1
|
Wang Z, Liao Y, Yan L, Liao B. Biological performance and membrane fouling of a microalgal-bacterial membrane photobioreactor for wastewater treatment without external aeration and carbonation. Environ Res 2024; 247:118272. [PMID: 38246292 DOI: 10.1016/j.envres.2024.118272] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/23/2023] [Revised: 01/10/2024] [Accepted: 01/18/2024] [Indexed: 01/23/2024]
Abstract
Biological nutrient removal processes involving the use of activated sludge (AS) to treat municipal wastewater normally result in high aeration energy consumption and significant greenhouse gas (GHG) emissions. Therefore, developing cost-efficient and environmentally friendly processes for wastewater treatment is vital. In this work, a novel non-aerated microalgal-bacterial membrane photobioreactor (MB-MPBR) was proposed, and its feasibility for organic contaminant and nutrient removals was evaluated, for the first time. The effects of inoculation ratio (microalgae to bacteria (M/B)) on the biological performance and membrane fouling were systematically investigated. The results showed that 95.9% of the chemical oxygen demand (COD), 74.5% of total nitrogen (TN), 98.5% of NH4+-N and 42.0% of total phosphorus (TP) were removed at an inoculation M/B ratio of 3:2 at steady state, representing a significant improvement compared to the M/B inoculation ratio of 1:3. Additionally, the higher inoculation M/B ratio (3:2) significantly promoted the biomass production owing to the favorable mutual exchange of oxygen and carbon dioxide between microalgae and bacteria. Cake layer formation was the primary fouling mechanism owing to the absence of aeration scouring on the membrane surface. The membrane fouling rate was slightly higher at the higher inoculation ratio (M/B = 3:2) owing to the increased biomass and extracellular polymeric substances (EPS) productions, despite the larger particle size. These results demonstrated that the non-aerated MB-MPBR could achieve superior biological performance, of which the inoculation M/B ratio was of critical importance for the initiation and maintenance of microalgal-bacterial symbiotic system, yet possibly caused severer membrane fouling in the absence of external aeration and carbonation. This study provides a new perspective for further optimizing and applying non-aerated MB-MPBR to enhance municipal wastewater treatment.
Collapse
Affiliation(s)
- Zhaozhao Wang
- College of Civil and Architectural Engineering, North China University of Science and Technology, Tangshan, 063210, PR China; College of Energy and Environmental Engineering, Hebei University of Engineering, Handan, 056038, PR China; Department of Chemical Engineering, Lakehead University, 955 Oliver Road, Thunder Bay, ON, P7B 5E1, Canada.
| | - Yichen Liao
- Department of Chemical Engineering, Lakehead University, 955 Oliver Road, Thunder Bay, ON, P7B 5E1, Canada
| | - Lina Yan
- College of Chemical Engineering, North China University of Science and Technology, Tangshan, 063210, PR China
| | - Baoqiang Liao
- Department of Chemical Engineering, Lakehead University, 955 Oliver Road, Thunder Bay, ON, P7B 5E1, Canada.
| |
Collapse
|
2
|
Zhang M, Leung KT, Lin H, Liao B. Evaluation of membrane fouling in a microalgal-bacterial membrane photobioreactor: Effects of SRT. Sci Total Environ 2022; 839:156414. [PMID: 35660432 DOI: 10.1016/j.scitotenv.2022.156414] [Citation(s) in RCA: 8] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/25/2022] [Revised: 05/29/2022] [Accepted: 05/30/2022] [Indexed: 06/15/2023]
Abstract
As a novel system, the microalgal-bacterial membrane photobioreactor (MPBR) has better performance than the conventional MBRs in membrane fouling control. Nevertheless, how the operating conditions affect its fouling performance is rarely reported. In this study, a microalgal-bacterial MPBR was set and continuously operated to treat synthetic wastewater. Effects of solids retention time (SRT, 10, 20, and 30 d) on the membrane fouling were investigated. The results showed that the relationship between membrane fouling and SRT was nonlinear and the fastest membrane fouling was observed at SRT 20 d. The predominant fouling mechanism was gel layer formation. X-ray photoelectron spectroscopy results showed a significant difference in the surface composition of the microalgal-bacterial consortia at different SRTs. The biological flocs at SRT of 20 d had the largest floc size, moderate filament abundance, and the highest content of bound EPS and SMP. The highest membrane fouling at SRT 20 d was mainly attributed to the highest concentration of EPS and SMP. Environmental stresses and fierce competition between microalgae and bacteria are considered to be the underlying reasons for the elevated production of EPS and SMP. In brief, optimizing the SRT value to control the balanced growth of microalgae and bacteria and keep them at an appropriate ratio is critical for delaying membrane fouling in microalgal-bacterial MPBR.
