SBIR-STTR Award

The plating and electronics industries are required by state and federal regulations to remove toxic, heavy metals from wastewater streams before discharge. The semiconductor and printed circuit industry alone removed over 7.2 tons of heavy metals from wastewater in 1983. Much of the recovered metals are discarded as sludges, because techniques for recovering and separating the metal ions are uneconomical. Bio-Clean has developed methods for immobilizing algae in silica gels which can be packed into columns and used much like ion exchange resins in the removal and recovery of heavy metal ions from solutions. Like ion exchange resins, the immobilized algae can be recycled, but in contrast to chelating ion exchange resins, hard water components (CA(II), Mg(II)) interfere minimally with the binding of transition metal ions. In addition, conditions have been developed for removing metallic oxoanions (CrO4-2 , MoO14-2) from aqueous solutions using immobilized algae. Furthermore, the binding capacity of the algae for certain metal ions may exceed ten percent of the dry weight of the algae. It appears that the cost of this system will be but a fraction of the cost associated with ion exchange technology.It is the purpose of this project to develop an economical process using immobilized algae to produce an effective system for removing heavy metal ions from industrial wastewaters.

The plating, electronics and metal finishing industries are required by state and Federal laws to remove toxic, heavy metal ions from wastewater streams prior to discharge. The most common treatment is the precipitation of metals as hydroxide sludges which are disposed in hazardous waste landfills. In this project, technology is being developed which can be used to recycle metals in industrial processes and thus eliminate hazardous waste disposal. Methods have been developed for immobilizing algae in silica gels which can be packed into chromatographic columns and used much like ion exchange resins in the removal and recovery of heavy metal ions from solutions. Like ion exchange resins, the immobilized algae can be recycled, but in contrast to chelating ion exchange resins, hard water components (calcium and magnesium) interfere minimally with the binding of transition metal ions. The purpose of the Phase I research was to test the algae-silica product with real industrial wastewaters for metal-removing capa- bilities, to ascertain the best algae-silica composition for metal removal, to test the longevity of the algae-silica material and to provide a brief analysis of the economics involved in using the algal technology in industrial water treatment. The results from Phase I were extremely encouraging and strongly suggest that the process will be commercially feasible. In Phase II, the Phase I studies will be extended by testing other industrial waters and by extending longevity studies. In addition, automatic equipment will be developed which can take the technology to the marketplace. Venture capital has been obtained to accelerate the Phase II activities described here.