Selective absorption and efficient biodegradation of petroleum pollutants by oleophilic porous activated sludge loading with microorganism

Abstract

Efficient elimination of organic pollutants from wastewater is of great importance for sustainable human development. In this work, we report the fabrication of oleophilic porous activated sludge loading with microorganism (OPAS-M), which was prepared through multi-step doping of the microorganism into the as-prepared porous network of activated sludge (AS) followed by a hydrophobic surface modification, so that it has selective adsorption properties to achieve oil-water separation in oily wastewater and high effective degradation organic pollutions. Thanks to its abundantly porous structure and oleophilic wettability, the petroleum pollutants in wastewater (using n-hexadecane as model compound) can be selectively absorbed inside the OPAS-M and then could be biodegraded by the loaded microorganism. Compared with that of free microbial and porous activated sludge loading with microorganism (PSA-M) which has a degradation efficiency of 58.80% and 74.37%, respectively, the OPAS-M possesses a higher removal efficiency of 84.7%. The degradation kinetics of free microorganism, PAS-M and OPAS-M all fit well with the first-order kinetic equation, their degradation half-life is measured to be 7.44 d, 3.56 d, and 2.23 d, respectively. In addition, OPAS-M has good stability and tolerance, and the degradation efficiency can reach more than 50% in a poor environment. The degradation mechanism of n-hexadecane was studied by GC-MS. The results showed that n-hexadecane was selectively adsorbed to the interior of OPAS-M, and it was be degraded by enzymes in microorganism into n-hexadecanol、n-hexadecaldehyde and n-hexadecanoic acid in turn, and finally converted to water and carbon dioxide. The combination of selective absorption and biodegradable OPAS-M may open up a green and efficient way in the biological remediation of organic pollutants.