RO and AMBER LE™ ultrafiltration skids.
Aquabio work in various industries including distilleries, breweries, maltings, dairy producers, food producers and meat processors.
Their AMBR LE™ process offers an efficient, low energy membrane bioreactor (MBR) solution. The company has recently been awarded a contract for a wastewater treatment and water reuse plant incorporating the technology at Dairy Crest’s Severnside Dairy in Gloucester, treating flows of up to 2.6 MLD.
“We understand that large volumes of energy are typically used within the food and drink industry so we continually aim to offer significant energy savings with our system,” Heslegrave said.
Diva Envitec are involved with emulsion making using nano-cavitation, caustic recovery, and waste to energy solutions utilizing food industry waste streams with high biochemical oxygen demand. Their sparging systems reduce the energy required to mix gases; this technology is used in the anaerobic digestion process to improve efficiency and reduce the energy requirement through effective mass transfer.
EFC Separations have developed technology for the treatment of industrial waste streams and the recovery of specific products from different types of process streams. They have projects dealing with by-products originating from food producing processes. The PCO2 product from Parker domnick hunter is strongly focused on bottling of carbonated soft drinks but they have other compressed air and gas treatment products suitable for protecting food and packaging..jpg)
Quality incident prevention system.
Mayes told us that Parker are mainly interested in what the customers are interested in. “We are changing our model from ‘engineering push’ to ‘customer pull’,” he said, “It’s time to take new steps – using market demands as a driver of innovation. So we are currently investigating a number of areas where our engineering skill set provides value to the end customer.”
In addition to whey protein concentration, brine clarification, and microbial removal in dairy processing, Synder Filtration is involved with corn wet milling, gelatin concentration, juice processing, dealcoholization, concentration of natural polymers, wine clarification, and concentration of sap. The company is developing more membranes to add to their microfiltration (MF), ultrafiltration (UF) and nanofiltration (NF) range.
Research and development at Synder focuses on both immediate and long term product development. “This means,” Yeh explained, “on most projects, we have an actual customer matched and ready to trial each new product once it's ready for testing.”
Membrane system for brine recovery.
Emerging markets
“An increasing proportion of water consumed in the UK is attributed to the food and drink industry,” Heslegrave explained, “and with water stress posing real risks to business, there must be a significant change to the way the industry addresses their water consumption. Water stress is a major concern, potentially limiting success and growth.” “However,” Vashishta added, “waste water recycling is a challenge.”
Water reuse solutions are growing rapidly to address this challenge with the realization of capital and efficiency savings, and the need for corporate responsibility targets. This helps to close the water cycle on industrial sites, which reduces the environmental impact, with both clean water extraction and waste water discharge costs reduced.
“Based on the information we receive from industry,” de Graaff explained, “a main focus point of the industry is the optimal valorization of all streams leaving the factories. Current waste streams can become valuable products when some additional work is done. This will mainly involve the removal of water to increase the concentration and subsequently the recovery of solid compounds.” The food and drink industry as a whole is moving into the convenience food market. “This will be in countries not traditionally convenience food-driven, “Mayes explained,” such as in Asia and Africa.”
“There is an emerging need for ever greater differentiation in food and beverage products,“ Yeh added, “and the advancement of membrane technology will be critical in delivering these new products. In dairy, for instance, it's now possible to fractionate proteins into highly refined nutraceutical and pharmaceutical grade products, and soon we will be able to fractionate the sugars as well.” Filtration and separation technology development will also be critical in improving process efficiency and reducing energy costs as food and beverage processers move toward more sustainable manufacturing standards.
Graph showing eutectic temperature and salt concentration.
Low energy bioreactor
The AMBR LE process from Aquabio is optimized to provide low energy biomass separation (see Figure 1). This is achieved by the control of recirculation and permeate pumps, and a backflush system. The system can take advantage of deeper bioreactor tanks and use static hydraulic pressure to assist the UF membrane filtration system. Automatic operation of the air blowers, aeration pumps, MBR system and RO enables the plant to operate on demand, allowing automatic shutdown during periods of lower demand. These factors combine to provide lower energy use compared with conventional crossflow or submerged membrane separation systems.
The process controls enable varying of hydraulic throughput, allowing the plant to automatically ramp up during periods of higher flow, whilst optimizing energy consumption at the average flow condition. Future hydraulic load can be accommodated by either operating the system at higher energy consumption, or with the installation of additional membrane modules. If a membrane bank is out of service for maintenance or cleaning then the other bank can increase hydraulic throughput.
