The high reutilization value potential of high-salinity anchovy fishmeal wastewater through microbial degradation

Abstract

To provide an option for the reutilization of high-salinity anchovy fishmeal wastewater (FMW), generated during the anchovy fishmeal manufacturing processes, its potential for biodegradation was assessed in 1-l five-neck flasks using a halotolerant and proteolytic microbial consortium. During the first 41 h of biodegradation, the pH, DO, ORP, and dry-sludge weight decreased as the total cell number of the microbial consortium increased steadily; the COD_Cr/TN ratios remained between 4.0 and 5.5, respectively, indicating the stable metabolic degradation of organic matter. The ORP tended to increase after 41 h, and the unpleasant fishy smell disappeared once positive ORP values were achieved. The removal percentages of COD_Cr and TN were 59.0 and 54.4 %, respectively, and the dry-sludge weight decreased from 115.5 to 68.0 g, with a degradation rate of 0.59 g h⁻¹, during the 80 h experiment. The supernatant from the culture of the anchovy FMW at 70 h (culture supernatant) was phytotoxin-free, and the level of total amino acids was 8.04 g 100 g⁻¹, comparable to that of commercial fertilizers. In hydroponic cultures containing red bean and barley, the culture supernatant demonstrated a good fertilizing ability. The culture supernatant also exhibited a high degree of antioxidant activity, with a 52.3 % hydroxyl radical-scavenging activity and 0.16 reducing power (at OD 700 nm). Moreover, the culture supernatant inhibited DNA damage from hydroxyl radicals, enhancing the reutilization value of anchovy FMW. This report presents the first description of high-salinity anchovy FMW possessing a high reutilization value potential both for agriculture and medicine.