Application of aquaporin-based forward osmosis membranes for processing of digestate liquid fractions

[EN] Forward osmosis is a low-energy water treatment emerging technology, which has demonstrated improved solute rejection and low fouling propensity. In this study, the applicability of aquaporin-based forward osmosis membranes during separation of biogas digestate liquid fractions was investigated. The results showed that Total Ammonia-Nitrogen rejection was higher than 95.5% in all experiments, independently of the type of draw solution (NaCl and hide preservation effluents), experimental period and the use of feed acidification. The results also confirmed that high draw osmotic pressures (i.e. 3.5¿M sodium chloride and hide preservation wastewater) combined with feed acidification had a negative effect on the membrane water permeability. Membrane rinsing after fouling was also successful in recovering the membrane initial water flux as well as removing the remaining foulants on the membrane surface. The membrane inspection results from Scanning-Electron Microscope, Energy-Dispersive X-Ray analysis and Fourier Transform Infrared¿Attenuated Total Reflectance showed that fouling in this application was mild and reversible after membrane rinsing. The applicability of aquaporin-based forward osmosis membranes during separation of biogas digestate liquid fractions has been demonstrated. The results showed the potential of this technology to achieve enhanced ammonia-nitrogen rejections and low-fouling propensity.The authors thank the tannery factory in the region of Murcia (Spain) for providing the wastewater samples as well as Depuración de Aguas del Mediterráneo (DAM, Spain) for funding the forward osmosis project. Thanks to August Bonmatí from IRTA GIRO Joint Research Unit IRTA-UPC, for providing the digestate liquid fractions, to Rebeca Vidal-Pérez as student assistant during the chemical analysis and to the Electron Microscopy Service from the Polytechnic University of Valencia (UPV, Spain). The authors further acknowledge funding from People Programme (Marie Curie Actions) of the European Union Seventh Framework Programme FP7/2007-2013/under REA grant agreement n° [289887].Camilleri-Rumbau, MDLS.; Soler-Cabezas, JL.; Christensen, KV.; Norddahl, B.; Mendoza Roca, JA.; Vincent Vela, MC. (2019). Application of aquaporin-based forward osmosis membranes for processing of digestate liquid fractions. Chemical Engineering Journal. 371:583-592. https://doi.org/10.1016/j.cej.2019.02.029S58359237

Fouling of a Spiral Wound Reverse Osmosis Membrane processing Swine Wastewater:Effect of Cleaning Procedure on Fouling Resistance

<p>Swine manure is a valuable source of nitrogen, phosphorus and potassium. After solid–liquid separation, the resulting swine wastewater can be concentrated by reverse osmosis (RO) to produce a nitrogen–potassium rich fertilizer. However, swine wastewater has a high fouling potential and an efficient cleaning strategy is required. In this study, a semi-commercial farm scale RO spiral-wound membrane unit was fouled while processing larger volumes of swine wastewater during realistic cyclic operations over a 9-week period. Membrane cleaning was performed daily. Three different cleaning solutions, containing SDS, SDS+EDTA and NaOH were compared. About 99% of the fouling resistance could be removed by rinsing the membrane with water. Flux recoveries (FRs) above 98% were achieved for all the three cleaning solutions after cleaning. No significant differences in FR were found between the cleaning solutions. The NaOH solution thus is a good economical option for cleaning RO spiral-wound membranes fouled with swine wastewater. Soaking the membrane for 3 days in permeate water at the end of each week further improved the FR. Furthermore, a fouling resistance model for predicting the fouling rate, permeate flux decay and cleaning cycle periods based on processing time and swine wastewater conductivity was developed.</p