Removal of color and estrogenic substances by fungal reactor equipped with ultrafiltration unit

Abstract

Removal/degradation of color components and endocrine disruptors (EDs) by a bioreactor employing a white rot fungus Trametes hirsuta IFO4917 equipped with ultramembrane filtration (UF) unit was proposed and experimentally investigated. Among 20 white-rot fungal strains, T. hirsuta IFO4917 was screened as a most effective white-rot fungus for removal/degradation of color and EDs. This strain could effectively decolorize humic acid and degrade a wide range of Eds: bisphenol A (BPA), nonylphenol (NP), 17 beta-estradiol, estrone and estriol, although di-(2-ethylhexyl) phthalate (DEHP) could not be degraded. A bench scale (10 L), sequencing batch reactor using this fungus was developed and applied to decolorization of a melanoidin containing synthetic wastewater (4,200 color unit). The fungus was immobilized onto polyurethane foam cubes to stably maintain the biomass, and UF was applied to achieve a complete solid/liquid separation. The wastewater was decolorized in a main bioreactor and the resultant biologically treated wastewater was subjected to UF to obtain permeate as the effluent. The concentrate containing the remaining colored components with higher molecular weights was returned to the fungal bioreactor for further decolorization. In this fungal/UF system, 70% of the decolorization was constantly achieved at HRT of 2 days. The fungal/UF system was scaled up to a pilot-scale plant (200 L), and applied to the treatment of the secondary effluent from a night soil treatment process containing color components (1,000 color unit) and some EDs, NP, 4-t-octylphenol (OP), DEHP and benzophenone. 65-70% of decolorization efficiency was achieved at a 1.5 day cycle sequencing batch operation. NP, OP and benzophenone were removed efficiently with removal of 94%, 89% and 81%, respectively. However, the removal of DEHP was not so effective (45%).