Perchlorate reduction in a HYDROGEN‐BASED MEMBRANE–BIOFILM REACTOR

Abstract

The perchlorate anion (ClO4–) has been found in potentially harmful concentrations in numerous water sources. Because perchlorate is not removed by conventional water treatment processes, new treatment processes are needed. Biological perchlorate reduction is a promising alternative. The authors investigated a hydrogen‐oxidizing hollow‐fiber membrane–biofilm reactor system for perchlorate removal. Hydrogen is an ideal electron donor for biological drinking water treatment because it presents no toxicity, is inexpensive, and is unlikely to persist as a source of biological instability in distributions systems. The reactor delivers hydrogen in an efficient and safe manner. Results showed that biological perchlorate reduction takes place concurrently with nitrate reduction, no specialized inoculation is required, and perchlorate can be removed to below the preliminary regulatory standards with no chemical addition other than hydrogen gas. The optimal pH is 8, and the accumulation of intermediates is unlikely. Full denitrification and pH control may be required for excellent perchlorate removal.

Microbial Degradation of Perchlorate: Principles and Applications

“…Perchlorate degradation has also been achieved in bioreactors using only inorganic amendments. These reactors are sustained by hydrogen gas delivered by pressurization, gas transfer across liquid films, or synthetic membranes (Giblin et al, 2000b;Miller and Logan, 2000;Nerenberg et al, 2002). These hydrogen-based technologies are promising technologies for water treatment because less biomass is produced by autotrophic processes than heterotrophic processes.…”

“…The degradation of perchlorate in a groundwater has also been demonstrated using a hollow-fiber membrane bioreactor (Nerenberg et al, 2002). The membrane module in the reactor contained 98 hollow fibers (93 cm long; 280 mm outside diameter) in a PVC pipe shell.…”

“…A PRB isolate, perc1ace, was able to completely remove perchlorate (130 mg/L) and to simultaneously remove more than 95% of the nitrate (20 mg/L) in a sand-packed bioreactor (Herman and Frankenberger, 1999). Coppola and McDonald (2000) reported that a mixed culture of W. succinogenes could completely degrade perchlorate (1.2-1.5 g/L), chlorate (3-3.5 g/L), and nitrate (0.2 g/L) in a 7-L continuously stirred tank reactor at a HRT of 16 h. Nerenberg et al (2002) showed that perchlorate and nitrate reduction to nondetectable levels could be concurrently achieved using a hydrogenfed, autotrophic membrane bioreactor. In pilot-scale tests, Min et al (2003) found that perchlorate and nitrate were both completely removed in a fixed-bed bioreactor.…”

Mass transfer in a membrane aerated biofilm

“…Le transfert de l'hydrogène au biofilm est alors mieux maîtrisé et les polluants sont consommés par des bactéries autotrophes. Des exemples de composés réduits dans la bibliographie sont : les nitrates (Lee et Rittmann, 2002 ;Ergas et Reuss, 2001 ;Terada et al , 2006) ; les perchlorates (Nerenberg et al, 2002(Nerenberg et al, et 2008 ; les bromates (Downing et Nerenberg, 2006 ; l'arséniate (Chung et al, 2006a), les chromates (Chung et al, 2006b) et les sélénates (Chung et al, 2006c) ; le 1,1,1 trichloroethane et le chloroforme (Chung et Rittman, 2007), … Lee et Rittmann (2002) observent, sur un biofilm réduisant les nitrates, un optimum de pression en hydrogène en deçà duquel les nitrates sont éliminés partiellement, et au delà duquel l'hydrogène se retrouve dans la phase liquide.…”

Perchlorate Biodegradation for Water Treatment

“…Various designs of hydrogen-based reactors have been tested in laboratory studies for treating nitrate (e.g., [47][48][49] and, more recently, chlorate (50) and perchlorate in drinking water (51)(52)(53). The expected advantage of these systems is the absence of any remaining organic electron donor in the treated water.…”