Characterisation of key components of biofertiliser produced from mackerel wastewater and commercialisation feasibility analysis of the biofertiliser production process for wastewater valorisation

Abstract

Microbial production of biofertiliser attracts much attention due to complete reuse of fish wastewater and enhanced yields in agriculture. Herein, key components of biofertiliser (cells and hydrolysates) were characterised to determine the quality of biofertiliser from mackerel wastewater (MWW). Through fed-batch biodegradation, a high number (5.33 × 109 CFU/mL) of viable cells and rich low-molecular-weight hydrolysates were obtained with a high degree of hydrolysis (48.1%). Cells exhibited plant growth-promoting activities, while hydrolysates (<2 kDa) exhibited high antioxidant activities of 84.17% for 2,2-diphenyl-1-picrylhydrazyl (DPPH) and 98.45 for 2,2′-azino-bis(ethybenzthiazoline-6-sulfonic acid) (ABTS). During hydroponics cells colonised wheat roots, enhancing wheat growth, health and antioxidant activities. Synergistic effects of key components on plant growth, health and functionality were observed in lettuce after 30 days of hydroponic growth, significantly higher than those of controls and comparable with those of a commercial fertiliser. Economic analysis of the commercial feasibility of biofertilser production revealed the effects of scale-up, and the predicted profitability of biofertiliser production from raw MWW in 150 L was $14,796.13/year. Therefore, MWW reuse could be beneficial for decreasing the environmental impacts and improving the efficiency of sustainable agriculture.