Affiliations 

  • 1 Graduate School of Engineering, Soka University, Tangi-machi, Hachioji, Tokyo, 192-8577, Japan; Research Fellow of Japan Society for the Promotion of Science (JSPS), Kojimachi Business Center Building, 5-3-1 Kojimachi, Chiyoda-ku, Tokyo, 102-0083, Japan. Electronic address: mu_sekine@soka.gr.jp
  • 2 Division of Engineering, University of Guanajuato, 77 Juarez Avenue, Guanajuato, 36000, Mexico
  • 3 Faculty of Science and Engineering, Soka University, Tangi-machi, Hachioji, Tokyo, 192-8577, Japan
  • 4 Graduate School of Engineering, Soka University, Tangi-machi, Hachioji, Tokyo, 192-8577, Japan
  • 5 Graduate School of Engineering, Soka University, Tangi-machi, Hachioji, Tokyo, 192-8577, Japan; Institute of Marine Biotechnology, Universiti Malaysia Terengganu, 21030 Kuala Terengganu, Terengganu, Malaysia
Chemosphere, 2020 Apr;244:125381.
PMID: 31805460 DOI: 10.1016/j.chemosphere.2019.125381

Abstract

Sulfide inhibition to nitrifying bacteria has prevented the integration of digestate nitrification and biogas desulfurization to simplify anaerobic digestion systems. In this study, liquid digestate with NaHS solution was treated using nitrifying sludge in a sequential-batch reactor with a long fill period, with an ammonium loading rate of 293 mg-N L-1 d-1 and a stepwise increase in the sulfide loading rate from 0 to 32, 64, 128, and 256 mg-S L-1 d-1. Batch bioassays and microbial community analysis were also conducted with reactor sludge under each sulfide loading rate to quantify the microbial acclimatization to sulfide. In the reactor, sulfide was completely removed. Complete nitrification was maintained up to a sulfide load of 128 mg-S L-1 d-1, which is higher than that in previous reports and sufficient for biogas treatment. In the batch bioassays, the sulfide tolerance of NH4+ oxidizing activity (the 50% inhibitory sulfide concentration) increased fourfold over time with the compositional shift of nitrifying bacteria to Nitrosomonas nitrosa and Nitrobacter spp. However, the sulfur removal rate of the sludge slightly decreased, although the abundance of the sulfur-oxidizing bacteria Hyphomicrobium increased by 30%. Therefore, nitrifying sludge was probably acclimatized to sulfide not by the increasing sulfide removal rate but rather by the increasing nitrifying bacteria, which have high sulfide tolerance. Successful simultaneous nitrification and desulfurization were achieved using a sequential-batch reactor with a long fill period, which was effective in facilitating the present acclimatization.

* Title and MeSH Headings from MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.