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A laboratory study of poultry abattoir wastewater treatment by membrane technology
Abstract
Ultrafiltration (UF) and nanofiltration (NF) were tested as potential methods of treating poultry abattoir chiller tank effluent for recycling. Various ultrafiltration and nanofiltration membranes were tested for their fouling propensities as well as for their ability to produce a permeate which meets Agriculture and Agri-food Canada's guidelines for recycling: total plate count of less than 1,000 organisms/mL; total coliform counts of less than 10 organisms/mL; total E. coli counts of less than 2 organisms/mL; total organic carbon less than 100 mg/L; and light transmittance of greater than 90%. Several UF membranes removed all bacteria and achieved the required 90% light transmittance but failed to meet the total organic carbon (TOC) target. However, the TOC effluent criterion was met by NF membranes. Both of the commercial thin film composite membranes not only produced permeate with less than 100 mg/L of TOC but also gave a reasonable flux of 46-66 L·m-2·h-1 . It should therefore be possible to develop a recycling system for chiller tank effluent using any of the above nanofiltration membranes. Recycling would reduce water consumption and wastewater disposal and has the potential to reduce energy costs by reusing pre-chilled water.
... Prior to discharge from the plant, poultry processors are required to remove the majority of the soluble and particulate organic material in their wastewater in order to achieve compliance with environmental regulations. With an estimated 2 to 5% of total carcass proteins lost in the effluent, PPW contains predominantly 35% of protein, resulting in much higher biological oxygen demand (BOD) and chemical oxygen demand (COD) than town sewage (Zhang, Kutowy, Jumar, & Malcolm, 1997). Poultry processing wastewater showed that 80% of the organic materials in the wastewater are in the form of particulate matter and that the mean particle size is 75-100 µm (Merka, 2004). ...
... The major portion of the suspended solids (55% of the 20-50 μm range particles) form an opaque haze and are believed to be emulsified oils of entrapped proteins and lipids as well as the bulk of the microorganisms (Picek, 1992). The remaining 5-10% of the particles are less than 5 mm in size and seem to be even more tightly bound with emulsified globules (Zhang et al., 1997). Shih and Kozink (1980) conducted studies on UF of PPW and found that 85% of total solids (TS) and 95% of COD in the wastewater were removed by the UF system. ...
... After 10 min of pasteurization, no colony was found on the TPC agar, indicating absence of microorganisms in these samples (Iwuoha & Umunnakwe, 1997). Ultrafiltration (UF) of poultry abattoir chiller tank effluent resulted in total plate count of less than 1000 organisms/mL, total coliform counts of less than 10 organisms/mL, total E. coli counts of less than 2 organisms/ mL and total organic carbon less than 100 mg/L; and light transmittance of greater than 90% (Zhang et al., 1997). ...
Poultry processing plants use relatively high amount of water with an average consumption of 26.5 L/bird during primary and secondary processing of live birds to meat. The used water contains proteins, fats, carbohydrates from meat, blood, skin and feathers, resulting in much higher biological oxygen demand (BOD) and chemical oxygen demand (COD). Hence the processors are required to remove majority of the soluble and particulate matter in the wastewater prior to discharge from the plant. Treatments for poultry wastewater include screening, diatomaceous earth filtration, ozonation, and chlorine dioxide. Food safety and inspection service regulations allow reconditioned water to replace potable water in prescribed ratios. Recycling of poultry wastewater by ultrafiltration improves the quality of recycled water and provides solution to water resource limitations. Ultrafiltration is basically a pressure-driven process that separates on the basis of molecular diameter. Membrane bioreactors (MBR) that integrate biological degradation of waste products with membrane filtration are also quite effective in removing organic and inorganic contaminants as well as biological entities from wastewater. Value added products like crude proteins could be separated through ultrafiltration from poultry wastewater, subsequently reducing the chemical oxygen demand. Ongoing research in membrane separation techniques involves exploration of new membrane materials and of new module design configurations to address issues of membrane fouling and treatment of waste streams containing high suspended solids or viscous wastes.
... Therefore, unconventional methods, e.g., pressure-driven membrane technologies, are being explored for PSWW treatment. These membrane filtration technologies can include microfiltration (MF), ultrafiltration (UF), nanofiltration (NF), and reverse osmosis (RO) [9,10]. They can overcome some limits of the conventional methods by removing colloids and suspended and macromolecular matter, and eliminating mineral substances and low-molecular organic compounds. ...
