Study on Novel Bioreactors Technology for Biodegradation of Oil Sands Process-Affected Water

Transcription

1 Study on Novel Bioreactors Technology for Biodegradation of Oil Sands Process-Affected Water Lei Zhu Supervisor: Dr. Tong Yu Department of Civil and Environmental Engineering University of Alberta

2 Background Athabasca, Cold Lake and Peace River, more than 75,000 square kilometres Approximately billion barrels of recoverable bitumen 3 rd largest proven oil reserves Clark Hot Water Extraction

3 1 billion m 3 by 2025 ¼ of Edmonton s area (176 Km 2 )

4 Biological Treatment Advantages Feasibility Low capital and operating costs Oxidation of organic compounds Removal of inorganic compounds Nitrogen removal Operational flexibility Reduction of aquatic toxicity Microbial activities have been reported in mature fine tailings (MFT) Commercial naphthenic acids was degraded using indigenous microbes from MFT Wastewater sludge from municipal WTP could also be amended to MFT for treatability test of OSPW

5 Research Objectives Long-term Goal: To develop a feasible biological process train using bioreactors for degradation of recalcitrant organic compounds in OSPW

6 Bioreactor Process Train

7 Biofilm Introduction Biofilm is microbial growth on a surface or interface and consists of microbial cells embedded in self-produced matrix of extracellular polymeric substance (EPS).

8 Bioreactor Selection 1. Due to the biofilm diffusion limit, MBBR and MABR can supply a good microenvironment for specialized microbes to digest toxic organic compounds 2. Both of them exhibits greater resistance to the adverse chemical conditions presented by industrial wastewater than conventional biological treatment 3. Both of them have long sludge retention time, which will be critical for specialized microorganisms to adapt the harsh environment 4. Both of them can achieve aerobic and anaerobic conditions inside the reactor

9 Bioreactor Design

10 Bioreactor Design

11 Water Characteristics Water quality of OSPW from Suncor Energy Inc Item Colour Odour Description/Concentration (mg/l) Brown Hydrocarbon-like COD 230 ph (Test Value: 7.94) Freezing Point 0 Alkalinity (mg/l CaCO 3 ) Cl SO NO 3- + NO (N mg/l) NH NAs (FT-IR) 68.9

12 Influent Pump Mechanical Mixer Influent Pump Controller Effluent Port Air Line Moving Bed Biofilm Reactor Settling Flask Influent Port Sampling Port Mechanical Mixer Controller Effluent Storage Tank

13 Compressed Air Input Internal Recycling Port N2 Input Membrane Aerated Biofilm Reactor Effluent Port Influent Port Internal Recycling Port 13

14 Reactor COD Performance MBBR Stage 1 Stage 2 Stage 3 MABR Stage 1 Stage 2

15 BOD Test Results 1. BOD in Raw OSPW, MBBR Effluent and MABR Effluent are very low, around 5 mg/l 2. The BOD/COD ratio in MBBR and MABR is larger than 0.3, which makes the environment comfortable for bacteria inside reactors 3. Ozonation is useful for increasing the biodegradability of the effluent from MBBR

16 FTIR Test Results

17 DNA Sequencing Test Results Statistics for 16S rrna Gene Library Sample Optimized Sequence Number OTU Number Coverage (%) Chao Shannon Raw OSPW ( ) S (39819, 47665) 4.30 MBBR Biofilm ( ) S (31362, 36301) 4.59 MBBR Suspended Solid ( ) S (26347, 31960) 4.12 MBBR Biofilm ( ) S (27985, 33448) 4.20 MABR Inoculum Sludge ( ) S (30448, 36582) 4.19 MABR Biofilm ( ) S (16334, 19827) 4.60

18 Miseq Illumina DNA Sequencing Test Results Top 10 microbial classified under Class Level Proteobacteria was the majority class and existed in all six samples; α,β, γ-proteobacteria of all reactor samples were lower than that of Raw OSPW Flavobacteria: great resistance under toxic and alkaline environment Ignavibacteria found in MABR Biofilm sample belongs to Chlorobi phylum, which relates to sulfur metabolism Nitrospira existed in biofilm sample which is involved in nitrification process

19 Miseq Illumina DNA Sequencing Test Results Heatmap for top 50 microbial classified under Genus Level Nine Common genus for all 6 samples Pseudomonas: metabolic capability of anteiso (β)-alkyl substituted aliphatic carbon chain; Flavobacterium and Rhodobacter : ternary substitution at positions other than the β-position to the carboxylic group of the main carbon chain. Steroidobacter: anaerobically on C- 18/19 as source of carbon with nitrate as the electron acceptor. Methyloversatilis relate to heavy metal and aromatic compounds resistant, methylotrophic Bioaugmentation happened in MBBR and MABR for All of the above three microbial genus.

20 Conclusions This process train with bioreactors was effective on enhancing biodegradation of recalcitrant organic chemicals and reducing the toxicity of OSPW. Due to the nutrients condition, toxicity level and operation conditions, the microbial community in raw OSPW was hugely different from that inside bioreactors. Bioreactors could select and enrich specific microorganisms which showed great resistance to the harsh environment and the capability of degrading carboxylic group of the main carbon chain. Bioaugmentation happening inside MBBR and MABR made the biodegradation of recalcitrant organic chemicals in OSPW faster and the acceleration of end-pit lake reclamation promising.

21 Acknowledgement Natural Sciences and Engineering Research Council of Canada (NSERC) Chinese Scholarship Council (CSC) Suncor Energy Inc.

22 Thank you for your attention. Questions?