Alchemix – Two Emissions Control Breakthroughs

Either one of this company’s two technologies are revolutionary. While they both sound too good to be true, it’s just possible that they’re for real. The company’s president, Robert Horton understands that people will be skeptical–he is himself, but takes the view that these things will either work or not. If they do, the implications are extraordinary.

They aren’t asking anybody to give them money until/unless the proof of the technology has been demonstrated. They’ve raised $2M already, have 13 employees, and tests are scheduled next month at AEP and Southern Co.

We first heard about this company at the Environmental Capital Network Forum in San Francisco last winter. At that time, they had planned to discuss only the first technology, but decided at the last minute to present the second one also. There has been a lot of progress since then. The text presented here is adapted from company materials.

The two technologies are:

1. Ash Conversion Technology (ACT) ? aims to produce a range of cementitious products from coal ash inside coal-fired utility boilers.

2. Catalytic Reduction Technology — Raphite™ is a naturally occurring low cost volcanic material which acts as a catalyst at elevated temperatures. Combustion gas oxides including SO2, NOx and possibly CO2 have been demonstrated to be substantially reduced after contacting Raphite coated surfaces at a temperature of approximately 900 F. It has the potential to reduce dramatically the cost and complexity of emissions control.

In the year 2000, Alchemix expects to offer coal-fired boiler operators turnkey services which will reduce ash disposal costs for clients and bring combustion gas emissions into regulatory compliance for a fraction of the cost of alternative approaches. At the same time, new liabilities to plant operators from ponded or solid refuse will be curtailed.

These services will be offered, on an intermediate to long term basis, on behalf of Alchemix by established and respected combustion engineering companies. Their incentive is compensation based on revenue rather than time, and the ability to offer low cost, long term services to a much expanded customer list.

Contact: Robert Horton, Chairman
Alchemix Corporation, Carefree, AZ

More Details

1. Ash Conversion Technology (ACT)

ACT aims to produce a range of cementitious products from coal ash in coal-fired utility boilers. It converts a waste stream with an average disposal cost of $16/T to a cement additive having a market value exceeding $40/T.

The process eliminates the need for calcining, the heating process usually required for cement production which produces great amounts of combustion gases and CO2 . This is significant, as the cementmaking is reported to be, per pound of product produced, the most polluting industrial process. The calcining of lime associated with cement production accounts for four percent (4%) of all CO2 released to the atmosphere worldwide. When demonstrated at bench scale, a five percent (5%) increase in energy efficiency has also been observed from the application of the ACT.

While characterization and acceptance of new cements may take years, an intermediate product, low carbon fly ash, can be produced now from the application of ACT.

Alchemix has an agreement with R.W. Beck, a leading combustion engineering company, and has ongoing discussions with Essroc Cement Corporation, the sixth largest cement company in the U.S., to fund the development and commercialization of the ACT. These agreements call for R.W. Beck to install and operate ACT. Essroc’s role would be to buy and distribute the products produced. To date, technology verification work conducted in June and July of 1999 at Pennsylvania State University has demonstrated the ability to produce low carbon fly ash. Data are not yet available indicating the quality of higher value products.

ACT is implemented by injecting supercritical water into the combustion gas stream in the boiler, downstream of the combustion zone, while combustion gases and the minerals they contain are still at high temperatures.

– Carbon present in the fly ash reacts with the water to form Carbon Monoxide and Hydrogen.
– The Carbon Monoxide and Hydrogen burn.
– Ash minerals become highly reactive and cementitious.
– Combustion of unburned carbon reduces particulate pollution significantly.
– Low carbon ash or various geopolymer cements can be selectively produced.

ACT makes it possible for coal-fired utility boilers to perform as mineral conversion devices simultaneously with their designed use as electricity generators. ACT is easy and inexpensive to employ as it involves only the measured injection of water into the combustion gas stream. The process converts directly — within the utility boiler — inorganic minerals which are usually emitted and collected as fly ash, into a salable low carbon fly ash cement additive or a variety of cements.

2. Catalytic Reduction Technology (Raphite™)

Raphite is a naturally occurring volcanic material which acts as a catalyst at elevated temperatures.

– Raphite would be installed in and on exhaust ducts leading from combustion zones of coal-fired boilers (quickly and at low cost).
– Raphite has been shown to substantially reduce combustion gas oxides including SO2, NOx and possibly CO2 when contacting Raphite coated surfaces at a temperature of approximately 900 F.

