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Oxygen uptake rate inhibition with PACT sludge
M I Sher1, W B Arbuckle, Z Shen
1Dodson-Stilson, 6121 Huntley Road, Columbus, OH 43229-1003, USA.
Journal of Hazardous Materials
|March 10, 2000
Summary
PACT sludge, enhanced with activated carbon, shows improved resistance to inhibitory compounds compared to traditional activated sludge. This enhanced resistance is linked to sorption and biomass changes, particularly at longer sludge ages.
Area of Science:
- Environmental Engineering
- Water Treatment Technologies
- Microbial Ecology
Background:
- Activated sludge processes are crucial for wastewater treatment.
- Powdered Activated Carbon Treatment (PACT) enhances biological treatment by adsorbing inhibitory compounds.
- Sludge age influences microbial community structure and resistance to toxicants.
Purpose of the Study:
- To evaluate the resistance of PACT sludge versus activated sludge to inhibitory compounds.
- To investigate the role of sorption and biomass characteristics in sludge resistance.
- To compare performance across different sludge ages (4, 8, and 12 days).
Main Methods:
- Oxygen uptake rate (OUR) experiments were conducted.
- Three inhibitory compounds were tested: 3,5-dichlorophenol (strongly adsorbed), phenol (moderately adsorbed), and zinc (poorly adsorbed).
- Inhibitory Concentration 50% (IC50) values were determined for unacclimated sludge.
Main Results:
- PACT sludge demonstrated better resistance to organic inhibitors (phenol, 3,5-DCP) across all sludge ages.
- Sorption of phenol onto PACT sludge explained IC50 differences at higher sludge ages.
- For zinc, PACT sludge showed greater resistance at 12-day sludge age, attributed to biomass changes rather than sorption.
Conclusions:
- PACT enhances sludge resistance to inhibition, especially for organic compounds.
- Both sorption and biomass composition contribute to improved toxicant resistance in PACT systems.
- Sludge age significantly impacts the effectiveness of PACT in mitigating inhibition.