The cost of a small membrane bioreactor

Area of Science:

• Environmental Engineering
• Water Treatment Technologies
• Bioreactor Systems

Background:

• Membrane bioreactors (MBRs) are crucial for wastewater treatment.
• Accurate cost estimation for small-scale MBRs is essential for widespread adoption.
• Previous cost studies often focused on very small or large municipal plants, leaving a gap for intermediate scales.

Purpose of the Study:

• To itemize and collate cost contributions of mechanical components for small MBRs (100-2,500 m3/d).
• To generate overall capital expenditure (CAPEX) and operating expenditure (OPEX) as a function of plant size.
• To compare these costs with existing data from smaller and larger MBR plants.

Main Methods:

• Detailed cost contributions of mechanical components were itemized.
• Heuristic data was used to develop cost curves for CAPEX, OPEX, and net present value (NPV) based on flow capacity.
• Calculated cost trends were compared with previously published studies.

Main Results:

• OPEX showed a logarithmic function of flow capacity, while CAPEX followed a power-based function.
• OPEX correlations demonstrated good agreement with literature data.
• CAPEX trends showed disparities attributed to differing cost assumption, but membrane separation component costs aligned well with published data.

Conclusions:

• The heuristic approach is appropriate for estimating costs of small-scale MBRs, particularly those with minimal installation expenses.
• The study provides valuable cost-size relationships for small MBRs, aiding in economic assessments.
• An overall NPV relationship was determined, offering a predictive model for small MBR economic viability.