No other single control technology effectively reduces both SO2 and NOX, and there is no commercial technology claiming measurable CO2 reduction. Where elemental carbon can be captured or reburned, added fuel efficiency is possible.

The cost of implementation will be low. Raphite’s active ingredients are combined in nature, so it requires only low cost mining and grinding prior to application, unlike other catalyts which require a combination of refined and rare metals.

Alchemix will offer Raphite technology, through an established combustion engineering partner, as a turnkey service. Alchemix is considering an exclusive engineering contract with a leading combustion engineering firm. That firm would advance necessary funds for commercialization and support Alchemix until financeable contracts are in hand. Alchemix has exclusive rights in the US for all uses of Raphite related to coal combustion.

Independent proof of concept testing at Four Corners by APS indicated 83% SO2 reduction and complete elimination of NOX. A measurable reduction of CO2 was also indicated. These excellent results were from field tests which were not optimized. Additional work towards commercialization at Four Corners is anticipated.

Additional work will be required to identify and understand all of the variables impacting the performance of Raphite.

The combined cost of available SO2 and NOX reduction strategies typically range from $20 to $45 per ton of coal burned. The prospective capital and operating cost to implement Raphite is expected to be less than $5 per ton.

More comprehensive field tests are now scheduled at Southern Research Institute and the 1300 MW Mountaineer plant of AEP. A portion of the costs of these tests are being paid for by Southern Companies and AEP, the two largest investor owned electric utilities in the world. Together they represent thirty percent (30%) of the coal fired utility capacity in the US, and are aggressively seeking lower cost solutions to multibillion dollar compliance issues.

DOE Distributed Power Program Review and Planning Meeting

Just received this notice a few minutes ago…

Below you will find details regarding a Distributed Power for the 21st Century program review and planning meeting. Please register promptly if you plan to attend. Registration forms should be emailed to

DOE Distributed Power Program Review and Planning Meeting

As a result of recommendations from stakeholders at a workshop on removing technical, regulatory and institutional barriers to distributed power, held in December 1998, a Distributed Power Program was initiated at the Department of Energy to address these barriers. The focus of the FY1999 program activities has been on addressing near-term barriers, namely, documenting interconnection issues, supporting the fast-track development of a uniform national interconnection standard, and providing technical assistance to state and local governments as they consider legislative and regulatory actions impacting distributed power.

To continue to build on the results of last December’s workshop, DOE will be having a Program Review and Planning Meeting in conjunction with a meeting of the IEEE SCC21 distributed power interconnection working group, September 27-29, 1999, at the Holiday Inn National Airport in Arlington, VA. This meeting will provide an opportunity for you to evaluate the program=s early efforts and to help formulate multi-year plans to address longer-term R&D needs. These longer-term needs will focus on capturing the full value of distributed power in an electricity market in which customers can sell power, employ load management, and provide operations support services (ancillary services) as easily as the utility, in an automated and adaptive electric power system. As we move into the next century, distributed power will provide the ultimate choice of electricity supply for consumers and will be the real foundation of competition in the electric power industry.

Please join your Distributed Power colleagues in this important meeting.

———————–(additional information sent as follow-up)————–
Just got word from Dick DeBlasio at NREL about the IEEE Working Group meeting and the DOE planning workshop. A decision was reached to open the IEEE meeting to everyone.

“Ed – the IEEE meeting SCC21 P1547 will be on Sept 28-30th, 1999 for 2 1/2 days following the September 27th DOE DPP review and planning meeting. The idea is that all are invited to all 3 1/2 days of meetings . Its one meeting that includes a full IEEE SCC21 P1547 working group session for 2 1/2 days and a DOE planning meeting. I hope that helps. Dick”

Science Mag. Energy Issue

Science Magazine’s recent (July 30) issue is a special edition with a major series of articles on Energy. Here are the table of contents, abstracts, and full text of the lead articles, which I downloaded from their website. If you want any of the articles, but don’t have access to either the magazine, or full text downloading (which may require a subscription), let me know.

Science Magazine, July 30, 1999

A Responsible Energy Future.
pg. 662. (Editorial) [Full Text]

Powering the Next Century.
pg. 677. (Introduction to special issue) [Full Text]

(Abstracts below for these 14 articles)

Bright Future–or Brief Flare–for Renewable Energy? pg. 678-680.

