Robustness of anaerobes exposed to cyanuric acid contaminated wastewater and achieving efficient removal via optimized co-digestion scheme

Kabir Abdullahi; Ahmed Elreedy; Manabu Fujii; Mona G Ibrahim; Ahmed Tawfik

doi:10.1016/j.jare.2020.02.006

Robustness of anaerobes exposed to cyanuric acid contaminated wastewater and achieving efficient removal via optimized co-digestion scheme

J Adv Res. 2020 Feb 17:24:211-222. doi: 10.1016/j.jare.2020.02.006. eCollection 2020 Jul.

Authors

Kabir Abdullahi¹, Ahmed Elreedy^{2

3}, Manabu Fujii², Mona G Ibrahim^{1

4}, Ahmed Tawfik⁵

Affiliations

¹ Environmental Engineering Department, Egypt-Japan University of Science and Technology, Alexandria 21934, Egypt.
² Department of Civil and Environmental Engineering, Tokyo Institute of Technology, Meguro-ku, Tokyo 152-8552, Japan.
³ Sanitary Engineering Department, Alexandria University, Alexandria 21544, Egypt.
⁴ Environmental Health Department, High Institute of Public Health, Alexandria University, Alexandria 21544, Egypt.
⁵ Water Pollution Research Department, National Research Centre, Giza 12622, Egypt.

Abstract

The impact of various industrial pollutants on anaerobes and the biodegradation potentials need much emphasis. This study aims to investigate the response of anaerobic microbial systems to cyanuric acid (CA) exposure; CA is toxic and possible carcinogen. First, the long-term exposure of mixed culture bacteria (i.e., municipal sludge) to low-strength wastewater containing 20 mg/L CA was conducted in an up-flow anaerobic staged reactor. Stable performance and sludge granulation were observed, and the microbial community structure showed the progression of genus Acinetobacter known as CA degrader. Second, batch-mode experiment was performed to examine the CA biodegradability at higher doses (up to 250 mg/L of CA) in the absence and presence of glucose as a co-substrate; response surface-based optimization was used to design this experiment and to estimate the optimum CA-glucose combination. CA removal of 77-98% was achieved when CA was co-digested with glucose (250-1,000 mg/L), after 7 days-incubation at temperature of 37 °C, compared to 34% when CA was solely digested. Further, the obtained methane yield dropped when CA exceeded over 125 mg/L, though the deterioration was mitigated by addition of higher concentration of glucose. Overall, we conclude that CA is efficiently degraded under anaerobic conditions when being co-digested with readily assimilable substrate.

Keywords: Anaerobic treatment; Co-digestion; Cyanuric acid; Industrial wastewater; Microbial dynamics.