April 28, 1999
(This executive summary is prepared by EOT's management based
on a comprehensive report prepared jointly by EOT and EBMUD's
staff. The full report is going through final review.)
Envirozone Technologies (EOT) Advanced Oxidation Process (AOP)
1000-GPM pilot plant is operating at EBMUD on its fifth phase
which started April 1, 1999.
This Executive Summary covers the period of operation from September
16, 1998 to March 31, 1999.
The system was designed to treat secondary effluent wastewater
at the EBMUD Main Wastewater Treatment Plant for disinfection
and the oxidation of complex organic compounds. The process utilizes
the synergistic effect of the combination of ozone and ultra violet
irradiation.
The following are highlights of the test:
Fecal Coliform
Test results showed that two minute of treatment time with 10-PPM
ozone followed by treatment of either low pressure or medium pressure
UV irradiation, consistently met (or better than) the regulatory
discharge requirement.
Inorganic Compounds
COD, TSS and nitrites were analyzed. EOT's treatment achieved
a reduction in Chemical Oxygen Demand (COD), Total Suspended Solids
(TTS) and Nitrite. EOT's process reduced nitrite up to 81% while
EBMUD's treatment (with sodium hypochlorite and sodium bi-sulfite)
showed 3096% increase.
Complex Organic Compounds
There are 207 regulated compounds that were tested for during
the study. There were approximately 30 that were detected, Out
of those, the emphasis was placed on 18 compounds. These were
divided into three groups that were selected for further analysis:
- Volatile organic compounds (VOCs)
- Semi-volatile organic compounds (semi-VOCs)
- Organophosphorous pesticides
There were 18 complex organic compounds that were detected in
the wastewater and impacted by the Envirozone process. Of these
18 compounds, 14 were decreased in concentration by EOT process,
four showed an increase, which is an oxidation-by-product, that
may be reduced or eliminated by further oxidation.
A significant achievement of this process is a 30% reduction
of MtBE in the effluent. This petroleum additive was further reduced
by 70% after three closed circulation cycles.
The compounds that were selected are listed below.
Note: Some compounds are analyzed by more than one laboratory
method.
EBMUD's disinfection with sodium hypochlorite/sodium bi-sulfite
had minor impact, as compared to EOT, on the reduction of complex
organic compounds that were detected in the wastewater. However,
EOT's process showed significant decreases in the same compounds.
Both treatments showed increases in three (harmless) compounds
(Acetone, Benzoic acid and 2-butanone). These are considered as
disinfection by products which can be reduced or eliminated by
extending the ozone/UV oxidation treatment.
ECONOMICS & ENVIRONMENTAL CONSIDERATIONS
The EOT treatment improved the quality of the effluent. It reduced
colors, deodorized, disinfected and reduced complex organic compounds,
thereby provided higher quality effluent to San Francisco Bay.
Without further treatment, the effluent could be suitable for
irrigation and other agricultural uses plus many other industrial
uses such as concrete mixes, equipment and aircraft washing.
With micro-filtration and Reverse Osmosis (R.O.) if needed, the
effluent could meet drinking water standards.
The economic impact of EOT's process makes it very attractive
for any discharge or use. For example, it would cost a ratepayer
$3. per year extra for discharging a much cleaner effluent into
the San Francisco Bay. Estimated operation and maintenance costs,
including depreciation, are 6-8 U.S. cents/1000 Gallons (EBMUD's
estimate for 55,000--GPM system)
The present 1000-GPM pilot plant estimated operational cost including
depreciation is $0.30/1000 Gallons (based on system maximum use
of power of 51-KWh. Capital cost is based on $2.2 million with
20-year depreciation. Energy cost at 4.5 U.S cents/KW, 24 hours
/day operation).
