Resin Fouling Research Articles

The fractal pack: New equipment for ion exchange operations in the sugar industry

The fractal pack is a new patented ion exchange configuration that is conceptually similar to a plate and frame filter press and contains a number of ion exchange plates held within a frame. With bed depths as shallow as 3 to 24 inches, this ion exchange system design results in a substantial reduction in capital cost by delivering the following benefits: compact equipment, modularity (by easy addition or removal of resin chambers from the existing frame), inexpensive capacity expansion / reduction and reduced installation costs. Furthermore, the capital and operating costs benefit from reductions in cycle times (and hence reduced resin fouling), regenerant use (and hence reduced chemical consumption and waste production), pressure drop, water consumption and product dilution. Increased resin loadings and longer life may also be possible. The plates are manufactured from corrosion resistant materials, making it possible to use aggressive resin regeneration chemicals if necessary. Testing has been carried out on both a small pilot / bench scale as well as a large pilot scale for several potential applications across a range of industries. In the sugar industry, successful performance has been demonstrated in the decolorization and softening of juice and syrups. Experimental work at various scales has confirmed that performance is maintained on scale-up to fractal pack plates of full industrial size.

Efficient Water Softening in Heavy Oil Steamflood Operations

Summary Pigging of once through steam generators (OTSGs) has indicated various types of scales, the most predominant of these being silicates of hardness causing ions. It was noted that scaling propensity can potentially go up with higher steam quality (SQ) as the reject stream gets concentrated with ions. However, models suggested that there are benefits of higher SQ in enhancing fuel savings (8%) and electricity savings (2%) when SQ was increased by 20%. The challenges of higher SQ were noted in terms of increased scaling tendency and therefore the need for improved softening. In Field D, the service cycle, the backwash cycle, and the brining cycle were optimized leading to a gain in throughput and reduction in salt consumption. Service cycle improvement gained 30 to 130% in throughput between two regenerations, backwash cycle improvement by fluidizing the bed to nearly 35% helped gain 10% in throughput, and reduction of brining cycle from 75 to 48 minutes helped reduce salt consumption by 56% without impacting the throughput. In Field B, a 6-month pilot revealed that shallow shell resins where ion exchange is more efficient due to inert core (better intraparticle diffusion control) can enhance the throughput by 30 to 80% and simultaneously reduce the number of regenerations by 15 to 30%. Resin fouling is still a major challenge to contend with as oil can foul the resin and throughput can decline by 0.5 to 3 folds. In a plant operation, where there are multiple softener and brine vessels, there is a need to optimize them as a system. Reliability, availability, and maintainability (RAM) models are used in Field C to (a) address equipment configuration optimization with impact on capital capacity expansion project scope, (b) understand how net soft water delivery capacity was affected by increases in inlet hardness, and (c) assess through a comparison scenario if the large cost of addressing the valve issue in an upstream nutshell filter was worth the lost production opportunity related to unplanned downtime.

Analysis of fouling and breakthrough of process related impurities during depth filtration using confocal microscopy.

Titer improvement has driven process intensification in mAb manufacture. However, this has come with the drawback of high cell densities and associated process related impurities such as cell debris, host cell protein (HCP), and DNA. This affects the capacity of depth filters and can lead to carryover of impurities to protein A chromatography leading to early resin fouling. New depth filter materials provide the opportunity to remove more process related impurities at this early stage in the process. Hence, there is a need to understand the mechanism of impurity removal within these filters. In this work, the secondary depth filter Millistak+ X0HC (cellulose and diatomaceous earth) is compared with the X0SP (synthetic), by examining the breakthrough of DNA and HCP. Additionally, a novel method was developed to image the location of key impurities within the depth filter structure under a confocal microscope. Flux, tested at 75, 100, and 250 LMH was found to affect the maximal throughput based on the max pressure of 30 psi, but no significant changes were seen in the HCP and DNA breakthrough. However, a drop in cell culture viability, from 87% to 37%, lead to the DNA breakthrough at 10% decreasing from 81 to 55 L/m2 for X0HC and from 105 to 47 L/m2 for X0SP. The HCP breakthrough was not affected by cell culture viability or filter type. The X0SP filter has a 30%–50% higher max throughput depending on viability, which can be explained by the confocal imaging where the debris and DNA are distributed differently in the layers of the filter pods, with more of the second tighter layer being utilized in the X0SP.

