Ozone enhances biological treatment of hydrothermal liquefaction aqueous stream from municipal sludge.

Hydrothermal liquefaction (HTL) is a promising alternative to anaerobic digestion for municipal sludge valorization due to biocrude oil and nutrient-dense hydrochar production, smaller footprint, enhanced micropollutant degradation, and minimized residual biosolids. However, integrating HTL into wastewater treatment plants necessitates on-site treatment of HTL aqueous, which is 80 % of byproducts by volume. HTL aqueous exhibits inhibition on downstream biological treatment due to high chemical oxygen demand (COD), total phenolics, ketones and nitrogen heterocyclics.