Contrasting microbial community composition and function perspective in sections of a full-scale coking wastewater treatment system

Abstract

To characterize the microbial community of the coking wastewater (CWW) treatment system and to study the effects of CWW characteristics and operational parameters on microbial communities, active sludge samples were collected from a full-scale CWW treatment plant using three-phase fluidized bed biological reactors. High-throughput MiSeq sequencing was used to examine the 16S rRNA genes of microbiology, revealing a distinct microbial composition among the active sludge samples of three sequential bioreactors. Pseudomonas, Comamonas, and Thiobacillus-related sequences dominated in the anaerobic bioreactor A, aerobic bioreactor O1, and aerobic bioreactor O2 active sludge with relative abundance of 72.59, 56.75, and 27.82 %, respectively. The physico-chemical characteristics of CWW were analyzed by standard methods and operational parameters were recorded to examine their effects on the microbial communities. The redundancy analysis (RDA) results showed that the bacterial communities of bioreactors A, O1, and O2 correlated strongly with cyanides, phenols, and ammonia, respectively. These results expand the knowledge about the biodiversity and population dynamics of microorganisms and discerned the relationships between bacterial communities and environmental variables in the biological treatment processes in the full-scale CWW treatment system.

Performance and microbial community composition in a long-term sequential anaerobic-aerobic bioreactor operation treating coking wastewater

“…2 and Table 1, anaerobic treatment removed over one third of COD and TOC, and more than half of phenolic derivatives and NHCs, showing that the anaerobic processes could play an important role in the treatment of CWW. The results of this study are consistent with those of Wang et al (2011) and Zhu et al (2016) who showed 20-30 % COD removal by mesophilic anaerobic treatment. The removal of total phenols (54.0 %) and phenolic derivatives (58.4 %) was achieved in the present study, and were considerably higher than that achieved in previous studies (Wang et al 2011, 20-30 %;Zhu et al 2016, 18.0 %), which might be partly due to the longer HRT (42 h) applied in this study.…”

“…Table 1 and Table S1 reveal that the combined anaerobic-aerobic system removed almost all phenol derivatives and NHCs along with significant removal of COD (81.8 %), SCN − (98.2 %), and CN − (85.4 %). The overall removal efficiency achieved in this study is in agreement with that obtained in previous studies (Zhu et al 2016;Sharma and Philip 2015;Jin et al 2013;Lai et al 2008;Maranon et al 2008), showing COD, total phenol, and SCN − removals of 63.0-86.5 %, 98.0-100.0 %, and 90.0-98.0 %, respectively, in integrated anaerobic-anoxic-aerobic treatment systems with or without sludge recirculation. Thus, the combined process not only significantly saved aeration energy but ensured better system stability when encountering fluctuations in wastewater compositions and toxic load (Chakraborty and Veeramani 2002).…”

“…Due to its reduced energy consumption, enhanced hydrolysis of organics, and detoxification of toxic compounds (Chakraborty and Veeramani 2002), anaerobic digestion is often used before an aerobic reactor for the treatment of high strength industrial wastewater (Wei et al 2012), including the treatment of CWW or coal gasification wastewater Zhu et al 2013Zhu et al , 2016. However, although the efficiency of pollutant removal (such as of phenols) is low in many cases (Zhu et al 2016), methane production appears to be limited under mesophilic conditions .…”

“…However, although the efficiency of pollutant removal (such as of phenols) is low in many cases (Zhu et al 2016), methane production appears to be limited under mesophilic conditions . Of note, free CN − in synthetic CWW has been reported to inhibit gas production (Sharma and Philip 2015).…”

“…Since these microbial populations are associated with pollutant removal efficiency, understanding community structure in different stages during long-term operated CWW treatment is important. Previous studies have focused on bacterial diversity surveys in full-scale CWW treatment systems, revealing the distribution of potential degraders of phenols, SCN − , and CN − (Zhu et al , 2016Ma et al 2015a;Wang et al 2015b). However, to better understand the profiles of acclimatized bacterial, archaeal, and fungal communities associated with degradation of different pollutants, research on controlled sequential anaerobic and aerobic CWW treatment systems is desirable.…”