Forward osmosis for concentration of anaerobic digester centrate.

The nutrient-rich liquid stream produced during the dewatering of digested biomass (i.e., the centrate) is commonly mixed with the influent raw wastewater at wastewater treatment facilities. This increases the nitrogen and phosphorus loading on biological processes, increases operating costs, and in some cases, results in increased nutrient concentrations in the final effluent. Forward osmosis (FO) is a membrane treatment process that was investigated at bench scale to determine its feasibility to concentrate centrate under both batch and continuous operating conditions. The continuous bench-scale system used FO as pretreatment for reverse osmosis (RO). Results demonstrated that high water flux and high nutrient rejection could be achieved. The combined FO/RO process exhibited sustainable flux over an extended time period. A mathematical model was developed in order to determine the specific energy, power, and membrane area requirements for a larger-scale centrate treatment process. Modeling results indicated that to optimize power and membrane area requirements, the system should be operated at approximately 70% water recovery.

[1]  Awwa,et al.  Standard Methods for the examination of water and wastewater , 1999 .

[2]  Menachem Elimelech,et al.  Influence of membrane surface properties on initial rate of colloidal fouling of reverse osmosis and nanofiltration membranes , 2001 .

[3]  Matthias Wessling,et al.  Nutrient removal by NF and RO membranes in a decentralized sanitation system. , 2005, Water research.

[4]  Edward Beaudry,et al.  DIRECT OSMOSIS FOR CONCENTRATING WASTEWATER , 1997 .

[5]  Hansruedi Siegrist,et al.  Biological treatment of ammonium-rich wastewater by partial nitritation and subsequent anaerobic ammonium oxidation (anammox) in a pilot plant. , 2002, Journal of biotechnology.

[6]  H. D. Stensel,et al.  Wastewater Engineering: Treatment and Reuse , 2002 .

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

[8]  W. Godwin.  Article in Press , 2000 .

[9]  C Hellinga,et al.  Full-scale application of the SHARON process for treatment of rejection water of digested sludge dewatering. , 2001, Water science and technology : a journal of the International Association on Water Pollution Research.

[10]  Raphael Semiat,et al.  Backwash of RO spiral wound membranes , 2005 .

[11]  Tzahi Y. Cath,et al.  Membrane contactor processes for wastewater reclamation in space: II. Combined direct osmosis, osmotic distillation, and membrane distillation for treatment of metabolic wastewater , 2005 .

[12]  Dana Karl Anderson.  Concentration of Dilute Industrial Wastes by Direct Osmosis , 1977 .

[13]  Michael Flynn,et al.  Membrane contactor processes for wastewater reclamation in space Part I. Direct osmotic concentration as pretreatment for reverse osmosis , 2005 .

[14]  M. Elimelech,et al.  Relating organic fouling of reverse osmosis membranes to intermolecular adhesion forces. , 2006, Environmental science & technology.

[15]  Gideon Oron,et al.  A two stage membrane treatment of secondary effluent for unrestricted reuse and sustainable agricultural production , 2006 .

[16]  Tzahi Y Cath,et al.  Removal of natural steroid hormones from wastewater using membrane contactor processes. , 2006, Environmental science & technology.

[17]  H. Siegrist,et al.  Prediction of recycle phosphorus loads from anaerobic digestion , 1997 .

[18]  Y Ueno,et al.  Three Years Experience of Operating and Selling Recovered Struvite from Full-Scale Plant , 2001, Environmental technology.

[19]  Robert L McGinnis,et al.  Desalination by ammonia–carbon dioxide forward osmosis: Influence of draw and feed solution concentrations on process performance , 2006 .

[20]  A. E. Greenberg,et al.  Standard methods for the examination of water and wastewater : supplement to the sixteenth edition , 1988 .