Martin Mondor

Nitrogen potential recovery and concentration of ammonia from swine manure using electrodialysis coupled with air stripping

The practice of intensive animal production in certain areas has resulted in excessive manure production for the available regional land base. Consequently, there is a need to develop treatment technologies to recover the valuable nutrients that manure contains so that the resulting product can be transported and used as fertilizer on agricultural land. The project presented here used electrodialysis in a dilution/concentration configuration to transfer the manure ammonia in the diluate solution by electromigration to an adjacent solution separated by an ion-exchange membrane under the driving force of an electrical potential. Then, air stripping from the electrodialysis-obtained concentrate solution without pH modification was used to isolate the ammonia in an acidic solution. An optimal process operating voltage of 17.5 V was first determined on the basis of current efficiency and total energy consumption. During the process, the swine manure pH varied from 8.5 to 8.2, values favourable for NH(4)(+) electromigration. Total ammonia nitrogen reached 21,352 mg/L in the concentrate solution, representing approximately seven times the concentration in the swine manure. Further increases in concentration were limited by water transfer from the diluate solution due to electroosmosis and osmosis. Applying vacuum to the concentrate reservoir was found to be more efficient than direct concentrate solution aeration for NH(3) recuperation in the acid trap, given that the ammonia recuperated under vacuum represented 14.5% of the theoretical value of the NH(3) present in the concentrate solution as compared to 6.2% for aeration. However, an excessively low concentrate solution pH (8.6-8.3) limited NH(3)volatilization toward the acid trap. These results suggest that the concentrate solution pH needs to be raised to promote the volatile NH(3) form of total ammonia nitrogen.

Fouling characterization of electrodialysis membranes used for the recovery and concentration of ammonia from swine manure.

The aim of the present study was to: (1) identify the nature of fouling for ED membranes (AMX and CMB, from Tokuyama Soda, Japan) used for the isolation and concentration of total NH(3)-N from swine manure, (2) determine the effect of fouling on membrane integrity, (3) establish the relation between fouling type and manure composition, and (4) estimate the efficiency of a two-step cleaning procedure to restore membranes properties. After processing 10 batches of swine manure (or 240 L/m(2)), the average current density as well as the membranes electrical conductivity and ion-exchange capacity decreased. The decline in process performance was associated with membrane fouling, since a significant deposit, possibly calcium carbonate and silica colloidal particles, was observed on the fouled AMX membranes. The electrical conductivity and ion-exchange capacity of the CMB membrane was completely restored by a two-step cleaning procedure using 0.5% NaOH and 1% HCl. However, for the electrical conductivity of the AMX membranes it was only partially recovered. The on-line cleaning procedure efficiency was assessed by measuring the stack average current density and the decrease of manure conductivity during 1h tests. Values for the cleaned membranes were, respectively, 95% and 91% the ones measured with the new membranes, and were significantly higher than for the fouled membranes.

Flaxseed‐Enriched Cereal‐Based Products: A Review of the Impact of Processing Conditions

The properties of cereals products, bread, pasta, muffins, cookies, cakes, and bars, enriched with flaxseed, were reviewed to highlight suitable processing conditions for the production of high-quality flaxseed-enriched products with the desired health attributes. The review highlights the contrasting effect of flaxseed enrichment on the mechanical and physical properties of cereal products according to product type, flaxseed enrichment level, and processing history. Flaxseed lipids remain stable for most processing and storage conditions, presumably due to the significant antioxidant properties of lignans, but information is lacking on the impact of home-handling, such as bread toasting, on lipid oxidation. Cereal products enriched with flaxseed generally exhibit similar or improved shelf life compared to equivalent products with no flaxseed enrichment, suggesting that flaxseed may limit starch retrogradation, maintain moisture content, and delay microbial growth. Sensory analysis shows lower organoleptic properties of most cereal products containing flaxseed, but similar consumer acceptance for cereal products without and with flaxseed enrichment up to 15% is reported in the literature. This review indicates the need to better understand the impact of flaxseed enrichment on product microstructure and to conduct an extensive assessment of the health effects of flaxseed-enriched products, since very few studies have focused on the quantification of the bioaccessibility, bioavailability, and activity of flaxseed bioactive compounds for a variety of processing conditions and product formulation.