... A few researchers explored NF for PSWW treatment by using standalone NF or combining NF with UF. Zhang et al. [10] evaluated some membrane filtration processes for poultry abattoir wastewater treatment to recycle the wastewater stream to meet the Canadian poultry wastewater reuse criteria. Their results showed that both NF membranes (DS: desal thin composite membrane and NF 45: thin-film composite membrane) produced permeate with less than 100 mg/L of TOC and gave a reasonable flux of 46 to 66 L/m 2 /h. ...
Poultry slaughterhouses produce a large amount of wastewater, which is usually treated by conventional methods. The traditional techniques face some challenges, especially the incapability of recovering valuable nutrients and reusing the treated water. Therefore, membrane technology has been widely adopted by researchers due to its enormous advantages over conventional methods. Pressure-driven membranes, such as microfiltration (MF), ultrafiltration (UF), nanofiltration (NF), and reverse osmosis (RO), have been studied to purify poultry slaughterhouse wastewater (PSWW) as a standalone process or an integrated process with other procedures. Membrane technology showed excellent performance by providing high efficiency for pollutant removal and the recovery of water and valuable products. It may remove approximately all the pollutants from PSWW and purify the water to the required level for discharge to the environment and even reuse for industrial poultry processing purposes while being economically efficient. This article comprehensively reviews the treatment and reuse of PSWW with MF, UF, NF, and RO. Most valuable nutrients can be recovered by UF, and high-quality water for reuse in poultry processing can be produced by RO from PSWW. The incredible performance of membrane technology indicates that membrane technology is an alternative approach for treating PSWW.
... An average of 26.5 L of water/bird is used in this set of processes. The chilling step can be highlighted since it generates high amounts of wastewater [9,10]. ...
... Membrane separation is pointed as a promising technology, capable of producing reclaimed water, due to the potential to remove all the microorganisms and suspended matter and allowing the minimization of chemical usage and disposal costs [10,21]. This process consists in the separation of two of more compounds employing a selective membrane. ...
Poultry processing plants generate large amounts of wastewater in the many steps necessary to provide high quality and safe products. Carcass chilling is one of these steps, where the temperature of the carcasse is reduced from 40 to 4 °C, for reducing the growth rate of microorganisms and affecting flavor, texture and appearance. In this operation, the carcasses are continually displaced through a series of two tanks (called pre-chiller and chiller) filled with cold water, thus being responsible for a considerable amount of wastewater generation. This work aimed to regenerate the wastewater of the pre-chiller tank employing microfiltration (pore size 0.10 and 0.20 µm) and ultrafiltration (MWCO 10 and 50 kDa) polymeric membranes in bench and pilot scales, with the final purpose of reuse. Membrane performance was evaluated in terms of the capacity of removing the contaminants and producing sufficient permeate flux in different working pressures. Bench scale ultrafiltration membrane presented the highest initial permeate flux of 112.1 L/m²h at 200 kPa. The four membranes tested presented good retention of microorganisms, with apparent rejection up to 100%. Pilot scale membranes presented better apparent rejection, with retentions above 99% for turbidity, apparent color and fat content. Moreover, organic matter retention was also very high, up to 94% for chemical oxygen demand and 92% for total organic carbon. The used of membranes seems to be a promising approach for recycling and reuse of poultry pre-chiller wastewater.
... In a poultry processing plant, live birds are slaughtered, scalded, de-feathered, eviscerated, cleaned and chilled [8,14]. PPW effluent (at the end of a poultry processing plant) is a combination of different wastewater streams, originating from the process steps listed above. ...
... In the chilling process, the birds are chilled in water containing antimicrobial agents [16,17]. The main contaminants in chiller water are blood, oil, grease and fat particles, with the total suspended solids (TSS) in the range of 200 to 600 mg L -1 [14]. ...
Ultrafiltration (UF) is an emerging technology of interest for the treatment of highly impaired industrial wastewaters. Here we focus on treating poultry processing wastewater (PPW) using UF. Although UF suffers from severe flux decline due to membrane fouling when treating PPW, we show that the flux decline could be significantly reduced using a pretreatment step. Electrocoagulation (EC) is studied as the pretreatment method. EC is shown to be effective in removing suspended solids and organic compounds which foul the membrane during UF. Higher EC reaction times result in higher contaminate removal. We show that for an EC reaction time of 5 min, equivalent to energy consumption of 0.15 kW h m⁻³, over 85% reduction of fats, oil and grease and total suspended solids results. Compared to individual UF, the EC-UF process results in lower flux decline and enhanced contaminate rejection. Finally, we run long-term EC-UF experiments, with and without membrane cleaning, to study the feasibility of the combined process.