Polymer-Coated Fiber Optic Sensor as a Process Analytical Tool for Biopharmaceutical Impurity Detection

Large-scale purification of monoclonal antibodies using Protein A affinity chromatography continues to be one of the dominant processes in the production of biopharmaceuticals. In order to reduce the processing cost, ensure the purity of the product, and enable safe resin reuse, it is important to (a) estimate the quality of these resins, and (b) quantify the process-related impurities. This article presents the possibility of using a sensitive, rugged optical system as a process analysis tool for the assessment of resin fouling by quantification of the impurities like Protein A, host cell proteins (HCPs), and histones present in the elute. We have developed a conducting polymer-coated fiber optic sensor to detect these impurities, a flow cell to bypass the column elute directly toward the sensor, and associated electronics to make it a portable device for onsite applications. Protein A impurities (3 to 100 ng/mL) have been measured in pure buffer samples, while HCPs (100 to 350 ng/mL) and histone impurities (5 ng/mL to $1~\mu \text{g}$ /mL approximately) were detected in composite elute samples. In comparison to enzyme linked immunosorbent assay (ELISA)-based techniques, this low-cost, user-friendly sensing device demonstrates fast detection and high sensitivity for real-time monitoring of all process-related impurities.

Analytical tools for monitoring changes in physical and chemical properties of chromatography resin upon reuse.

Protein A resins are often reused for multiple cycles to improve process economy during mAb purification. Significant reduction in binding capacity and product recovery are typically observed due to the presence of unwanted materials (foulants) deposited on the resin upon reuse. In this paper, we have used a wide spectrum of qualitative and quantitative analytical tools (particle size analysis, HPLC, fluorescence, SEM, MS, and FTIR) to compare the strengths and shortcomings of different analytical tools in terms of their capability to detect the fouling of the resin and relate it to chromatographic cycle performance. While each tool offers an insight into this complex phenomena, fluorescence is the only one that can be used for real-time monitoring of resin fouling. A correlation could be established between fluorescence intensity and the process performance attributes (like yield or binding capacity) impacted upon resin reuse. This demonstration of the application of fluorescence for real-time monitoring correlated empirically with process performance attributes and the results support its use as a PAT tool as part of a process control strategy. While the focus of this paper is on fouling of protein A chromatography resin, the approach and strategy are pertinent to other modes of chromatography as well.

The combined influence of hydrophobicity, charge and molecular weight on natural organic matter removal by ion exchange and coagulation

Three different source waters were investigated using virgin and pre-used anion exchange resins, coagulation, and ion exchange combined with coagulation (IEX&Coagulation). The hydrophobicity, size distribution and charge of natural organic matter (NOM) were used to evaluate its removal. Dissolved organic carbon (DOC) removal by pre-used IEX resin was 67–79%. A consistent ratio of different hydrophobicity fractions was found in the removed DOC, while the proportion and quantity of the molecular weight fraction around 1 kDa was important in understanding the treatability of water. For pre-used resin, organic compounds were hypothesised to be restricted to easily accessible exchange sites. Comparatively, virgin resin achieved higher DOC removals (86–89%) as resin fouling was absent. Charge density and the proportion of the hydrophobic fraction were found to be important indicators for the specific disinfection byproduct formation potential (DBP-FP). Treatment of raw water with pre-used resin decreased the specific DBP-FP by between 2 and 43%, while the use of virgin resin resulted in a reduction of between 31 and 63%. The highest water quality was achieved when the combination of IEX and coagulation was used, reducing DOC and the specific DBP-FP well below that seen for either process alone.

