Effects of phosphate addition on methane fermentation in the batch and upflow anaerobic sludge blanket (UASB) reactors

Abstract

Ammonia inhibition of methane fermentation is one of the leading causes of failure of anaerobic digestion reactors. In a batch anaerobic digestion reactor with 429 mM NH3-N/L of ammonia, the addition of 25 mM phosphate resulted in an increase in methane production rate. Similar results were obtained with the addition of disodium phosphate in continuous anaerobic digestion using an upflow anaerobic sludge blanket (UASB) reactor. While methane content and production rate decreased in the presence of more than 143 mM NH3-N/L of ammonium chloride in UASB, the addition of 5 mM disodium phosphate suppressed ammonia inhibition at 214 mM NH3-N/L of ammonium chloride. The addition prevented acetate/propionate accumulation, which might be one of the effects of the phosphate on the ammonia inhibition. The effects on the microbial community in the UASB reactor was also assessed, which was composed of Bacteria involved in hydrolysis, acidogenesis, acetogenesis, and dehydrogenation, as well as Archaea carrying out methanogenesis. The change in the microbial community was observed by ammonia inhibition and the addition of phosphate. The change indicates that the suppression of ammonia inhibition by disodium phosphate addition could stimulate the activity of methanogens, reduce shift in bacterial community, and enhance hydrogen-producing bacteria. The addition of phosphate will be an important treatment for future studies of methane fermentation.

Evaluation of the Potential to Produce Biogas and Other Energetic Coproducts Using Anaerobic Digestion of Wastewater Generated at Shrimp Processing Operations

“…Phosphate and sulfur levels were all within a reasonable concentration range for maintaining an anaerobic digester . Nitrogen compounds were low in terms of a [COD] to [N] ratio (typically less than 30) where typically a ratio of 100 or higher is preferred. , The [COD]:[phosphate] ratio of 98 for this wastewater was considered more than enough based on the reports of others. , These nutrient data justified the nutrient amending protocol used throughout this study (see Materials and Methods Section), which involved only nitrogen amending (as NH 3 ). Also, there was enough sulfur, so adding sulfur was not needed.…”

“…32,33 The [COD]:[phosphate] ratio of 98 for this wastewater was considered more than enough based on the reports of others. 34,35 These nutrient data justified the nutrient amending protocol used throughout this study (see Materials and Methods Section), which involved only nitrogen amending (as NH 3 ). Also, there was enough sulfur, so adding sulfur was not needed.…”

Novel Self-Transmissible and Broad-Host-Range Plasmids Exogenously Captured From Anaerobic Granules or Cow Manure

“…The granules were sampled from a lab scale upflow anaerobic sludge blanket (UASB) reactor for methane fermentation (total volume was 1 L) on September 11, 2015; November 4, 2015; December 7, 2015; and May 17, 2016. The reactor was supplied with 0.3 g/L glucose, 1.45 g/L K 2 HPO 4 , and 0.75 g/L KH 2 PO 4 as model waste water, and the other conditions were implemented similarly as described elsewhere ( Suzuki et al, 2015 ). The cow manure was sampled from cows that were not fed with antibiotics, in the Sumiyoshi field of the University of Miyazaki, Japan, on April 11, 2016; October 11, 2016; and May 16, 2017.…”