Recovery and Survival of Prototheca Microalgae During Wastewater Treatment Process

Area of Science:

• Environmental microbiology
• Microalgal ecology
• Pathogen detection

Background:

• Prototheca are non-pigmented microalgae, typically saprophytic but known opportunistic pathogens in animals and humans.
• Previous studies indicated Prototheca's presence in sewage, but relied on limited historical data.
• Updated Prototheca taxonomy necessitates re-evaluation of their environmental reservoirs.

Purpose of the Study:

• To investigate the prevalence and distribution of Prototheca in municipal wastewater using refined methods.
• To assess the efficacy of wastewater treatment processes in removing Prototheca.
• To understand the implications of Prototheca in treated effluent for environmental release.

Main Methods:

• Collected 96 wastewater samples from three treatment plants over three months.
• Analyzed samples from four distinct stages of the wastewater treatment process.
• Utilized a new, refined experimental methodology for algal recovery and identification.

Main Results:

• Prototheca were detected in 78.1% of samples (74 out of 96).
• Highest populations were in raw sewage, with counts reduced 100-fold by treatment (up to 99.9% removal).
• Pathogenic species, notably Prototheca wickerhamii, dominated both influent and effluent.

Conclusions:

• Wastewater treatment plants are significant habitats for Prototheca.
• Treated wastewater effluent may serve as a pathway for environmental release of Prototheca.
• Regular monitoring and guideline limits for Prototheca in wastewater are recommended.