US 2022/0204377 A1Published application

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

AssigneeInvestigaciones Forestales Bioforest S.A.

InventorsÁlvaro Mauricio GONZÁLEZ VOGEL, Rafael Ignacio QUEZADA REYES

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Abstract

Process for upgrading effluent treatment plants for pulp and paper production processes, where salts are removed from the effluent for water reuse and chemical recovery. The process comprises a first dialysis system for salt removal, a second treatment system for recovery or re-concentration, and optionally a post-treatment of the re-concentrate preventing liquid discharges to the environment. In the first system, a reversible electrodialysis or reversible pulsed step is carried out, separating the salts from the effluent, which are sent to the second treatment system to concentrate the salts (re-concentrate) or transform them into useful chemicals for the same process (recovery). Chemical recovery is achieved by electrodialysis with bipolar membranes or metathesis, to reduce the re-concentrate stream, which cannot be reused in the same plant. Lastly, this stream may be treated by spray drying, crystallization or evaporation.

Claims14

Dependent claims

A process for the recovery of water from pulp and paper mill effluent treatment plants free of organic matter and salts for subsequent recirculation, 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, the tertiary treatment system selected from:
electrocoagulation, chemical coagulation, photooxidation, electrooxidation, chemical oxidation, flotation filtration, centrifugation, or 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,
c) passing part of the effluent free of remaining suspended solids obtained in step (b) through a first dialysis system selected from a pulsed electrodialysis reversal (pEDR) or an electrodialysis reversal (EDR) to form a concentrate and a dialyzed effluent,
d) passing the concentrate obtained in step (c) through a second treatment system for at least one of the recovery of chemicals or re-concentration of salts as a reject re-concentrate stream with a content of salts not useful for a pulp and paper production process.

2 more elements

Dependencies are inferred from the claim text.