Double membrane gasholder for biogas storage: Odor pollution risk and permeation characteristics

Abstract

Biogas is an important and sustainable biofuel. Encouraged by renewable energy policies, the biogas industry has developed rapidly worldwide. Double membrane gasholders are widely used as biogas storage facilities. This work aimed to reveal the odorant permeation characteristics of double membrane gasholders, evaluate the related odor pollution risk, and identify the priority odorants for permeation prevention. Gas samples below the inner membrane, between the inner and outer membranes, and in the ambient environment were collected and analyzed. Odor potential and contribution were evaluated using the odor activity value (OAV). The relationship between the samples was explored by the Pearson correlation analysis. The permeation characteristics of the major odor contributors were analyzed by comparing odorant concentrations in samples from both sides of the membrane. Terpenes were found to be the dominant compounds (>75%) inside the double membrane gasholder. The total OAVs of the gas below the inner membrane, between the inner and outer membranes and in the ambient environment were 47,500, 484, and less than 100, respectively. Terpenes and sulfur compounds were the dominant odor contributors (>95% in total) for the gas inside the double membrane gasholder. The composition of the gas between the membranes was significantly correlated to that of the gas below the inner membrane (r2 = 0.98, p ≤ 0.001), but had a poor correlation with that of the gas in the ambient environment (r2 < 0.01). Odorant permeation occurred through both the inner and outer membranes. Hydrogen sulfide and limonene were selected as the main indicators for determining the permeability of the double membrane gasholder. Suggestions were made for the permeability test methods and material selection for double membrane gasholders.