Combined organic and colloidal fouling in forward osmosis: Fouling reversibility and the role of applied pressure

Abstract In this study, we systematically investigated the propensity and reversibility of combined organic–colloidal fouling in forward osmosis (FO) under various solution chemistries (pH and calcium ion concentrations) and applied hydraulic pressure on the feed side. Alginate, silica colloids, and their mixture (i.e., combined organic–colloidal) were used as model foulants. Our findings demonstrate that combined organic–colloidal foulants caused more rapid flux decline than the individual foulants due to the synergistic effect of alginate and silica colloids. As a result, much lower flux recovery was achieved by physical cleaning induced by increasing the cross-flow rate, in contrast to single foulants of which the fouling layer was easily removed under all solution conditions. Interestingly, less flux decline was observed at neutral pH for combined fouling, while acidic conditions were favorable for alginate fouling and basic solutions caused more silica fouling, thereby providing clear evidence for the combined fouling effect. It was also found that calcium ions enhanced water flux decline and induced the formation of less reversible combined organic–colloidal fouling layers. Lastly, the role of applied hydraulic pressure on the feed side in FO was examined to elucidate the mechanism of fouling layer formation, fouling reversibility, and water flux recovery. Higher fouling propensity and lower fouling reversibility of combined organic–colloidal fouling were observed in the presence of applied hydraulic pressure on the feed side. This observation suggests that the lower fouling propensity and greater fouling reversibility in FO compared to reverse osmosis (RO), are attributable to unpressurized operating conditions in FO.

[1]  Menachem Elimelech,et al.  Comparison of fouling behavior in forward osmosis (FO) and reverse osmosis (RO) , 2010 .

[2]  J. McCutcheon,et al.  Influence of concentrative and dilutive internal concentration polarization on flux behavior in forward osmosis , 2006 .

[3]  Menachem Elimelech,et al.  A novel ammonia-carbon dioxide forward (direct) osmosis desalination process , 2005 .

[4]  Tong Zhan,et al.  Flux patterns and membrane fouling propensity during desalination of seawater by forward osmosis. , 2012, Water research.

[5]  Baltasar Peñate,et al.  Current trends and future prospects in the design of seawater reverse osmosis desalination technology , 2012 .

[6]  Amy E. Childress,et al.  Forward osmosis: Principles, applications, and recent developments , 2006 .

[7]  I. Pinnau,et al.  Fouling of reverse osmosis membranes by biopolymers in wastewater secondary effluent: Role of membrane surface properties and initial permeate flux , 2007 .

[8]  R. A. Tidball,et al.  Waste heat powered reverse osmosis plants , 1981 .

[9]  Menachem Elimelech,et al.  Colloidal Fouling of Reverse Osmosis Membranes: Measurements and Fouling Mechanisms , 1997 .

[10]  Long D. Nghiem,et al.  Membrane fouling and chemical cleaning in water recycling applications , 2010 .

[11]  Gurdev Singh,et al.  Impact of feed water acidification with weak and strong acids on colloidal silica fouling in ultrafiltration membrane processes. , 2008, Water research.

[12]  Menachem Elimelech,et al.  Fouling of reverse osmosis membranes by hydrophilic organic matter: implications for water reuse , 2006 .

[13]  Menachem Elimelech,et al.  Silica scaling and scaling reversibility in forward osmosis , 2013 .

[14]  Anthony G Fane,et al.  Colloidal interactions and fouling of NF and RO membranes: a review. , 2011, Advances in colloid and interface science.

[15]  Menachem Elimelech,et al.  Fouling and cleaning of RO membranes fouled by mixtures of organic foulants simulating wastewater ef , 2011 .

[16]  M. Elimelech,et al.  Organic fouling of forward osmosis membranes: Fouling reversibility and cleaning without chemical reagents , 2010 .

[17]  Mingheng Li.  Reducing specific energy consumption in Reverse Osmosis (RO) water desalination: An analysis from first principles , 2011 .

[18]  Menachem Elimelech,et al.  Forward with osmosis: emerging applications for greater sustainability. , 2011, Environmental science & technology.

[19]  Menachem Elimelech,et al.  Combined influence of natural organic matter (NOM) and colloidal particles on nanofiltration membrane fouling , 2005 .

[20]  Amy E. Childress,et al.  The forward osmosis membrane bioreactor: A low fouling alternative to MBR processes , 2009 .

[21]  M. Elimelech,et al.  The Future of Seawater Desalination: Energy, Technology, and the Environment , 2011, Science.

[22]  H. Ngo,et al.  A mini-review on membrane fouling. , 2012, Bioresource technology.

[23]  Menachem Elimelech,et al.  Energy requirements of ammonia-carbon dioxide forward osmosis desalination , 2007 .

[24]  Thomas Melin,et al.  State-of-the-art of reverse osmosis desalination , 2007 .

[25]  Menachem Elimelech,et al.  Chemical and physical aspects of organic fouling of forward osmosis membranes , 2008 .

[26]  Yaolin Liu,et al.  Combined fouling of forward osmosis membranes: Synergistic foulant interaction and direct observation of fouling layer formation , 2012 .

[27]  Menachem Elimelech,et al.  Synergistic effects in combined fouling of a loose nanofiltration membrane by colloidal materials and natural organic matter , 2006 .

[28]  Linda Zou,et al.  Recent developments in forward osmosis : opportunities and challenges. , 2012 .

[29]  Menachem Elimelech,et al.  Chemical and physical aspects of natural organic matter (NOM) fouling of nanofiltration membranes , 1997 .

[30]  Menachem Elimelech,et al.  Global challenges in energy and water supply: the promise of engineered osmosis. , 2008, Environmental science & technology.

[31]  R. Sheikholeslami,et al.  Silica fouling and cleaning of reverse osmosis membranes , 2001 .

[32]  K. Xiao,et al.  A new perspective on the effect of complexation between calcium and alginate on fouling during nanofiltration , 2011 .

[33]  Menachem Elimelech,et al.  Colloidal fouling in forward osmosis: Role of reverse salt diffusion , 2012 .

[34]  C. D. Lundin,et al.  A multi-barrier osmotic dilution process for simultaneous desalination and purification of impaired water , 2010 .