Integrated system coupling non-thermal plasma and anaerobic digestion to reduce microalgae and microcystin = Integrated system coupling non-thermal plasma and anaerobic digestion to reduce microalgae and microcystin

다국어 초록 (Multilingual Abstract)

Rising temperature in the summer and large amounts of nutrient loadings lead to serious algal blooms on the surface water. It is a problem because some microalgae can cause water quality deterioration and release ecological toxic substances such as microcystin thus continuous biomass harvesting should be done iteratively. Research on how to treat the harvested microalgae has been carried out and anaerobic biotechnology is getting special attention due to the advantage of being able to manufacture renewable energy in the form of biogas. However, the cell wall degradation of the harvested algae and the effect of certain cyanobacterial toxins on anaerobic microbial activity are obstacles to anaerobic digestion. In this study, biochemical methane potential (BMP) tests were conducted after the pretreatment of non-thermal plasma (NTP), a kind of advanced oxidation process, to enhance the potential for anaerobic biodegradation and toxicity reduction for harvested microalgae. We also investigated the inhibition effect of existing microcystin based on anaerobic digestion efficiencies. The BMP test was conducted with the initial substrate concentration of 1.0 ~ 2.0 gVS/L in a serum bottle (100 mL). Results show that the biogas yield was 124 mLCH₄/gVS in the NTP pretreated reactor, whereas the reactor without pretreatment showed about 20% lower yield. At the initial concentration of microcystin in 8,835 μg/L, about 50% of microcystin was removed during pretreatment. On the other hand, insufficient removal of microcystin seems to be associated with the release of microcystin from destroyed cyanobacteria. In summary, this study confirms that NTP pretreatment is effective in increasing the anaerobic digestion efficiency, but optimization on NTP application seems necessary due to microcystin release from the microalgae.