Bio-leaching of toxic metals from geothermal waste. A preliminary engineering analysis

Technical Report · Sat Feb 01 00:00:00 EST 1986

DOI:https://doi.org/10.2172/5293588· OSTI ID:5293588

Dobryn, D G; Brisson, A L; Lee, C M; Roll, S M

The feasibility of a biological facility to treat geothermal sludge from a base case 50-MW double-flash geothermal power plant in the Imperial Valley, California was evaluated. The effect of sludge and nutrient concentration, agitation air bubbling and sterility on the rate of metal solubilization by the bacteria Thiobacillus thiooxidans and ferrooxidans was examined. All experiments were performed in batch flasks and monitored daily for bacterial growth. T. Thiooxidans leached 36% of the zinc in the sludge after 288 hr but leached little chromium. T. ferrooxidans removed 60% of the chromium in the sludge after 250 hr but did not leach zinc. Sludge to medium ratios of greater than 10% were toxic to the microorganisms studied. the experimental results were used to design a biological solid-waste treatment plant. The design basis used was 5 wt % sludge in the leaching vessel with a residence time of 10 days. The non-regulated waste resulting from the treatment plant could be used for land fill or construction materials. The total capital cost for the bio-leaching plant is $3.3 million with an annual operating cost of $690,000. The total cost of this plant is about 0.2 cents/kWh of electricity produced, which is essentially the same cost as hauling the solid waste to a hazardous disposal site. This cost accounts for about 5% of the cost of producing electricity from geothermal power (4 cent/kWh).

• Research Organization: Massachusetts Inst. of Tech., Brookhaven, NY (USA). School of Chemical Engineering Practice-Brookhaven Station
• DOE Contract Number: AC02-76CH00016
• OSTI ID: 5293588
• Report Number(s): BNL-38523; ON: DE86015082
• Resource Relation: Other Information: Portions of this document are illegible in microfiche products
• Country of Publication: United States
• Language: English

Related Subjects

15 GEOTHERMAL ENERGY
GEOTHERMAL POWER PLANTS
ACTIVATED SLUDGE PROCESS
BENCH-SCALE EXPERIMENTS
CHROMIUM
COST
LEACHING
SLUDGES
THIOBACILLUS FERROXIDANS
THIOBACILLUS OXIDANS
ZINC
BACILLUS
BACTERIA
DISSOLUTION
ELEMENTS
MANAGEMENT
METALS
MICROORGANISMS
POWER PLANTS
PROCESSING
SEPARATION PROCESSES
SULFUR-OXIDIZING BACTERIA
THERMAL POWER PLANTS
TRANSITION ELEMENTS
WASTE MANAGEMENT
WASTE PROCESSING
Geothermal Legacy