Performance evaluation of attached-growth high rate algal pond equipped with an artificial light source | |
| Author | Jinda, Kesirine |
| Call Number | AIT Thesis no.EV-19-08 |
| Subject(s) | Microalgae--Biotechnology--Evaluation Wastewater--Treatment Algal biofuels--Dewatering |
| Note | A thesis submitted in partial fulfillment of the requirements for the degree of Master of Science in Environmental Engineering and Management |
| Publisher | Asian Institute of Technology |
| Abstract | Domestic wastewater containing high nutrients (Nitrogen and Phosphorus) is a big pollution problem worldwide which generally lead to various adverse ecological effects e.g. eutrophication. High Rate Alae Pond (HRAP) is considered to be a beneficial solution employing microalgae-bacteria symbiosis to treat wastewater and enhance more benefit from its biomass product. However, various limitations of the HRAP should be improved for increasing performance of the system. Consequently, a novel Attached-Growth High Rate Algal Pond (AHRAP) system equipped with artificial light source; combined light sources and attached media were expected to obtain more suitable light distribution and commercialize the microalgae cultivation system. Hence, this study aims to determine potential use of AHRAP system for enhancing microalgae biomass, maximizing protein productivity and treating domestic wastewater. Operation of AHRAP system was conducted in third phase, mixing of real AIT domestic wastewater and microalgae inoculum in ratio of 7:3 was used as culture media. Initially, culture media was cultivated in the AHRAPs for 7 days. Additionally, the three AHRAPs with 400L of working volume and specific area of attached media approximately 4.14 m2·m3 were operated under various conditions. The AHRAPs illuminated by optical fiber (OF; 46 to 121 μmol·m-2·s1), LED light (LED; 100 to 300 μmol·m-2·s1), and combined optical fiber and LED light (OF+LED; 46 to 300 μmol·m-2·s1) were fed by high strength domestic wastewater (domestic and blackwater) and operated with mixing linear velocity range 15 cm·s-1 under 4, 8, and 15 days of HRT. Results of the study, the pH was in range of 6.62 to 9.42 in all AHRAPs. Highest DO concentration was observed in OF+LED (0.84 to 8.05 mg/L). The result found that only sunlight penetration barely reached at the bottom (depths >0.35m) and lead to “light-limited zone” in control pond (average; 19 μmol·m-2·s-1). Luckily, applied light sources significantly promoted higher light intensity at depths > 0.35m and increasing of microalga biomass productivity, highest biomass growth approximately 33.55±11.018, and 27.24±8.73 g·m-2·d-1 at 0.35m, and 0.65m, respectively within 46 days. Maximum protein productivity approximately 34 g·m-2·d-1 (68 percent of protein content) was enhanced by OF+LED. For removal efficiency, the highest TCOD removal was found in OF+LED (88 and 94 percent at HRT to 8 and 15 days). Corresponded to TN removal efficiency was observed highest in OF (60 percent ). TP removal efficiency, the OF+LED provided highest value approximately 69 percent under HRT 15 days. This study found that applied light sources in attached growth cultivation promoted better light transmittance from light sources directly to microalgal biofilm. However, different light sources were not affect the organic removal efficiency but it had effects on TN and TP removal regarding to different light intensity contributed different microalgae growth for eliminating nitrogen and phosphorus concentration in culture media. Furthermore, the first-order and Stover-kincannon kinetic model could be mostly applicable to COD and phosphorus removal, but fairly applicable to nitrogen removal in AHRAP system. Therefore, the AHRAP lighted by OF+LED provides optimum operation conditions and beneficial approach for operating deeper HRAP enhancing microalgae biomass and protein productivity along with treating wastewater with economically viable. |
| 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;Weerakorn Ongsakul; Shipin, Oleg V.; |
| Scholarship Donor(s) | Bangchak Initiative and Innovation Center (BICC@AIT) ;Royal Thai Government Fellowship; |
| Degree | Thesis (M.Sc.) - Asian Institute of Technology, 2019 |