Effects and associated mechanisms of surfactants on wastewater treatment in the context of Covid-19

Abstract

Hand washing enhanced by the Covid-19 has caused more surfactants to flow into wastewater treatment plants (WWTPs), which might affect both wastewater treatment and sludge disposal. Surfactants in municipal wastewater are usually at 5~20 mg·L−1, but it could climb to 10~30 mg·L−1 during the pandemic. Only about 1% of the influent surfactants generally remains in the effluent, and approximately 10%~20% is adsorbed into excess sludge. Although the content of surfactants in wastewater is not so high, their special amphiphilic molecular structures could reduce oxygen transfer efficiency, destroy sludge flocs, and affect the activity and abundance of microorganisms associated with nitrogen and phosphorus removal. As for sludge treatment, however, surfactants seem positive on dehydration, cell disintegration, solubilizing sludge flocs, and even anaerobic digestion like hydrolysis and acidification. Thus, it is a high priority to address the source, structure and migration &transformation of surfactants first, then to elucidate their influences and associated countermeasures on wastewater treatment, and finally to demonstrate their positive impacts on sludge treatment/disposal. The review is proposed to pay attention to the long-term effect of surfactants at a high content due to the pandemic, so as to study future operational measures that could alleviate the negative effects on wastewater treatment and simultaneously utilizes the positive effects on sludge treatment. © 2021, Science Press. All right reserved.