Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

UC Riverside scientists modify existing chemical scrubber to environmentally friendly, all-natural filter

08.05.2003


Converting one third of chemical scrubbers worldwide could save up to two billion dollars each year


The UC Riverside researchers packed polyurethane foam cubes inoculated with hydrogen sulfide-degrading bacteria into the Orange County Sanitation District chemical scrubber. (Photo credit: M. Deshusses.)


The Orange County Sanitation District scrubber and biotrickling filter. (Photo credit: M. Deshusses.)



Scientists at UC Riverside have pushed the current limit of a technique for biologically removing hydrogen sulfide from sewage emissions a step further. Marc Deshusses, associate professor in the department of chemical and environmental engineering, and his postdoctoral researcher, David Gabriel, report in the Proceedings of the National Academy of Sciences (PNAS) that they have modified an existing full-scale chemical scrubber at the Orange County Sanitation District (OCSD), California, to a biological trickling filter.

"Hydrogen sulfide odors, which have the smell of rotten eggs, can be treated in biological reactors called biotrickling filters at rates similar to those observed in chemical scrubbers," said Deshusses. "Biotreatment is cheaper, safer, and more environmentally friendly. In our paper, we also show that you can convert existing chemical scrubbers to biological trickling filters quite easily."


Chemical scrubbing suffers from important drawbacks, such as high operating costs, generation of halomethanes that are known air toxics, and the requirement for hazardous chemicals, which pose serious health and safety concerns.

In biological trickling filters or biotrickling filters, the waste air stream is passed through a packed bed on which pollutant-degrading bacteria are placed in the form of a biofilm. These bacteria absorb and degrade gaseous pollutants. After the bacteria begin to multiply, their efficiency at converting hydrogen sulfide to sulfate is nearly 100 percent. Moreover, the system removes more odorant chemicals, including other sulfur and nitrogen compounds.

"We did extensive research in the laboratory prior to and during the field demonstration at OCSD in an attempt to explain why we obtained such a high performance from the biotrickling filter," said Deshusses.

The UC Riverside researchers packed polyurethane foam cubes inoculated with hydrogen sulfide-degrading bacteria into the OCSD scrubber. They also replaced the existing liquid pump with a smaller one, disconnected the chemical supply system, and modified the control systems.

Emission of objectionable odors is a major problem for wastewater treatment and other processing facilities. For odor control, biological treatment is a promising alternative to conventional control methods, but so far biotreatment always required significantly larger reactor volumes than chemical scrubbers.

In the PNAS paper, the researchers report that effective treatment of hydrogen sulfide in the converted scrubber was possible even at gas contact times as low as 1.6 seconds, comparable to usual contact times in chemical scrubbers.

"Continuous operation of the converted scrubber for more than 8 months showed stable performances and robust behavior for hydrogen sulfide treatment, with pollutant removal performance comparable to that achieved using a chemical scrubber," said Deshusses. "Our study demonstrates that biotrickling filters can replace chemical scrubbers and be a safer, more economical technique for odor control."

An estimated 10,000-40,000 scrubbers for odor control operate at publicly owned treatment works in the United States and probably more than 100,000 scrubbers worldwide. "Many of those scrubbers treat hydrogen sulfide only," said Deshusses, "hence, based on the results of our study, they could potentially be converted to biotrickling filters."

An overall cost-benefit analysis of the scrubber that was converted at OCSD shows that total annual savings in operating costs (essentially chemicals and electricity) are about $30,000 per year for the biotrickling filter compared to chemical scrubbing. The estimated commercial cost of converting the chemical scrubber to a biotrickling filter was about $40,000-60,000, which compares well with the annual savings in operating costs.

"If one assumes that 25 to 40 percent of the chemical scrubbers worldwide could be converted to biotrickling filters," said Deshusses, "it would represent a total market of $1-3 billion and would result in net energy and chemical savings of approximately $0.25-2 billion per year."

The study was performed during 2001-2002 and is still on-going. Research was funded by OCSD.

The University of California, Riverside is home to some of the best scientists and engineers in the world in addition to its world-class research centers. The Bourns College of Engineering is well known for its research in embedded systems and networking in computer science, for environmental sciences (e.g., low emission vehicles, air pollution research), nanotechnology and research in intelligent systems.

Iqbal Pittalwala | UC Riverside
Further information:
http://www.newsroom.ucr.edu/cgi-bin/display.cgi?id=580
http://www.engr.ucr.edu/~mdeshuss/
http://www.ocsd.com/

More articles from Ecology, The Environment and Conservation:

nachricht Scientists on the road to discovering impact of urban road dust
18.01.2018 | University of Alberta

nachricht Gran Chaco: Biodiversity at High Risk
17.01.2018 | Humboldt-Universität zu Berlin

All articles from Ecology, The Environment and Conservation >>>

The most recent press releases about innovation >>>

Die letzten 5 Focus-News des innovations-reports im Überblick:

Im Focus: Artificial agent designs quantum experiments

On the way to an intelligent laboratory, physicists from Innsbruck and Vienna present an artificial agent that autonomously designs quantum experiments. In initial experiments, the system has independently (re)discovered experimental techniques that are nowadays standard in modern quantum optical laboratories. This shows how machines could play a more creative role in research in the future.

We carry smartphones in our pockets, the streets are dotted with semi-autonomous cars, but in the research laboratory experiments are still being designed by...

Im Focus: Scientists decipher key principle behind reaction of metalloenzymes

So-called pre-distorted states accelerate photochemical reactions too

What enables electrons to be transferred swiftly, for example during photosynthesis? An interdisciplinary team of researchers has worked out the details of how...

Im Focus: The first precise measurement of a single molecule's effective charge

For the first time, scientists have precisely measured the effective electrical charge of a single molecule in solution. This fundamental insight of an SNSF Professor could also pave the way for future medical diagnostics.

Electrical charge is one of the key properties that allows molecules to interact. Life itself depends on this phenomenon: many biological processes involve...

Im Focus: Paradigm shift in Paris: Encouraging an holistic view of laser machining

At the JEC World Composite Show in Paris in March 2018, the Fraunhofer Institute for Laser Technology ILT will be focusing on the latest trends and innovations in laser machining of composites. Among other things, researchers at the booth shared with the Aachen Center for Integrative Lightweight Production (AZL) will demonstrate how lasers can be used for joining, structuring, cutting and drilling composite materials.

No other industry has attracted as much public attention to composite materials as the automotive industry, which along with the aerospace industry is a driver...

Im Focus: Room-temperature multiferroic thin films and their properties

Scientists at Tokyo Institute of Technology (Tokyo Tech) and Tohoku University have developed high-quality GFO epitaxial films and systematically investigated their ferroelectric and ferromagnetic properties. They also demonstrated the room-temperature magnetocapacitance effects of these GFO thin films.

Multiferroic materials show magnetically driven ferroelectricity. They are attracting increasing attention because of their fascinating properties such as...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

10th International Symposium: “Advanced Battery Power – Kraftwerk Batterie” Münster, 10-11 April 2018

08.01.2018 | Event News

See, understand and experience the work of the future

11.12.2017 | Event News

Innovative strategies to tackle parasitic worms

08.12.2017 | Event News

 
Latest News

More genes are active in high-performance maize

19.01.2018 | Life Sciences

How plants see light

19.01.2018 | Life Sciences

Artificial agent designs quantum experiments

19.01.2018 | Physics and Astronomy

VideoLinks
B2B-VideoLinks
More VideoLinks >>>