Micronutrient Recovery from Inedible Plant Residues in Activated Sludge Cultures and Phanerochaete chrysosporium Inocula 1999-01-2066

Micronutrient recovery was investigated in two microbial systems, activated sludge and Phanerochaete chrysosporium (P. chrysosporium). Hydroponically grown crops, namely, tomato, peanut, wheat and a 50:50 mixture of peanut and wheat were used in the study. The experiments were conducted in shaker flasks on a 1% solids basis at 25°C for all crops and at 25°C, 40°C, 50°C and 60°C for tomato plant material. The micronutrient content of the leachate was determined initially and after 16, 32, 64, and 128 days of incubation. In order to determine the extent and rate of micronutrient release during the initial stages of incubation, when most of the solids degradation occurs, two separate experiments were conducted in batch reactors for 16 days. The micronutrient content of the batch reactor leachate was monitored on a daily basis. Micronutrients assessed included boron, manganese, iron, magnesium, zinc, copper, calcium, phosphorus and potassium. The effects of biological treatment, biological agents, and incubation time on micronutrient recovery were evaluated. The micronutrient content of the leachate, obtained from untreated inedible solid residues, is in general sufficiently high to support hydroponic plant growth. However, addition of certain micronutrients may be necessary depending on the type of crop leached. Recovery of micronutrients in the biologically treated samples exhibited substantial fluctuations both with incubation time and biological agent employed and was in general lower than micronutrient concentrations obtained from simple leaching.