Direct Contact Membrane Distillation of Artificial Urine for Sugar Beet Production in a Hydroponic System

Abstract

Appropriate nutrient sources and optimized doses of plant nutrients for space and lunar farming have remained key challenges prompting investigations to sort out biologically viable options including human urine. Therefore, a trial was performed to compare the hydroponic growth of sugar beets using a standard nutrient solution and the same nutrient solution with a 10% replacement of an artificial urine solution that had been concentrated using direct contact membrane distillation (DCMD). The response variables included yield-contributing traits and root parameters (plant height, stem diameter, length and fresh weight of leaf and root, whole plant fresh weight), along with beet characteristics (diameter, length, and fresh weight at harvest). The results revealed that 10% synthetic urine treatment produced significantly taller plants (33%, 3%, and 8% at the 4th, 6th, and 10th week after sowing, respectively) and recorded 52% and 40% greater leaf width at the 4th and 6th weeks, respectively, compared to the control. In contrast, 10% replacement with synthetic urine in the nutrient performed statistically below par compared to the control treatment by producing 9% and 17% lower leaf width at the 8th and 10th weeks, respectively. Additionally, at the harvest, 10% synthetic urine treatment gave taller plants with greater stem length and root length (2.3%, 8.6%, and 59%, respectively) than the control. Moreover, the same treatment remained superior by showing higher root weight and stem diameter at harvest but performed below par compared to the control in leaf width and whole plant fresh weight. At harvest, both treatments remained statistically non-significant in terms of beet length, however the control surpassed synthetic urine treatment by yielding 37% and 103% higher width and fresh weight of beets, respectively. Based on recorded findings, it may be inferred that synthetic urine holds potential as a valuable plant nutrient source for producing sugar beets in an indoor hydroponic system, though not comparable in some respects with the control (standardized plant nutrient medium) for some plant measurements.

Keywords

• lunar agriculture
• membrane
• sugar beet
• sodium chloride stress
• synthetic urine
• beet weight
• hydroponic system
• deep space