Application of Aspergillus niger F5 as an alternative technique to harvest microalgae and as a phosphorous removal treatment for cassava biogas effluent wastewater

Abstract

Wastewater treatment using microalgae often produces effluents with unassimilated nutrients such as phosphorous with relatively high cost of harvesting process. The current study aims to develop a fungal pellet that solubilizes phosphate as a bio-adsorbent for enhancing microalgae harvesting process and additional removal of phosphorous to increase the harvestability of the algae and overcome the occurrence of unassimilated nutrients in the wastewater that often become problems in the algal-based wastewater treatment system. Isolated strains with phospate solubilizing activity, Aspergillus niger F5 and Aspergillus awamori F2, were found to show stable algal cells adsorption efficiency with less desoprtion as the increase of glucose concentration. Additional of A. niger F5 pellets after the total phosphorus (TP) concentration became stationary in cassava wastewater treatment using Chlorella vulgaris TISTR 8580 was found to significantly increase TP and chemical oxygen demand (COD) removals. Another approach by co-culturing the A. niger F5 and C. vulgaris TISTR 8580 also increased the removal efficiencies but less effective in trapping algal cells. However, total nitrogen removal decreased with both methods of application. With 70% adsorption efficiency, the addition of A. niger F5 pellets after reaching the stationary phase of TP removal in monoculture of C. vulgaris TISTR 8580 demonstrated a promising result for harvesting and enhancing the nutrient removal purposes algal-fungal pellet application.