Iron and sulfur bacteria are principal causes of biofouling of well screens, pumps, treatment and processing equipment, and in extreme cases, distribution systems. Associated problems are high pumping cost, rapid pump and valve deterioration, corrosion of all ferrous material in contact with the water, increased disease risk (shielding, nurturing media), and bad taste, odor and color.The problem varies from only a nuisance to elimination of the only reasonable source of water in some areas. It is world-wide but follows some patterns of intensive contamination.Treatment has been attempted for several hundred years, with varying degrees of success. Generally, the common methods (chemical and mechanical) are only effective for short periods when contamination is severe and covers the area. Continuous chlorine trickle into the well or dosing with each pump cycle tend to prolong the effective period of treatment but are still not permanent in most severe cases.A means is needed to sterilize the well and surrounding aquifer and to retard bacteria growth or maintain the kill.Radiation offers the opportunity to achieve both objectives, safely. At doses less than commonly used to preserve potatoes, fish, and grains, sterilization can be accomplished. Existing techniques will allow triple encapsulation of active materials, ensuring no leaks, no contact with the water or aquifer and, therefore, no radioactive matter outside the shielded rod.Lab facilities in place at Georgia Tech for a test of sterilizing sewage sludge were used to analyze static and flowing models for lethal radiation dose and maintenance dose following a chemical kill. The level of radiation required was less than expected for both lethal and maintenance doses for the primary biofouling bacteria studied but somewhat higher for pseudomonas.From model results, steam enhanced chemical treatment followed by radiation seems likely to be economically feasible for many wells failing because of biofouling.Phase II will include advanced modeling and development of well-scale apparatus at the Georgia Tech laboratory followed by in-situ research at either Hawkinsville, Georgia, or the Savannah River Nuclear Plant. The research issues will include preliminary prototype development. Nuclear source containment and monitoring will be primary issues along with securing and physical placement of the radiation canisters. More detailed microbiological investigation and a wider range of contaminated waters (lab tests) are planned.Several related issues with potential commercial value have evolved from the Phase I study. Steam enhancement of chemical treatment is included in the Phase I study results and produced dramatic improvements in the chemical effect. Radiation treatment for water intake fouling by asiatic clams was proposed by George Alford and Bill Rogers, and offers significant promise in water supply, power generation, and industrial applications.Elimination of biofouling from pressure relief wells in dams and levees would produce world-wide benefits of staggering proportions. Elimination of biofouling of membranes, specifically reverse osmosis membranes, is of significant economic value. Control or elimination of external sources of opportunistic pathogens (including iron related bacteria) from hospitals offers great promise.
