Membrane hybrid system for removal of PFOS and PFOA in industrial wastewater : application of conventional adsorbents and nanoparticles | |
| Author | Romchat Rattanaoudom |
| Call Number | AIT Diss. no.EV-11-05 |
| Subject(s) | Sewage--Purification Perfluorooctanoic acid |
| Note | A dissertation submitted in partial fulfillment of the requirement for the degree of Doctor of Engineering in Environmental Engineering and Management Inter-University Program on Environmental Toxicology, Technology and Management, School of Environment, Resources and Development |
| Publisher | Asian Institute of Technology |
| Abstract | Perfluorooctane sulfonate (PFOS) and perfluorooctanoic acid (PFOA), anthropogenic compounds, are mainly used in industries such as semiconductor manufacturer, etc. The conventional wastewater treatments have failed to remove these compounds from industrial effluents. Therefore, they have been detected in different water matrixes for many decades. Moreover, the announcement of PFOS as new "Persistent Organic Pollutants" in 2009 has raised concerns and indicated a research need to develop effective treatment technologies to remove the compound from industrial wastewater. This study investigated sorption, direct membrane filtration and membrane hybrid processes for removal of these compounds from the wastewater. Moreover, iso-propanol (IPA), a major contaminant found in the wastewater, was tested to investigate its effect on efficiency of the treatments. This study revealed that hybrid nanofiltration (NF) with application of powder activated carbon (PAC) and hydrotalcite was the most effective treatment. In sorption experiment, six different adsorbents (PAC, hydrotalcite, anionic resin, chitosan, alumina, ZnO nanopowder) were tested. Among them, PAC and hydrotalcite showed more than 97% compounds removal therefore, they were further studied for the sorption behavior. The kinetic study revealed that the equilibrium sorption of PAC was reached within 4 hours whereas that of hydrotlacite was achieved within 1 hour. There was no significant effect of pH on the sorption capacity. However, low solution pH (pH 3) resulted in higher initial sorption rate of both adsorbents than high solution pH (pH 7 in PAC test and pH 9 in hydrotalcite test). The isotherm study indicated that monolayer of compounds were adsorbed onto PAC surface having 0.88 and 1.03 mmol g-1 of q01 with PFOS and PFOA, respectively. While in hydrotalcite case, multilayer of compounds being adsorbed was revealed. Furthermore, 10 g/L of IP A decreased sorption efficiency up to 10% in both adsorbents. The membrane filtration experiment reveals that TS80 membrane having highest salt rejection presented more than 98% of compounds removal. But the severe reduction of its permeate flux, which was up to 40% within 12 h of filtration, presented. Drop of permeate flux was enhanced with increasing compound concentration and addition of IP A. XN45 (another NF), UEIO and UA50 (two UF membranes) demonstrated 44-86% of compounds removal, in which PFOS removal was higher than that of PFOA. In hybrid membrane experiment, TS80 hybrid process with application of PAC and hydrotalcite was found to be the most effective scheme for removal of PFOS and PFOA. It revealed greater than 99% of compounds removal with a high permeate flux as compared to direct membrane filtration. In addition to its action as a barrier in reducing direct compound attachment to membrane, adsorbent on membrane also resulted in scouring effect leading to reduction of fouling. The scouring action was confirmed by similar vertical acting forces especially on PAC particles. Moreover, hydrotalcite layer on membrane was found to enhance around 8% and 30% of PFOS and PFOA rejection respectively by XN45. IPA had no significant effect on efficiency of the hybrid process in terms of compound removal and permeate flux as compared to other treatments. Furthermore, in the comparison of adsorbent amounts used in hybrid processes and sorption alone, the amounts used in the former were less than 80% of those used in the later, to achieve the same removal efficiency. |
| Year | 2011 |
| Type | Dissertation |
| 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) | Visvanathan, Chettiyappan ; Jutamaad Satayavivad |
| Examination Committee(s) | Preeda Parkpian ;Dutta, Joydeep ; Fujii, Shigeo |
| Scholarship Donor(s) | Chulabhorn Research Institute I Mahidol University I RTG Fellowship (CRI-MU-RTG) |
| Degree | Thesis (Ph.D.) - Asian Institute of Technology - Chulabhorn Research Institute - Mahidol University, 2011 |