Bioreactor Strategies for the Treatment of Growth‐Inhibitory Waste: An Analysis of Thiodiglycol Degradation, the Main Hydrolysis Product of Sulfur Mustard

Abstract

The microbial degradation of thiodiglycol, the primary hydrolysis product of sulfur mustard, by a pure culture of Alcaligenes xylosoxydans ssp. xylosoxydans (SH91) was accomplished in laboratory scale stirred tank reactors. This is a major component of the overall biodegradation process proposed for the complete mineralization of sulfur mustard. Several configurations were evaluated for degradation efficiency including batch, repeated batch, continuous stirred tank reactor (CSTR), and two-stage series CSTR. The repeated batch reactor provided the highest degradation rate of thiodiglycol. Further, this method degraded thiodiglycol in the liquid broth to below the detection limits (0.03 mM). Both batch and repeated batch experiments were simulated by an unstructured mathematical model. Simulation results were in agreement with the experimental data, particularly at low TDG concentration (around 30 mM). This study demonstrates the degradation of thiodiglycol using bioreactors and, more generally, is an experimental study of bioreactor designs for the degradation of growth-inhibitory substances.

Biological treatment of concentrated hazardous, toxic, andradionuclide mixed wastes without dilution

“…The results with acetonitrile, a toxic compound with poor biokinetic properties, further suggest that drip-feed biotreatment would offer a safe alternative for the treatment of other highly toxic, but biodegradable substances, such as sarin, VX, and mustard (Kilbane and Jackowski 1996, Lee et al 1996, Shem et al 1995. Challenges facing the safe disposal of chemical warfare materiel (CWM) is similar to the challenges facing the safe disposal of mixed wastes.…”

“…Avoiding substrate inhibition is the most significant challenge in designing biological treatment systems for concentrated or toxic wastes (Lee et al 1996, Wolfram et al 1997, Vanderberg et al 1999, Chang et al 2002, Schwinkendorf et al 1995, Shem et al 1996.…”

“…Studies examining the treatment of inhibitory wastes typically utilize or evaluate continuous stirtank reactors (CSTRs) or a variety of batch reactor configurations (Lee et al 1996, Wolfram et al 1997, Vanderberg et al 1999, Schwinkendorf et al 1995, Shem et al 1995. Substrate inhibition of treatment is commonly avoided by diluting a toxic waste to a concentration below the corresponding half-saturation constant (K s ) or some reference concentration known to be non-toxic (Lee et al 1996, Wolfram et al 1997 Wolfram and collaborators demonstrated that bacteria could be used to degrade common solvent constituents of mixed wastes, including methanol and acetonitrile (Wolfram et al 1997).…”

“…Substrate inhibition of treatment is commonly avoided by diluting a toxic waste to a concentration below the corresponding half-saturation constant (K s ) or some reference concentration known to be non-toxic (Lee et al 1996, Wolfram et al 1997 Wolfram and collaborators demonstrated that bacteria could be used to degrade common solvent constituents of mixed wastes, including methanol and acetonitrile (Wolfram et al 1997). …”

“…Biological treatment of mustard and mustard hydrolysis products have been demonstrated (Kilbane and Jackowski 1996, Lee et al 1996, NRC 2000, NRC 2002, Shem et al 1995, but projects examining the biological treatment of nerve agents have failed due to poor bioreactor design (NRC 2000). Novel reactor configurations, such as the drip-feed bioreactor, could offer practical alternatives to the disposal of difficult to handle waste streams.…”