Sea salt bittern-driven forward osmosis for nutrients enrichment and recovery from black water | |
| Author | May Zaw |
| Call Number | AIT Thesis no.EV-19-12 |
| Subject(s) | Water--Purification--Membrane filtration Wastewater--Treatment Osmosis |
| Note | A thesis submitted in partial fulfillment of the requirements for the degree of Master of Engineering in Environmental Engineering and Management |
| Publisher | Asian Institute of Technology |
| Abstract | Black water contains a large amount of nutrients (80% Phosphorous & 50% Nitrogen in a volume of municipal wastewater) that are available for resource recovery. In this study, forward osmosis (FO) technology was proposed to enrich and recover N & P from pretreated black water namely low strength black water (effluent from a solar septic tank) and high strength black water (influent of a solar septic tank). In addition, sea salt bittern (SSB) was attempted as a novel draw solution of FO to enhance the filtration performance of the process. The performance of synthetic SSB as a draw solution was firstly investigated. High water flux of 25.67 ± 3.36 L/m2⋅hr was obtained by SSB, which was 1.7 times compared with synthetic sea water draw solution. Meanwhile, high Mg2+ accumulation was observed in feed solution which may enhance the recovered nutrients in form of Mg2+ salt. The limitation of SSB is low reverse solute selectivity due to high reverse solute flux. The performance of nutrients enrichment was studied. Low water flux was observed in high strength pretreated black water (3.42 ± 1.52 L/m2⋅hr) than low strength (14.17 ± 2.20 L/m2⋅hr) due to much severe membrane fouling. At feed volume reduction of 80%, 2-fold and 3.5-fold of TKN were enriched in low strength and high strength pretreated black water and 2.5-fold of phosphate was similarly enriched in both pretreated black water by the FO process. Total mass balance was calculated in low strength and high strength test systems. N and P in feed solution were enriched highly in high strength pretreated black water from mass balance calculation. Enriched N was mainly maintained in liquid phase. However, the form of recovered phosphorous varied with feed solution pH. With feed solution above pH 8.5, the phosphorous can be recovered in solid phase. The results of SEM-EDS further supported these findings, which indicated the recovered phosphorous in solid phase possibly Magnesium phosphate. |
| 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 (EV) |
| Chairperson(s) | Xue, Wenchao; |
| Examination Committee(s) | Visvanathan, C.;Thammarat Koottatep; |
| Scholarship Donor(s) | Loom Nam Khong Pijai (Greater Mekong Subregion) Scholarships; |
| Degree | Thesis (M.Eng.) - Asian Institute of Technology, 2019 |