Implementation of the PURON® Technology: Submerged Hollow Fiber Modules In a commercial system the individual fiber bundles are connected in rows. Several of these rows are mounted in a stainless steel frame forming a membrane module. The PURON® module is available in standard sizes of 1500, 500 and 250 square meters of membrane area. The design of the PURON® module was specially developed to meet the extremely tough requirements of a membrane bioreactor (MBR) when utilized in wastewater treatment.