Wastewater Nutrient Recovery via Fungal and Nitrifying Bacteria Treatment

Abstract

In efforts to reduce the consumption of fossil fuels and promote recycling biowaste, there is an interest in the production of post-hydrothermal liquefaction wastewater (HTL-AP) from the hydrothermal liquefaction (HTL) process that converts wet biomass into biocrude oil. This study explores ways of transforming potentially toxic HTL-AP into a fertilizer source for hydroponic cropping systems. This study specifically investigates the integration of the white-rot fungus Trametes versicolor with nitrifying bacteria (Nitrosomonas and Nitrobacter) to convert the organic nitrogen compounds into inorganic nitrogen while also producing the enzyme laccase, which has been shown to remove toxic compounds. This study aims to increase the concentration of nitrate-N to valorize wastewater as a suitable fertilizer by measuring several parameters, including laccase activity, pH, nitrate-N, and ammonia/ammonium-N concentrations, and analyzes interactions to optimize the conversion process. The data support the claim that the simultaneous inoculation of T. versicolor and nitrifying bacteria significantly increases nitrate-N concentrations in HTL-AP, as it increased by 17 times, or an increase of 32.69 mg/L. In addition, HTL-AP treated with T. versicolor and nitrifying bacteria reduced the treatment time by 120 h, highlighting a reduction in personnel time and energy consumption. Therefore, this research accentuates sustainability through fungal and bacterial treatments to develop eco-friendly hydroponic fertilizers. Future research should explore the potential of utilizing the combination of T. versicolor and nitrifying bacteria for the treatment of other industrial wastewaters.