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Improving secondary sludge biodegradability using free nitrous acid treatment
Maite Pijuan1, Qilin Wang, Liu Ye
1The University of Queensland, Advanced Water Management Centre, QLD 4072, Australia.
Bioresource Technology
|May 22, 2012
Summary
Free nitrous acid (FNA) treatment significantly enhances sludge biodegradability. FNA effectively reduces biomass viability and activity, leading to substantially increased consumption of treated sludge during aerobic digestion.
Area of Science:
- Environmental Science
- Microbiology
- Wastewater Treatment Engineering
Background:
- Secondary sludge accumulation poses a significant challenge in wastewater treatment.
- Improving sludge biodegradability is crucial for efficient sludge management and disposal.
- Current methods for sludge treatment often have limitations in effectiveness and cost.
Purpose of the Study:
- To investigate the efficacy of free nitrous acid (FNA) as a novel treatment to enhance the biodegradability of secondary sludge.
- To assess the biocidal effects of FNA on activated sludge biomass.
- To compare the biodegradability of FNA-treated sludge with untreated sludge under aerobic digestion conditions.
Main Methods:
- Secondary sludge was subjected to free nitrous acid (FNA) treatment for varying durations (8-48 hours).
- The biocidal effect of FNA was evaluated by measuring the viable fraction and biological activity of the sludge biomass.
- FNA-treated and untreated sludge were aerobically digested using a full-scale activated sludge system for 6 and 14 days.
Main Results:
- FNA treatment significantly reduced the viable fraction and biological activity of activated sludge biomass.
- Ninety percent of FNA-treated sludge was consumed during 14-day aerobic digestion, compared to 41% for untreated sludge.
- Fifty percent of FNA-treated sludge was degraded within a shorter 6-day aerobic digestion period.
Conclusions:
- Free nitrous acid (FNA) treatment is a highly effective strategy for improving the biodegradability of secondary sludge.
- FNA exhibits a potent biocidal effect, reducing sludge biomass activity and enhancing subsequent aerobic digestion.
- This novel FNA-based approach offers a promising solution for more efficient and effective sludge management in wastewater treatment plants.
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