Abstract
A brackish borehole located at a rural school in northern Tanzania contains excessive salinity (TDS = 3632 mg/L) and fluoride concentration (F− = 47.6 mg/L). This field study evaluated the feasibility of a solar-powered nanofiltration/reverse osmosis (NF/RO) system in treating this brackish water to make it potable. Key performance parameters such as permeate productivity, fluoride retention and specific energy consumption (SEC) were compared among four different NF/RO membrane modules (BW30, BW30-LE, NF90, and NF270). The NF90 membrane exhibited the best overall performance, balancing permeate productivity and quality, with 1582 L of clean drinking water being produced with an average SEC of 1.6 kWh/m3 over a solar day, while the NF270 could not meet the guideline values for fluoride. Further, the impact of fluctuating solar energy on system performance was studied. Very brief periods of heavy cloud cover in the afternoon affected transmembrane pressure and feed flow, and thus caused the permeate quality to temporarily exceed the guideline values. However, when considering that the permeate was stored in a product tank and was produced over the whole solar day, the system equipped with the NF90 membrane was able to produce high-quality drinking water that, on average, easily meets the guideline values despite the energy fluctuations.
| Original language | English |
|---|---|
| Pages (from-to) | 445-452 |
| Number of pages | 8 |
| Journal | Separation and Purification Technology |
| Volume | 170 |
| Early online date | 28 Jun 2016 |
| DOIs | |
| Publication status | Published - 1 Oct 2016 |
Funding
Two Leverhulme Royal Society Africa Awards , SADWAT-Tanzania and SUCCESS , are acknowledged for partial project funding. A PhD studentship for Junjie Shen is provided by Energy Technology Partnership (ETP) Scholarship with the Drinking Water Quality Regulator for Scotland (DWQR) being the industrial sponsor. The authors would like to express their gratitude to: Peniel Shali (Hai Institute of Technology, Tanzania) for the guidance in collecting water; Godfrey Mkongo (NDRS, Tanzania) for his hospitality, cooperation and permission to carry out the experiments at NDRS; Geert Aschermann (TU Berlin, Germany) for his active participation in the field trial; and Dr Gudrun Abbt-Braun (Karlsruhe Institute of Technology, Germany) for arranging the ICP-OES analysis of the feedwater samples. Dow Chemicals are thanked for generously donating many NF/RO modules, and GE Power & Water (Zenon) for the provision of the UF module.
Keywords
- Brackish groundwater
- Energy fluctuations
- Fluoride
- Nanofiltration
- Photovoltaics
- Reverse osmosis
ASJC Scopus subject areas
- Analytical Chemistry
- Filtration and Separation
