Full-Scale O3/Micro-Nano Bubbles System Based Advanced Oxidation as Alternative Tertiary Treatment in WWTP Effluents

Abstract

Wastewater treatment plant effluents can be an important source of contamination in agricultural reuse practices, as pharmaceuticals are poorly degraded by conventional treatments and can enter crops, thereby becoming a toxicological risk. Therefore, advanced tertiary treatments are required. Ozone (O3) is a promising alternative due to its capacity to degrade pharmaceutical compounds, together with its disinfecting power. However, mass transfer from the gas to the liquid phase can be a limiting step. A novel alternative for increased ozone efficiency is the combination of micro-nano bubbles (MNBs). However, this is still a fairly unknown method, and there are also many uncertainties regarding their implementation in large-scale systems. In this work, a combined O3/MNBs full-scale system was installed in a WWTP to evaluate the removal efficiency of 12 pharmaceuticals, including COVID-19-related compounds. The results clearly showed that the use of MNBs had a significantly positive contribution to the effects of ozone, reducing energy costs with respect to conventional O3 processes. Workflow and ozone production were key factors for optimizing the system, with the highest efficiencies achieved at 2000 L/h and 15.9 gO3/h, resulting in high agronomic water quality effluents. A first estimation of the transformation products generated was described, jointly with the energy costs required.

Total Coliforms and Escherichia coli Inactivation as Surrogates of Ozone Pharmaceutical Removal in Secondary Effluents: The Microlog Concept

“…Ozonation is an established technique for treating municipal wastewater, demonstrating robust results in the removal of organic compounds, , disinfection, , toxicity reduction, , and other benefits. This potential has made ozonation one of the most efficient treatments in large-scale wastewater installations, with its use widespread worldwide. − …”

“…Installed alone or in combination with other advanced technologies in the tertiary treatment of wastewater treatment plants (WWTPs), ozonation can contribute to both human health and environmental protection . During ozonation of secondary effluent, numerous pathogens can be inactivated, ,, while many of the currently known contaminants of emerging concern (CECs) are degraded to safer levels. ,, The efficiency of ozonation has been demonstrated over the past decades, thereby promoting its utilization in various treatment schemes as a vital tool for achieving standard effluent quality suitable for reuse in numerous applications. ,− …”

Polarizing Perspectives: Ion- and Dipole-Induced Dipole Interactions Dictate Bulk Nanobubble Stability

“…Bulk nanobubbles (NBs) are a class of materials that consist of bubbles with dimensions on the nanometer scale that have captured the interest of scientists and engineers from a variety of disciplines. − These materials have found application in an assortment of areas, such as water treatment and disinfection, − agriculture and hydroponics, − and most recently, advanced chemical oxidation processes. − Unlike bubbles of larger diameter (>1 μm), NBs are known to be stable in water for long periods of time. − The standard model currently adopted in the literature to explain this stability involves a balance between the Laplace pressure and the pressure from electrostatic interactions at the NB-solvent interface. In general, we can express this balance using the Young–Laplace equation as follows: P 0 + P YL = P NB + P e where P 0 is the pressure of the atmosphere outside the solution, P YL is the Laplace pressure, P NB is the pressure inside the NB, and P e is the electrostatic pressure.…”

Use of Nanobubbles to Improve Mass Transfer in Bioprocesses

“…This capability is particularly advantageous for industries facing stringent environmental compliance requirements. By employing nanobubbles, facilities can reduce their reliance on chemical treatments, which are often costly and environmentally hazardous [118].…”