Simultaneous recovery of phosphate and degradation of antibiotics by waste sludge-derived biochar.

Recovery of phosphorus (P) from wastewater has led to growing public concern considering its scarcity and future availability as well as its detrimental environmental impacts. However, the recovered P is inevitably contaminated with co-existing antibiotics like tetracycline (TC) and sulfamethazine (SMT) which will pose serious risks to the health of human and animals after being spread to the environment. In this study, we propose a novel scheme that can recover P from synthetic wastewater and at the same time degrade the co-existing antibiotics. To achieve such a goal, a series of biochar (BC) were prepared from calcination of waste sludge and were used both as the adsorbent for P recovery and as the catalyst for peroxymonosulfate (PMS) activation and antibiotic degradation. Results showed that the sludge source (i.e. S m : municipal sludge, S p : paper mill sludge), calcination atmosphere (i.e. air-deficient, N 2 , vacuum) and temperature (i.e. 600 and 800 °C) exhibited significant influence on P adsorption capacity. Generally, the BC calcined in N 2 showed better P uptake, and increase of calcination temperature from 600 °C to 800 °C could further improve P uptake. Though BC p-N-600 (prepared from S p in N 2 at 600 °C) showed faster and higher P uptake (56.3 mg/g) than its counterpart BC m-N-600 (33.2 mg/g), BC m-N-600 showed stronger catalytic activity and more stable performance in the complex pollutant system (P + SMT). It was proposed that P was recovered primarily through the chemisorption and precipitation mechanism, while SMT was nearly completely degraded primarily by the ROS generated from PMS activation. [Display omitted] • Sludge-derived biochar (BC) can be used as both P adsorbent and PMS activator. • BC showed perfect uptake for P, with CaO and MgO as main adsorption sites. • BC could activate PMS efficiently for antibiotic degradation. • BC from municipal sludge was more stable in complex pollutant removal. • The recovered P showed no contamination of antibiotics and oxidation byproducts. [ABSTRACT FROM AUTHOR]