Q: What is the “iron bacteria” problem?
A: Better described as iron biofouling, the problem popularly known as “iron bacteria” is both complex and widespread. Iron and other biofouling consists of biofilms which include living and dead bacteria, their sheaths, stalks, secretions and other leavings, and embedded metal hydroxide particles. “Iron bacteria” is one type of biofouling among several, including the characteristic white sulfur slime of sulfur springs.
Manganese and even aluminum biofouling is also found in ground water systems. These biofilms are natural and usually harmless. Natural iron biofouling often acts as a preliminary iron filter in wells and therefore can serve a positive function as well.
Biofouling can be a nuisance, however. Generally, iron biofouling is the cause of iron build up in wells and pipes. Bacterial iron may build up quickly compared to mineral encrustation. In addition to causing problems in wells, the bacteria may colonize tanks and water treatment devices, as well as spring outfalls.
Iron biofouling generally causes side effects such slight and intermittent sulfide odor, and breakthroughs of red water. It may also cause pitting-type corrosion of steel and iron.
Features of water systems may aggravate certain symptoms. These include inappropriate well, filter, or plumbing design or material choice; construction; poor choices in water treatment; and well use patterns.
Q: How does biofouling and its control affect water treatment?
A: Bacteria, oxidized iron and manganese, sulfur, and other slimy products are slow killers of resin beds and many iron/manganese removal and filtration devices. Biofilms overwhelm and defeat carbon filters–even “bacteriostatic” types and bactericidal resins. They also attack or plug reverse osmosis membranes and cartridge filters.
Aeration-type or redox-media, backwashable, iron filters tolerate biofouling pretty well and make good screening filters for most water systems, small or large. They have to be designed and maintained well, taking the biofouling in consideration including making sure the backwash is effective in removing most of the accumulated iron debris in the filter bed periodically.
Q: When is the best time to cleanup a biofouling problem such as iron bacteria?
A: The best time, obviously, is as early as possible before real damage occurs and treatment methods are most effective. This is usually long before noticeable plugging, loss of efficiency, and other gross symptoms become noticeable. The key to catching a growth before it causes problems is preventive monitoring, starting when the well is new, or at any favorable point. This advice also applies to private water and monitoring wells.