Biologically mediated solids reduction and nutrient recovery from inedible tomato, wheat and peanut plant material for advanced life support systems

Nutrient recovery and biodegradation of inedible biomass is an integral part of an Advanced Life Support (ALS) System for space travel. This study investigates the mineralization and nutrient regeneration of hydroponically grown crops, namely, tomato, peanut, wheat, and a 50:50 mixture of peanut and wheat. Bench scale parametric studies were conducted on a 1% solids basis in shaker flasks and batch reactors under various growth conditions of temperature and incubation times utilizing activated sludge and Phanerochaete chrysosporium (P. chrysosporium) inoculate. It was determined that the majority of solids destruction occurs within the first 16 days of incubation under the methods employed in this study. Overall solids destruction in all crops ranged from 30% to 60% for both activated sludge and P. chrysosporium cultures indicating no substantial degradation enhancement due to inocula. Incubation temperature had a minimal effect on total solids reduction but appeared to influence the leachability of certain micronutrients. Percent recovery was nearly 100% for certain micronutrients and as low as 5% for others. Recovery of nitrogen was sufficiently high for both activated sludge and fungal systems indicating that the final effluent is suitable for hydroponic plant growth. Although substantially reduced during treatment, chemical oxygen demand (COD) content of the leachate remains at levels that may inversely impact hydroponic growth of plants and may require further reduction.; In addition to shaker flask studies, several experiments using either activated sludge or P. chrysosporium were conducted in bioreactors and column treatment systems. Two separate experiments were conducted in batch reactors using inedible crop residues and frequent measurement of nitrate and nitrite, COD and TKN were performed to monitor biological behavior during a 16-day period. A column treatment system utilizing inedible crop residue as packing material was designed and operated in batch and continuous modes with the objective of reducing carbon content from an influent grey water stream while degrading solids.