The design of the aeration system and bioreactor provides excellent chemical oxygen demand reduction. Use of UF membranes provides a complete barrier to suspended solids ensuring high quality final effluent for watercourse discharge and providing an ideal water quality for downstream RO treatment. The high biomass concentration and hydraulic buffering within the bioreactor enable the system to cope with varying influent. The selected operating parameters enable a low sludge production, reducing offsite tankering.
UF and MF membrane casting machine.
Low fouling
The RO system consists of two stages of low fouling RO membranes housed in an array of membrane vessels. At high pressure a low conductivity permeate is forced through the RO membranes, leaving a concentrate stream to pass along the module. The reject from the first stage is used to feed the second stage to achieve recovery of up to 70%. The recovered water can be reused for both potable and non-potable purposes.
High flux performance combined with optimized installed membrane area and long membrane life means that whole life costs for operation and membrane replacement are lower than alternative systems. The designs are also modular and do not rely on specific membrane suppliers.
Aquabio MBR and RO technology is proven for industrial wastewater treatment and water recycling in numerous full scale installations in the UK and internationally including dairy, food processing, cereal, malting, distillery, brewery and contaminated ground water applications. Out-of-tank and low level installation of aeration equipment, UF membrane system and instrumentation in conjunction with good design practice provides easy access for plant maintenance and cleaning. The standard UF mechanical design incorporates lifting points for membrane removal.
“Energy efficiency is key to this process,” Heslegrave explained, “ensuring that both CAPEX to OPEX are optimized. The system has been designed to operate efficiently, with easy configuration for operational times at off peak electricity costs. As the system utilizes an external membrane solution there is no requirement for air scouring as with submerged membrane systems. The control system allows for managed flux rates,” Heslegrave added, “which are used to optimize energy consumption relative to the plant load. Short and long term trending of energy use help assist with energy optimization.”
Brine recovery
Raw sugar with a high ICUMSA (International Commission for Uniform Methods of Sugar Analysis) value has to be de-colorized. There are two traditional methods of color removal in sugar refineries, both relying on absorption techniques with the liquor being pumped through columns of adsorptive medium. One option open to the refiner is to use granular activated carbon (GAC) which removes most organic material including color. The carbon is regenerated in a hot kiln where the organic material is burnt off from the carbon. This is a costly process in terms of energy required.
The more recently developed option is to use an ion exchange resin, which although removes less color than GAC, helps to remove the inorganic contaminants too. The resin process uses the charge on the organic material to separate it from the sugar by absorption.
The ion exchange resin operates in batch mode; when the resin gets saturated it has to be regenerated chemically using a caustic brine solution at 12-13 pH. The cleaning is very efficient, but this gives rise to large quantities of dark brown colored liquid effluent. This has been a deterrent to the industry and various technologies are being employed to re-cycle and manage this effluent.The RO membrane process for brine recovery has been efficient but typically only 40-50% brine could be recovered. Due to the neutralizing process, all caustic was lost.
Diva Envitec Pvt Ltd have developed the ‘Poresep Membrine Process’ to recover the caustic brine (Figure 2). This uses modified membranes with functional charge to carry out the separation, and brine recovery is achieved without the need for neutralizing, as compared to conventional systems. The process comprises a series of pre-treatments followed by the Membrine process, where the color is removed from the effluent at high temperature and pH. Diva Envitec say that the process results in savings in energy and chemical costs.
In the process minimal make-up of caustic and salt is required and so no acid is needed for neutralizing. There is high flux and high temperature stability at high pH, up to 13, and up to 85-90 75-80% caustic brine is recovered back into the system. Colored concentrate can be further recovered as an option, making caustic brine recovery as high as 90-95%. There is also the benefit of low effluent loading as most of the color is precipitated out at this stage..
“Cooling and neutralizing the spent brine to suit conventional membranes was very costly,” Vashishta explained, “as it required a lot of heat loss and also expensive chemicals. The new process does not require cooling the liquid, so no energy is lost. There is no need to neutralize the solution as the system has a capability to works at high pH.”
Crystallization technology
Eutectic freeze crystallization (EFC) takes place at the eutectic point, which occurs in many mixtures where equilibrium exists between ice, salt and a solution with a specific concentration. This specific concentration is called the eutectic concentration and the temperature at which this equilibrium is found is the eutectic temperature (Figure 3).
EFC Separations have applied the concept of eutectic freeze crystallization in their EFC-process. A water stream containing dissolved salt is fed to the EFC crystallizer where ice and salt are crystallizing simultaneously at the eutectic point of this specific system.
