We can't find the internet
Attempting to reconnect
Something went wrong!
Hang in there while we get back on track
Fate of microplastics in sludge concentration: Experimental evaluation of gravity thickening and flotation processes.
Summary
This study was the first to systematically evaluate how microplastics behave during sludge concentration processes in wastewater treatment, finding that polymer density and operational conditions strongly influence their distribution between liquid and solid phases. Up to 64% of low-density HDPE was released into the clarified stream during gravity thickening, while high-density PTFE remained entirely in the clarified water during dissolved air flotation.
Microplastics (MPs) are commonly retained in the sludge line of wastewater treatment plants (WWTPs), yet their behaviour during sludge concentration processes remains poorly understood. This study is the first to systematically evaluate MPs distribution in sludge concentration processes, revealing the critical role of polymer density and retention time. MPs behaviour was evaluated in gravity thickening and dissolved air flotation (DAF) using real sludge samples doped with three polymers of contrasting densities: HDPE, PET, and PTFE. MPs were quantified in both liquid and solid phases through oxidative digestion and Raman spectroscopy. Results showed that up to 64 % of HDPE was released into the clarified stream during gravity thickening, while PET and PTFE remained mostly in the sludge. In DAF, 63 % of HDPE was recovered in the floated sludge, whereas 100 % of PTFE was found in the clarified water. These findings highlight the influence of polymer properties and operational conditions on MPs separation and suggest that sludge concentration units can play a key role in enhancing MPs removal prior to final sludge management.