Hydroponic Crop Production Using Recycled Nutrients from Inedible Crop Residues

The coupling of plant growth and waste recycling systems is an important step toward the development of bioregenerative life support systems. This research examined the effectiveness of two alternative methods for recycling nutrients from the inedible fraction (residue) of candidate crops in a bioregenerative system; 1) extraction in water, or leaching, and 2) combustion at 550 °C, with subsequent reconstitution of the ash in acid. The effectiveness of the different methods was evaluated by 1) comparing the percent recovery of nutrients, and 2) measuring short- and long-term plant growth in hydroponic solutions, based on recycled nutrients.