CO2 bubbling pretreatment to remove the inhibition of lime disinfection wastewater in a swine manure anaerobic digestion system

Abstract

Under the African swine fever epidemic, the extensive use of lime disinfectants has seriously inhibited anaerobic digestion (AD). In this study, the subject was swine manure containing lime disinfectant wastewater. The research set up a carbon dioxide (CO2) bubbling pretreatment device before it entered AD to explore the effect of breaking the inhibition of lime disinfectant. The results showed that the initial pulmonary hypertension (pH) of 11.0 and CO2 bubbling time of 8 h had the best effect, which could reduce calcium ion (Ca2+) by 73.0%, and the biogas production of the batch AD test increased by 28 times. In the continuous AD test, the Ca2+ of CK increased to 7.67 g/L, while the S1 pretreated by CO2 bubbling stabilized at 2.6 g/L, the biogas production in S1 was 112.4% higher than in CK. CO2 bubbling pretreatment reduces the concentration of Ca2+ in swine by utilizing the combination of exogenous CO2 and Ca2+, breaking the inhibitory effect on AD, and thereby improving the performance of the AD system. The test used CO2 in biogas to break the inhibition of lime disinfectants on AD, which was a convenient and feasible pretreatment process.