Selective Nitrates removal from waste water using coupling membrane electrolysis and catalytic method

MARIA L. BOSKO; FERNANDA ALBANA MARCHESINI; MARCO ANTONIO RODRIGUEZ; JANE Z FERREIRA; EDUARDO E MIRO; ANDREA MOURA BERNARDES

Lisboa

Workshop; Workshop Cyted Membranes for industry; 2013

Instituo politecnico de Lisboa - Cyted

At present, health and environment protection are major concerns and avoiding the contamination of the air, soils and water is a challenge. Nitrogen compounds are some of the major pollutants; they are essentially originated by human activity, including agriculture, animal processing industries, vehicles and waste treatment. Alternative processes should be studied to meet the new environmental and technological requirements. Among the alternatives for nitrates and nitrite abatement in drinking water, catalytic hydrogenation has been a matter of several research studies in the last decade. However, besides the desired reaction that converts the contaminants into nitrogen, undesired ammonia is produced [1,2]. On the other hand, electrodialysis has recently achieved a great development for water denitrification. This process is both useful for water purification and in the concentration of ionic species in solution. Several authors have evaluated the electrodialysis processes for nitrates removal from drinking water in terms of process parameters and application conditions [6-13] and demonstrated the ability of the process to remove nitrate from brackish waters. However, these authors have highlighted that the main disadvantage of this method is the uncertain destination of the nitrate concentrated residue. A viable option to decrease these ion concentrations could be the membrane electrolysis coupled with catalytic reduction technique. In these systems, the reactions occur in the presence of an electric field and the exchange membrane is employed to separate the electrode compartments, thus impeding the migration of products, and avoiding reoxidation reactions (reversible reactions). After this process, nitrates and nitrites residuals are treated with a bimetallic catalyst (Pd,In supported in alumina) in order to reduce the highs ions concentrations and produce water which reaches the levels fix by the regulations. reactions occur in the presence of an electric field and the exchange membrane is employed to separate the electrode compartments, thus impeding the migration of products, and avoiding reoxidation reactions (reversible reactions). After this process, nitrates and nitrites residuals are treated with a bimetallic catalyst (Pd,In supported in alumina) in order to reduce the highs ions concentrations and produce water which reaches the levels fix by the regulations. . In these systems, the reactions occur in the presence of an electric field and the exchange membrane is employed to separate the electrode compartments, thus impeding the migration of products, and avoiding reoxidation reactions (reversible reactions). After this process, nitrates and nitrites residuals are treated with a bimetallic catalyst (Pd,In supported in alumina) in order to reduce the highs ions concentrations and produce water which reaches the levels fix by the regulations.