Using molecular tools to assess biofilms in onsite systems.

Area of Science:

• Environmental microbiology
• Water treatment technologies
• Australian environmental regulation

Background:

• Onsite sewage treatment systems (both blackwater and greywater) are increasingly diverse and regulated in Australia due to drought impacts.
• Decentralized sewage management options are becoming more prevalent in commercial applications.
• Existing regulatory guidelines are evolving to address various onsite system scenarios.

Purpose of the Study:

• To investigate onsite sewage treatment using novel molecular tools alongside traditional methods.
• To analyze the biological communities within a new peat-based biofilter system.
• To compare treatment efficacy and microbial diversity in different operational contexts.

Main Methods:

• Utilized fluorescent in situ hybridization (FISH) and full-cycle ribosomal RNA (rRNA) analysis for microbial community assessment.
• Monitored standard water quality parameters including biochemical oxygen demand (BOD5), suspended solids (SS), and thermotolerant coliforms (TC).
• Conducted a 20-week intensive sampling program on systems at a New South Wales caravan park and a Queensland domestic residence.

Main Results:

• rRNA analysis at the New South Wales site indicated a highly diverse microbial community, consistent with its established operation.
• FISH analysis at the Queensland site revealed a less diverse and younger microbial community.
• Both rRNA and FISH identified organisms primarily associated with nutrient removal functions.

Conclusions:

• Novel molecular tools provide detailed insights into onsite sewage treatment systems.
• Microbial community structure varies with system age and operational history.
• The identified microbial communities possess nutrient-removing capabilities, crucial for effective wastewater treatment.