The biosorption of Pb2+ and Cd2+ in a fixed bed column by immobilised Chlorella sp. was characterised in a fixed bed column. Effect of initial concentration of Pb2+ and Cd2+, pH, and pellet size on the biosorption capacity was studied, at laboratory scale, using a factorial experiment design 2(3), in a 10 cm heightx1 cm of diameter continuous flow column packed with immobilised biomass. Equilibrium uptake of Pb2+ and Cd2+, increased with increasing initial metal ion concentration. It was favoured to pH 5, with a pellet of 5 mm of diameter. Langmuir model described the biosorption equilibrium of both metals.The biosorption of each single cation was studied too in a large column (50 cm heightx5 cm of diameter) at bench scale with a range of flow of 40 to 80 mL min(-1). The mass transfer coefficient was determined fitting the experimental data to continuity equations that were discretised in the radial terms with orthogonal collocation method.

Polyhydroxybutyrate (PHB) is a bacterial biopolymer with interesting features that make it useful in diverse areas of human development. The problem around this biomaterial is its high production cost, so researchers have focused their attention on the search of economic substrates to be used in the fermentation process. The present work is focused on designing a formulation based on mesquite honey and nejayote for cellular biomass and PHB generation by Bacillus cereus 4N, relying on the central compounds design and factorial design as statistical tools. The substrates employed were characterized by bromatological analysis and the biopolymer obtained from the fermentation process was analyzed by FT-IR. These results show that mesquite honey at 15 g/L influence a high cellular biomass