**4. Conclusions**

For the treatment of wastewater containing organic matter in suspension, such as a fish packing plant, to be effective, it is necessary to know both the chemical and physical properties of the suspended solids and the water to be treated. The addition of chitosan to wastewater with a high content of organic matter (fish packing plant), triggers a series of processes that begins with the hydrolyzation of the chitosan, followed by the destabilization of the particles by simple specific adsorption of the hydrolysis products and finally sedimentation and separation of organic matter from water. It should be noted that the cationic behavior of chitosan chains allows a better interaction between suspended particles and chitosan itself. Considering the above, the use of biopolyelectrolytes in the coagulation-flocculation process efficiently removes the suspended solids allowing high efficiencies in the removal of COD and TOC, it is worth mentioning that an excess in the dose of bio-polyelectrolyte will re-suspend the settled solids increasing operating costs. This work contributes to the objectives of sustainable development allowing the sanitation and recovery of wastewater using coagulant-flocculating agents that are eco-friendly with the environment.
