between Reverse Osmosis (RO) & MEDIA G2
The issues regarding Reverse Osmosis used by other manufacturers are:
- Excessive cost
- RO only removes Arsenic 5
- All the plumbing would have to be of
non-metallic nature. The building would have to be re-plumbed for this type
- 50% of the water would be wasted going to
drain which would contain arsenic
- Reverse Osmosis media is not an arsenic
removal mechanism per se; rather, they have to dose a substantial amount of
ferric chloride and sodium hypochlorite up front of the filters to form a
precipitate that is trapped on their media. Their ceramic media has good
uniformity compared to a sand filter but has no "magic" aside from that.
That's why it lasts forever-it doesn't react with anything in the water.
- Adding ferric chloride requires storage
and metering of dangerous chemical on site. Ferric is highly corrosive and
will eat through stainless steel, concrete, etc. To satisfy OSHA, secondary
containment will have to be constructed and special materials of
construction needed for all components (piping, dosing pumps, etc). If
metering pumps malfunction and no chemical is injected arsenic can pass to
- Ferric chloride adds ongoing operational
costs that MEDIA G2® does not have.
- Reverse Osmosis relies on iron
co-precipitation for arsenic removal; this method creates a relatively
large amount of waste sludge. For this reason, their system is set to
backwash often due to the high-pressure drop created by the sludge build-up
in the filters.
- Their system backwashes at a pressure
drop of 20 psig which requires more pumping power to overcome than MEDIA
G2® which always operated at <10 psig.
- Even in Reverse Osmosis's Environmental
Technology Verification (ETV), the filter outlet exceeded the maximum
allowable arsenic concentration of 10 ppb in at least one occasion.
Unreliable performance will lead to problems with DEQ.
Key points on MEDIA G2® for this
- There are no chemicals required. The only
cost is capital cost, as backwashing will be automated (say once/month),
requiring no labor; O & M costs will be nil as no chemicals are required.
- Based on the utilization the expected
media will last many years before ever needing servicing.
- ADI's MEDIA G2® is already being used in
Michigan under the scrutiny of USEPA and has received excellent reports.
There should be no obstacles to obtaining a rapid approval from the State
for its use. On the other hand, approvals may be difficult to obtain for