Water treatment processes using biocatalysts
The microorganism-containing biocatalysts disclosed have a large population of the microorganisms irreversibly retained in the interior of the biocatalysts. The biocatalysts possess a surprisingly stable population of microorganisms and have an essential absence of debris generation from metabolic activity of the microorganisms. The biocatalysts are composed of highly hydrophilic polymer and have an internal, open, porous structure that promotes community phenotypic changes.
1. A process for treating water containing at least one soluble compound of metal or semi-metal comprising:
(a) continuously introducing said water into a reaction zone containing a biocatalyst, said biocatalyst comprising a solid structure of hydrated hydrophilic polymer defining an interior structure having a plurality of interconnected major cavities having a smallest dimension of between 5 and 100 microns and wherein said biocatalyst has a Hydration Expansion Volume (HEV), which is calculated in volume percent, of 1000 or more and a population of microorganisms for reducing said at least one soluble compound of metal or semi-metal, wherein the population is irreversibly retained in the interior structure, wherein the concentration of the population of microorganisms in the interior structure is about 60 grams per liter or more based upon the volume defined by the exterior of the solid structure when fully hydrated, and wherein the microorganisms maintain their population such that the population does not decrease by more than 50 percent nor increase by more than 400 percent;
(b) contacting the water with said biocatalyst for a time sufficient to reduce the concentration of said at least one soluble compound of metal or semi-metal in the water;
(c) maintaining said biocatalyst under metabolic conditions sufficient to metabolically reduce the oxidation state of the metal or semi-metal of the at least one soluble compound of metal or semi-metal to form an elemental metal or a semi-metal or a precipitated compound thereof; and
(d) withdrawing water having a reduced concentration of said at least one soluble compound of metal or semi-metal from the reaction zone.
2. The process of claim 1 wherein the HEV of the biocatalyst is at least 20,000 and the concentration of the population of microorganisms in the interior of the solid structure is at least 100 grams per liter based upon the volume defined by the exterior of the solid structure.
3. The process of claim 1 wherein the solid structure of the biocatalyst defines an external skin having pores of an average diameter of between 1 and 10 microns and wherein the pores comprise 1 to 30 percent of the surface area of the external skin.
4. The process of claim 1 wherein the major cavities of the biocatalyst are quiescent.
5. The process of claim 1 wherein the biocatalyst contains an exo-network of said population of microorganisms, wherein the microorganisms are spaced-apart in the form of individual cells or biofilms that are interconnected by an extracellular polymeric substance in the form of strands to form the exo-network.
6. The process of claim 1 wherein the biocatalyst further comprises polysaccharide.
7. The process of claim 1 wherein the biocatalyst further comprises a solid sorbent.
8. The process of claim 1 wherein the population of microorganisms irreversibly retained in the biocatalyst is a population of photosynthetic microorganisms and the biocatalyst further comprises a phosphorescent material.
9. The process of claim 1 wherein the biocatalyst further comprises at least one isolated enzyme.
10. The process of claim 1 wherein the microorganism population irreversibly retained in the biocatalyst exhibits at least one phenotypic change selected from the group consisting of metabolic shift, enhanced rate of bioconversion, enhanced toxin resistance, strain stability, and stasis capability, as compared to a planktonic population of said microorganism.