Patent ID: 7520980

Claim:
A multi-stage bioreactor system for microbiological treatment of wastewater, the bioreactor system comprising at least one highly-flexible substrate for providing a superficial environment conducive for supporting biomass growth, which substrate comprises a large plurality of threads, the threads being disposed in a generally longitudinal direction and comprising a plurality of synthetic filaments, and at least two spaced apart cross-support elements disposed across and associated with the plurality of threads, so as to provide support for and loosely associate the threads, wherein (A) the thread segment aspect ratio, which is a ratio of distances between adjacent cross-support elements relative to side-to-side or lateral distances between adjacent threads, exceeds 50 to 1 and (B) the length extension of the threads, which is a ratio expressed in percent, between the length of a section of substrate between adjacent cross-support elements and the average length of the threads forming that section, is in the range of 80% to 98%.