No abstract

Managing waste brine from strong base anion exchange processes used for hexavalent chromium removal is an important operational, environmental, and economic consideration. This study investigates the use of nanofiltration to recover excess regenerant salt and reduce the waste volume using brine collected from full‐ and pilot‐scale installations. Using a 2 N sodium chloride regeneration solution, divalent anions (i.e., sulfate and chromate) exhibited high rejections (>0.97), and monovalent anions (i.e., chloride and nitrate) exhibited low to negative rejections (−0.2 to 0.05), allowing preferential passage of excess regenerant salt. A batch concentration model was developed for a case study. Waste can be concentrated to 0.6 bed volume and a significant fraction of the regenerant salt can be recovered. This process would require about 20 m2 of membrane area per 1,000 L of resin to treat waste in 8 h, which could be implemented in a mobile treatment unit serving multiple decentralized systems.

No abstract

A full-scale pilot hybrid sequencing batch membrane bioreactor (SBR-MBR) wastewater treatment system is being tested at the Colorado School of Mines (Golden, Colorado). The pilot system was developed by Aqua-Aerobic Systems, Inc. (AAS, Rockford, Illinois). The preliminary objective of the pilot study is to assess the economic and technical feasibility of using the SBR-MBR process as a sustainable onsite and decentralized approach for wastewater treatment. The reliability and robustness of the biological treatment is also being evaluated over a variety of challenging influent and environmental conditions. Process optimization is underway to reduce energy, carbon, and chemical requirements. Preliminary results from system startup operation of the SBR-MBR system (since February 2009) are presented and accompanied by a discussion of process requirements and economic considerations.