Time–Temperature Management Along the Food Cold Chain: A Review of Recent Developments

The cold chain is responsible for the preservation and transportation of perishable foods in the proper temperature range to slow biological decay processes and deliver safe and high-quality foods to consumers. Studies show that the efficiency of the cold chain is often less than ideal, as temperature abuses above or below the optimal product-specific temperature range occur frequently, a situation that significantly increases food waste and endangers food safety. In this work, field studies on time-temperature conditions at each critical stage of the cold chain are reviewed to assess the current state of commercial cold chains. Precooling, ground operations during transportation, storage during display at retail and in domestic refrigerators, and commercial handling practices are identified and discussed as the major weaknesses in the modern cold chain. The improvement in efficiency achieved through the measurement, analysis, and management of time-temperature conditions is reviewed, along with the accompanying technical and practical challenges delaying the implementation of such methods. A combination of prospective experimental and modeling research on precooling uniformity, responsive food inventory management systems, and cold chains in developing countries is proposed for the improvement of the cold chain at the global scale.

Drying of Durum Wheat Pasta and Enriched Pasta: A Review of Modeling Approaches.

Models on drying of durum wheat pasta and enriched pasta were reviewed to identify avenues for improvement according to consumer needs, product formulation and processing conditions. This review first summarized the fundamental phenomena of pasta drying, mass transfer, heat transfer, momentum, chemical changes, shrinkage and crack formation. The basic equations of the current models were then presented, along with methods for the estimation of pasta transport and thermodynamic properties. The experimental validation of these models was also presented and highlighted the need for further model validation for drying at high temperatures (>−100°C) and for more accurate estimation of the pasta diffusion and mass transfer coefficients. This review indicates the need for the development of mechanistic models to improve our understanding of the mass and heat transfer mechanisms involved in pasta drying, and to consider the local changes in pasta transport properties and relaxation time for more accurate description of the moisture transport near glass transition conditions. The ability of current models to describe dried pasta quality according to the consumers expectations or to predict the impact of incorporating ingredients high in nutritional value on the drying of these enriched pasta was also discussed.

Correction to Protein-Protein Multilayer Oil-in-Water Emulsions for the Microencapsulation of Flaxseed Oil: Effect of Whey and Fish Gelatin Concentration.

The impact of whey protein isolate (WPI) and fish gelatin (FG) deposited sequentially at concentrations of 0.1, 0.5, and 0.75% on the surface of primary oil-in-water emulsions containing 5% flaxseed oil stabilized with either 0.5% fish gelatin or whey protein, respectively, was investigated. The results revealed that the adsorption of WPI/FG or FG/WPI complexes to the emulsion interface led to the formation of oil-in-water (o/w) emulsions with different stabilities and different protection degrees of the flaxseed oil. Deposition of FG on the WPI primary emulsion increased the particle size (from 0.53 to 1.58 μm) and viscosity and decreased electronegativity (from -23.91 to -11.15 mV) of the complexes. Different trends were noted with the deposition of WPI on the FG primary emulsion, resulting in decreasing particle size and increasing electronegativity and viscosity to a lower extent. Due to the superior tension-active property of WPI, the amount of protein load in the WPI primary emulsion as well as in WPI/FG complex was significantly higher than the FG counterparts. A multilayer emulsion made with 0.5% WPI/0.75% FG exhibited the lowest oxidation among all of the multilayered emulsions tested (0.32 ppm of hexanal) after 21 days, likely due to the charge effect of FG that may prevent pro-oxidant metals to interact with the flaxseed oil.

