The biological iron removal process uses naturally occurring bacteria to catalyze the oxidation of
dissolved iron. Chemical oxidants, such as chlorine or potassium permanganate that are
traditionally used in conventional iron removal processes, are eliminated. Reported advantages of
the biological process when compared with conventional chemical oxidation processes include
reduced chemical use, higher filtration rates, and the ability to efficiently treat source waters that
contain high concentrations of iron (greater than 6 milligrams per liter [mg/L]).
The City of Florence (City), Oregon, has chosen the biological iron removal process for expansion
of its existing water treatment plant facility. The City currently practices conventional chemical
oxidation to reduce dissolved iron levels in its source water from about 7 mg/L to below the
secondary maximum contaminant level of 0.3 mg/L.
Prior to selecting the biological iron removal process as its preferred treatment approach, the
City conducted a five-month pilot study of the process to assess its feasibility, performance and
economics. Parameters of particular interest during the pilot study included iron removal
efficiency, filtration rates, bacteriological water quality of the treated water, and process stability.
Testing was conducted with filtration rates ranging from about 3 gallons per minute per square
foot (gpm/sf) to 12 gpm/sf with dissolved oxygen levels being maintained at levels from 1 mg/L
to about 7 mg/L. Results showed the process to be stable and capable of achieving greater than
95 percent iron removal at all filtration rates tested. No adverse effects on the bacteriological
quality of the water were noted. An economic evaluation of the process showed that while
capital costs of the biological process are greater than those of conventional chemical oxidation,
long term savings would be realized because of reduced chemical use.
Includes 2 references, tables, figures.
| Edition : | Vol. - No. |
| File Size : | 1
file
, 360 KB |
| Note : | This product is unavailable in Ukraine, Russia, Belarus |
| Number of Pages : | 11 |
| Published : | 06/16/2002 |
