Comparison of disinfection by-products formed by preoxidation of sulfamethazine by K2FeO4 and O3 and the influence on cytotoxicity and biological toxicity

Siwen Li; Yingzi Lin; Gaoqi Wang; Suiyi Zhu; Gen Liu; Chunyan Shi; Lei Chen

doi:10.3389/fchem.2022.904867

Comparison of disinfection by-products formed by preoxidation of sulfamethazine by K₂FeO₄ and O₃ and the influence on cytotoxicity and biological toxicity

Front Chem. 2022 Aug 19:10:904867. doi: 10.3389/fchem.2022.904867. eCollection 2022.

Authors

Siwen Li^{1

2}, Yingzi Lin^{3

4}, Gaoqi Wang³, Suiyi Zhu^{1

2}, Gen Liu^{1

2}, Chunyan Shi^{3

5}, Lei Chen³

Affiliations

¹ School of Environment, Northeast Normal University, Changchun, China.
² Science and Technology Innovation Center for Municipal Wastewater Treatment and Water Quality Protection, Northeast Normal University, Changchun, China.
³ School of Municipal & Environmental Engineering, Jilin Jianzhu University, Changchun, China.
⁴ Key Laboratory of Songliao Aquatic Environment, Ministry of Education, Jilin Jianzhu University, Changchun, China.
⁵ The University of Kitakyushu, Kitakyushu, Japan.

Abstract

This study researched the formation of disinfection by-products (DBPs) in sulfamethazine (SMZ) chlorination after preoxidation by K₂FeO₄ and O₃ and the influence of preoxidation on cytotoxicity and biological toxicity. Then, the study emphatically analyzed the influencing factors such as NaClO dosage, pH value, reaction temperature, fulvic acid (FA), and bromide and iodide ions. The results showed that preoxidation by K₂FeO₄ effectively inhibited the formation of DBPs of haloketones (HKS) and trihalomethanes (THMs), with an average inhibition rate of over 60%. The formation of DBPs after preoxidation by O₃ was higher than that by K₂FeO₄; preoxidation by K₂FeO₄ reduced the influence of NaClO dosage, temperature, and pH value on the production of DBPs after SMZ chlorination. The cytotoxicity and biological toxicity of SMZ chlorination after preoxidation were evaluated and compared by calculating the LC₅₀ value of DBPs and the luminescent bacteria method. The results of both calculation methods showed that the toxicity of DBPs after preoxidation by K₂FeO₄ was lower than that by O₃ preoxidation. K₂FeO₄ and O₃ preoxidation improved the SMZ removal efficiency by 8.41 and 10.49%, respectively, and inhibited the formation of most DBPs, but the preoxidation promoted the formation of highly toxic DBPs (HANs). The toxicity of DBPs formed in SMZ chlorination after preoxidation by K₂FeO₄ and O₃ was slightly higher than that of chlorination disinfection alone, but it was still within the safe range. This study provides more new details about the formation and toxicity changes of DBPs in the process of SMZ chlorination after preoxidation.

Keywords: DBP; chlorine disinfection; preoxidation by ozone; preoxidation by potassium ferrate; toxicity.