Denitrifiye anaerobik metan oksidasyonu (DAMO) mikroorganizmaları: Varlıklarının ve zenginleştirilmelerinin incelenmesi

DAMO process has the potential of decreasing CH4 emissions in the aquatic ecosystems, and the nitrite and nitrate levels in the natural ecosystems and receiving bodies. The seed source is very critical to enrich slowly growing DAMO microorganisms successfully in a short time. In this study, the occurrence and activity of DAMO microorganisms in different inoculum sources were investigated by activity tests and molecular analyses. Seed sources used in this study were paddy field soil (private rice field in Kızılırmak District, Çankırı, Turkey), freshwater sediment (Lake Eymir, Ankara, Turkey), anaerobic digester sludge (ASKİ Ankara Central Wastewater Treatment Plant) and return activated sludge of a biological nutrient removal system (İSKİ Ambarlı Advanced Wastewater Treatment Plant). Paddy field soil, freshwater sediment, and anaerobic digester sludge and their combinations were observed to show potential DAMO activity. Return activated sludge of a biological nutrient removal system was not observed to be a good choice for the enrichment of DAMO microorganisms due to its high biodegradable organic matter content which gives denitrifiers and methanogens great advantage over DAMO species. The enrichment of both Damo-Bacteria and Damo-Archaea was also investigated in sequencing batch reactors (SBRs). Two enrichment studies were carried out, one at low influent concentrations and low hydraulic retention time (HRT), and the other at high influent nitrite and nitrate concentrations and high HRT. Higher DAMO-specific activities were obtained at high HRT and higher initial nitrite and nitrate concentrations. However, the enrichment of DAMO microorganisms cultivated in this study showed very low nitrite and nitrate removal rates although the molecular evidence supported their presence in the cultures. The main reason for the low activity of DAMO species was associated with SBR configuration, which did not facilitate gas transfer and the availability of methane. The effect of granular activated carbon (GAC) on the activity of DAMO co-culture was investigated. The positive effect of GAC application was observed on both Damo-Bacteria and Damo-Archaea activity, which might be due to the increased dissolved methane availability and, in turn, improved contact between biomass and dissolved methane. Application of GAC decreased the time for enrichment by 3-fold. This study is the first to report the occurrence and activity of DAMO microorganisms in Turkey, which are promising for the treatment of wastewaters with high CH4 and nitrogen (N) content. Results revealed that enrichment of both DAMO species is possible. Improvement of the activity in shorter periods needs further investigation.