Potential for Recovery of Plant Macronutrients from Space Habitat Wastes for Salad Crop Production

Crop production in space habitats is currently under consideration as part of an advanced life support system. The scenarios for crop production vary depending on the mission objectives. For a mission scenario such as the International Space Station (ISS), current efforts propose only salad crop production. However in order to grow salad crops, there is a need for plant nutrients (elements) such as N, P, K, Ca, etc., which constitutes about 10% of dry weight of the plant. Nitrogen and potassium are the major elements needed by salad crops and currently require resupply on Station. However, it is feasible that these macronutrients could be recovered through the waste materials generated by the crew. The proposed concepts are non-oxidative and simple in design.

This paper considers the potential for reclaiming macronutrients from urine and gray water concentrates from water recovery systems. The potential gains from reducing resupply from use of urine and gray water concentrates are listed. A detailed discussion of the processing means to recover the nutrients is given.