Method for recovering water and chemicals from plants for treating effluents from pulp and paper factories

A process for the recovery of water from an effluent treatment plant for a Kraft process, free of organic matter and salts for subsequent recirculation, preventing discharge of liquids into an environment, the process comprising:

• a) passing previously physically and biologically treated effluent in the effluent treatment plant to a tertiary treatment system for coarse removal of remaining organic matter, wherein the tertiary treatment system is selected from the group consisting of:
• electrocoagulation, chemical coagulation, photooxidation, electrooxidation, chemical oxidation, flotation, filtration, centrifugation, and cyclone separation, to obtain an effluent with organic matter content of less than 100 ppm,
• b) passing the effluent obtained in step (a) through a filtration system to generate an effluent free of remaining suspended solids from the tertiary treatment system,
• c) passing part of the effluent free of remaining suspended solids obtained in step (b) through a first dialysis system, which is a pulsed electrodialysis reversal (pEDR) system, to form a concentrate and a dialyzed effluent,
• d) passing the concentrate obtained in step (c) through a second treatment system, which corresponds to an electrodialysis step, for the recovery of chemicals and re-concentration of salts as a reject re-concentrate stream with a content of salts not useful for a pulp and paper production process, and
• e) passing the reject re-concentrate stream obtained in step (d) to a drying system to form a condensate and a solid by-product, which is a soluble salt, to be reused in another application and to prevent the discharge of liquids in the environment.