The simultaneous treatment of different produced water streams with the forward osmosis membrane distillation hybrid system (FO-MD) has been suggested recently. This work
investigates the need for pretreatment of produced water prior to filtration with FO-MD in order
to reduce the level of fouling and scaling in the system. The desalter effluent (DE) stream was
selected as FO feed solution, and the water oil separator (WO) stream was used as FO draw
solution/MD feed solution, and a significant flux decline was observed in FO and MD within the
first 5 hours of operations. SEM and EDX analysis indicated that the formation of scale layer on
both membranes was the main reason for the sharp flux decline. Silica was the major contributor
to the scaling of the support layer of the FO membrane. While the scaling layer on MD membrane
consisted mainly of CaSO4 crystals with some deposition of Silica. Therefore, electrocoagulation
(EC) was selected for the pretreatment of produced water to target the removal of Ca, SiO2 and
SO4 ions in order to reduce the likelihood of inorganic fouling in FO-MD. The different
parameters of EC, namely, the current density, electrolysis time, and initial pH were tested at a
wide range of values of 7-70 mA/cm2
, 10-60 minutes, 5-9, respectively. calcium and sulfate ions
were not effectively removed at the relatively high applied current density of 70 mA/cm2
, while
high removal of silica was achieved even at low applied current densities. The optimum
conditions of EC for silica removal were found to be 7 mA/cm2 for the current density and 10
minutes for the electrolysis time which resulted in a 97% removal of silica. it was found that due
to pretreatment, the average FO and MD fluxes increased by 49% (9.93 LMH) and 39% (8.55
LMH), respectively. Therefore, even though EC did not show promising results in terms of the
removal of calcium and sulfate, efficient silica removal was achieved with minimum energy
requirements which suggests that it could have a potential to be integrated with the FO-MD
hybrid system for the treatment and reclamation of produced water.
| Identifer | oai:union.ndltd.org:kaust.edu.sa/oai:repository.kaust.edu.sa:10754/670251 |
| Date | 07 1900 |
| Creators | Alqulayti, Abdullah |
| Contributors | Ghaffour, NorEddine, Biological and Environmental Science and Engineering (BESE) Division, Saikaly, Pascal, Fortunato, Luca, Saqib Nawaz, Muhammad |
| Source Sets | King Abdullah University of Science and Technology |
| Language | English |
| Detected Language | English |
| Type | Thesis |
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