|
Description:
|
The fate of a common commercial surfactant was investigated in biological reactors intended for long -term space applications . A NO2" reducing packed -bed bioreactor was employed to evaluate degradation of surfactant present in a typical space station greywater stream . The research was conducted to determine if a commercial surfactant could be used in the place of the current cleansing formulation and be degraded in biological water recycle system proposed for space travel . The commercial cleansing formulation used in the research was Pert Plus® for Kids (PPK ) , which contains sodium laureth sulfate (SLES ) as the active surfactant . Experiments included a combination of microcosm experiments as well as a continuous -flow packed -bed bioreactor . The hydraulic retention time of the packed -bed bioreactor was varied through changes in flow rate to yield different steady -state values for NO2' reduction TOC , COD and SLES removal . Steady -state conditions allowed for the determination of degradation potential of both PPK and SLES . It was found that both constituents degraded well under NO2" reducing conditions . Stoichiometric relationships were used to determine if measured parameters could accurately predict the observed SLES degradation . Frora these relationships , it was found that other less common degradation pathways (biotic and /or abiotic ) could have transformed SLES . Also , bacterial kinetics were determined for the currently used surfactant , Igepon T42 ™ , and the commercial surfactant , SLES .
From the rates determined it was found that Igepon T42™ exhibits faster degradation rates compared to the SLES . It was also found that the rates determined for SLES were concentration dependent . During this evaluation both PPK and SLES were effectively degraded under NO2" reducing conditions indicating their possible use in a WRS . |