Collapse
Affiliation(s)
- Meijia Zhang
- Biotechnoloy Research Program, Lakehead University, 955 Oliver Road, Thunder Bay, ON P7B 5E1, Canada; Department of Chemical Engineering, Lakehead University, 955 Oliver Road, Thunder Bay, ON P7B 5E1, Canada; Department of Biology, Lakehead University, 955 Oliver Road, Thunder Bay, ON P7B 5E1, Canada; College of Geography and Environmental Sciences, Zhejiang Normal University, Jinhua 321004, PR China.
| | - Kam-Tin Leung
- Biotechnoloy Research Program, Lakehead University, 955 Oliver Road, Thunder Bay, ON P7B 5E1, Canada; Department of Biology, Lakehead University, 955 Oliver Road, Thunder Bay, ON P7B 5E1, Canada.
| | - Hongjun Lin
- College of Geography and Environmental Sciences, Zhejiang Normal University, Jinhua 321004, PR China.
| | - Baoqiang Liao
- Biotechnoloy Research Program, Lakehead University, 955 Oliver Road, Thunder Bay, ON P7B 5E1, Canada; Department of Chemical Engineering, Lakehead University, 955 Oliver Road, Thunder Bay, ON P7B 5E1, Canada.
| |
Collapse
|
3
|
Zhang M, Leung KT, Lin H, Liao B. Membrane fouling in a microalgal-bacterial membrane photobioreactor: Effects of P-availability controlled by N:P ratio. Chemosphere 2021; 282:131015. [PMID: 34090001 DOI: 10.1016/j.chemosphere.2021.131015] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/16/2021] [Revised: 05/11/2021] [Accepted: 05/26/2021] [Indexed: 06/12/2023]
Abstract
Microalgal-bacterial membrane photobioreactor (MB-MPBR) is a promising technology to simultaneously remove organics and nutrients from wastewater. However, membrane fouling in MB-MPBR was seldom studied. In this study, potential effects of P-availability on biomass properties and membrane fouling in MB-MPBR were investigated. Under a nitrogen sufficient condition, a lower N:P ratio of 3.9:1 (P-rich) caused more severe membrane fouling. The dominant fouling mechanism was cake layer formation. Serial characterization showed a smaller particle size distribution (PSD), more free microalgae and significantly different surface composition of microalgal-bacterial flocs at N:P ratio of 3.9:1 compared with that of 9.7:1. The variations on PSD and surface composition were fully consistent with that of filtration resistance and thus considered as the primary contributors to the different fouling performance. The above results suggested that controlling microalgae/bacteria consortium in a good ratio by optimizing operating conditions is the key event for membrane fouling control in MB-MPBRs.
