Ecotoxicity Evaluation of Pure Peracetic Acid (PAA) after Eliminating Hydrogen Peroxide from Commercial PAA

Underlying the mechanisms of pathogen inactivation and regrowth in wastewater using peracetic acid-based disinfection processes: A critical review

Peracetic acid (PAA) disinfection is an emerging wastewater disinfection process. Its advantages include excellent pathogen inactivation performance and little generation of toxic and harmful disinfection byproducts. The objective of this review is to comprehensively analyze the experimental data and scientific information related to PAA-based disinfection processes. Kinetic models and modeling frameworks are discussed to provide effective tools to assess pathogen inactivation efficacy. Then, the efficacy of PAA-based disinfection processes for pathogen inactivation is summarized, and the inactivation mechanisms involved in disinfection and the interactions of PAA with conventional disinfection processes are elaborated. Subsequently, the risk of pathogen regrowth after PAA-based disinfection process is clearly discussed. Finally, to address ecological risks related to PAA-based disinfection, its impact on the spread of antibiotic-resistant bacteria and the transfer of antibiotic resistance genes (ARGs) is also assessed. Among advanced PAA-based disinfection processes, ultraviolet/PAA is promising not only because it has practical application value but also because pathogen regrowth can be inhibited and ARGs transfer risk can be significantly reduced via this process. This review presents valuable and comprehensive information to provide an in-depth understanding of PAA as an alternative wastewater disinfection technology.

Occurrence, effects, and ecological risks of chemicals in sanitizers and disinfectants: A review

In response to the novel coronavirus referred to as severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) – a virus that causes COVID-19 disease has led to wide use of sanitizers and disinfectants. This, in turn, triggered concerns on their potential deleterious effects to human health and the environment due to numerous chemicals incorporated in both product categories. Here, the current state of science regarding the occurrence and ecological effects of different classes of chemicals in these products (e.g., ultraviolent filters, fragrances, etc.) are summarized in different natural (e.g., rivers) and engineered (e.g., wastewater treatment plants) systems. Data collected in the literature suggests chemicals incorporated in sanitizers and disinfectants are present in the environment, and a large portion are toxic to fish, algae, and daphnia. Using the risk quotient approach based on occurrence data, we found eight chemicals that posed the highest risk to aquatic organisms in freshwater systems were benzalkonium chloride, 4-chloro-m-cresol, sodium ortho phenyl phenate, hydrogen peroxide, 1, 2-propanediol, 4-Methyl-benzilidine-camphor, ethylhexyl methoxy cinnamate, and octocrylene. Considering limited occurrence and effects information for most chemicals, further studies on environmental monitoring and potential consequences of long-term exposure in aquatic ecosystems are recommended.

Toxicity of the antiparasitic lipopeptide biosurfactant SPH6 to green algae, cyanobacteria, crustaceans and zebrafish

A lipopeptide with biosurfactant properties produced by the bacterium Pseudomonas H6 (SPH6) has antiparasitic effects and may serve as an alternative to chemotherapeutants against aquatic pathogens in aquaculture. We have elucidated its ecotoxicological potential by short-term standardized tests, including a growth rate inhibition test with algae (Raphidocelis subcapitata), a lethality test on the cyanobacteria Phormidium autumnale, a lethality test using crustaceans (Daphnia magna), a fish embryo acute toxicity test and a fish acute toxicity test using zebrafish (Danio rerio). The decrease of the biosurfactant concentration in zebrafish test water during 24 h was measured. The toxicity for crustaceans was highest (LC₅₀ = 20 mg/L), followed by the test with the zebrafish embryo (LC₅₀ = 27 mg/L). The juvenile zebrafish fish (complete mortality occurred between 40 and 80 mg/L), the cyanobacteria (LC₅₀ = 80 mg/L) and the green algae (EC₅₀ = 170 mg/L) showed higher tolerance. The determination of SPH6 concentrations in fish tank (up to 50% elimination over 24 h) suggested that the compound may become adsorbed to tank walls, absorbed by fish or degraded. Further studies should determine its impact under different environmental settings (e.g. temperature) relevant for different branches of the aquaculture sector.