process developed by Stanford University (Stanford, Calif.) postdoctoral
scholar Yaniv Scherson both converts nitrogen extracted from wastewater into
nitrous oxide gas and uses the gas to increase power output of engines at water
resource recovery facilities (WRRFs).
coupled aerobic-anoxic nitrous decomposition operation (CANDO) converts the
most common form of reactive nitrogen, ammonium, into gas and allows facilities
to generate renewable energy from wastewater, according to a Stanford Woods
Institute for the Environment news release.
principal steps include biotic conversion of ammonia to nitrite; abiotic/biotic
conversion of nitrite to nitrous oxide; and decomposition or combustion of
nitrous oxide to nitrogen, oxygen, and energy, according to Scherson’s nitrogen
removal and energy recovery poster. While the first and final steps both are
established processes, Scherson’s work focuses on the efficient conversion of
nitrite to nitrous oxide. His research presents two partial-denitrifying
strategies that involve an abiotic reaction of ferrous iron and nitrite to form
nitrous oxide and a biotic pathway using heterotropic denitrifying organisms, the
and energy recovery offer a potential alternative to treating nitrogen as a
waste and an opportunity to improve the efficiency of WRRFs by lowering oxygen
demand, reducing biomass production, and increasing energy recovery from
organic matter and reactive nitrogen, the poster says.
Scherson and his team at Stanford have demonstrated the technology’s
success in a laboratory with synthetic wastewater. They formed a partnership
with Delta Diablo Sanitation District (Antioch, Calif.) as well as conducted a
successful bench-scale system in the laboratory. The team is building a
pilot-scale demonstration unit at the district’s facility and expects to run
the unit for at least 12 months, the news release says.
Paul L. Busch award recipient
Chul Park, associate professor at the University
of Massachusetts Amherst, has received the 2013 Paul L. Busch Award. Park and
his research group have developed an algal-solids biogranule that improves the
ability to treat wastewater and nutrients without aeration, according to a Water
Environment Research Foundation (WERF; Alexandria, Va.) news release.
The biogranule — developed in response to the
difficulty with effectively and affordably gathering algae for algae-based wastewater
treatment processes — is composed of algae and bacteria within one granular biomass.
It can be formed in the wastewater treatment process. Because the algae and
bacteria cohabitate within the granule, it offers a consistent and efficient symbiotic
treatment process, the news release says.
The research project potentially could change
how wastewater is treated and the levels of energy consumption associated with
treatment. Park will use the monetary award to demonstrate the biogranule’s ability
to treat wastewater with low oxygen requirements and to efficiently collect biomass
that can be anaerobically digested to generate methane, the news release says.
“This research has the potential to provide a
new direction for treatment and can be used for mainstream treatment, for
sidestream treatment, or as a tertiary nutrient removal process,” according to John
T. Novak, the Nick Prillaman professor emeritus in the department of Civil and Environmental
Engineering at Virginia Polytechnic Institute and State University (Blacksburg,
Va.), in the news release.
The WERF Endowment for Innovation in Applied
Water Quality Research presented Park with the annual award, which includes a
$100,000 grant that will support Park’s research. For more information see www.werf.org/PaulLBusch.
Analyzing ammonia control to limit aeration
Researchers have evaluated the fundamentals of ammonia control with a
focus on feedforward control concepts. An article in the January issue of Water
Environment Research presents a case study discussion reviewing different
ammonia-based control approaches.
for limiting aeration is applied either to reduce aeration costs or to reduce
ammonia peaks in effluent. Benefits of limiting aeration include energy
savings, possible reduction in external carbon addition, and possible
improvement in denitrification and biological phosphorus performance, the
mainly has been based on feedback control to constrain complete nitrification
by maintaining approximately 1-2 mg/L of ammonia in the effluent. Recently,
feedforward ammonia control has received attention for optimal aeration of
activated solids systems. “This paper aims to clarify some of the misconception
about this control topic,” the article says.
from EnviroSim Associates Ltd. (Hamilton, Ontario, Canada) and Hampton Roads
Sanitation District (Virginia Beach, Va.) determined that in most instances,
feedback control meets the objectives for both aeration limitation and
containment of ammonia peaks in effluent. “Feedforward control, applied
specifically for switching aeration on or off in swing zones, can be beneficial
when the plant encounters particularly unusual influent disturbances,” the
recommend applying careful analysis to determine whether feedforward control
offers benefits over standard feedback control. They also recommend using
dynamic simulation to develop a tailored design for a specific plant and
offering a tool to test whenever process control strategies need to be
implemented, the article says.
“Ammonia-Based Feedforward and Feedback Aeration Control in Activated Sludge
Processes,” appears in the January issue of Water Environment Research and
can be downloaded free at http://goo.gl/6tsmxX.
Water Environment Research allows open access to one article per
issue on a range of important technical topics such as nutrient removal,
stormwater, and biosolids recycling.