Collapse
Affiliation(s)
- Meijia Zhang
- Biotechnoloy Research Program, Lakehead University, 955 Oliver Road, Thunder Bay, ON, P7B 5E1, Canada; Department of Chemical Engineering, Lakehead University, 955 Oliver Road, Thunder Bay, ON, P7B 5E1, Canada; Department of Biology, Lakehead University, 955 Oliver Road, Thunder Bay, ON, P7B 5E1, Canada; College of Geography and Environmental Sciences, Zhejiang Normal University, Jinhua, 321004, PR China
| | - Kam-Tin Leung
- Biotechnoloy Research Program, Lakehead University, 955 Oliver Road, Thunder Bay, ON, P7B 5E1, Canada; Department of Biology, Lakehead University, 955 Oliver Road, Thunder Bay, ON, P7B 5E1, Canada
| | - Hongjun Lin
- College of Geography and Environmental Sciences, Zhejiang Normal University, Jinhua, 321004, PR China
| | - Baoqiang Liao
- Biotechnoloy Research Program, Lakehead University, 955 Oliver Road, Thunder Bay, ON, P7B 5E1, Canada; Department of Chemical Engineering, Lakehead University, 955 Oliver Road, Thunder Bay, ON, P7B 5E1, Canada.
| |
Collapse
|
4
|
Zhang M, Leung KT, Lin H, Liao B. The biological performance of a novel microalgal-bacterial membrane photobioreactor: Effects of HRT and N/P ratio. Chemosphere 2020; 261:128199. [PMID: 33113666 DOI: 10.1016/j.chemosphere.2020.128199] [Citation(s) in RCA: 27] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/02/2020] [Revised: 08/20/2020] [Accepted: 08/27/2020] [Indexed: 06/11/2023]
Abstract
A microalgal-bacterial membrane photobioreactor (MB-MPBR) was developed for simultaneous COD and nutrients (N and P) removals from synthetic municipal wastewater in a single stage for a long-term operation over 350 days. The effects of hydraulic retention time (HRT) and N/P ratio on the biological performance were systematically evaluated for the first time. The results showed that a lower N/P ratio (3.9:1) and shorter HRT (2 d) promoted more biomass production, as compared to a high HRT (3 d) and a high N/P ratio (9.7:1). The highest biomass concentration (2.55 ± 0.14 g L-1) and productivity (127.5 mg L-1·d-1) were achieved at N/P ratio of 3.9:1 and HRT of 2 d due to the highest nitrogen and phosphorus loadings under such conditions. A COD and ammonia-N removal efficiency of over 96% and 99%, respectively, were achieved regardless of HRTs and N/P ratios. In the absence of nitrogen or phosphorus deficiency, shorter HRT (2 d) yielded a higher nitrogen and phosphorus uptake but lower removal efficiency. In addition, the imbalance N/P ratio (9.7:1) would decrease nitrogen or phosphorus removal. Overall, the results suggested that it was feasible to simultaneously achieve complete or high removal of COD, nitrogen, and phosphorous in MB-MPBR under the appropriate conditions. This study demonstrated for the first time that MB-MPBR is a promising technology that could achieve a high-quality effluent meeting the discharge standards of COD and nutrients in one single step.
Collapse
Affiliation(s)
- Meijia Zhang
- Biotechnoloy Research Program, Lakehead University, 955 Oliver Road, Thunder Bay, ON, P7B 5E1, Canada; Department of Chemical Engineering, Lakehead University, 955 Oliver Road, Thunder Bay, ON, P7B 5E1, Canada; Department of Biology, Lakehead University, 955 Oliver Road, Thunder Bay, ON, P7B 5E1, Canada
| | - Kam-Tin Leung
- Biotechnoloy Research Program, Lakehead University, 955 Oliver Road, Thunder Bay, ON, P7B 5E1, Canada; Department of Biology, Lakehead University, 955 Oliver Road, Thunder Bay, ON, P7B 5E1, Canada
| | - Hongjun Lin
- College of Geography and Environmental Sciences, Zhejiang Normal University, Jinhua, 321004, PR China
| | - Baoqiang Liao
- Biotechnoloy Research Program, Lakehead University, 955 Oliver Road, Thunder Bay, ON, P7B 5E1, Canada; Department of Chemical Engineering, Lakehead University, 955 Oliver Road, Thunder Bay, ON, P7B 5E1, Canada.
| |
Collapse
|