Synergistic algal/bacterial interaction in membrane bioreactor for detoxification of 1,2-dichloroethane-rich petroleum wastewater

• Published in: Journal of hazardous materials Vol. 470; p. 134125
• Main Authors: Alhajeri, Nawaf S., Tawfik, Ahmed, Elsamadony, Mohamed, Al-Fadhli, Fahad M., Meng, Fangang
• Format: Journal Article
• Language: English
• Published: Netherlands Elsevier B.V 15-05-2024
• Subjects: Bacteria - metabolism; Biodegradation pathways; Biodegradation, Environmental; Bioreactors; Dechlorination; Enzymes activities; Ethylene Dichlorides - metabolism; Membranes, Artificial; Microbial/algal; Petroleum - metabolism; Waste Disposal, Fluid - methods; Wastewater - chemistry; Wastewater, 1,2 –dichloroethane; Water Pollutants, Chemical - metabolism; Microbial/algal; Dechlorination; Wastewater, 1,2 –dichloroethane; Enzymes activities; Biodegradation pathways
• ISSN: 0304-3894; 1873-3336; 1873-3336
• DOI: 10.1016/j.jhazmat.2024.134125

The study addressed the challenge of treating petroleum industry wastewater with high concentrations of 1,2-dichloroethane (1,2-DCA) ranging from 384 to 1654 mg/L, which poses a challenge for bacterial biodegradation and algal photodegradation. To overcome this, a collaborative approach using membrane bioreactors (MBRs) that combine algae and bacteria was employed. This synergistic method effectively mitigated the toxicity of 1,2-DCA and curbed MBR fouling. Two types of MBRs were tested: one (B-MBR) used bacterial cultures and the other (AB-MBR) incorporated a mix of algal and bacterial cultures. The AB-MBR significantly contributed to 1,2-DCA removal, with algae accounting for over 20% and bacteria for approximately 49.5% of the dechlorination process. 1,2-DCA metabolites, including 2-chloroethanol, 2-chloro-acetaldehyde, 2-chloroacetic acid, and acetic acid, were partially consumed as carbon sources by algae. Operational efficiency peaked at a 12-hour hydraulic retention time (HRT) in AB-MBR, enhancing enzyme activities crucial for 1,2-DCA degradation such as dehydrogenase (DH), alcohol dehydrogenase (ADH), and acetaldehyde dehydrogenase (ALDH). The microbial diversity in AB-MBR surpassed that in B-MBR, with a notable increase in Proteobacteria, Bacteroidota, Planctomycetota, and Verrucomicrobiota. Furthermore, AB-MBR showed a significant rise in the dominance of 1,2-DCA-degrading genus such as Pseudomonas and Acinetobacter. Additionally, algal-degrading phyla (e.g., Nematoda, Rotifera, and Streptophyta) were more prevalent in AB-MBR, substantially reducing the issue of membrane fouling.
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•The synergistic algal-bacterial process successfully removed 92.6% of 1,2-DCA.•123.0 mg/gVS of TB-EPS utilized by algae lead to membrane fouling reduction.•Algae released metabolites that served as electron donors for dechlorination of 1,2-DCA.•Pseudomonas (1.8%) and Acinetobacter (9.8%) were promoted in the presence of algal cells.•1,2-DCA was partially removed by Scenedesmaceae sp. (1.8%) and Chlorophyta (1.4%).