Magnetite as an enhancer in methanogenic degradation of volatile fatty acids under ammonia-stressed condition. (1st July 2019)

• Record Type: Journal Article
• Authors: Lee, Joonyeob; Koo, Taewoan; Yulisa, Arma; Hwang, Seokhwan
• Is Part Of: Journal of environmental management. Volume 241(2019)
• Page Start: 418
• Page End: 426
• Publication Date: 2019-07-01
• Subjects: Anaerobic digestion -- Iron oxide -- Ammonia inhibition -- Methanogen -- Bacteria -- Syntrophic consortia; Environmental policy -- Periodicals; Environmental management -- Periodicals; Environment -- Periodicals; Ecology -- Periodicals; 363.705
• DOI: 10.1016/j.jenvman.2019.04.038
• Languages: English
• ISSNs: 0301-4797

Abstract

Abstract: Anaerobic batch tests with a 2 2 full-factorial design of ammonia (1.5, 6.5 g N/L) and magnetite concentrations (0, 20 mmol/L) were conducted separately for methanogenic degradation of acetate, propionate, and butyrate (volatile fatty acids (VFAs)) to 1) quantify the effect of magnetite as an enhancer in methanogenic degradation of each of the VFAs in conditions without ammonia stress (1.5 g N/L) and with ammonia stress (6.5 g N/L), and 2) identify methanogenic consortia that are related to such enhancement. Among the three VFAs, methanogenic degradation of propionate was the least feasible (57% lower specific methanogenic activity R CH4 and three times longer lag time λ than acetate degradation). At low ammonia concentration, only propionate showed improvement in R CH4 (46%) with supplementation of magnetite. In the ammonia-stressed condition without magnetite, R CH4 decreased by 38–58% and λ increased 2.2–8.8 times for all VFAs; magnetite supplementation significantly alleviated these effects. These results demonstrate that magnetite supplementation effectively increases methanogenic degradation of the VFAs even under ammonia-stressed conditions. 16S metagenomic sequencing revealed that distinctive methanogenic consortia were active in the different combinations of substrate, ammonia and magnetite. Alkaliphilus, Hyphomonadaceae SWB02 and Clostridia DTU014, Clostridia D8A-2, Christensenellaceae R-7 group and Rikenellaceae DMER64 were identified as potential syntrophic bacteria that can establish magnetite-mediated direct electron transfer with methanogens ( Methanosaeta concilii, Methanosaeta harundinacea, Methanolinea tarda, Methanoculleus bourgensis and Methanosarcina spp.) during methanogenic degradation of VFAs. The results may be useful as a reference to develop effective strategies using magnetite supplementation to remediate anaerobic digestion processes that have been afflicted by VFA accumulation and ammonia inhibition. Highlights: Magnetite effect on AD of VFAs under NH3 -stressed condition was tested. Methanogenic degradation of propionate was improved by magnetite addition. Magnetite alleviated NH3 inhibition of methanogenic degradation of VFAs. Distinctive syntrophic consortia were responsible for such enhancement effect.