Evaluating composite ion exchangers (CIX) for improved stability of anaerobic biological reactors

An extensive laboratory study demonstrated that the stability of anaerobic biological processes can be improved and the process failure prevented by retaining specialty functionalized polymers inside the reactors. Such functionalized polymers, referred to as composite ion exchanger (CIX), are essentially microbeads of chelating exchanger encapsulated in fibrous, cloth-like polytetrafluoroethylene or Teflon. During the course of the investigation, severe stresses were introduced into a train of anaerobic reactors through organic and heavy-metal overloading of the feed. The reactors containing CIX successfully survived the stresses by dissipating the inhibitory hydrogen ions and dissolved heavy metals from the aqueous phase. The reactors containing no CIX always failed under stress conditions, all other conditions remaining identical. The CIXs were found to be chemically stable, durable, did not require any intermittent cleaning or regeneration, and occupied less than one percent of the reactor volume. Due to its thin-sheet like morphology, CIX can be easily introduced into or withdrawn from a biological medium without any difficulty. The proposed control technique does not warrant any external intervention and may replace the need for continuous dosage of excess alkalinity.