The effect of anionic surfactants on aeroponic cultivation of lettuce in space applications

Abstract

Design of efficient and robust life support systems will require huge effort. In closed systems such as future extra-terrestrial colonies or spaceships, all produced wastes will have to be perfectly purified and all resources will have to be recovered. This isn't possible now even in life support systems built on Earth. Future extra-terrestrial closed life support system will have to be robust and simple as possible to decrease risk of failure and transport costs. One of the attempts to simplify the treatment of wastes is to use greywater as water source in soil-less cultivation without pretreatment. In this paper results of two lab-scale aeroponic experiments are shown. These experiments were aimed at determining possibility of using grey water directly as water source for aeroponic cultivation of lettuce. Two surfactants (SBDS,SMCT) with concentrations varying from 0.08 to 1.5 g/L and model grey water (containing SLES surfactant) were tested. Experiments shown that high concentrations of SBDS and SMCT are detrimental for lettuce growth while similar concentration of SLES inhibit but do not stop lettuce growth. With lower concentrations of surfactants growth of lettuce is possible. Moreover results shows decrease in surfactants mass in model grey water used as nutrient solution which may indicate development of bacteria in root zone that are able to use surfactants as substrates.