Compatibility Assessment of Membrane Processes for Closed-Loop Water Recovery and Recycling

Closed-loop water recovery and recycling systems are receiving attention for industrial and municipal water treatment applications due to the increasing concern over water use and the need for developing more efficient systems for water treatment. Closed-loop water recovery is especially important for space travel and has a wide range of applications on Earth. Membrane filtration processes are often considered for down stream treatment to improve water quality due to the ability of reverse osmosis (RO) membranes to reject contaminants while passing relatively pure water. However, integration of treatment processes requires in depth analysis of design and operational parameters based on the upstream process characteristics and downstream performance expectations. This paper presents the important design and operational performance parameters for interfacing membrane filtration systems with aerobic membrane bioreactors based on the experimental studies conducted at the Kennedy Space Center, Florida. The experiments were conducted with the effluent from the aerobic rotational membrane system (ARMS) to assess the downstream compatibility of the bioreactor effluent with membrane filtration. ARMS is a compact membrane bioreactor which converts ammonia to nitrates in wastewater. Oxygen is provided through the rotating hallow fiber membrane module which supports the biofilm. A series of cross flow filtration tests were run using an RO membrane (BW30LE) by Filmtech (Dow North America, Midland, Michigan) and SEPA CFII membrane test cell (Osmonics, Clearwater, Minnesota). The performance parameters inclusing flux, fouling potential, operational compatibility, and biofouling potential of the membrane were evaluated.