Zero Liquid Discharge

UEM has the experience and the technology tie-ups to offer economical zero liquid discharge (ZLD) systems. ZLD systems, which maximize the recycle quality water produced from wastewater and discharge only solid waste as a byproduct, often include reverse osmosis (RO) followed by evaporation and crystallization of RO rejects. The energy cost for volume reduction via evaporation and crystallization is substantially higher than the energy cost of volume reduction via RO membranes. Thus, in order to reduce the life cycle cost of a ZLD system, maximizing recovery from the RO system is essential.

To this end, UEM is a licensee of the high efficiency reverse osmosis (HEROTM) process and has the ability to offer this process as a part of our ZLD solutions.  The HERO process removes barriers to RO recovery typically encountered in conventional RO systems, such as:

  1. Hardness scaling – the HERO pretreatment process removes the hardness scaling tendency of the RO feed water.
  2. Silica scaling – the HERO process is operated at a high pH. At a high pH, the solubility of silica increases such that silica concentration is no longer a barrier to high recovery.
  3. Organic fouling – at a high pH, organics are either saponified or ionized, increasing the solubility of organics and preventing the precipitation (i.e. fouling) of organics on the RO membranes.
  4. Biofouling – at a high pH, bacterial cells are lysed or inactivated, thus preventing biological fouling of the RO membranes.

Together with UEM’s experience and technical expertise in conventional industrial and municipal wastewater treatment, UEM has the ability to offer complete ZLD solutions from the point of effluent generation to the point of dry salt and recycled water production.