Combined Ozone and Biological Treatment of Oak Wood Leachate

Abstract

In the present study, we investigated the possibility of treating oak wood leachate with a combined ozone and biological treatment. Wood leachate is characterized by high amounts of organic carbon and is reported as being toxic to aquatic organisms. Ozone was used as a pre‐treatment before using aerobic degradation. The biological treatment was applied for seven days and evaluated using head‐space respirometry. Target pollutant in this investigation was polyphenols in combination with more general parameters, such as chemical oxygen demand (COD), total organic carbon (TOC) and colour. A custom made bubble column reactor was used, 1.5 L of wood leachate was exposed to 0–4 g/L of ozone, corresponding to a specific ozone dose between 0.7–7 g/L O3/g of initial COD. Oak wood leachate was found to be easily degraded by ozone, with >90% of polyphenols degraded. COD was degraded by 73%, TOC by 61% and colour by 97% by ozone. Furthermore, a positive correlation between biodegradation and ozone pre‐treatment was found.

Removal of dissolved organic matter from the woodchip bioreactor start-up by foam fractionation

“…Field et al (1988) found that 30-50% of the soluble COD from bark water could be acidified into volatile fatty acids (VFAs) and between 7 and 36% could be converted by methanogenesis to methane after 8-9 days of anaerobic digestion. In the case that near complete removal of the remaining DOM was required, post-treatment by combined ozone and biological treatment may be effective at treating woodchip leachate (Zenaitis et al 2002;Svennson et al 2015).…”

“…Furthermore, ozonation has shown to be more effective than biological treatment alone for removing DOM from woodchip filter effluent. For example, in a laboratory study by Svennson et al (2015), 1.5 L of oak wood leachate was exposed to ozone at specific ozone doses between 0.7 and 7 g/L O 3 /g of initial COD removing .90% of polyphenols, up to 73% of COD, 61% of total organic carbon (TOC) and 97% of colour. A positive correlation between biodegradation and ozone pre-treatment was found.…”