Bench-scale study on zero excess activated sludge production process coupled with ozonation unit in membrane...

Area of Science:

• Environmental Engineering
• Wastewater Treatment
• Sludge Management

Background:

• Excess activated sludge (EAS) production is a major challenge in domestic wastewater treatment.
• Membrane bioreactor (MBR) and sludge ozonation (SO) are promising technologies for sludge reduction.
• Coupling MBR and SO offers a potential integrated solution for sludge minimization.

Purpose of the Study:

• To investigate the efficacy of a coupled MBR-SO process for domestic wastewater treatment and EAS reduction.
• To identify and analyze key operational parameters influencing the MBR-SO process performance.
• To develop mathematical models for understanding the relationships between operational factors and process outcomes.

Main Methods:

• A bench-scale MBR-SO process was operated for 80 days to treat domestic wastewater.
• Excess activated sludge was subjected to ozonation for cell lysing.
• Mathematical modeling was employed to analyze operational parameters like flow-rate ratios (q/Q) and sludge lysing ratios (xi).

Main Results:

• The ratio of flow-rate draining to ozonation unit (q) to influent wastewater flow-rate (Q) was identified as the primary operational parameter.
• Stable mixed liquid suspended solid (MLSS) concentration around 8,000 mg/L was maintained with a zero observed sludge yield coefficient (Y(obs)).
• The process achieved excellent effluent quality, except for limited TP removal (3.62%), with low energy consumption (USD 0.0053/m³).

Conclusions:

• The coupled MBR-SO process effectively minimizes EAS production while maintaining excellent effluent quality.
• Optimized operational parameters, particularly q/Q and xi, are crucial for process efficiency and sludge reduction.
• Mathematical models accurately predicted sludge reduction trends, validating the operational parameter settings.