... The birds are chilled in water containing an antimicrobial agent in order to suppress bacterial growth [11]. Zhang et al. [12] and Avula et al. [4] indicated that the main contaminants of the chiller wastewater (CW) are blood, fat, oils and micro pollutants. They note TSS values of 600-800 mg L −1 in CW. ...
... This is not surprising given the source of the two wastewaters (See Fig. 1). The particle size distribution obtained here is in general agreement with previous studies [4,12]. Fig. 5 gives the permeate flux at the start of the filtration process for brand new as well as the membranes after cleaning. ...
... Proteins from carcass debris and blood are the major pollutants besides fat in poultry processing wastewater (PPW). With an estimated 2 to 5% of total carcass proteins lost in the effluent (Holleman, 1992), PPW contains predominantly 35% of protein, resulting in much higher biological oxygen demand (BOD) and chemical oxygen demand (COD) than town sewage (Zhang et al., 1997). In the US more than 25 million broiler chickens are processed everyday and at least 5 to 6 gal of water per bird are required in processing (Jackson et al., 1999). ...
... Unfortunately, due to the presence of both fat and protein in the feed stream, the effectiveness of the process was greatly hindered due to severe fouling of membrane, leaving considerable discrepancy for this process to find industrial applications. The importance of pretreatment on the performance of membrane-based processes was confirmed by Zhang et al. (1997) in their attempt to investigate the feasibility of recycling chiller water using membranes made from different polymeric materials. ...
The feasibility of using ultrafiltration (UF) to recover protein from poultry processing wastewater (PPW) after primary treatment was investigated. By using polysulfone membrane with 30,000 molecular-weight-cut-off, almost all crude proteins in PPW were retained, subsequently reducing the chemical oxygen demand (COD) in the effluent to less than 200 mg L(-1). Similar to the processing of proteinaceous materials, the average fluxes reached only 100 Lm(-2) h(-1). By identifying the optimal values of key operation parameters, including pH, volumetric flow rate, and transmembrane pressure (6.74, 683 mL min(-1) and 14 psi, respectively) using response surface methodology (RSM), the flux was improved to higher than 200 Lm(-2) h(-1). Although severe membrane fouling was still inevitable after processing, flushing the membrane with a cleaning reagent was found capable of effectively restoring membrane performance.
... whereas TSS and FOG removal were 98% and 99%, respectively [72]. Pressure driven membrane processes have proven to be successful in the separation of valuable organic and inorganic compounds in black liquor as well as being energy-efficient in several studies [73][74][75]. In recent studies, separation processes are being coupled to improve effluent quality. ...
Biological wastewater treatment processes such as activated sludge and anaerobic digestion remain the most favorable when compared to processes such as chemical precipitation and ion exchange due to their cost-effectiveness, eco-friendliness, ease of operation, and low maintenance. Since Abattoir Wastewater (AWW) is characterized as having high organic content, anaerobic digestion is slow and inadequate for complete removal of all nutrients and organic matter when required to produce a high-quality effluent that satisfies discharge standards. Multi-integrated systems can be designed in which additional stages are added before the anaerobic digester (pre-treatment), as well as after the digester (post-treatment) for nutrient recovery and pathogen removal. This can aid the water treatment plant effluent to meet the discharge regulations imposed by the legislator and allow the possibility for reuse on-site. This review aims to provide information on the principles of anaerobic digestion, aeration pre-treatment technology using enzymes and a hybrid membrane bioreactor, describing their various roles in AWW treatment. Simultaneous nitrification and denitrification are essential to add after anaerobic digestion for nutrient recovery utilizing a single step process. Nutrient recovery has become more favorable than nutrient removal in wastewater treatment because it consumes less energy, making the process cost-effective. In addition, recovered nutrients can be used to make nutrient-based fertilizers, reducing the effects of eutrophication and land degradation. The downflow expanded granular bed reactor is also compared to other high-rate anaerobic reactors, such as the up-flow anaerobic sludge blanket (UASB) and the expanded granular sludge bed reactor (EGSB).
... PWW physicochemical parameters showed variation overtime in organic and inorganic loads, whose trends follow the chronology of the different production chain operations. According to Zhang et al. (1997), industrial poultry wastewater is mainly composed of proteins (35%), lost from the carcass, that bring about high levels of COD and BOD. The slaughtering process and the periodic cleaning of residual particles are the main sources of pollution, with the organic matter being the main pollutant (Awang et al. 2011). ...