Process development in the Quality by Design paradigm: Modeling of Protein A chromatography resin fouling

Protein A chromatography is quite commonly used for capture of monoclonal antibodies from the clarified cell culture broths. Protein A resins are expensive and economic feasibility demands that the resin be reused for 50–300 cycles. Resin reuse is, however, accompanied by resin fouling, impacting both the binding and mass transfer characteristics of the resin. In the present study, we attempt to model the variations in binding and mass transfer characteristics of a commercially available Protein A resin, mAbSelect SuRe™, as a function of resin’s reuse. Simplified linear driving force modeling and kinetic modeling of Protein A chromatography step elution cycling data has been successfully used to predict resin performance up to 100 cycles based on fouling data up to 50 cycles. Fouling factor for Protein A resin has been empirically modeled as a function of binding and mass transfer characteristics of resin and the resin’s reuse using a combination of Buckingham’s π theorem and statistical analysis. The proposed empirical model enables reliable prediction of performance of Protein A resin as well as offers an improved understanding of the underlying mechanism behind the decline in resin performance during fouling.

Implementation of a fluorescence based PAT control for fouling of protein A chromatography resin

AbstractBACKGROUNDProtein A chromatography fouling is accompanied by two major events, one is the loss of protein A ligands and other is fouling due to non‐specific, irreversible interactions of foulants with resin particles. This paper presents implementation of process analytical technology based control for fouling of protein A chromatography resin using a novel, fluorescence based approach. This approach enables direct, in situ measurement of protein A ligand density as well as monitoring of resin fouling during resin reuse.RESULTSA novel, fluorescence based process analytical technology (PAT) tool has been designed and used for screening a variety of cleaning protocols. A two‐step cleaning protocol was created using this methodology. The above mentioned fluorescence based approach was successfully used to monitor fouling and to take a decision on when to initiate cleaning. This resulted in effective maintenance of dynamic binding capacity and step yield at 50 cycles (DBC: 97% of the original value vs 65% with conventional protocols and yield: 93% of the original value vs 73% with conventional protocols) and at 200 cycles (> 90% of the original value).CONCLUSIONSThe proposed fluorescence based approach has been effectively used for monitoring and control of resin fouling upon reuse, thereby resulting in a substantial increase in resin lifetime. © 2017 Society of Chemical Industry

Maximizing the functional lifetime of Protein A resins.

Protein A chromatography is currently the industry gold-standard for monoclonal antibody and Fc-fusion protein purification. The high cost of Protein A, however, makes resin lifetime and resin reuse an important factor for process economics. Typical resin lifetime studies performed in the industry usually examine the effect of resin re-use on binding capacity, yield, and product quality without answering the fundamental question of what is causing the decrease in performance. A two part mechanistic study was conducted in an attempt to decouple the effect of the two possible factors (resin hydrolysis and/or degradation vs. resin fouling) on column performance over lifetime of the most commonly used alkali-stable Protein A resins (MabSelect SuRe and MabSelect SuRe LX). The change in binding capacity as a function of sodium hydroxide concentration (rate of hydrolysis), temperature, and stabilizing additives was examined. Additionally, resin extraction studies and product cycling studies were conducted to determine cleaning effectiveness (resin fouling) of various cleaning strategies. Sodium hydroxide-based cleaning solutions were shown to be more effective at preventing resin fouling. Conversely, cold temperature and the use of stabilizing additives in conjunction with sodium hydroxide were found to be beneficial in minimizing the rate of Protein A ligand hydrolysis. An effective and robust cleaning strategy is presented here to maximize resin lifetime and thereby the number of column cycles for future manufacturing processes. © 2017 American Institute of Chemical Engineers Biotechnol. Prog., 33:708-715, 2017.

