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Simple improvement of digested sludge quality: is postaeration the key?
M Vojtiskova1, B Satkova1, J Bindzar1
1Department of Water Technology and Environmental Engineering, Faculty of Environmental Technology, University of Chemistry and Technology Prague, Technicka 5, 166 28 Prague 6, Czech Republic
Summary
Postaeration improves sludge quality by removing total ammonia nitrogen (TAN) and enhancing dewaterability. This simple process offers significant benefits for sludge management and disposal.
Area of Science:
- Environmental Engineering
- Wastewater Treatment
Background:
- Postaeration, introducing digested sludge to aerobic conditions, is understudied despite its potential benefits.
- Limited data exists on postaeration's impact on sludge quality and sludge liquor.
Purpose of the Study:
- To investigate the effects of postaeration on total ammonia nitrogen (TAN) removal, sludge dewaterability, and micropollutant concentrations.
- To evaluate the influence of hydraulic retention time (HRT) and aeration intensity on postaeration performance.
Main Methods:
- Batch experiments were conducted to assess initial impacts on TAN and dewaterability.
- A semi-continuous batch reactor was used to study postaeration under varying HRTs (8, 6, 4, 2 days) and aeration intensities.
- Analysis included TAN, sludge cake total solids (TS), and micropollutant concentrations (pharmaceuticals, EOX, AOX).
Main Results:
- Postaeration achieved 40-60% TAN removal, with stripping and biological oxidation being key mechanisms.
- Sludge dewaterability improved by 5-30% (relative increase in sludge cake TS concentration).
- TS degradation was observed, suggesting further reduction in final sludge volume. Optimal results were noted at the longest HRT (8 days).
Conclusions:
- Postaeration is an effective technology for enhancing sludge quality and reducing disposal volumes.
- TAN removal and sludge dewaterability are significantly influenced by HRT and aeration.
- Further research into micropollutant removal and process optimization is warranted.
