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

Abstract

This study presents the sulfite pre-treatment 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 pre-treatment 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.