Employment of immobilised lipase from Candida rugosa for the bioremediation

A planar bioreactor, equipped with a polypropylene membrane on which a lipase was immobilised, has been employed in a bioremediation process involving water polluted by dimethylphthalate (DMP), a model for a class of endocrine disruptors. The dependence ofenzymeactivity on pH, temperature andDMP concentration has been characterised under isothermal conditions, whereas the kinetics parameters have been studied under non-isothermal conditions. The following sequence was found for the values of lipase affinity, Km, towards the DMP: K(free-m) < K(imm-m,non-isoth) < K(imm-m,isoth). A comparison of the results obtained under isothermal and non-isothermal conditions indicated that there was an advantage in using non-isothermal bioreactors in the environmental field. These advantages in particular resulted in: (i) an increase in the enzyme activity proportional to the applied transmembrane temperature difference and (ii) a reduction in the bioremediation times and, consequently, the process costs. The advantages in using bioremediation processes in the place of classical membrane processes, such as ultrafiltration or reverse osmosis, are also discussed.