Oct. 24, 2002  14  US 2002/0153319 Al  TABLE  4  TABLE  5  TABLE  6  TABLE 7  silica/boron leakage exceeds normal threshold values.  Reduction of strongly ionized species concentration in the  RO permeate is of relatively less significance, since most  post-RO ion exchange is ultimately silica or boron limited.  [0147]  Compared to 60 to 70 percent boron rejection in  conventional thin film composite  RO  operation, the new  process provides approximately 99 percent boron rejection.  In a double pass configuration, the new process is capable of  producing a permeate with lower than detectable limits of  boron content.  [0148]  Another very significant advantage in operating ion  exchange with permeate from a HERO brand RO system is  that sodium leakage from cation resin is reduced by several  orders of magnitude, due to the high ambient pH of the  influent.  As  a result, longer run times between regeneration  for existing ion exchange systems means lower chemical  and manpower needs, lower regeneration waste volume, etc.  For new systems, or for existing systems undergoing expan› sion, the new HERO brand RO process design and operation  can have a strong positive impact on the ion exchange  system capital cost as well.  [0149]  (B) High Recovery Rates  [0150]  Since hardness-causing ions such as calcium, mag› nesium, barium, strontium, aluminum, iron, manganese,  etc., have been removed prior to the RO, undesirable pre› cipitation of species such as calcium carbonate, calcium  fluoride,  calcium sulfate,  barium sulfate,  magnesium  hydroxide, aluminum/magnesium silicate, etc., does not  occur in the  HERO  brand  RO  process, and thus that type of  precipitation no longer limits the recovery achievable by an  RO  system. Importantly, silica solubility, is increased dra› matically at the normal  HERO  brand  RO  operating  pH  (preferably of approximately 11). Sustainable long-term  operation with silica levels in the 450 to 500 ppm range (in  the  RO  reject) has been proven, and theoretical models  indicate that levels of 1,000 ppm or higher may be achiev› able in this new  RO  operational method.  [0151]  Based on 25 ppm silica in the RO feed, 95 percent  recovery RO operation (approximately 500 ppm in the  reject) has been proven by testing. Still, 97.5 percent recov› ery (approximately 1,000 ppm silica in the RO reject) is  theoretically feasible, whether or not practical from an  operational point of view. Since silica usually represents the  ultimate limiting criterion, in terms of maximum allowable  recovery in an RO system, increased silica solubility along  with essentially total absence of species such as calcium,  barium, etc., in RO feed, should allow RO operation at very  high recovery rates (90 to 98 percent) with the vast majority  of feedwaters.  [0146]  regenerations. Absence of carbon dioxide, as well  as bicarbonate in the RO permeate (due to a high pH,  typically at least 10), will also increase on-line time before  Note: See Section 5.0 for basis.  [0145]  [0144]  Notes:  1. Analysis of RO feed is not shown in the table, nor is the hydroxide  content of RO reject and RO Product.  2. The chemistry is based on 90 percent RO recovery, while maximum  recovery feasible is approximately 96 percent.  3. Except for pH, all constituents are reported as mg/1 as CaCO$_{3 }$ [0143]  COMPARISON OF HERO  TM  RO VS. CONVENTIONAL RO  Rejection (%)  Rejection (%)  Passage (%)  Passage (%)  Constituent  Conventional  HERO  Conventional  HERO  Sodium  98  99.73  2  0.27  Potassium  90  99.98  10  0.02  Chloride  98  99.99  2  0.01  Silica  99  99.87  0.13  Boron  70  98.51  30  1.49  TOC  95  99.66  5  0.34  Passage Factor  Passage  Conv/HERO  Reduction(%)  7.4  87  500.0  99  200.0  99  7.7  87  20.1  95  14.7  93  WATER ANALYSIS  Raw Water  RO Reject  RO Product  Na+ K  125  1.350  <1  Ca  7  0  0  Mg  13  0  0  HC03  85  50  <1  C03  0  50  <1  N03  10  <1  SO4  30.8  308  <1  Cl  28.2  282  <1  SiO2  50  500  <1  pH  7.1  10.8  10.2  COST ESTIMATE OF A RETROFIT  Water/Waste Water Savings  Antiscalant Elimination  Power Savings  Additional Chemical Costs  Additional Miscellaneous Costs  Net Annual Savings  Conversion (Capital) Cost  Simple Pay-Back Period  244,000 (US $/Yr)  30,000 (US $/Yr)  17,000 (US $/Yr)  (40,000) (US $/Yr)  (20,000) (US $/Yr)  231,000 (US $/Yr)  200,000 (One Time)  10.4 (Months)  COST COMPARISON  Equipment Capital Cost (US $MM)  Operating Cost (US $/1,000 US Gallon)  HERO  Conventional System  System  12  5.75  7.8  <4.00 