Isolation and identification of microorganisms and their aerobic biodegradation of fish-meal wastewater for liquid-fertilization

To reutilize the wastewater generated during the process of fish-meal production (FMW), seven thermophilic microorganisms were newly isolated and their characteristics of aerobic biodegradation of FMW were examined in a 5 l-bioreactor. It clearly showed that the amino-acid composition (12.54 g 100 g sample −1) in the final broth of the biodegradation using 8-folds diluted FMW was almost twice that of non-biodegraded FMW. The levels of amino acids in the final broth were also comparable to those in a commercial fertilizer. When more (32-folds) diluted FMW was used as a substrate, phytotoxicity of biodegraded final broth was further reduced with disappearance of a strong unpleasant smell in the end. The final broth of biodegradation using 32-folds diluted FMW required only 2-folds dilution to meet the minimum GI criterion of a phytotoxin-free fertilizer. All the results suggest the promising potential of biodegraded FMW for the production of fertilizer, which is expected to yield high economic value.