Separation of the produced ice and salt from the crystallizing solution is achieved by utilizing the density difference between the three phases present (ice, salt and crystalizing solution). In the crystallizer, gravitational separation is taking place, with ice leaving from the top and a salt slurry extracted from the bottom. The liquid coming from the slurry stream is recycled back to the EFC process.
The ice product yields a water stream after melting. Before melting the ice crystals have a very high purity (>99.99% water). The purity of the water product is determined by the amount and concentration of the crystalizing solution adhering to the ice crystals. Depending on the destination of the water product, suitable ice/liquid separation can be achieved. In cases where high purity water is needed a washing stage can be used. Alternatively, post-treatment with RO or ion exchange can be considered to meet the desired water quality, with concentrate recycled back into the EFC process. The energy requirement for conversion of an aqueous stream into clean water and solid salt is relatively low with the EFC process, because about seven time’s higher enthalpy change occurs in the evaporation of water compared to freezing the same amount of water. Although efficient evaporative systems can decrease this difference in energy requirement, EFC Separations say that their process is still favorable from an energy perspective.
Applications of the process include the recovery of valuable inorganics from a process or a waste stream. The process can also be used to reduce the salt content of a waste water stream to improve water reuse strategies, and to treat RO concentrate. The additional benefits of the EFC process are the less corrosive environment (leading to cheaper construction materials for treating salt water), no thermal degradation of the products (no taste or color changes) and less biological activity.
“The concept of EFC,” de Graaff explained, “relies on the relatively low heat of fusion of water.” This is approx. 330 kJ/kg compared to the heat of evaporation at 2500 kJ/kg. “This leads to lower energy consumptions for the extraction of water from the streams that are treated,” added de Graaff.
Soft drinks production
Soft drinks consist primarily of carbonated water, sugar, and flavorings. There are over 500 types of soft drinks on the market. The carbonation of the beverage is undertaken by forcing CO2 into the liquid and storing under pressure; the presence of this gas creates bubbles and fizzing in the liquid when pressure is reduced.
The CO2 that is injected into the beverage must be free of particles, microorganisms and unwanted chemical compounds. Existence of these contaminants may result in a ‘quality incident’ which may occur where a delivery of out-of-specification CO2 has been made to the plant or where CO2 has been contaminated on-site during production processes.
The PCO2 process, from Parker domnick hunter, (see Figure 4) protects CO2 quality by preventing accidental contamination during the beverage bottling process. Using a comprehensive six stage multi-layer adsorbent technology, the PCO2 range includes Maxi PCO2 and Mplus PCO2 for plant scale protection of sparkling beverage bottling production.
Both processes offer CO2 purification, removing a wide range of potential carbon dioxide impurities, while offering low pressure drop. The system guarantees the gas quality so it remains within industry and company guidelines, preventing detrimental consequences to the finished beverage, producers’ reputation and their bottom-line.
Due to its compact design the PCO2 allows simple installation with low maintenance and is installed in over 150 countries worldwide. The PCO2 meets ISO9001:2000 standards and complies with FDA Code of Federal Regulations title 21 CFR.
“Energy efficiency is not the main driver for the customer with this innovation,” Mayes said, “the main driver is insurance against contamination. Food grade carbon dioxide can come from a variety of sources, and whilst it will be certified at shipment, a combination of transfer and storage processes prior to final use can lead to contamination. This product protects against that.”
Dairy processing applications
Synder Filtration is one of the leading suppliers of membrane filtration products for the dairy industry, manufacturing NF, UF and MF membranes for a wide variety of process applications including fat/microbial removal and protein fractionation. One particular membrane, FR, has been adopted in recent years.
With a molecular weight cut-off of 800 kDa, this PVDF membrane is well-suited for applications such as protein fractionation and fat/microbial removal. The pore size is large enough to allow whey proteins and sugars to permeate through the membrane, but small enough to reject casein micelles, colloids, and bacteria. The asymmetric pore structure provides an optimal balance of both flux and rejection, with tighter surface pores for better control of rejection and larger macrovoids for greater permeate throughput.
The use of cross flow filtration technology prevents the build-up of solids on the surface of the membrane, as is common in conventional filtration techniques. The cross flow creates a sweeping force across the membrane surface which helps to reduce the formation of the gel layer, thereby improving the overall membrane life. This type of MF membrane technology is widely used throughout the dairy industry as a purification step in the processing of whey protein isolate. MF allows the whey proteins to pass through to the permeate stream, while holding back the micellar casein in the concentrate.
This selective separation is ideal for separating high volumes of valuable pure whey proteins which can be further concentrated and purified using tighter UF membranes. Typically, continuous UF stages are employed before and after the MF stage, along with diafiltration in the final stages of concentration to enhance this type of separation efficiency. Larger membrane feed spacer sizes can also maximize the solid concentration in the later stages of filtration.
