Engineering of membrane biosorption

Membrane biosorption is a new integrated process for xenobiotics removal from a water environment. The mathematical model has been presented in the paper based on biosorption equilibrium and kinetics as well as relevant mass balances of the integrated system. To achieve steady-state conditions the biosorbent has to be renewed on the membrane surface prior to its saturation with the solute. This can be done either by periodical backflushing in the case of supercritical flux when the biosorbent forms the cake or by continuous renewal with cross flow (turbulence and shear stresses) during subcritical conditions. The engineering aspects of the process design and optimisation are discussed in the paper. The permeate flux has to be adjusted to actual kinetics of the sorption. The choice of optimal time intervals for batch mode with backflushing and proper hydrodynamical conditions for continuous cross-flow mode were also demonstrated. Membrane biosorption is especially feasible for removal of diluted components with high retention. The naturally occurring microorganisms may be applied as a sorbent. Membrane biosorption is a cheap and efficient method of xenobiotics separation and therefore may be applied for environmental protection purposes.

Membrane biosorption is a very effective integrated process of separation, which is especially feasible for removal of diluted xenobiotics from a water environment [1–5]. The biofilm on an UF membrane surface can be used as a separation barrier for soluted components such as heavy metal ions. To achieve steady-state conditions, this layer must be renewed by means of periodical backflushing (at super-critical conditions) or continuously by shear stresses or turbulences during cross-flow subcritical flux conditions [10–14]. The process may be controlled and optimised by means of: membrane selection, hydrodynamic conditions, permeate recovery, size of the tank and membrane surface. Membrane biosorption is an effective and cheap process due to its high capacity and good selectivity. The naturally occurring microorganisms may be used as a biosorbent without any preparation. The mathematical model presented in the paper may be also used for the description of similar integrated systems comprising sorption and membrane separation of relevant sorbents.