Fixation of spent Saccharomyces cerevisiae biomass for lead sorption

Spent Saccharomyces cerevisiae cells from a beer fermentation process were evaluated for lead cation sorption. The crude biomass was washed with water and acetone prior to any other treatment. Although the washed biomass showed substantial lead ion sorption it was susceptible to microbial spoilage. Different aldehydes were tested as chemical fixation agents; however, most of them caused drastic lowering of the metal uptake capacity. However, benzaldehyde was not only an excellent fixation agent, but the biomass treated with it also retained its original lead sorption capacity. A mechanism for the fixation process is suggested.