Efficiency and bacterial diversity of an improved anaerobic baffled reactor for the remediation of wastewater from alkaline-surfactant-polymer (ASP) flooding technology

Abstract

Alkaline-surfactant-polymer (ASP) flooding technology is used to maximize crude oil recovery. However, the extensive use of alkaline materials makes it difficult to treat the water used. Here, an improved multi-zone anaerobic baffled reactor (ABR) using FeSO4 as electron acceptor was employed to treat the wastewater from ASP flooding technology, and the effects on major pollutants (hydrolyzed polyacrylamide, petroleum substances, surfactants suspended solids) and associated parameters (chemical oxygen demand, viscosity) were evaluated. Gas chromatography-mass spectrometry (GC-MS) was used to follow the degradation and evolution of organic compounds while high-throughput DNA sequencing was used to determine the bacterial diversity in the ABR. The results obtained after 90 d of operation showed decreases in all parameters measured and the highest mean removal rates were obtained for petroleum substances (98.8%) and suspended solids (77.0%). Amounts of petroleum substances in the ABR effluent could meet the requirements of a national standard for oilfield reinjection water. GC-MS analysis showed that a wide range of chemicals (e.g. aromatic hydrocarbons, esters, alcohols, ketones) could be sequentially removed from the influent by each zone of ABR. The high-throughput DNA sequencing showed that the bacteria Micropruina, Saccharibacteria and Synergistaceae were involved in the degradation of pollutants in the anaerobic and anoxic reaction zones, while Rhodobacteraceae and Aliihoeflea were the main functional microorganisms in the aerobic reaction zones. The results demonstrated that the improved ABR reactor had the potential for the treatment of wastewater from ASP flooding technology.

Removal of Cr (VI) and microbial community analysis in PCB wastewater treatment based on the BESI® process

“…Table 3 shows the total number of sequencing reads available representing Operational Taxonomic Units (OTUs) in samples obtained from each reactor of the BESI ® process. The coverage rate for the samples (> 99.8%) indicated that a high proportion of the reads could be explained by the OTUs [ 31 ]. The most OTUs were found in anaerobic sludge (A1-a), which represented the inlet section of the reactor.…”

“…indicated that a high proportion of the reads could be explained by the OTUs [31]. The most OTUs were found in anaerobic sludge (A1-a), which represented the inlet section of the reactor.…”

“…The most abundant bacterial taxa were Synergistaceae (31.90%) and Trichococcus (26.59%). Among them, Synergistaceae, Trichococcus, Clostridium sensu stricto 1, and vadinBC27 can decompose simple organics such as glucose into acids, CO 2 and H 2 O [47][48][49], which were mostly small molecular organic-degrading bacteria. It showed that the function of microbial community has been transformed from macromolecular organic-degrading bacteria to small-molecular organicdegrading bacteria.…”