A modified oxic-settling-anaerobic activated sludge process using gravity thickening for excess sludge reduction

Area of Science:

• Environmental Engineering
• Wastewater Treatment
• Biotechnology

Background:

• Conventional activated sludge (CAS) processes generate significant excess sludge.
• The Oxic-Settling-Anaerobic (OSA) process offers a cost-effective upgrade to reduce sludge production.
• Current OSA methods rely on oxidation-reduction potential (ORP) control, adding cost and complexity.

Purpose of the Study:

• To develop a simplified OSA process for excess sludge reduction.
• To investigate the efficacy of a gravity thickening sludge holding tank in the OSA process.
• To eliminate the need for ORP control in OSA sludge reduction.

Main Methods:

• Implementation of a gravity thickening sludge holding tank within the OSA process.
• Evaluation of sludge production and settleability.
• Assessment of treatment capacity under modified conditions.

Main Results:

• The modified OSA process significantly reduced excess sludge production.
• Sludge settleability was improved without compromising treatment capacity.
• The gravity thickening sludge holding tank was identified as the key component for sludge reduction.

Conclusions:

• Gravity thickening in the OSA process is an effective strategy for sludge reduction.
• This modification simplifies OSA operation by removing the need for ORP control.
• The enhanced OSA process offers a cost-effective and efficient solution for wastewater sludge management.