The purpose of this study was to evaluate the short-term irrigation effect with industrial poultry wastewater on young olive trees (Olea europaea L. cv. Chemlali). Industrial poultry wastewater can be considered as a bio-fertilizer due to its richness in nutritive elements (SO42−, HCO3−, total nitrogen, and K+). The physicochemical analysis of wastewater showed a high concentration of TSS, COD, BOD, COT, NO3−, and conductivity. Measurements indicated that poultry wastewater enhanced plant growth, leaves dry matter, and ashes in comparison with tap water, as well as poultry wastewater diluted with tap water; however, a decrease in total soluble sugars (glucose and fructose) was detected in leaves. The determination of fatty acid profile of young olive trees leaves irrigated with poultry wastewater showed richness on saturated fatty acids in comparison with mono- and poly-unsaturated ones. In addition, oleic acid (C18:1) presented the lowest content in leaves of trees irrigated with poultry wastewater irrigation. According to those results, poultry wastewater lends itself to being a hydric alternative and at the same time a source of nutrients that can help fill the water deficit in semi-arid countries and avoid costly waste disposal for slaughterhouses.
... Another major pollutant in the poultry process water is residual protein from carcass debris, blood, FOG and feathers (Avula et al. 2009;Yordanov 2010). The poultry process water contains predominantly 35% of protein, resulting in a much higher BOD and COD being observed in the wastewater from such facilities, as opposed to municipal sewerage (Zhang et al. 1997;Avula et al. 2009). ...
The process of anaerobic digestion has been and still remains the most efficient, cost effective and environmentally benign treatment process for poultry slaughterhouse wastewater (PSW). The PSW is characterized by a high concentration in chemical oxygen demand (COD), Biological Oxygen demand (BOD) and Fats, Oil including Grease (FOG). The reactor configuration influences the performance of such anaerobic system in the treatment of such oily wastewater. The up-flow reactor configuration provided by the Up-flow Anaerobic Sludge Blanket (UASB) Bioreactor or the Expanded Granular Sludge Bioreactor (EGSB) are highly dependent on up-flow velocity, which often contributes to periodical sludge washout during the treatment of PSW with high FOG and total suspended solids (TSS) concentration, resulting in poor reactor performance in comparison with the downflow reactors such as the Static Granular Bed Reactor (SGBR), which achieves high organic load removal efficiency particularly when treating PSW due to its ability to retain sludge granules and solidified residue within the reactor. The washout of the sludge results from sludge floatation, which is induced by the inhibition of the anaerobic granular biomass by the accumulation of long chain fatty acids (LCFAs) from a poor hydrolysis. The aim of this review is to highlight reactor configuration deficiencies, and to elaborate on the advantages of using anaerobic digestion for the treatment of FOG-laden PSW, with a focus on reactor performance. Additionally, a comparative analysis between up-flow reactors, such as the UASB including EGSB, and downflow reactors, such as SGBR, was performed.
... Most of the water is used for scalding, defeathering, evisceration and equipment sanitation including the slaughtering facility. Roughly 2 to 5% of total proteins, including carcass debris and fats, oil and grease (FOG) from the carcass, are lost to the wastewater stream, resulting in high strength wastewater with high biological oxygen demand (BOD 5 ) (Avula et al. 2009) and chemical oxygen demand (COD), compared to domestic wastewater (Zhang et al. 1997). This indicates the need for intensive treatment prior to discharge to the environment (Avula et al. 2009), i.e. into receiving bodies such as rivers and lagoons. ...
The poultry slaughterhouse industry consumes a large volume of potable water for bird processing and equipment cleaning, which culminates in the generation of high strength poultry slaughterhouse wastewater (PSW). The wastewater contains high concentrations of organic matter, suspended solids, nitrogen and nutrients. Most poultry slaughterhouses in South Africa (SA) discharge their wastewater into the municipal sewer system after primary treatment. Due to its high strength, PSW does not meet SA's industrial discharge standards. Discharge of untreated PSW to the environment raises environmental health concerns due to pollution of local rivers and fresh water sources, leading to odour generation and the spread of diseases. Thus, the development of a suitable wastewater treatment process for safe PSW discharge to the environment is a necessity. In this study, a biological PSW treatment process using an Expanded Granular Sludge Bed (EGSB) was evaluated. Response surface methodology coupled with central composite design was used to optimize the performance of the EGSB reactor. The dependant variable used for optimization was chemical oxygen demand (COD) removal as a function of two independent variables, hydraulic retention time (HRT) and organic loading rate (OLR). The interactions between HRT, OLR and COD removal were analysed, and a two factorial (2FI) regression was determined as suitable for COD removal modelling. The optimum COD removal of 93% was achieved at an OLR of 2 g-COD/L/d and HRT of 4.8 days. The model correlation coefficient (R2) of 0.980 indicates that it is a good fit and is suitable for predicting the EGSB's COD removal efficiency.
