IGEM:MIT/2007/Red Team

Cost Analysis

• US Dept. of the Interior; Bureau of Reclamation Hg and Cd Cost sheet [1]

Large Scale (250,000 gal/day)

Filtration and Coagulation

• $260k Equipment
• $75k per year
• Only for insoluble Hg and Cd
• High sludge volume

Lime Softening

• $255k Equipment
• $37k per year
• Lots of sludge
• Will require filtration and coagulation
• In lime softening, hydrated lime that is, calcium hydroxide, Ca(OH)2is added to water to precipitate calcium carbonate before the water is used. The amount of lime required will depend on hardness levels. The process requires a settlement period and its effectiveness is governed by the pH of the water. Lime softening is a complex process and therefore is usually limited to situations where constant monitoring is available.

Reverse Osmosis

• $600k Equipment
• $400k per year
• Frequent monitoring

Granular Activated Carbon

• $680k Equipment
• $125k per year
• Bacteria can grow on carbon surface
• Effectiveness varies on contaminant type

Ion Exchange

• $180k Equipment
• $8k per year
• Requires Salt storage
• [2]
• Strong Acid Cation exchanger Works best with Cadmium...not mercury
• Chelation for Hg is 1867x stronger than Cd...would require 2 times

Small Scale (Home Use)

Reverse Osmosis

• $200
• 450 gallons
• $.44/gal
• [3]

Granular Activated Carbon and Ion Exchange

• Brita Filter
• 1000 gal for $220 per year
• $9 for 40 gal upkeep
• So $.22/gal

E.coFilter

• Liquid Cultures Cheapest
• LB Powder: $60/kg
• 40 L of broth per kg
• $1.5 per L
• Assumes takes .5 L of broth to grow enough bacteria to filter 1 L
• So $.75 per L, or $1.5/gal

Ways to improve

• Reuse broth
• Reuse bacteria

Problems

• How to ensure all bacteria is gone?
• Price