Bruce Rittmann

Rittmann is one of the pioneers in developing and applying mathematical models of biofilms, which are microorganisms that grow attached to a solid surface. Although some biofilms are infamous for causing infections or fouling the surfaces of pipes, ships, and membranes, Rittmann focuses on the good biofilms used to treat contaminated water. Mathematical modeling is a powerful tool to integrate the several microbiological, chemical, and transport processes that occur together in a biofilm. Models can represent the gradients in substrates that the microorganisms metabolize, the products generated by the microorganisms, and the different types of microorganisms that exist together in biofilms. Rittmann's PhD dissertation focused on biofilm modeling, and he and his team have expanded the scope and power of biofilm modeling up through today.

Originally working in cooperation with David Stahl, Rittmann introduced the powerful tools of molecular biology to environmental engineering, helping create the exciting field known today as Environmental Biotechnology, in which the goal is to manage microbial communities so that they provide services to society. The tools of molecular microbial ecology directly interrogate the genetic information in microorganisms. They make it possible to determine what types of microorganisms are present in the complex communities of environmental biotechnologies, what reactions those microorganisms can carry out, what reactions they are carrying out, and how they interact with each other and their environment. Now working hand-in-glove with Center colleague Rosa Krajmalnik-Brown, Rittmann is using molecular microbial ecology to understand and manage microbial communities in a wide range of microbiological processes used for removing pollution from water, generating renewable resources, and improving human health.

Rittmann and several colleagues were the first to define soluble microbial products (SMP), which comprise a wide range of soluble organic molecules that microorganisms release to their environment. With Chrysi Laspidou, Rittmann linked SMP to the solid-phase products generated by microorganisms, the extracellular polymeric substances (EPS); they created the “unified model” of SMP, EPS, and active biomass, and it has been expanded and applied to all types of microbiological processes. Being major sinks for electrons and carbon, SMP and EPS have profound impacts on the performance of environmental biotechnologies in terms of effluent quality and the composition of the biomass.

Bioremediation refers to the microorganism-based clean up of contaminated soils and associated water. Rittmann's PhD research involved bioremediation of organic micropollants from wastewater recharge to aquifers. His work expanded to the bioremediation of chlorinated solvents, petroleum hydrocarbons, and radionuclides. Rittmann helped establish and direct the field of in situ bioremediation through the publication of two National Academy reports from committee he chaired: In Situ Bioremediation: When Does it Work? (1993), and Natural Attenuation for Groundwater Remediation (2000).

Rittmann is the inventor of the Hydrogen-based Membrane Biofilm Reactor (MBfR),[3] which can be used to reduce and detoxify a wide range of oxidized pollutants commonly found in water: e.g., nitrate, perchlorate, chromate, selenate, trichloroethene, and uranyl. In the MBfR, H₂ gas is delivered directly to H₂-oxidizing bacteria that live on the outer surface of a bubble-less gas-transfer membrane. The oxidized contaminants in the water moving past the biofilm are reduced to harmless or readily removed forms. Rittmann holds six patents on the MBfR, which is commercialized at the ARo (Autotrophic Reduction of) technology by APTwater. The MBfR won the 2011 Environmental Engineering Excellence Award from the American Academy of Environmental Engineers.[4]

Rittmann’s photobioreactor team is working towards finding practical ways to utilize photosynthetic microorganisms to capture sunlight energy and convert CO₂ into valuable feedstock for fuels and chemicals. The team focuses on advanced photobioreactor systems that give high productivity of the target product. The product can be part of the biomass itself or chemical synthesized and excreted by the photosynthetic microorganisms. The latter theme is in cooperation with Willem Vermaas of ASU’s School of Life Sciences. The ultimate goal is to make CO₂ a resource for generating renewable fuels and chemicals.

Microbial electrochemistry utilizes bacteria that are able to transfer electrons to the anode of an electrochemical cell. Called “anode-respiring bacteria,” they are able to oxidize organic molecules and create an electrical current that can be used to generate electrical power, hydrogen gas, hydrogen peroxide, or other reduced materials, depending on conditions at the cathode of the electrochemical cell. Working with Center colleagues César Torres and Sudeep Popat, Rittmann is advancing the fundamental science and technology bases for microbial electrochemistry, with the ultimate goal of using the technology to capture the energy in organic waste streams as valuable energy or chemical outputs.

The human intestines harbor a very high diversity of microorganisms that interact with the human host in ways that profoundly affect the host’s health. Working with Center colleagues Dr. Rosa Krajmalnik-Brown and Andrew Marcus, Rittmann is helping to uncover the microorganisms that are essential for good health, as well as means to enhance the activity of our “good” bacteria. The team’s work is characterized by its comprehensive nature and orientation towards microbial ecology. The utilize high-throughput genomics, metabolomics, and quantitative modeling to understand the complex interactions among the many microorganisms and the human host, as well as to uncover means to manage the microbial communities towards good health outcomes.

• Committee on In Situ Bioremediation; Commission on Engineering and Technical Systems; Division on Engineering and Physical Sciences; National Research Council (1993). Bruce Rittmann (ed.). In Situ Bioremediation: When Does It Work?. Washington, DC: Routledge. ISBN 978-0309048965.
• Rittmann, B. E.; E. Seagren; B. A. Wrenn; A. J. Valocchi; C. Ray; L. Raskin (1995). In Situ Bioremediation. Park Ridge, NJ: William Andrew, Inc. ISBN 978-0815513483.
• Committee on Intrinsic Remediation; Water Science and Technology Board; Board on Radioactive Waste Management; National Research Council; Commission on Intrinsic Remediation (2000). Bruce Rittmann (ed.). Natural Attenuation for Groundwater Remediation. Washington, DC: National Academy Press. ISBN 978-0309069328.
• Rittmann, Bruce; McCarty, Perry (2001). Environmental Biotechnology: Principles and Applications. New York: McGraw-Hill. ISBN 978-0071181846.

Complete list