Membrane Engineering for Biogas Valorization

Abstract

Membrane operations nowadays drive the innovative design of important separation, conversion, and upgrading processes, and contribute to realizing the main principles of “green process engineering” in various sectors. In this perspective, we propose the re-design of traditional plants for biogas upgrading and integrating and/or replacing conventional operations with innovative membrane units. Bio-digester gas streams contain valuable products such as biomethane, volatile organic compounds, and volatile fatty acids, whose recovery has important advantages for environment protection, energy saving, and waste valorization. Advanced membrane units can valorize biogas by separating its various components, and establishing environmentally friendly and small-scale energivorous novel separation processes enables researchers to pursue the requirements of circular economy.

Combined Pre-Treatment Technologies for Cleaning Biogas before Its Upgrading to Biomethane: An Italian Full-Scale Anaerobic Digester Case Study

“…The membrane-based technology was chosen for the biogas upgrading (CO 2 removal) system. Indeed, the advantages of using membranes for upgrading biogas to biomethane compared with other technologies are known [34] and make this technique the most used in Europe. The used membranes are selective for CO 2 permeation, leaving CH 4 in the retentate flow (>98% content) but unable to separate biogas contaminants that remain in the bio-CH 4 stream.…”

Fabrication and testing of mixed matrix membranes of UiO‐66‐NH2 in cellulose acetate for CO2 separation from model biogas

“…12 Though CA is extensively used in membrane separation, due to its low toxicity and biodegradability, researchers are revisiting and focusing on the CA membranes in various applications. 13 The major disadvantage is the low permeability for CO 2 (around four Barrer), although high selectivity of CO 2 over CH 4 (around [15][16][17][18][19][20][21][22][23][24][25], and plasticization of CA in presence of CO 2 . 14 The improvement in plasticization resistance and better separation performance was observed with different modification techniques such as blending with polymers, surface coating, and MMMs.…”

“…23 Second, operating the membrane separation at lower pressures improves the economic viability by reducing the compression cost. 24 Finally, tested MMMs were characterized by Fourier transform infrared spectroscopy (FTIR), Thermo-gravimetric analysis (TGA), Differential scanning calorimetry (DSC), and Scanning electron microscope (SEM). Then, the experimental data were compared with predicted data using the Maxwell model, Lewis-Nielsen model, Higuchi model, and Bruggeman model.…”

“…The first reason is the plasticization of CA, leading to a drop in selectivity for CO 2 with increased pressure 23 . Second, operating the membrane separation at lower pressures improves the economic viability by reducing the compression cost 24 . Finally, tested MMMs were characterized by Fourier transform infrared spectroscopy (FTIR), Thermo‐gravimetric analysis (TGA), Differential scanning calorimetry (DSC), and Scanning electron microscope (SEM).…”

Possibilities of Biogas Upgrading on a Bio-Waste Sorbent Derived from Anaerobic Sewage Sludge

“…It is also estimated that bio-CNG used as a fuel for vehicles will increase worldwide from 2% today to 27% in 2050 [2,12]. Currently, in the EU, biomethane is consumed as a natural gas substitute in the amount of 20 TWh/year, Energies 2022, 15, 6461 2 of 14 resulting in a 0.4% share in the gas network and will further increase to 5-8% by 2030 to meet the European goals [13,14].…”