Bioregeneration of Spent Anion Exchange Resin for Treatment of Nitrate in Water

• Published in: Environmental science & technology Vol. 48; no. 3; pp. 1541 - 1548
• Main Authors: Meng, Xiaoyang, Vaccari, David A, Zhang, Jianfeng, Fiume, Antonio, Meng, Xiaoguang
• Format: Journal Article
• Language: English
• Published: Washington, DC American Chemical Society 04-02-2014
• Subjects: Anion Exchange Resins - chemistry; Applied sciences; Bacteria, Anaerobic - growth & development; Biodegradation, Environmental; Biomass; Conductivity; Denitrification; Desorption; Drinking water and swimming-pool water. Desalination; Exact sciences and technology; Filtration; Kinetics; Models, Theoretical; Nitrates; Nitrates - analysis; Nitrates - chemistry; Nitrogen - analysis; Pollution; Resins; Sewage - microbiology; Solutions; Water Pollutants, Chemical - analysis; Water Pollutants, Chemical - chemistry; Water Purification - methods; Water treatment and pollution; Drinking water treatment; Microbial activity; Water treatment; Filtration; Anionic resin; Nitrogen compounds; Nitrates; Sustainable development; Waste management; Membrane separation; Regeneration; Upgrading; Waste reuse; Denitrification; Biological treatment; Resource management
• ISSN: 0013-936X; 1520-5851
• DOI: 10.1021/es4043534

Anion exchange resin treatment is a commonly used technique for removal of nitrate from water. However, spent anion exchange resins are themselves regenerated using brine solution, which produces spent solution containing a high concentration of nitrate and salt. The present study developed a bioregeneration technique for conversion of nitrate on the spent resins to nitrogen gas while eliminating the use of brine solutions. Batch experiments were conducted to investigate the effect of biomass content, pH, salinity, and molar ratio of exogenous organic carbon to nitrate on the kinetics of bioregeneration. The bioregeneration rate decreased when pH increased from 7 to 10. It increased with increasing microbial concentration from 8.3 to 13.8 g/L as volatile suspended solid (VSS) and with decreasing conductivity of the regeneration suspension from 31 to 9 mS/cm. Spent exchange resins were effectively regenerated within 5 h under the optimal conditions and the regenerated resins could be used repeatedly for filtration removal of nitrate from water. A desorption–denitrification model was developed to describe bioregeneration kinetics. Modeling results indicated that the bioregeneration was through desorption of nitrate from the spent resin and subsequent denitrification of the soluble nitrate. Denitrification was the rate-limiting process. This research demonstrated the feasibility of using a biological process to regenerate nitrate-saturated resins.