Chemical Engineering January 2018 - 27

Microvi Biotech Inc.
Microvi Biotech Inc.:
Denitrovi™ biocatalytic nitrate removal
Nitrate is one of the foremost drinking water
challenges today, contaminating groundwater
around the world and posing threats to
human health. For the past ten years, Microvi
has been working to provide a new solution
to overcome the challenges of nitrate contamination.
This technology, called Denitrovi,
is based on Microvi's MicroNiche Engineering
platform, where novel materials science
is used to control how microorganisms behave
and perform in industrial bioprocesses.
Conventional nitrate removal. Nitrate is
highly mobile in groundwater and does not
adsorb, volatilize or naturally degrade in the
majority of groundwater aquifers. Nitratecontaminated
groundwater can be treated
through two different approaches: 1) separation
of nitrate (via anion exchange, reverse
osmosis or nanofiltration) or 2) degradation
of nitrate. The first approach is costly, energy-intensive
and produces concentrated
waste streams that require secondary treatment.
The second approach - biological
nitrate degradation (or denitrification) - is
an ancient and energetically favorable microbial
metabolic process that reduces
nitrate to N2. The denitrification reaction
occurs under anoxic conditions, coupling
nitrate (electron acceptor) to an electron
donor, such as carbon or hydrogen. Nitrate
degradation is an attractive alternative to
separation since it does not require high
energy or inherently generate concentrated
waste streams. However, conventional biological
denitrification technology is characterized
by major disadvantages, including
organism washout, slow reaction rates and
sludge production.
In conventional biological denitrification
treatment, the paradigm has remained the
same for more than 100 years: repeatedly
grow and remove the microorganisms that
remove the nutrients. This fundamental paradigm
imposes limitations in five key areas
that govern the size and cost of biological
treatment systems in general: substrate diffusion,
mixing, settling, solids production
and carbon consumption. Each factor contributes
to low organism densities, significant
sludge production and ultimately large
footprints and volumes required proportionally
to high hydraulic residence times (HRTs).
Denitrovi technology. Microvi is the first
company to deconstruct the dominant paradigm
in biological water treatment. The company's
founder, Fatemeth Shirazi invented a
new approach to microenvironmental engineering
called MicroNiche Engineering. The
Conventional technologies
Pre-treatment
Polluted water
Secondary waste
Microvi's Denitrovi technology
Pre-treatment
Polluted water
MicroNiche Engineering platform is a combinatorial
materials-science platform that
can take nearly any kind of microorganism
and using an in silico model, parameterize
microorganism-material compositions with
functionalities unachieveable using conventional
techniques.
Whereas
conventional
biological treatment technologies use various
techniques to simply grow and retain
biomass, MicroNiche Engineering utilizes
functional
cellular microenvironments that
help control phenotypes, behaviors and
self-organization. Denitrovi uses speciallytargeted,
high-performance natural microorganisms
that are completely incorporated at
very high density within material composites.
These composites provide a protective microenvironment
with unique geometry and
physiochemical properties.
The Denitrovi technology provides a paradigm
shift for translating natural microbial fitness-enhancing
behaviors into an industrially
relevant format. The synthetic Denitrovi biocatalysts,
as a highly hydrated, hydrophillic
polymer complex, mimics key fitness advantages
found in natural microorganism communities
while maintaining a controlled system
over extended periods of time.
Using Denitrovi, nitrate-contaminated water
enters a reactor and the nitrate is degraded
by microorganisms housed in biocatalysts
and converted into N2. The key chemical engineering
feat achieved by the technology is
that it generates no sludge.
Commercialization. In January 2017, Microvi
and Sunny Slope Water Company of
Pasadena, Calif. launched a new, 200-million-gal/yr
facility that uses Denitrovi to remove
nitrate from groundwater. At Sunny
Slope, the technology reduces nitrate from
~40 mg/L to <5 mg/L in a matter of minutes
of contact time, while virtually eliminating the
secondary waste stream that would otherwise
be associated with a biological technology.
Most importantly, the technology was
found to be 50% of the cost of existing treatment
technologies, such as ion-exchange.
CHEMICAL ENGINEERING WWW.CHEMENGONLINE.COM
JANUARY 2018
27
Denitrovi reactors
Post-treatment
Clean
water
FIGURE 6. The Denitrovi
process (lower) requires
fewer steps than conventional
biological denitrification
processes (upper), without
generating sludge
Disposal or
incineration
Traditional systems
Post-treatment
Clean
water
http://WWW.CHEMENGONLINE.COM
Chemical Engineering January 2018

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