Mycofiltration for Metal Removal in Underperforming Wastewater Treatment Plants: Regulatory Implications for South Africa

To improve wastewater treatment, technologies such as mycofiltration, i.e., the treatment of contaminated water by passing it through a network of fungal mycelia, can be employed. This study sought to evaluate the performance of a local wastewater treatment plant (WWTP) in the removal of selected metals, perform mycofiltration on the wastewater, and assess metal removal in the filtrate. Wastewater influent and effluent samples were collected and analysed for Sodium (Na), Potassium (K), Calcium (Ca), Magnesium (Mg), Aluminium (Al), Arsenic (As), Cadmium (Cd), Chromium (Cr), Cobalt (Co), Copper (Cu), Iron (Fe), Lead (Pb), Manganese (Mn), Mercury (Hg), Molybdenum (Mo), Nickel (Ni), Phosphorus (P), Selenium (Se), Titanium (Ti) and Zinc (Zn). A Pleurotus ostreatus mycofilter was cultured and packed into Pyrex columns (3.3 x 15 cm). Wastewater samples were mycofiltered at a constant flow rate, and metal removal efficiency was assessed. The wastewater quality index (WWQI) was also calculated. The WWTP performed poorly, as only Na, Fe, and P had lower levels in the effluent compared to the influent. There were no changes between influent and effluent metal concentrations for most metals. After mycofiltration of the wastewater influent, P, Hg, Na, Fe, K and Cu were removed with an efficiency of 99%, 50%, 48%, 31%, 30%, and 23%, respectively. Mycofiltration of the wastewater effluent removed P, K, Pb, Hg and Fe with an efficiency of 99%, 52%, 51%, 51% and 10%, respectively. Mycofiltration could not remove metals such as Ca, Cr and Cd. The WWQI for the WWTP effluent, the mycofiltered influent and the mycofiltered effluent were 604.6, 582.2, and 548.0, respectively. Mycofiltration thus slightly improved wastewater quality as denoted by the lower indices. The findings demonstrate the potential use of mycofiltration as a science-informed bioaugmentation strategy for WWTPs to enhance regulatory compliance.