Wastewater engineering, treatment and reuse; 4th edition
by Metcalf and Eddy also recognizes the SymBio® Process. Under
Process design considerations on pg 790, it is mentioned that, “ Depending
on the operating conditions, the SymBio® Process have been
shown to be capable of producing very low effluent total nitrogen
concentrations”. On page 795, a brief description of the
SymBio® Process is given. It also says, “Effluent NO3-N
and NH4-N concentrations of less than 3.0 and 1.0 mg/L repectively,
have been achieved”.
Enviroquip has written several technical
papers which have been presented and published in conferences
and magazines respectively. Papers explaining the significance
of SymBio® process in municipal as well as industrial applications
have been published.
Patents
Technical Papers
FLAT-PLATE MICROFILTRATION MEMBRANE BIOREACTOR DESIGNED
Increasing concerns for sensitive receiving water are expected to drive effluent nitrogen
(N) and phosphorus (P) limits to exceptionally low levels for many wastewater treatment
plants throughout the U.S (< 0.1 mg TP/L and < 3-5 mg TN/L). Meeting these limits will
require a new generation of effective treatment strategies to control both soluble and nonsoluble
discharges. This paper will discuss the development and the evaluation of a flatplate
microfiltration membrane bioreactor (MBR) technology designed for highly
effective nitrogen and phosphorous removal using combined biological and chemical
processes. Since 1990, approximately 1,500 wastewater treatment plants worldwide have
successfully utilized this MBR technology to consistently produce water that exceeds
most reuse quality standards.
Such MBR configurations have been demonstrated to achieve very low nutrient
concentrations, in part because membrane systems provide a nearly complete removal of
effluent solids and the nutrients they contain. Such systems provide the added benefits of
nearly complete removal of bacterial pathogens, and even some viruses. These
characteristics make the MBRs ideal components of water reuse systems, which will
likely ensure their increased use.
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Industrial Wastewater 2002 SymBio Paper
The activated sludge process is one of
the oldest large-scale applications of
biotechnology. It differs from other
microbiological processes in that
there is little or no control over raw
material and moderate control over operating
conditions, yet it is expected to produce a
uniform finished product. Activated sludge
contains mixtures of microorganisms that are
the true “bioreactors” responsible for the
process performance. Hence, good plant
operation requires information on microorganism
activity. Intracellular coenzyme nicotinamide
adenine dinucleotide (NADH) provides
this information, and it can be measured
using an on-line fluorescence technique.
NADH measurement is especially useful in
monitoring and controlling nitrification and
denitrification. In biological nitrogen removal,
ammonia is converted to nitrite and then to
nitrate by nitrifying bacteria in the presence
of oxygen. Nitrate is subsequently reduced to
molecular nitrogen (N2) by denitrifying bacteria.
Organic matter is oxidized with oxygen as
well as nitrate, both acting as electron acceptors.
These various metabolic conversion
pathways cumulatively result in new bacterial
biomass, carbon dioxide, and molecular nitrogen
(See Figure 1, below). Phases of nitrification
and denitrification can be separated spatially
by having sludge circulate between
tanks or zones with differing oxygen concentrations.
The phases also can be separated
chronologically — in plants with alternating
processes, sludge remains in a single tank
while oxygen concentration is manipulated.
NADH measurement can be used to
control aeration equipment so that both
nitrification and denitrification proceed
simultaneously in the same tank. As part of
the proprietary SymBio process from ENVIROQUIP
Inc. (Austin, Texas), an NADH fluorescence
sensor is installed in the aeration
tank. Based on the NADH fluorescence
signal, aeration is adjusted to maintain
oxygen at the desired low level.
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Monitoring of Denitrification by Pseudomonas aeruginosa
The NADH (P) H fluorescence of Pseudomonas aeruginosa dropped sharply upon addition of nitrate to an anaerobic culture, indicating that denitrification is not limited by mass transfer of nitrate through cell membrane to reach nitrate reductase. The effect of added nitrate concentration on fluorescence drop followed by a typical saturation kinetics.
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Oscillation NAD (P) H fluorescence in Escherichia coli culture performing dissimilative nitrate/nitrite reduction
When nitrate was added to anaerobic resting cultures of E.coli, two profiles of NAD(P)H fluorescence were observed. E coli is known to reduce nitrate to ammonia via nitrite as an aerobic respiration mechanism. The profile showing single-stage response corresponded to situations where the nitrite formed from nitrate reduction was immediately converted to ammonia. The other profile showing two-stage response resulted from a much slower reduction of nitrite than nitrate.
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Study of Nitrate Metabolism
Public concern about environmental nitrate contamination has increased significantly. To invstigate the nitrate metabolism of Escherichia coli, profiles of NAD(P)H fluorescence responding to nitrate/nitrite additions to anaerobic E.coli cultures at the resting or minimum-growth state were monitored by on on-line fluorometer.
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Water World 2005 - MBR Casino Applications
US casinos place their bets on MBRs
The combined requirements of a small footprint and simple operation has prompted several casino owners in the
USA to opt for MBRs in selecting new WWTPs. Hiren K Trivedi, technical manager at Enviroquip, presents three
case studies and describes the technology employed.
Rolling Hills Casino
When the Paskenta band of
Nomlaki native Americans went
looking for a solution to the ailing
wastewater treatment (WWT)
facility at the Rolling Hills Casino
in Corning, California, they opted
for MBR technology. The MBR
facility replaced an activated
sludge system, which produced
frequent complaints about odours,
had drainfield failure and was
expensive to operate and maintain.
The major drivers for technology
selection were an extremely
fast-track schedule, small footprint
requirement, expandability, ease of
operation and the ability of the system
to provide high-quality wastewater.
The facility was designed for
a total build-out capacity of
757m3/d, but initially has only
378m3/d of membrane capacity
installed.
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WEFTEC 2000 SymBio Paper
The conventional methods of nitrogen removal are typically based on a two-part process.
Ammonia is first oxidized to nitrite and subsequently to nitrate under aerobic conditions by the
autotrophic microorganisms. Nitrate is then dissimilatively reduced to nitrogen gas under anoxic
conditions by the heterotrophic bacteria.
This paper describes a method (the SymBioTM process, protected by USA patents 5,506,096,
5,557,415, 5,700,370 and 5,906,746) of maintaining simultaneous nitrification and denitrification
in a single tank at very low dissolved oxygen concentrations. Bacterial content of the reduced
forms of coenzymes nicotinamide adenine dinucleotide (NADH) changes with the metabolic
condition of the biomass. The NADH concentration is monitored on-line by a sensor that takes
advantage of the fluorescent properties of NADH. The changes in fluorescence signal are used to
control the dissolved oxygen concentrations at the desired level. This allows each sludge floc
particle to maintain a balance between the nitrifying and the denitrifying fraction, thus achieving
both simultaneously in the same basin
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