An energy-efficient upconcentration of the bio-based carboxylic acids using multiple-effect evaporators

Area of Science:

• Biochemical Engineering
• Waste Valorization
• Sustainable Chemistry

Background:

• Municipal solid waste (MSW) organic fraction is a source of short-chain carboxylic acids (SCCA) via anaerobic fermentation.
• Residual biogas from solid fraction digestion can provide energy for SCCA upconcentration.

Purpose of the Study:

• To propose and simulate an integrated process chain for upconcentrating SCCA from MSW.
• To evaluate the energy efficiency, yield, and carbon footprint of the proposed process.

Main Methods:

• Process simulation using Aspen Plus® for multiple-effect evaporator scenarios.
• Validation of simulation models across different pressure ranges.
• Techno-economic assessment of various evaporator configurations.

Main Results:

• Upconcentration of SCCA from 20 g/L to 526 g/L using a four-effect evaporator with minimal acid loss.
• Energy requirement of 9.8 kWh/kg SCCA, supplied by biogas from solid residue digestion.
• A 50% reduction in carbon footprint (1.24 kg CO2-eq./kg SCCA) compared to fossil-based SCCA production.

Conclusions:

• The integrated process chain is effective for high-yield SCCA upconcentration from MSW.
• The process offers significant environmental benefits, including reduced carbon emissions.
• The study provides a techno-economic basis for implementing this sustainable SCCA production method.