Water Softeners and Air Filtration Systems - new water test-system redesign

The system I have in place was designed to treat my well water based on a test in 12/03.

Total Coliform positive
Hardness 20.3706 mg/l
calcium 4.2 mg/l
magnesium 2.4 mg/l
total chloride 21 mg/l
nitrite nitrogen 0.01 mg/l
nitrate nitrogen <0.2000 mg/l
copper <0.0100 mg/l
iron 9.3 mg/l
manganese 0.46 mg/l
pH 6.1
color 90
turbidity 2.6 NTU
Arsenic 2 ug/l
sodium 12.8 mg/l
cadmium <0.5000 ug/l
fluoride 0.26 mg/l
detergent 0
e. coli 0
uranium 238 <0.5000 ug/l
zinc 0.007 mg/l


The system injects a measured amount of household bleach via a Stenner pump prior to an 80 gallon retention tank (Well Mate). This kills the bacteria and precipitates the iron. Then into a 2 cf resin tank of Filter Ag to remove the precipitated iron. Then to a 2.5cf resin tank with a mixture of 2 cf of activated carbon to remove the residual chlorine and 0.5 cf of calcite to raise the ph. Both resin tanks are controlled by automatic control valves from a company called Watersoft. The system has been a bit troublesome, but has generally worked OK.

The most recent water test results are similar to the Dec 2003 results with the notable exception that the raw well water is no longer positive for coliform, the iron and manganese a bit higher and the pH a bit lower:
test results 10/2006 (by a different lab)

Total Coliform 0
Hardness 21 mg/l
Calcium not tested
magnesium not tested
total chloride 16 mg/l
nitrite nitrogen <0.2 mg/l
nitrate nitrogen <2.0 mg/l
copper <0.05 mg/l
iron 11 mg/l
manganese 0.53 mg/l
pH 5.8
color not tested
turbidity not tested
Arsenic <5.00 ug/l
sodium 12 mg/l
cadmium not tested
fluoride <0.4 mg/ll
detergent not tested
e. coli 0
uranium 238 not tested
zinc not tested

additional tests
lead total <0.01 mg/l

I would like to utilize the equipment I already have in place but slightly redesign the system because:

1. The water is no longer positive for coliform so I don't need to use bleach. I don't like that idea anyway because chlorination can cause a bunch of different potentially nasty molecules to form, THM for example.

2. precipitating iron at the low pH is not very efficient (I presently get a bit of bleed through at high flow rates)

I would like to design a sort of "homemade" Provectr unit by:

1. retrofitting the UT-80 retention tank to a hydropneumatic set up like this http://www.wellmate.com/cat-hpseries.html

2. Injecting soda ash instead of bleach to correct the pH before the oxidation of the iron

3. switching the 2 cf resin tank to Birm. Since I am no longer chlorinating the water the chlorine won't adversely affect the Birm which has better iron filtering capacity than Filter Ag.

4. keeping the 2.5 cf resin tank as activated carbon as a polishing tank.

My questions/concerns are:

1. How quickly does the soda ash correct the pH and will it happen quickly enough to allow for the efficient oxidation of the iron in the hydropneumatic tank.

2. Is an 80 gallon hydropneumatic tank big enough to precipitate 11 ppm iron.

3. Is 2 cf of Birm sufficient to remove 11 ppm of precipitated iron

4. When the Birm tank backwashes it will be backwashing with "dirty" iron precipitate containing water.

Any help would be appreciated.

Dave

With out the bleach and the retention tank, you will have no iron oxidation! Chlorine is the oxidizer.The Birm will not function long with out air or chlorine for pre oxidation. I would stay with exactly what you have to control that high of iron, regardless of the lack of coliform. You could inject soda ash with your bleach solution to help with your iron oxidation before your retention tank to raise the ph and oxidize quicker in the retention tank. Just make sure to clean your injection fitting at least once a year where it enters your water stream. Good Luck