2. ENERGY: Solar Homes for the Masses. pg. 679.

3. NEXT GENERATION AUTOMOBILES: U.S. Supercars: Around the Corner,
or Running on Empty? pg. 680-682.

Toyota’s Hybrid Hits the Streets First, pg. 681.

Bringing Fuel Cells Down to Earth, pg. 682-685.

Company Aims to Give Fuel Cells a Little Backbone. pg. 683.

Turning Engineers Into Resource Accountants. pg. 685-686.

In This Danish Industrial Park, Nothing Goes to Waste. pg. 686.

9. A Realizable Renewable Energy Future. John A. Turner, pg.

10. Underinvestment: The Energy Technology and R&D Policy Challenge.
Robert M. Margolis and D. M. Kammen, pg. 690-692.

11. Photovoltaic Technology: The Case for Thin-Film Solar Cells.
A. Shah, et. al., pg. 692-698.

12. Ceramic Fibers for Matrix Composites in High-Temperature
Engine Applications.
P. Baldus, M. Jansen, and D. Sporn, pg. 699-703.

13. Thermoelectric Cooling and Power Generation.
F. J. DiSalvo, pg. 703-706.

14. Environmental Engineering: Energy Value of Replacing Waste Disposal
with Resource Recovery. R. Iranpour,, pg.706-711.

Powering the Next Century (Introduction to special issue)
Richard Stone and Phil Szuromi

Twenty-five years ago, Science devoted an entire issue to what then was perceived as a major threat to Western society: the energy crisis. Some authors presciently wrote of conservation and improved fossil fuel recovery, while others missed the mark by heralding new eras of nuclear and alternative energy. For a deeper understanding of that turning point between energy naïveté and energy realism, see articles from that and subsequent issues posted at our Web site.

Unexpectedly cheap oil prices in the United States, impossible to foresee in the immediate aftermath of the crisis, are rooted in both economics and politics. Greater oil resources are now available thanks to new reserves and enhanced recovery technologies. [The extent of existing oil resources is under debate (Science, 21 August 1998, p. 1128).] Oil-exporting nations have not maintained the political resolve to keep oil prices inflated by limiting production, and the Persian Gulf War demonstrated the resolve of Western nations to use force to protect oil resources in the Middle East.

Western policy-makers are now debating how to rein in the environmental costs of oil use, such as oil spills and rising concentrations of greenhouse gases. To meet the pollution reduction challenges, energy producers are blazing trails in energy efficiency and reviving alternative energy sources. This special issue explores the science and policy of emerging technologies. Most are works in progress. Fuel cells, for example, are limited largely by ion transfer rates across fragile membranes, whereas the efficiency of heat engines is limited in part by the operating temperatures of metals; ceramics are being explored as hardier alternatives. Improving thermoelectric devices for refrigeration requires finding materials with high electronic conductivity but low thermal conductivity, properties that normally tend to increase or decrease together.

Alternative fuels are also being developed, but they face their own hurdles. Using hydrogen in fuel cell vehicles, for example, would require billions of dollars to create the infrastructure to deliver the gas. Meanwhile, the present infrastructure could become vastly more energy efficient–a shortcoming the young field of industrial ecology is trying to address. Many resources that could be recycled, such as waste water or flare gas, often are not. Where political will translates into legislation, such as California’s demand for alternatively fueled vehicles and the deregulation of its electricity market, investments in new technologies have happened. Where political will has faltered, such as not establishing firm targets for carbon dioxide emissions, developments have been slow.

In his editorial in that 1974 issue of Science, Phil Abelson noted, “Had we been driving smaller, less gas-consuming cars, there would have been no energy crisis. Some other forms of transportation consume less gasoline, and their use should be encouraged.” The logic remains irrefutable a quarter of a century later. Advances in energy technology will likely need to be assisted, however, by changes in our own habits of energy use, willingly or not.


A Responsible Energy Future (Editorial)
Rush Holt*

Affordable energy is the lifeblood of modern society. Without it, the network of transportation, agriculture, health care, manufacturing, and commerce deemed essential by many of the world’s inhabitants would not be possible. Yet our use of energy releases sulfur dioxides, metals such as cadmium and mercury, and greenhouse gases and other noxious pollutants that damage our quality of life. Moreover, when we use fossil fuels, we make ourselves dependent on an energy source that cannot be relied upon forever.