Regeneration of pilot-scale ion exchange columns for hexavalent chromium removal

Due to stricter regulations, some drinking water utilities must implement additional treatment processes to meet potable water standards for hexavalent chromium (Cr(VI)), such as the California limit of 10 μg/L. Strong base anion exchange is effective for Cr(VI) removal, but efficient resin regeneration and waste minimization are important for operational, economic and environmental considerations. This study compared multiple regeneration methods on pilot-scale columns on the basis of regeneration efficiency, waste production and salt usage. A conventional 1-Stage regeneration using 2 N sodium chloride (NaCl) was compared to 1) a 2-Stage process with 0.2 N NaCl followed by 2 N NaCl and 2) a mixed regenerant solution with 2 N NaCl and 0.2 N sodium bicarbonate. All methods eluted similar cumulative amounts of chromium with 2 N NaCl. The 2-Stage process eluted an additional 20–30% of chromium in the 0.2 N fraction, but total resin capacity is unaffected if this fraction is recycled to the ion exchange headworks. The 2-Stage approach selectively eluted bicarbonate and sulfate with 0.2 N NaCl before regeneration using 2 N NaCl. Regeneration approach impacted the elution efficiency of both uranium and vanadium. Regeneration without co-eluting sulfate and bicarbonate led to incomplete uranium elution and potential formation of insoluble uranium hydroxides that could lead to long-term resin fouling, decreased capacity and render the resin a low-level radioactive solid waste. Partial vanadium elution occurred during regeneration due to co-eluting sulfate suppressing vanadium release. Waste production and salt usage were comparable for the 1- and 2-Stage regeneration processes with similar operational setpoints with respect to chromium or nitrate elution.

In-column ATR-FTIR spectroscopy to monitor affinity chromatography purification of monoclonal antibodies.

In recent years many monoclonal antibodies (mAb) have entered the biotherapeutics market, offering new treatments for chronic and life-threatening diseases. Protein A resin captures monoclonal antibody (mAb) effectively, but the binding capacity decays over repeated purification cycles. On an industrial scale, replacing fouled Protein A affinity chromatography resin accounts for a large proportion of the raw material cost. Cleaning-in-place (CIP) procedures were developed to extend Protein A resin lifespan, but chromatograms cannot reliably quantify any remaining contaminants over repeated cycles. To study resin fouling in situ, we coupled affinity chromatography and Fourier transform infrared (FTIR) spectroscopy for the first time, by embedding an attenuated total reflection (ATR) sensor inside a micro-scale column while measuring the UV 280 nm and conductivity. Our approach quantified the in-column protein concentration in the resin bed and determined protein conformation. Our results show that Protein A ligand leached during CIP. We also found that host cell proteins bound to the Protein A resin even more strongly than mAbs and that typical CIP conditions do not remove all fouling contaminants. The insights derived from in-column ATR-FTIR spectroscopic monitoring could contribute to mAb purification quality assurance as well as guide the development of more effective CIP conditions to optimise resin lifespan.

Mechanistic understanding of fouling of protein A chromatography resin

This paper aims to provide a thorough understanding of how fouling of Protein A resin takes place. Binding and mass transport properties of widely used agarose-based Protein A resin, MabSelect SuRe™, have been examined to understand the mechanism of resin fouling. There could be various factors that impact resin fouling. These include product/impurity build-up due to components in the feed material and ligand degradation due to the use of harsh buffers. To unravel their contributions, cycling studies were performed with and without product loading. The results presented in this paper provide a lucid understanding of the causative factors that limit Protein A chromatographic resin lifetime. The capacity fall for protein A resin at the end of 100th cycle due to use of feed material was found to be five times greater than that without using feed material. Compared to the fresh resin, the cycled resin samples shows 24% reduction in particle porosity and 51% reduction in pore mass transfer coefficient. Transmission electron microscopy (TEM) was used to qualitatively monitor accumulation of foulants on the cycled resin. Fouled resin sample contained a dense residue in the interior and exterior of resin particle both as a film at the bead surface and as granules. The surface activation energy increased five times in the case of fouled resin sample. The major event in fouling was identified as the non-specific adsorption of the feed material components on resin, signaling that pore diffusion is the rate limiting step. It is anticipated that these findings will assist in development of a more robust and economical downstream manufacturing process for monoclonal antibody purification.

Fouling of anion exchange resin by fluorescence analysis in advanced treatment of municipal wastewaters

The application of anion exchange resins (AERs) has been limited by the critical problem of resin fouling, which increases the volume of the desorption concentrate and decreases treatment efficiency. To date, resin fouling has not been well studied and is poorly understood compared to membrane fouling. To reflect the resin fouling level, a resin fouling index (RFI) was established in this work according to the decrease of DOC removal after regeneration of the resin for the advanced treatment of municipal wastewater. Comparing the linear fitting results between the RFI and the fluorescence intensity indicated that the resin fouling was related to the protein-like substances with fluorescence peak T in the region of excitation wavelength <250 nm and emission wavelength <380 nm. Using their fluorescent characteristics as a label, the protein-like substances causing the fouling were further identified as hydrophilic components with molecular weights greater than 6500 Da.

