Phosphorus removal using algae bacterial consortia in photo sequencing batch reactor (PSBR) | |
| Author | Mathew, Joseph |
| Call Number | AIT Thesis no.UWEM-17-02 |
| Subject(s) | Phosphate removal Photobacterium phosphoreum |
| Note | A thesis submitted in partial fulfillment of the requirements for the Degree of Master of Science in Urban Water Engineering and Management jointly offered by the Asian Institute of Technology, Thailand and UNESCO-IHE, The Netherlands |
| Publisher | Asian Institute of Technology |
| Series Statement | Thesis ; no. UWEM-17-02 |
| Abstract | For the development of agriculture and industrial sector phosphorus is an important element and since it has a very slow matter cycle it’s been obtained by mostly mining from the phosphate rock reserves which are limited. An urgent need has arisen to close the phosphorus cycle by recovering and recycling it from the municipal wastewater which otherwise pollute the waterbodies. When the municipal wastewater is treated with an anaerobic digester there is a high concentration of inorganics such as bicarbonates, ammonia and phosphate. The research study aims to recover/recycle phosphorus by chemical stripping in the mixed liquor of Photo Sequencing Batch Reactor (PSBR) via biologically mediated precipitation of calcium phosphate. The effluent coming from the anaerobic digester is treated using PSBR. In situ photo oxygenation by algae in PSBR helps bacteria to remove COD and nitrify the ammonia under controlled conditions. To achieve calcium phosphate precipitation, high pH is required which may affect the nitrifying biomass in PS BR. The effect of pH increase on the nitrifying biomass was studied by setting up two reactors having HRT of 24 hr. and SRT of 20 days in Phase 2, wherein reactor 1 was kept at controlled pH for 7 hr. and uncontrolled pH in the last 4 hr. of react stage. Reactor 2 was kept at controlled pH throughout the study period. Two PSBRs were setup with inoculum of algae obtained from AIT pond and sludge inoculum obtained from the sludge of AIT sewage treatment plant. Synthetic wastewater was used as influent for both the reactor s having characteristic similar to the effluent from anaerobic digester. Ammonium removal rate of 2.53±0.93 mg N - NH 3 . L - 1 . hr - 1 in Reactor 1 and 2.25±0.28 mg N - NH 3 .L - 1 .hr - 1 in Reactor 2 was observed. The pH controller was switched off in Reactor 1 during Phase 2 and allowing photosynthesis of algae to biologically increase pH when alkalinity was low in last 4hr. of the react stage. A pH of 8.3 and 9 were achieved at the end of react stage by varying the light intensity of led light. Calcium chloride was dosed to the mixed liquor of the reactor and allowed to settle for 30 mins. Phosphorus removal efficiency of 74 %± 19% at pH 9 and 25 %±7% at pH 8.3 was observed. Thus, biologically and chemically induced phosphorus removal/recovery was achieved in the reactor without affecting the nitrification process |
| Year | 2017 |
| Corresponding Series Added Entry | Asian Institute of Technology. Thesis ; no. UWEM-17-02 |
| Type | Thesis |
| School | School of Engineering and Technology |
| Department | Department of Civil and Infrastucture Engineering (DCIE) |
| Academic Program/FoS | Urban Water Engineering and Management (UWEM) |
| Chairperson(s) | Thammarat Koottatep;Steen, Nico Pieter van der |
| Examination Committee(s) | Annachhatre, Ajit P.;Shrestha, Sangam;Hullebusch, Eric Van |
| Scholarship Donor(s) | Bill & Melinda Gates Foundation through Sustainable Decentralized Wastewater Management in Developing Countries Project;UNESCO-IHE;AIT |
| Degree | Thesis (M. Sc.) - Asian Institute of Technology - UNESCO-IHE, 2017 |