With the apparent conditions in the United States today, what could induce us to change our energy habits now? Almost daily, gasoline prices reach record lows, and U.S. citizens have not waited in line for gas for decades. Our fossil fuel engines and turbines burn more cleanly and more efficiently now than ever before.

Nevertheless, the truth is that our current system of energy use is unsustainable; our energy habits will have to change. For, although fossil fuel supplies are limited, total energy use will rise rapidly in coming years as global economic development continues. What is more, according to many scientists, current greenhouse gas emissions–let alone any greater emissions in the future–threaten to produce serious environmental changes.

Some scientists have predicted that projected greenhouse gas emissions for the coming decade could produce climate changes as significant as an increase of 5º to 6ºF (2.8º to 3.3ºC) in average global temperature, a one-half meter rise of sea level, and even an increase in the intensity of hurricanes and tropical storms. Worst-case scenarios? Perhaps. But other negative effects of fossil fuel pollution, such as smog, acid rain, water contamination from leaky fuel tanks, oil refinery emissions, and oil spills, are already very real in many regions of the globe, in both industrialized and developing nations. Even without global warming, these immediate problems are enough to warrant change.

For developing countries, cheap, polluting, and inefficient technologies are often the only affordable option. The United States is in a position to develop better alternatives. We should take the initiative. Our current investment in research and development in energy is nothing short of irresponsible. The U.S. national energy product exceeds $500 billion annually. Yet barely 1% of that amount is invested in R&D. The President’s Committee of Advisors on Science and Technology (PCAST) has recommended that the Department of Energy’s applied energy-technology R&D budget be nearly doubled to $2.4 billion by 2003. In my view, this recommendation should be considered a minimum figure.

This money would be well spent. Those who position themselves to manage the coming changes in energy use will stand to gain enormously. American companies would profit from the development of more efficient, cleaner–and therefore more desirable–technologies; the American economy would benefit from the expertise built up by further research; and American citizens would benefit from a cleaner, safer environment.

Just as the federal government has a responsibility to invest now in basic medical research to ensure the health of present and future generations, so it has a responsibility to invest now in basic energy research to ensure both our near-term and long-term economic and environmental health. The justification for this commitment seems clear to many of us trained in science and technology. Yet with energy prices low, the necessary political will may be lacking. Will apprehension about negative effects–greater pollution and global climate change–provoke people to examine our energy habits and take action? Or will the possible economic opportunities attract attention and provoke action? A huge potential market awaits, promising an opportunity to enhance the quality of life of all the world’s people. Meanwhile, researchers and policy-makers must continue to seek ways to make relevant to our communities the nature of our global energy challenges and opportunities.

The author is a U.S. Congressman from central New Jersey, a physicist, and the former Assistant Director of Princeton University’s Plasma Physics Laboratory.


Abstract 1 of 14

ENERGY: Bright Future–or Brief Flare–for Renewable Energy?

Kathryn S. Brown

PALM SPRINGS, CALIFORNIA–Solar, wind, and other forms of renewable energy are making surprising gains as some U.S. states open their power markets to competition. But with fossil fuel prices near all-time lows, experts are split on whether alternative energy can maintain its momentum. Concerns about climate change are the strongest force pulling in favor of renewables, but if the Kyoto climate change treaty falters and global warming forecasts become less dire, the fossil fuel era is likely to continue into the foreseeable future.

Abstract 2 of 14

ENERGY: Solar Homes for the Masses
Alexander Hellemans

Near Amersfoort, the Netherlands, the NV REMU power company is leading a $13 million project to build 500 houses with roofs covered with photovoltaic panels–the world’s largest attempt at so-called “building-integrated photovoltaics.” By the time the homes are finished next year, they should be drawing 1.3 megawatts of energy from the sun, enough to supply about 60% of the community’s energy needs.

Abstract 3 of 14

U.S. Supercars: Around the Corner, or Running on Empty?
David Malakoff

GOLDEN, COLORADO–A collaboration between automakers and the federal government to develop high-mileage, low-emission cars is set to unveil its first prototypes–probably diesel-electric hybrids–next year. However, critics charge that the program is betting on the wrong technologies by emphasizing polluting diesel engines instead of potentially cleaner technologies such as hydrogen fuel cells; others question why the government is subsidizing the effort when Toyota has already built a fuel cell car on its own dime (see sidebar). Moreover, with the United States’ current low gas prices, observers don’t expect to see consumers cruising in the new supercars anytime soon.