Fouling of an anion exchange chromatography operation in a monoclonal antibody process: Visualization and kinetic studies

Fouling of chromatographic resins over their operational lifetimes can be a significant problem for commercial bioseparations. In this article, scanning electron microscopy (SEM), batch uptake experiments, confocal laser scanning microscopy (CLSM) and small-scale column studies were applied to characterize a case study where fouling had been observed during process development. The fouling was found to occur on an anion exchange (AEX) polishing step following a protein A affinity capture step in a process for the purification of a monoclonal antibody. Fouled resin samples analyzed by SEM and batch uptake experiments indicated that after successive batch cycles, significant blockage of the pores at the resin surface occurred, thereby decreasing the protein uptake rate. Further studies were performed using CLSM to allow temporal and spatial measurements of protein adsorption within the resin, for clean, partially fouled and extensively fouled resin samples. These samples were packed within a miniaturized flowcell and challenged with fluorescently labeled albumin that enabled in situ measurements. The results indicated that the foulant has a significant impact on the kinetics of adsorption, severely decreasing the protein uptake rate, but only results in a minimal decrease in saturation capacity. The impact of the foulant on the kinetics of adsorption was further investigated by loading BSA onto fouled resin over an extended range of flow rates. By decreasing the flow rate during BSA loading, the capacity of the resin was recovered. These data support the hypothesis that the foulant is located on the particle surface, only penetrating the particle to a limited degree. The increased understanding into the nature of the fouling can help in the continued process development of this industrial example.Scanning electron microscopy (SEM), batch uptake experiments, confocal laser scanning microscopy (CLSM) and small-scale column experiments were applied to characterize a case study where fouling had been observed on an anion exchange chromatography in a monoclonal antibody process. The results suggest the foulant is located on the particle surface, resulting in a minimal decrease in saturation capacity, but having a significant impact on the kinetics of adsorption, severely decreasing protein uptake rate.

Cu (II) removal from tequila using an ion-exchange resin

An ion-exchange resin was employed to remove copper from tequila. Elemental analysis, batch and column copper uptake measurements were performed to assess the extent of metal removal; FTIR and XPS were employed to elucidate the copper complexes formed on the surface of resin; GC was used to investigate resin fouling and the extent of methanol removal. A modified Langmuir isotherm was used to explain adsorption equilibrium data. A ligand density of 2.21 mmol/g as sulphonic group, was measured. Maximum copper uptake by resin was 0.59 mmol/g. GC results from column experiments revealed methanol changes from 311 mg/100 ml anhydrous alcohol (AA) to 212 mg/100 ml AA, complying with Mexican regulations. Tequila solution with copper (5.3 l, 7.3 mg/l) was treated to breakthrough point in column experiments reaching 0.5 mg/l of copper at effluent. These results comply with the Mexican regulation for copper concentration (⩽2 mg/l) showing the promise of resin for industrial applications in removal of copper and methanol from tequila.

A mechanistic study of Protein A chromatography resin lifetime

A mechanistic study into Protein A chromatographic resin lifetime limitations is presented. Binding and mass transport properties of two widely used agarose-based Protein A resins were studied to distinguish between the roles of resin fouling due to product/impurity build-up and ligand degradation as contributory factors towards the decline in binding capacity with use. Cycling studies were conducted with and without product loading on the columns to separate out the influence of resin fouling. Ligand degradation under the mildly alkaline conditions used for column regeneration was determined to be the primary cause for Protein A resin capacity decline with usage. The use of lower concentrations of caustic and the use of stabilizing excipients to protect the Protein A ligand during cleaning and sanitization were found to be useful techniques in maintaining column performance. The results presented in this paper provide a clearer understanding of the causative factors that limit Protein A chromatographic resin lifetime. It is anticipated that these findings will assist in the development of more robust and economical downstream manufacturing processes for monoclonal antibody and Fc fusion protein purification.

