JULIO A. MARTINEZ-VALDIVIESO 
Biotechnology Division, Cuban Institute for Research on Sugarcane By-Products (ICIDCA)
Vía Blanca # 804 and Carretera Central, 11000 Havana, Cuba
miguel.otero@icidca.edu.cu

KEYWORDS: Distillery Slops Decontamination,
Single Cell Protein, Feed Protein, Potassium Removal
.
Abstract 

YEASTSaccumulate varied amounts of most of the minerals present in their growth media.
Much of the 7.5–8.1% ash found in the yeast grown for baking or harvested from beer is
potassium phosphate, but yeast has the ability to accumulate other ions provided (but not
necessarily needed) in high concentration. Distillery slops still contain about 70% of all potassium contributed to the soil in cane fields as chemical fertiliser, thus fertigation with these wastewaters has to be carefully
calculated since otherwise soil salinisation can occur.
When grown in a medium composed of distillery slops, nutrient salts (ammonium
phosphate and sulfates) and a microbial growth enhancer Candida utilisshows a great
resistance to potassium concentration in continuous culture.
Yeast cells were propagated under the above conditions with increasing amounts of
K2O from 2.5 g/L concentration (distillery slops from molasses fermentation) up to 25 g/Lin propagation medium. Specific growth rate (µmax) ranged from 0.32 to 0.28 h–1 for the extreme values
mentioned above, while biomass-substrate yield coefficients were 0.23 to 0.18.
These results suggest that yeast propagated on supplemented distillery slops could
significantly reduce the potassium content of these wastes making them more suitable for
irrigation purposes. According to the nutritional assessment reported, the potassium accumulated has no
deleterious effect on animal health.

Co-Products Proc. Int. Soc. Sugar Cane Technol., Vol. 27, 2010

COGENERATION POTENTIAL IN COLOMBIAN SUGAR MILLS

By
EDGAR F. CASTILLO M., ADOLFO L. GÓMEZ, 
DIEGO COBO and CARLOS AGUIRRE 
Colombian Sugarcane Research Center CENICAÑA,
Cali, Colombia
efcastillo@cenicana.org

KEYWORDS: Cogeneration, Colombia, Distillation,
Electricity, Ethanol, Steam, Sugar.

Abstract

NOWADAYS, the Colombian sugar industry is involved in an expansion process, mainly
related to the diversification of final products.
In this way, since 2005 five ethanol distilleries are running, covering just 65% of
total ethanol demand. Distilleries were designed coupled with a composting plant, based on
vinasses and sludges from the sugar plant.
Both distilleries and composting plants show many features which make them a
special case in the ethanol market, so theyproduce a maximum of 3 L vinasse/L ethanol.
Besides, in all cases, the thermal and electrical power requirements at the ethanol
plant are supplied by the sugar plant.
In this paper, a brief description of technological features of the typical process
configuration followed by the Colombian sugar industry is shown.
It comprises the steam consumption distribution by sections, the common
configuration of the heat exchanger network (HEN) developed for vegetal steam usage and
the role of the energetic self-sufficiency ofthe factory played by the bagasse quality.
A set of possible scenarios for improving energy efficiency in a selected mill which
comprises a modified HEN can be formulated, including a revamping of existing boiler and
finally a new boiler operating at higher pressure.
Based on the previous information, the state of the main Colombian cogeneration
projects based on sugar cane and its potential impact on national energy supply is shown.
Finally, the paper describes how Colombian governmental requirements for
cogeneration plants are trying to establish a legal framework for this novel industrial activity
in the country.

Co-Products Proc. Int. Soc. Sugar Cane Technol., Vol. 27, 2010