Abstract 4 of 14

Toyota’s Hybrid Hits the Streets First
Dennis Normile

TOKYO–As U.S. automakers struggle to draft blueprints for their future fuel-efficient cars (see main text), the Toyota Motor Co. has beaten them to the punch with a gas-electric hybrid that gets about double the gas mileage and spews half the carbon dioxide of similarly sized sedans. What’s more, the Prius has made it to market without the benefit of taxpayer-sponsored research and without any looming domestic requirements for zero-emissions vehicles.

Abstract 5 of 14

Bringing Fuel Cells Down to Earth
Robert F. Service

Automakers are banking on fuel cells, used to run equipment aboard spacecraft, to power the first zero-emission vehicles; the type of fuel that supplies the cells could determine how deeply
these cars penetrate the market. Engineers and clean-air experts say the simplest and cleanest option is hydrogen gas itself, while car and oil companies would prefer to equip vehicles with
miniature chemical factories to convert liquid fuels, such as gasoline or methanol, into hydrogen gas that can be fed into fuel cells. Critics, meanwhile, argue that the converters likely will
be expensive and prone to breaking down.

Abstract 6 of 14

Company Aims to Give Fuel Cells a Little Backbone
David Voss

ELKTON, MARYLAND–Before fuel cell-makers can challenge utility companies for our business, they must first lower the price and ratchet up the power of their devices. A crucial part of the strategy is to improve the membrane assembly, which serves as catalyst, electrode, and chemical separator. Researchers are achieving promising results using fluoropolymers, but cost remains an obstacle.

Abstract 7 of 14

Turning Engineers Into Resource Accountants
Jocelyn Kaiser

A new discipline is trying to persuade companies that tracking the flow of materials and energy over a product’s lifetime makes good business sense. The philosophy has begun to pay off–mainly in Europe–in everything from appliances designed with reusable parts to schemes for capturing precious metals that may otherwise end up in landfills or riverbeds. However, a cradle-to-grave approach to doing business hasn’t yet caught fire in the United States.

Abstract 8 of 14

In This Danish Industrial Park, Nothing Goes to Waste
Jocelyn Kaiser

If there’s anything that sums up the hopes of industrial ecology (see main text), it’s a tiny pipeline-laced town in eastern Denmark called Kalundborg, where companies have been swapping byproducts like gypsum and waste water for up to 25 years. This “industrial symbiosis” is drawing keen interest from policy-makers in the United States, although opinions vary on its odds of success.

Abstract 9 of 14

A Realizable Renewable Energy Future
John A. Turner

The ability of renewable resources to provide all of society’s energy needs is shown by using the United States as an example. Various renewable systems are presented, and the issues of energy payback, carbon dioxide abatement, and energy storage are addressed. Pathways for renewable hydrogen generation are shown, and the implementation of hydrogen technologies into the energy infrastructure is presented. The question is asked, Should money and energy be spent on carbon dioxide sequestration, or should renewable resources be im plemented instead.

National Renewable Energy Laboratory, Golden, CO. E-mail:

Abstract 10 of 14

Underinvestment: The Energy Technology and R&D Policy Challenge
Robert M. Margolis, 1* Daniel M. Kammen 2*

This Viewpoint examines data on international trends in energy research and development (R&D) funding, patterns of U.S. energy technology patents and R&D funding, and U.S. R&D intensities across selected sectors. The data present a disturbing picture: (i) Energy technology funding levels have declined significantly during the past two decades throughout the industrial world; (ii) U.S. R&D spending and patents, both overall and in the energy sector, have been highly correlated during the past two decades; and (iii) the R&D intensity of the U.S. energy sector is extremely low. It is argued that recent cutbacks in energy R&D are likely to reduce the capacity of the energy sector to innovate. The trends are particularly troubling given the need for increased international capacity to respond to emerging risks such as global climate change.

1 Science, Technology and Environmental Policy (STEP) Program, Woodrow Wilson School of Public and International Affairs, Princeton University, Princeton, NJ .
2 Energy and Resources Group (ERG), University of California, Berkeley, CA .
* To whom correspondence should be addressed. E-mail:;

Abstract 11 of 14

Photovoltaic Technology: The Case for Thin-Film Solar Cells
A. Shah, 1 P. Torres, 1* R. Tscharner, 1 N. Wyrsch, 1 H. Keppner 2

The advantages and limitations of photovoltaic solar modules for energy generation are reviewed with their operation principles and physical efficiency limits. Although the main materials currently used or investigated and the associated fabrication technologies are individually described, emphasis is on silicon-based solar cells. Wafer-based crystalline silicon solar modules dominate in terms of production, but amorphous silicon solar cells have the potential to undercut costs owing, for example, to the roll-to-roll production possibilities for modules. Recent developments suggest that thin-film crystalline silicon (especially microcrystalline silicon) is becoming a prime candidate for future photovoltaics.