Capacity loss in an organically fouled anion exchanger

One of the most important contaminants that ion-exchange resins are exposed to is fouling by organic materials. Especially, anion-exchange resins are more sensitive to fouling by organic materials. The fouling of anion-exchange resins by organic materials is primarily caused by the degradation of products of cation ion exchangers and humic and fulvic acids. Organic fouling causes product water with low quality and few anion exchangers and shortens the service time. Also the need for rinsing water and the use of regeneration chemicals increase. Operating capacity losses occurring due to the fouling of anion-exchange resin by humic acid were quantitatively determined. SAK 254 (Spektraler Absorptions Koeffizient = spectral absorption coefficient), DFZ 436 (DurchsichtsFarbZahl = indexes of transparency), conductivity and sulfate measurements were made to determine capacity losses, which were obtained as 21%, 23%, 25% and 30% after the fouling studies of anion-exchange resin by the amounts of 0.13, 0.25, 0.5 and 1.0 mg/L humic acid, respectively. It was found that even small concentrations of humic acid resulted in a considerable amount of capacity losses in anion-exchange resin.

Chemical Evaluation of Nutrient Supply From Fly Ash–Biosolids Mixtures

Prediction of plant nutrient supply from fly ash and biosolids (sewage sludge and poultry manure) may enhance their agricultural use as crop fertilizer. Two mild extraction methods (42‐d equilibration with ion‐exchange resins; 2‐d equilibration with pH 4.8 buffered nutrient solution) and analysis of nutrient data by the Diagnosis and Recommendation Integrated System (DRIS) were tested with 29 fly ash samples, four biosolids samples, and their mixtures. The resin method was useful for major nutrient (N, P, K, Ca, Mg, S) extraction from fly ashes and organic materials, particularly where mineralizable fractions of N and P under aerobic conditions are required. However, resins were inefficient in extracting P from high‐Fe sewage sludges because organic waste samples caused premature failure of semipermeable membranes and fouling of resins. Extraction of fly ash with dilute buffered nutrient solution was more successful because micronutrient recovery was improved, major nutrients were correlated to the resin method, both addition and removal of nutrients were recorded, DRIS analysis was possible, and equilibration was rapid (2 d). The overall nutrient supply from these extremely variable fly ashes was: (high micronutrient, low major nutrient supply). For biosolids, the major nutrients ranked: P &gt; N ≈ Ca &gt; S &gt; Mg &gt; K (sewage sludges), and N &gt; Ca ≈ K &gt; P &gt; Mg &gt; S (poultry manures). In mixtures of fly ash with 26% sewage sludge the order was: Ca &gt; S &gt; N &gt; Mg &gt; P &gt; K, while in mixtures of fly ash and 13% poultry manure, the nutrients ranked: Ca &gt; K ≈ N ≈ S &gt; Mg &gt; P. Optimal plant nutrition (especially N–P–K balancing) should be possible by mixing these three waste materials.

Ion exchange kinetics in ultra pure water systems

AbstractThe continuous production of ultra pure water on an industrial scale uses ion exchange mixed beds as a major method of reducing ionic impurities to sub‐μg dm−3 concentrations. Under such demanding operating conditions, particularly the high flow rate and high volume requirements of condensate purification in the power generation industry, it is the kinetics rather than the equilibria of the exchange processes that becomes the main controlling factor. The interactions between anion and cation exchange rates have been studied, particularly with respect to changes in the aqueous phase pH within a bed of exchange resins. The cause and effects of cation exchange resin fouling, both in laboratory tests and in practical applications, have been investigated. The most suitable choice of ion exchange system for ultra pure water production, whether mixed or separate beds, is discussed.

Determination of the total capacities of strongly basic anion‐exchange resins

AbstractThe method of Fischer &amp; Kunin for the determination of the total weakly and strongly basic capacities of strongly basic anion‐exchange resins has been investigated; some modification has been found to be necessary. When resins from de‐ionisation plant are examined, very large errors are possible unless effects caused resin fouling are overcome. Some suggestions are made to explain effects observed in de‐ionisation plant with resins which are fouled by organic matter.