In-situ Cu-loaded sludge biochar catalysts for oxidative degradation of bisphenol A from high-salinity wastewater

Safe disposal of excess sewage sludge (SS) produced from chemical/biochemical water treatment processes has been a worldwide concern. In this work, sewage sludge biochar-based Cu-loaded catalysts (CSBC) were synthesized by a simple impregnation-pyrolysis method. The impregnated Cu2+ in SS was converted to Cu-0/Cu-I species after pyrolysis, which greatly improved the removal efficiency of bisphenol A (BPA). BPA (100 mg/L) could be completely removed within 130 min in CSBC/Peroxydisulfate (PDS) system, compared to 77.8% in sewage sludge biochar/PDS system. Meanwhile, CSBC performed well over a wide pH range of 3 similar to 9. In CSBC/PDS system, singlet oxygen (O-1(2)) dominated non-radical pathway had been proved to play an essential role in BPA degradation, boosting the oxidative treatment of phenolic wastewater under high-salinity. Results showed that the removal efficiency of BPA reached 93.6%, 91.0% and 84.6% in high-salinity wastewater with salinities of 16, 80, and 160 g/L, respectively. The total estimated cost of CSBC (1 kg) was $5.053 and the cost of BPA-containing wastewater (100 mg/L) treatment was estimated approximately 0.02 $/L, indicating its cost-effectively potential in practical applications. This study not only provides a new value-added reuse method for sewage sludge treatment and disposal, but also a new strategy for the effective treatment of high-salinity organic wastewater.