Membrane filtration of the liquid fraction from a solid–liquid separator for swine manure using a cationic polymer as flocculating agent

The liquid fraction from a solid–liquid separator for swine manure, which used a cationic polymer to promote particle flocculation, was processed by one nanofiltration and two reverse osmosis spiral-wound membranes. Eight different liquid fraction batches (750 to 1750 L) were concentrated at volumetric concentration ratios (VCRs, initial to final volumes) ranging from 2.3 to 4.2. Membrane fouling intensity was highly variable, as water flux recovery after concentration cycles ranged from 13% to 88%. The most severe fouling was caused by a liquid fraction that had relatively low suspended solids (SS) (774 mg/L) and was concentrated at a low VCR of 2.6. Raw manure collected the same day also contained low SS, suggesting that fewer sites were available for polymer adsorption and thus more polymer remained in the liquid. However, because of the high opacity of the samples, residual polymer could not be detected in any feed or concentrate samples. Fouling was not totally irreversible as over 97% of membrane flux could be recovered by cleaning with acidic and alkaline solutions. Further tests with spiked liquid fractions indicated that fouling due to residual polymer in solution started to occur at a polymer concentration of 3 and 11 mg/L in initial and concentrated effluents, respectively. If a cationic polymer is used to pretreat manure, the amount of added polymer would have to be closely related to SS content as opposed to manure volume, in order to leave very little residual polymer in solution.

Electrodialysis in food processing

Electrodialysis is a membrane technology that is used increasingly in the food sector to concentrate, purify, or modify the properties of foods. Electrodialysis can be performed in a dilution-concentration mode (conventional electrodialysis) when anion exchange and cation exchange membranes are used, or for pH modification when bipolar membranes are used (electrodialysis with bipolar membranes). Advantages of the technology include a modular design, product purification with no dilution, efficiency, pH variation and adjustment with no addition of external solutions, and the lack of requirements for additional thermal treatment. Today, the most important use of conventional electrodialysis is the desalination of brackish water for the production of potable water. However, other applications are gaining increasing importance including large-scale industrial installations in the food industry, whey and molasses demineralization, tartaric stabilization of wine, and deacidification of fruit juices). Electrodialysis using bipolar membranes is also used at the industrial scale to produce organic acid. Other applications currently under development that have potential for future industrial applications include the production of plant protein isolates, production of acid caseinates, fractionation of whey proteins, regeneration of wastewater resulting from food processing, and separation of peptides using an ultrafiltration–electrodialysis integrated process. The chapter summarizes some of the key industrial scale applications of both electrotechnologies in the food sector. Furthermore a few selected applications under development are briefly presented, with emphasis on the applications having the most potential to help in environmental protection.

Study of total dry matter and protein extraction from canola meal as affected by the pH, salt addition and use of zeta-potential/turbidimetry analysis to optimize the extraction conditions

Total dry matter and proteins were differentially and preferentially extracted from canola meal (CM) under different conditions. The effect of the extraction medium pH, CM concentration and salt concentrations were found to have different influences on the extractability of total dry matter and proteins from CM. The pH of the extracting medium had the most significant effect. The maximal total dry matter (42.8±1.18%) extractability was obtained with 5% CM at pH 12 without salt addition, whereas the maximal for total protein (58.12±1.47%) was obtained with 15% CM under the same conditions. The minimal extractability for the dry matter (26.63±0.67%) was obtained with 5% CM at pH 10 without salt added and the minimal protein extractability was observed in a 10% CM at pH 10, in 0.01 NaCl. Turbidity and ζ-potential measurements indicated that pH 5 was the optimum condition for the highest protein extraction yield. SDS-PAGE analysis showed that salt addition contributes to higher solubility of canola proteins specifically cruciferin fraction, although it reduces napin extraction.

Fouling of a spiral-wound reverse osmosis membrane processing swine wastewater: effect of cleaning procedure on fouling resistance.

ABSTRACT 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.