inherently superior to engineered buffers.
So theoretically you should be able to de-sign
a reservoir to get the same effect.
One of the things a reservoir gives you
is response time. If something goes wrong
in the treatment process or you determine
there’s a problem, it gives you time to re-spond
before customers are drinking the
water. So the question is how can we get
that same type of response time through
some kind of engineered system.
The other concept that still needs de-veloping,
and the regulators are still re-ally
uncomfortable with, is what happens
if treatment malfunctions. If one of our
membrane filters ruptures, how do we
know immediately? We need process
control and detection technologies that
are capable of doing that in real time so
that if there’s some sort of upset in the
treatment process, you can react appro-priately
and make sure the water remains
safe as it’s served to customers.
These challenges are solvable. The Wa-teReuse
Research Foundation and the
Water Research Foundation are collab-orating
on their research agendas and
we’re supporting that combined effort to
answer some of these questions.
Source: Did the presentations at the
conference give you hope the industry is
moving forward with these issues?
McDaniel: Every time I go to a conference,
I see that we’re making incremental
progress toward this goal. And a lot of
the instrument manufacturers and the
treatment equipment manufacturers
understand that this could be a huge
business for them so they’re also putting
money toward it.
Source: Besides the Terminal Island
Water Reclamation Plant, which treats
water for the seawater barrier, you
spoke about the Hyperion Wastewater
Treatment Plant near LAX as a possible
source of potable water.
McDaniel: We’re working very close-ly
with our Bureau of Sanitation, which
operates the Hyperion plant. We’ve got
200,000-300,000 acre feet a year of po-tentially
reclaimable water going out to
the ocean. But we’re not going to be able
to take advantage of it with a tertiary or
purple pipe project because there’s just
not enough purple pipe demand in the
service area. So we’re going to have to
figure out some way of reusing that wa-ter.
I’ll go ahead and say a direct pota-ble
reuse project for Hyperion is the only
way we’re going to tap into that water.
Not just tap into, but we really want to
use all of it.
Source: At this stage where do you see
DPR in the portfolio of water supply
strategies at LADWP?
McDaniel: We’ve made a conscious de-cision
to pursue recycled water, including
DPR, before we start marching down the
road toward ocean water desalination.
My prediction from 2014 is that you’ll
see DPR in Los Angeles before you’ll see
ocean water desalination. The net pro-duced
water from Hyperion could ac-count
for a third of the water supply for
the City of Los Angeles. There is a lot that
would have to be worked out in terms of
transmission, and there are a lot of insti-tutional
barriers. For example, if we’re us-ing
somebody else’s pipe, do we swap wa-ter?
But right now the city is using about
600,000 AF of water—if there’s 200,000
AF potentially available at Hyperion that
could be a big part of our water supply.
Source: Besides transmission there are
also the issues of energy and the DPR
McDaniel: DPR is pretty much the same
technology as ocean water desalination,
but you’re separating fewer solids. I use
the word separating as opposed to filter-ing
because when you get into reverse
osmosis, you’re separating the water mol-ecules
from the non-water molecules. The
energy that goes into that is pretty much
directly related to how many non-water
molecules you’re trying to separate from
the water. In salt water you have a much
higher load you’re trying to separate out.
It’s more energy intensive than wastewa-ter.
So from an energy profile, water re-cycling
is much preferred to desal. Even
DPR, which is a high level of water recy-cling
still comes out favorable to desal.
And when you look at the cost of pump-ing
imported water over the Tehachapi
mountains, it’s right in there at the same
energy cost. So from an energy perspec-tive,
swapping imported water from the
Bay Delta for DPR water is probably not
a bad trade.
There are different ways the waste
stream is being dealt with. Obviously we
want to try to minimize any sort of tox-ic
discharges, so one of the key things in
advanced water treatment is your source
control program. There have been some
studies that show that you can mix it in
with outflows from sewage treatment
plants and it can have a fairly neutral ef-fect.
This is something that really needs
to be studied and it’s very specific, de-pending
on what the individual waste
stream is. We’re working with a group
at Stanford, which has funding from the
National Science Foundation to work on
renewing the nation’s urban water infra-structure.
They’re looking at zero brine
discharge where you basically produce a
solid that can be landfilled. The challenge
is that a lot of this kind of thing is energy
intense. But it’s an intriguing thought to
Source: I recently heard in a presentation
that LADWP is pursuing recycling water
from onsite water treatment systems. It
seems there’s a whole culture being de-veloped
around the idea that we have to
close the water cycle.
McDaniel: Yes. It’s one of those things
where the technology has been proven
feasible and now it’s a cost issue. UCLA
is very interested in taking a look at that
and we did a preliminary study for USC.
At the time, maybe five years ago, the
costs were not realistic for doing it on a
large scale. But it’s one of those things we
want to keep looking at because there are
some places where you’re never going to
get purple pipe to because it’s too cost-ly
and the supplies are limited. So onsite
generation for certain types of facilities
makes a lot of sense. S