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Corespondance Regarding Lowered Costs Using Sulfree™

Process Engineer
San Francisco Public Utilities Commission
Water Pollution Control Division
750 Phelps Street, San Francisco, CA 94124-2161
ENGINEERING

After meeting you at the plant trial at the San Francisco Airport, we had discussed and scheduled a meeting to discuss a plant trial at the South East collections area. In order to better serve you and the city of San Francisco, I asked for information regarding present use rates for other chemical addendums added to this system’s wastewater treatment plant in order to give you a cost comparison between technologies.

Presently, the wastewater treatments used for odor and hydrogen sulfide control were:
900 gallons Hydrogen Peroxide at 2.87/gallon 1100 gallons of Ferrous Chloride at 35% , 11 pounds per gallon and .245/lb on dry basis 200 gallons of Bleach solution at say 95¢/gallon.
There was also Ferric Chloride added at the digestor for Struvite control and as a co-precipitator.

The other parameters of the plant were given 65 MGD and 1-2 ppm average sulfide concentration. For our recommended treatment rate for odor control/ mercaptan control/ hydrogen sulfide removal we would recommend adding Sulfree at 3 gallons per million gallons treated.

Present treatment methods cost determination is as follows:
900gallons Hydrogen Peroxide * $2.79/gallon = $2511.00 1100 gal Ferrous Chloride * 1100 gallons *11 lbs/gal*$0.245/dry pound= $1037.58 200 gal Chlorine Bleach* $1.20/gallons= $240.00
Total = $3788.58 per day on 59.28/million gallons/day or $1,382,831,70/year

Proposed treatment costs using Sulfree are as follows:
65 million gallons at 3 gallons per million treated=195 gal/day*$8.00/gal =$1560.00/day Total =$1560.00/day or $24.00/million gallons/day or $569,400/year. This would give capability to remove up to 4 ppm Hydrogen Sulfide and mercaptans Required Treatment rates to control Hydrogen Sulfide odors would be less than this—closer to 2 gallons per million gallons of wastewater, or $379,600.00/year Cost savings for treating San Francisco’s wastewater would be $831,431.70/year at the recommended treatment level and $1,003,231.70 at the required level. These calculations were based on figures given us.

At the meeting on June 12,2008 discussion was made that the city was spending 2 million per year on chemical addendums to remove Hydrogen Sulfide and treat wastewater. These figures also do not include Ferric Chloride additions that occur at your digestor for Struvite control. Guard Products has also addendums that can be added for anti-Struvite control. These would cost an additional $100.00/day at recommended treatment levels. I hope this cost comparison can assist you in considering Sulfree for a wastewater treatment alternative.
Thank you for your consideration.

Chemist, Guard Products