Hydrogen-based, hollow-fiber membrane biofilm reactor for reduction of perchlorate and other oxidized contaminants

Abstract

Many oxidized pollutants, such as nitrate, perchlorate, bromate, and chlorinated solvents, can be microbially reduced to less toxic or less soluble forms. For drinking water treatment, an electron donor must be added. Hydrogen is an ideal electron donor, as it is non-toxic, inexpensive, and sparsely soluble. We tested a hydrogen-based, hollow-fiber membrane biofilm reactor (MBfR) for reduction of perchlorate, bromate, chlorate, chlorite, chromate, selenate, selenite, and dichloromethane. The influent included 5 mg/L nitrate or 8 mg/L oxygen as a primary electron accepting substrate, plus 1 mg/L of the contaminant. The mixed-culture reactor was operated at a pH of 7 and with a 25 minute hydraulic detention time. High recirculation rates provided completely mixed conditions. The objective was to screen for the reduction of each contaminant. The tests were short-term, without allowing time for the reactor to adapt to the contaminants. Nitrate and oxygen were reduced by over 99 percent for all tests. Removals for the contaminants ranged from a minimum of 29% for chlorate to over 95% for bromate. Results show that the tested contaminants can be removed as secondary substrates in an MBfR, and that the MBfR may be suitable for treating these and other oxidized contaminants in drinking water.

Trash to treasure: production of biofuels and commodity chemicals via syngas fermenting microorganisms

“…Among these limitations are low syngas kLa, low cell-biomass, sporulation, as well as substrate and product inhibition. Engineering syngas fermenting microorganisms for enhanced biofilm development can help overcome their inherently low biomass yield while enabling the use of reactors with enhanced gas mass transfer rates such as airlift reactors [59] or membrane biofilm reactors [60] as well as other types of biofilm-based reactors suitable for syngas fermentation [15,57]. More effective biofilms can be formed by increased exopolysaccharide production [61] or by manipulating other factors that are known to modulate biofilm formation in Clostridium species [62].…”

Kinetics of microbial bromate reduction in a hydrogen‐oxidizing, denitrifying biofilm reactor

“…Our previous research showed that hydrogen-based bromate reduction occurs under denitrifying conditions (Nerenberg and Rittmann, 2004). The objectives of this research were to (1) determine whether a hydrogen-based, denitrifying membrane biofilm reactor (MBfR) can reduce bromate to below the 10-mg/L treatment objective; (2) assess the effects of pH, nitrate, nitrite, and bromate on bromate reduction rates; (3) determine the kinetics of hydrogen-based bromate reduction under denitrifying conditions; (4) explore bromate reduction in a pure-culture, denitrifying MBfR.…”

Changes in the Structure and Function of Microbial Communities in Drinking Water Treatment Bioreactors upon Addition of Phosphorus

“…In some of these processes, preozonation is applied to improve the biodegradability of refractory organic matter (25,35,37,43). In other processes, termed stimulated biological treatment processes in the current study, electron donors are added to support microbial activity for the removal of contaminants that can serve as electron acceptors, such as nitrate (20), perchlorate (7,30), and other oxidized anions (34).…”