The City of McAllen, Texas, with the assistance of CH2M HILL and the
co-sponsorship of the United States Bureau of Reclamation (BOR), Electric Power
Research Institute, and the Texas Water Development Board, has pilot tested an
integrated membrane bioreactor (MBR)/reverse osmosis (RO) treatment train to
reclaim municipal wastewater to a quality suitable for use as a new drinking
water supply in the process called indirect potable reuse. Previous testing by
the City (Phase 1) demonstrated the applicability and cost of microfiltration
(Memcor and ZeeWeed systems) to enhance the quality of secondary effluent for
subsequent treatment by RO and the feasibility of a membrane bioreactor system
(ZenoGem) to produce RO feedwater directly from minimally processed sewage. Phase
2 testing, reported on in this paper, is designed to demonstrate, when treating
screened, degritted sewage, reliable operation of both the MBR and RO processes
and that the effluent from such a train can meet all federal primary and state
secondary drinking water regulations and comply with state requirements for
indirect potable reuse. Results show the ZenoGem process to be reliable, require
minimal operator attention and maintenance, produce an effluent that can be
processed by RO with little fouling and that easily exceeds the City's current
effluent discharge requirements relative to biological oxygen demand (BOD), total
suspended solids (TSS), and ammonia. The ZenoGem permeate quality exceeds RO
feedwater criteria for turbidity and silt density index and the RO system
performance confirms minimal membrane fouling by particles. However, the high
calcium hardness and phosphate levels in the City's wastewater (and ZenoGem
permeate) caused mineral precipitation within the RO system when operated at
higher recoveries. Precipitation can be controlled, however, by increased
acidification of the RO feedwater. Includes 2 references, tables, figures.
| Edition : | Vol. - No. |
| File Size : | 1
file
, 330 KB |
| Note : | This product is unavailable in Ukraine, Russia, Belarus |
| Number of Pages : | 18 |
| Published : | 01/01/2000 |
