Roles of attached-growth media in algal biomass productivity and domestic wastewater treatment of algal-bacterial photobioreactor | |
| Author | Prutchaya Wisakum |
| Call Number | AIT Thesis no.EV-19-18 |
| Subject(s) | Microalgae--Biotechnology Wastewater--Treatment Sewage--Purification--Biological treatment Algal biofuels--Dewatering |
| Note | A thesis submitted in partial of fulfillment of the requirements for the degree of Master of Engineering in Environmental Engineering and Management |
| Publisher | Asian Institute of Technology |
| Abstract | Microalgae are considered as one of the most abundant sources of biofuel, biochemical products such as protein. Microalgae cultivation with domestic wastewater is possible for algae biomass production due to sufficient nutrients in wastewater. Furthermore, microalgae also found the potential of wastewater remediation because algae can uptake substrates in the wastewater. To reduce cost of algae harvesting from suspended biomass cultivation, algal biofilm with attached-growth media in PBR is purposed due to the easier ways to harvest and immobilized system also can reduce to footprint of the photobioreactor. The different attached-growth media can have different biomass attachments. Hence, this research aims to evaluate the biomass productivity on the different attached-growth media, photobioreactor treatment performances and crude protein contents under various operational conditions. In the first phase, the different attached-growth medias including fiber mesh, nylon mesh, polycarbonate plate, and polyethylene plate were prepared. Then, suspended algae growth was performed in the second phase by mixing AIT’s domestic wastewater with Chlorella sp. inoculum at the ratio of 70:30 respectively. Simultaneously, the prepared attached-media were tested to find the biomass productivity, then high biomass productivity attached media were obtained which are fiber mesh and nylon mesh. These two medias were used to install in PBRs under operational conditions in the next phase. In the operation phase, Tubular photobioreactors with 4.8L of effective volume, illuminated by red+blue LED (222 μmol/m2-s) were operated under low, medium and high strength wastewater with HRT of 6 days. Then, the last phase is kinetic model development, the HRTs were varied from 3,6,9 and 12 days under the same condition with operation phase. From the experimental results, the highest average value of biomass productivities obtained from high strength wastewater due to the most sufficient of nutrients supplied, and biomass productivity of fiber mesh were more than nylon mesh by 1.12 and 0.83 g/m2-d respectively, because the biomass harvested from fiber mesh was easier. For treatment performances of PBRs, attached-growth media did not affect to the removal efficiencies. The removal efficiencies of organic compounds were achieved 90% removal on both high strength and medium strength wastewater whereas the minimum obtained from low strength wastewater with less than 50% removal due to the limitation of heterotrophic bacteria. The TN removal efficiencies could be achieved more than 60% for both medium and low strength wastewater and the lowest TN removal efficiencies obtained from high strength wastewater with accounted for 37% removal. The highest TP removal efficiencies, removal efficiency was more than 40% under low strength wastewater, and the lowest removal efficiency obtained at high strength wastewater with the average of 26%. For crude protein contents, there were not different between wastewater loadings; hence, organic loadings, nitrogen loadings, and phosphorus loadings did not affect the crude protein contents. The crude protein contents were nearly constant with the average of 39.45% corresponding to crude protein content in Chlorella sp. which is the predominant species in the system. Furthermore, Stover-Kincannon model and first order model could be fit for both organic and nitrogen removal. In contrast, the first order model could be fit only the phosphorus removal. |
| Year | 2019 |
| Type | Thesis |
| School | School of Environment, Resources, and Development (SERD) |
| Department | Department of Energy and Climate Change (Former title: Department of Energy, Environment, and Climate Change (DEECC)) |
| Academic Program/FoS | Environmental Engineering and Management (EV) |
| Chairperson(s) | Thammarat Koottatep; |
| Examination Committee(s) | Chongrak Polprasert ;Visvanathan, C.;Weerakorn Ongsakul; |
| Scholarship Donor(s) | Royal Thai Government Fellowship; |
| Degree | Thesis (M.Eng.) - Asian Institute of Technology, 2019 |