Evaluation of the ultrasound effect on treated municipal wastewater

Abstract

In this research, ultrasound (US; 26 kHz) application was evaluated as tertiary treatment of treated municipal wastewater coming from conventional activated sludge (AS) and constructed wetland (CW) systems. The degree of disinfection was evaluated through the total (TC) and faecal (FC) coliforms and by somatic coliphages (SCs) determinations. The experiments were carried out without temperature control at times of 200, 400 and 600 s and with temperature control (298.1 K) at 600, 1200 and 1800 s. Changes in the concentrations of C, N and P were also studied. The results shown that treatment without temperature control allowed 100% inactivation for TC, FC and SC at 600 s, while maximum with temperature was achieved at 1800 s. Temperature was an important factor influencing pathogens inactivation. In both cases, microorganism concentrations complied with different international guidelines for the reuse of treated wastewater. At 1800 s sonication concentrations of biochemical oxygen demand, chemical oxygen demand and total phosphorus were reduced 39.5, 39.4, 50.0 and 37.3% TN in the AS-treated water and 24.0, 49.8, 20.2 and 7.7% in the CW-treated water, respectively. In both cases, the formation of [Formula: see text] and [Formula: see text] radicals is most likely related to the observed pollutants removal. While energy consumption of ultrasound was higher than other advanced treatments such as electrocoagulation, its implementation allows the simultaneous removal of pathogens and organic pollutants without the generation of toxic by-products. In conclusion, ultrasound can be implemented as tertiary treatment of municipal wastewater for the removal of biological and organic pollution, according to reuse guidelines in terms of pathogens presence.

Methods Used in Disinfections of Wastewater and Sewage Sludge – Short Review

“…Nowadays, research is being conducted on the use of low and high frequency ultrasound in disinfection of sewage and sewage sludge on an increasing scale. They confirm the effectiveness of ultrasonic waves in destroying microorganisms [8,16,17,45,46].…”

The effect of ultrasound for algae growth control on zooplankton

“…Ultrasonic technology can be used also to treat various kinds of WWs. For example, Vázquez-López et al (2019) reported on the efficient removal of microbiological parameters, biochemical oxygen demand, chemical oxygen demand, and total phosphorous with US (200 W, 24 kH). However, for WW treatment purposes highpower US devices are used, which can induce cavitation phenomena (Gao et al, 2014), and the generation of H• and OH• radicals, which contribute to the oxidation of microbial cells and chemical compounds (Vázquez-López et al, 2019).…”

Comparison of ultrasound and UV technologies to control bulking and foaming in a wastewater treatment facility. A case study in an industrial park in Morelos, Mexico

“…Ultrasound has been successfully applied to inactivate pathogens and remove contaminants present in wastewater (Vázquez-López et al, 2019), as well as for the hydrolysis of activated sludge (Al-Hoqani et al, 2022). Ultrasound transducers transform electrical current into mechanical energy and generate mechanical vibrations and acoustic cavitation (the phenomenon of growth and collapse of bubbles due to the action of acoustic waves).…”