The removal of fat and microbes from whey and micellar casein via MF is equally as important as it helps extend the shelf-life of milk products and produces higher-purity whey protein concentrate and isolate. It is beneficial for cheese making and can be used as a pretreatment step to pasteurization to help eliminate all vegetative spores from milk products.
Economic alternatives
Polymeric MF membranes such as FR are good economic alternatives compared to ceramic membranes for the separation of whey and casein proteins. Synder’s FR membrane is able to significantly reduce energy consumption compared to conventional ceramic membranes, delivering an efficient separation of casein versus whey protein. Additionally, PVDF has good chemical and heat resistivity, allowing for robust cleaning and sanitation procedures.
Before the advent of polymeric membranes, evaporators and spray dryers were the primary method of concentrating and drying dairy products into powder form. Membrane technology allowed milk, whey, lactose and other milk-derived products to be concentrated more efficiently prior to energy intensive evaporation and spray drying. “So, in a sense,” Yeh explained, “sustainability and energy efficiency have always been at the core of membrane technology, in addition to allowing greater separation and purification of products.”
Recently, Synder has been investing in feed spacer design. “This could significantly reduce the load on downstream evaporators and spray dryers, helping to save tremendous amounts of energy and capital cost while increasing capacity of existing sites,” Yeh added.
In addition to higher solids handling, the high pH and temperature resistant version of the FR membrane may also help improve membrane flux and recovery from harsher cleaning conditions that may be required with high solids concentration. These ‘PHT’ membranes can be sanitized without the use of chlorine, which further reduces chemical usage and overall environmental impact.
Future trends
Both energy and water consumption will be major drivers within the food and drink industry over the next 10 years. “These are already emerging as a major focus within the industry,” Heslegrave said, “due to rising energy costs and increasing water demand, with water scarcity already becoming a real concern within the industry. Industry targets to reduce water consumption have already been set by The Federation House Commitment.”
The FHC was launched in 2007 with a goal to help the food and beverage sector reduce water use across the manufacturing process. Following a recommendation from the Food Industry Sustainability Strategy (FISS), this aimed to reduce water usage by 20% by 2020 against a 2007 baseline. “It will also be important to reduce the water footprint by improving the internal water cycles,” de Graaff added.
“The drive to functional and convenience foods,” Mayes said, “is likely to continue. That appears to have unleashed a burst of innovation and we’re helping make sure that safe compressed air and gasses are delivered as ingredients to the process.” Heslegrave agreed and added, “The food and drink industry is led by the consumer and the consumer is demanding more pre-prepared, pre-packaged foods which ultimately lends itself to increased water use and wastage in terms of discharge volumes. In addition to this the industry faces pressures from consumers themselves to reduce carbon footprint or improve environmental credentials, making an investment in on-site wastewater treatment and water reuse an increasingly attractive option.”
“Besides stringent discharge regulations,” Yeh added, “and legislative measures aiming at reducing the consumption of water, cost reduction, environmental awareness, waste minimization, and product quality improvement will be important drivers in the sector. Manufacturers are always looking for additional ways to reduce costs, and membrane filtration through the use of spiral-wound elements is an excellent alternative to both ceramic and hollow-fiber membrane configurations. Membrane filtration can be used for wastewater treatment, allowing facilities to reuse water needed for different processes throughout all stages of production, or to meet strict discharge requirements.”
Products such as the FR membrane have the potential to contribute and help manufacturers produce even higher-quality products at reasonable costs.“The industry is likely to employ a ‘reduce, reuse, recycle’ methodology to reduce volumes of water used per production unit and will look for external support to achieve these best practices,” Heslegrave added. “This will help identify strategies to reduce water use and utilize alternative sources of water. Reuse of process waste water will provide opportunities for very significant water efficiency and security improvement.”
“Given that there are many driving factors regarding environmental regulation and legislative measures,” Yeh said, “the filtration industry is likely to assess the needs of end-users and shift towards creating better, dependable products that can help resolve some of the issues that they are facing. Whether it is through synthesizing polymers to provide better chemical resistivity, or modifying element modulations to increase element durability and throughput, filtration manufacturers will have to reassess the priorities of customers in order to provide products that will be beneficial for both end-user and environment.”
“Process Intensification and disruptive technologies are required in different stages of food processing. Technologies which show energy savings, cost competitiveness and improve material efficiency and environmental performance will replace the conventional way of processing food," Vashishta concluded.
