Welcome from the Philippines !! Don't ask just pretend I am enjoying.
I have a water supply which I need advice on treating. I understand that this is rare to see natural water with this high of level , so experts with real life experience in treating this please.
There are 3 wells used and although high and lows are given, if you need exact concentrations per well, I do have the analysis available.
The level of boron in mg/l is 1.602. Cadmium 0.01 mg/l. Arsenic is 0.709 mg/l. That is about it on the health related, here is other relative facts available.
Well output appx. 5 litres per second. There are 3 wells used from vicinity.
color is 30 to 150 units with maximum of 10 color units acceptable. Turbidity 7.92 at worst, normally below 1.00 NTU Chloride 140 to 180 with limit at 250 no problem there Hardness Total 70 to 105 mg/l as CaCO3 Iron 2.065 to 3.01 mg/l manganese 0.15 to 1.10 depending on season and well used PH is normally between 7.14 and 7.80 Sodium 65 to as high as 220 mg/l with 200 being maximum allowed TDS All wells relatively high from 494-722 ppm. Silica from 30 to 35 mg/l.
I will be working here on this project at hand. Anything else you need to know I will answer immediately with. Who knows, maybe this will make it in the magazine as a story?
And welcome from New Zealand! This water is pretty rough. The only similar water we've treated is deep thermal bore water, with an element of seawater intrusion.
The obvious problems here apart from high arsenic are hardness, iron, manganese, boron, and sodium. There are probably several options for treatment including full deionisation. One option is ion exchange (water softening) which will deal with the hardness, iron and manganese - provided the metals are in soluble form and not oxidised. The only way we found we could deal with elevated boron after softening was to elevate the pH to 10.5 and run water through double-pass RO with post pH correction back to 7.5. RO will remove the TDS and arsenic III but not arsenic V. Specific AS V removal media will probably be required.
I'm sure you will get many other opinions! Good luck!
Since the posting, the following has developed. I just got off the phone with the well owner and we will use only the better of the wells. The updated analysis would be:
Arsenic @ 0.031 mg/l MCL @ 0.03 mg/l
Boron @ 1.602 mg/l MCL @ 0.5 mg/l
NO OTHER HEALTH RELATED PROBLEMS HERE, The other known quantities:
TDS @ 509 ppm
PH @ 7.14
sodium @ 140-145 mg/l
T. Hard @ 103 mg/l CaCO3
sulfate @ 109 mg/l
mangan@ 0.195 mg/l
chlorides 120
Turbidity less than 1 ntu
bicarb 453.232
potassium 25
silica 35
Alkalynity 453 not listed as m or t
conduct. 987 us/cm (can't find the backwards u on this keypad, LOL)
This is updated as of this posting, Maximum useage will be 20-30,000GPD
Treating flow rate will be between 30-40 GPM. For human consumption.
I have contacted Jim and gave him our ion exchange resins recommendations. Because we cannot promote our own products here I will tell you all what I proposed generically.
To remove the boron and arsenic one should use a Boron Selective Resin for Boron removal and use an Arsenic Selective Resin for Arsenic removal. The arsenic removal system should be 2 units in series (lead/lag). The boron removal system should be 2 units in parallel (1 in service and 1 in stanby or regeneration). The arsenical removal media is not regenerated but is disposed of as the lead vessel exhausts, that vessel rebedded and put in the lag position with the lag unit moved to the lead position. The boron removal units are regenerated on site using acid and caustic.
The details are available on request by contacting me privately.
For your info, a good .pdf article on Boron vs RO/NF membranes is attached
Double-Pass RO seems an avenue but implies POWER, pH correction, adequate pre-treatment and $$$$
Depending of the RO/NF membranes selected, one can punch in the water analysis within the proprietary Membranes Manufacturer software and then get expected end product and simulate configurations...
In addition to previous post, attached is a descriptive of the Toray RO membrane discussed within the Boron .pdf article
As a note, RO polymeric membranes tolerate wide pH variation without adverse effect.
Check out NanoH2O website for their announcement of a futuristic new RO material which will use 20% less energy for the same amount of permeate. They say that products shall be available sometime in 2010.
Yes, the boron selective resin is the most promising.
RO is less likely. Boron (Borate) will pass through an RO membrane especially at low pH's. The rejection is best at an alkaline pH 10-10.5. So double-pass to get the boron level down is reasonable.
Taoward Lee Ecosystems, Inc. Phone: 949 646-9494 Fax: 949 646-5557
Boron can be removed from water with a uniform particle size weak base anion exchange resin for selective Boron removal. Arsenic can be removed with titanium based filter media which removes both As(III) and As(V). Contact us directly for specifications.
We have evaluated the various options and since this is for human consumption and we have to keep operational expenses to a minimum, the plan Gary has described was deemed most promising. We will now be trying to find suppliers for the regenerants so that the process can go forward. Would like to thak everyone on their input and we will be updating this at a future post. Again thanks to all.
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