Sulfite pretreatment on the anaerobic sludge digester for improving methane production and volatile solid reduction

Abstract

This study presents the sulfite pretreatment in order to improve sludge biodegradability and methane production during anaerobic digestion. Different SO3 concentrations (0-500 mg/L SO3) have been used to investigate the sulfite pretreatment considering sludge disintegration. First, a 24 h period has been applied to determine the pre-treatment effects. At the end the period, 500 mg/L SO3 achieved the highest performance in terms of volatile solid reduction and increase in soluble chemical oxygen demand concentration. 13.84 % of organic matter reduction, 18.9 % of increase in soluble chemical oxygen demand and 1.18 % of disintegration degree are obtained. After that, effects of sulfite pre-treatment on methane production have been investigated during anaerobic digestion. Similarly, the anaerobic digester which fed with pretreated sludge using 500 mg/L SO3 showed the highest methane production with 96.5 mL CH4/g VS. Besides, in first time for the sulfite pre-treatment of sludge, Monte Carlo simulation has been used to estimate the volatile solid reduction and methane production considering removed chemical oxygen concentration and changes of volatile solid concentrations As a result of simulation, maximum organic matter reduction is found as 33 % and while methane production was 26,83 % LEL.