US 6,387,669 B1 · Methods for producing hydrogen (BI) sulfide and/or removing metals

Abstract

The present invention is a process wherein sulfide production by bacteria is efficiently turned on and off, using pH adjustment. The adjustment of pH impacts sulfide production by bacteria by altering the relative amounts of H2S and HS— in solution and thereby control the inhibition of the bacterial metabolism that produces sulfide. This process can be used to make a bioreactor produce sulfide “on-demand” so that the production of sulfide can be matched to its use as a metal precipitation reagent. The present invention is of significance because it enables the use of a biological reactor, a cost effective sulfide production system, by making the biological reactor produce hydrogen sulfide “on demand”, and therefore responsive to production schedules, waste stream generation rate, and health and safety requirements/goals.

Claims16

Dependent claims

A method of decreasing and increasing sulfide production within a bioreactor containing at least one species of bacteria which is reducing an oxidized sulfur compound to a sulfide compound in an aqueous media at a predetermined rate, the method comprising the steps of:

a. decreasing the reduction of the oxidized sulfur compound by reducing the pH of the aqueous media to a level at which the rate of reduction of said oxidized sulfur compound is substantially zero and the rate of decay of said bacteria is substantially zero,
b. increasing the reduction of the oxidized sulfur compound by raising the pH of the aqueous media to a level at which the rate of reduction of said oxidized sulfur compound is substantially returned to the predetermined rate.

a. decreasing reduction of the oxidized sulfur compound is accomplished by reducing the pH of the aqueous media to a level at which the rate of reduction of said oxidized sulfur compound is less than or equal to ten percent of the predetermined rate, and the rate of decay of said bacteria allows less than two percent of the biomass concentration of the bacteria to decay in a twenty four hour period and
b. increasing the reduction of the oxidized sulfur compound is accomplished by raising the pH of the aqueous media to a level at which the rate of reduction of said oxidized sulfur compound is returned at least ninety percent of the predetermined rate.

Dependencies are inferred from the claim text.

Methods for producing hydrogen (BI) sulfide and/or removing metals

Life of this patent

Methods for producing hydrogen (BI) sulfide and/or removing metals

Life of this patent

Abstract

Claims16