###### Abstract
Usually, the amount of biosorbent required in wastewater treatment is very large in a static regime (aerated open biosorption tank) and convenient in a dynamic regime (fixed/packed bed reactor) and has caused biosorbents to be a nonselective adsorbent for a wide range of molecular and ionic species found in wastewater, and they can also be used under aggressive or severe conditions that are often required for performing high biosorption capacities. Improving the performances of the biosorption process is also possible through the use of a new type of biosorptive material, resulting from the immobilization of non-living/living cells on inert support (e.g., sand, paper or textile fibers, polymers, activated carbon, etc. ), in a stage of cultivation or in the in situ immobilization of biomass/living biosorbents on inert supports within a biosorption process reactor (by physical adsorption, chemosorption due to covalent bonding, reticulation, enhancement, cross-linking), or encapsulation/entrapment (with a polymeric matrix) of residual microorganisms or microbial biomass. Several microorganisms have demonstrated high biosorption capacities compared to conventional adsorbents (ion-exchanging resins and celluloses, activated charcoal, various polymeric materials). However, their use is limited due to mechanical-physical problems, which can be solved by immobilization, obtaining particles with good physico-chemical stability (higher mechanical resistance). Several aspects need to be taken into account when selecting an appropriate immobilization technique, as immobilization involves additional costs, the diffusion of a contaminant through a support that increases the time and decreases the efficiency of the process, and also decreases the capacity of biosorbent due to interactions between the support and all active site of the biosorbent [17; 19; 20; 21; 22]. Immodilization on different media/supports gives microorganisms improved properties, but especially improves their ease of handling and their ready application for effluent treatment through a biosorption process. Immobilization techniques can be divided into two groups [23; 24; 25; 26]:passive--based on the property of the microorganism film formation. The supporting materials are in contact with the cellular suspension of a tested micro-organism for a period of time (before sterilization and inoculation with the starting microorganism suspension), after which a microorganism film is formed on the supporting surface. This technique offers a number of advantages over other immobilization methods, including the ease of immobilization (natural catching/fixing), no need for the addition of chemicals, high rate of mass transfer in particles, and ease of the immobilization technique extension. However, this technique can only be applied to microorganisms with a natural tendency to attach or aggregate on a solid support. 2. active--based on gel capture/entrapment and chemical cross-linking (covalent binding to vector compounds and reticulation). Gel capture/entrapment is the most widely used technique for immobilizing microorganisms within a polymeric matrix, made using natural polysaccharides (chitosan, agar, carrageenan or alginates), proteins (gelatin, collagen), or synthetic polymers (acrylamide, photo-reticulated resins, polyurethane). However, chemical entrapment or cross-linking has greater disadvantages when micro-organisms are intended for immobilization, because chemical interaction (covalent binding or reticulation-involving glutaraldehyde or photocrossable resins) causes damage to the cell surface, drastically reducing cell viability. Considering this basic information, our paper presents experimental results of a biosorption process study performed in a fixed-bed column for the removal of Brilliant Red HE-3B (BRed) anionic dye from aqueous solutions (low concentrations of anionic dye, <10 mg/L). All experiments were carried out using dead/non-living residual _Bacillus_ sp.