Biopolymers recovery from biological sludge and its use as phosphorus biosorbent

ABSTRACT Biopolymers can be recovered from aerobic sludge and used for environmental applications, such as phosphorus adsorbent material, instead being sent to sanitary landfills. In this resource recovery perspective, this work aimed to study the recovery of alginate-like exopolymer (ALE) from activated sludge (AS) compared to aerobic granular sludge (AGS). ALE-based biosorbent was prepared and tested to remove phosphorus from aqueous solutions, and the adsorption kinetics and isotherm models were studied. The recovery yield of ALE from a full-scale wastewater treatment plant (WWTP) AS (18.7%) was close to that obtained from a pilot-scale AGS (22%). ALE recovered from AS presented hydrogel properties and humic substances in its composition, which are important features for future applications. The equilibrium of the adsorption was reached after 10 minutes. The Langmuir isotherm model and the PFO kinetic model best fitted to the experimental data, resulting in maximum adsorption capacity of 8.164 mgP·gALE. Thus, ALE recovered from AS has the potential to be used as a phosphorus biosorbent from effluents and further used as a nutrient delivery system with hydrogel properties.