1 Institute of Microtechnology (IMT), University of Neuchâtel, Neuchâtel, Switzerland.
2 University of Applied Science, Le Locle, Switzerland.
* To whom correspondence should be addressed. E-mail:

Abstract 12 of 14

Ceramic Fibers for Matrix Composites in High-Temperature Engine Applications
Peter Baldus, 1 Martin Jansen, 2* Dieter Sporn 3

High-temperature engine applications have been limited by the performance of metal alloys and carbide fiber composites at elevated temperatures. Random inorganic networks composed of silicon, boron, nitrogen, and carbon represent a novel class of ceramics with outstanding durability at elevated temperatures. SiBN3C was synthesized by pyrolysis of a preceramic N-methylpolyborosilazane made from the single-source precursor Cl3Si-NH-BCl2. The polymer can be processed to a green fiber by melt-spinning, which then undergoes an intermediate curing step and successive pyrolysis. The ceramic fibers, which are presently produced on a semitechnical scale, combine several desired properties relevant for an application in fiber-reinforced ceramic composites: thermal stability, mechanical strength, high-temperature creep resistivity, low density, and stability against oxidation or mo lten silicon.

1 Bayer AG, ZF-MFA, Leverkusen, Germany.
2 Max-Planck-Institut für Festkörperforschung, Stuttgart, Germany.
3 Fraunhofer Institut für Silicatforschung, Germany.
* To whom correspondence should be addressed.

Abstract 13 of 14

Thermoelectric Cooling and Power Generation
Francis J. DiSalvo

In a typical thermoelectric device, a junction is formed from two different conducting materials, one containing positive charge carriers (holes) and the other negative charge carriers (electrons). When an electric current is passed in the appropriate direction through the junction, both types of charge carriers move away from the junction and convey heat away, thus cooling the junction. Similarly, a heat source at the junction causes carriers to flow away from the junction, making an electrical generator. Such devices have the advantage of containing no moving parts, but low efficiencies have limited their use to specialty applications, such as cooling laser diodes. The principles of thermoelectric devices are reviewed and strategies for increasing the efficiency of novel materials are explored. Improved materials would not only help to cool advanced electronics but could also provide energy benefits in refrigeration and when using waste heat to generate electrical power.

Department of Chemistry and Chemical Biology, Cornell University, Ithaca, NY. E-mail:

Abstract 14 of 14

Environmental Engineering: Energy Value of Replacing Waste Disposal with Resource Recovery
R. Iranpour, 1* M. Stenstrom, 2 G. Tchobanoglous, 3 D. Miller, 4 J. Wright, 5 M. Vossoughi 6

Although in the past, environmental engineering has been primarily concerned with waste disposal, the focus of the field is now shifting toward viewing wastes as potential resources. Because reclamation usually consumes less energy than producing new materials, increasing reclamation not only reduces pollution but saves energy. Technological innovations contributing to this shift are summarized here, and are variously classified as emerging technologies or research topics, as either new departures or incremental improvements, and as opportunistic innovations, or examples of a unifying strategy. Both liquid and solid waste examples are given, such as a recent discovery of effects in disinfecting microfiltered reclaimed wastewater with ultraviolet light. In addition to its value in reducing pollution and conserving energy, this reorientation of environmental engineering could contribute to a more general shift toward greater cooperation among organizations dealing with the environment.

1 Applied Research Group, Hyperion Treatment Plant, Los Angeles Sanitation, Santa Monica, CA.
2 Dept of Civil and Environmental Engineering, UCLA, Los Angeles, CA
3 Dept of Civil and Environmental Engineering, UC-Davis, Davis, CA
4 Tech Research, Los Angeles, CA
5 Dept of Civil Engineering, Purdue University, West Lafayette, IN.
6 Biochemical and Bioengineering Research Center, Sharif University, Tehran, Iran.
* To whom correspondence should be addressed. E-mail:

Copyright © 1999 by the American Association for the Advancement of Science.