... Discharge of inorganic and organic pollutants into water bodies has greatly affected the ecological balance and cause harmful effects on flora [3]. In the food industry water recycling is applied; olive oil [4], beverage industry [5,6], fishmeal [7,8], poultry and sausage production industry [9][10][11][12] and dairy industry [13]. Researchers have shown there are different solutions and techniques for the water treatment and recovery such as using plants to remove material; [14]; sedimentation ponds [15] and fermentation; [16] etc. ...
... The recovery of proteins from PPWs by UF was investigated by several authors (Lo, Cao, Argin-Soysal, Wang, & Hahm, 2005;Saravia, Houston, Toledo, & Nelson, 2005;Shih & Kozink, 1980;Zhang, Kutowy, Jumar, & Malcolm, 1997). In the work of Lo et al. (2005) PPWs were pretreated by dissolved air flotation to remove most fat substances. ...
The industrial transformation of food and beverages requires a huge quantity of water that generates highly polluted wastewaters. This chapter gives an overview of membrane-based processes for water reuse and environmental control in the treatment of wastewaters from the food-processing industry. Applications involving the use of pressure-driven membrane operations, electrodialysis, membrane bioreactors, and integrated membrane systems are analyzed and discussed. Typical applications for the treatment of process waters from fruit and vegetables, dairy, fish, meat, soya, and wine industries are illustrated, highlighting advantages and drawbacks compared with conventional technologies.
... In some cases, it has only been possible to reduce the number of microorganisms to an acceptable level. According to Zhang et al. (1997), implementing the filtration process in treating waste from poultry industry reduced the number of E. coli-related bacteria to 10 cfu/mL, and E. coli to <2 cfu/mL. Such values of microbiological indicators were accompanied by the presence of a total number of bacteria at the level of <1,000 cfu/mL. ...
... In addition, water that is used during slaughtering operations can accumulate contaminants, fecal materials and even pathogenic bacte-ria (Mijinyawa and Lawal, 2008;Ramesh et al., 2009) Prior to discharge from the plant, poultry processors are required to remove the majority of the soluble and particulate organic material in their wastewater in order to achieve compliance with environmental regulation (Bohdziewicz et al., 2003) Proteins from carcass debris and blood ate the major pollutants besides fat in poultry processing wastewater. With an estimated 2-5 % of total carcasses protein lost in the effluent, wastewater contains predominantly 35 % of protein, resulting in much higher biological oxygen demand (BOD) and chemical oxygen demand (COD) than town sewage (Zhang et al., 1997). The composition of wastewater from the poultry slaughtering industry varies from one plant to another depending on the type of systems, the operation methods, and processing capacity. ...
YORDANOV, D., 2010. Preliminary study of the efficiency of ultrafiltration treatment of poultry slaughter-house wastewater. Bulg. J. Agric. Sci., 16: 700-704 Poultry slaughterhouses use relatively high amount of water with an average consumption of 26.5 L/bird during primary and secondary processing of live birds to meat. The used water contains proteins, fats, carbohy-drates from meat, blood, skin and feather, resulting in much higher biological oxygen demand (BOD) and chemi-cal oxygen demand (COD). A lot of attention has been focused on the development of unconventional methods for wastewater treatment. The possibility of using the ultrafiltration for poultry wastewater treatment was inves-tigated. The results showed that the ultrafiltration could be an efficient purification method. Its application re-sulted in about 99 % and 98 % removal of fats and suspended substances. The efficiency of COD and BOD 5 removal exceeded 94 %.
... A jacketed glass extraction column with dimensions of 600Â90 mm was used for column extraction while the batch extractions were done in glass beakers. Initial membrane evaluation and characterization for separations was done using NRC cells (Sourirajan & Matsuura, 1985;Zhang, Kutowy, Kumar & Malcolm, 1997) as well as Sepacell (supplied by Osmonics, Minnetonka, MN, USA). ...
... A jacketed glass extraction column with dimensions of 600Â90 mm was used for column extraction while the batch extractions were done in glass beakers. Initial membrane evaluation and characterization for separations was done using NRC cells (Sourirajan & Matsuura, 1985;Zhang, Kutowy, Kumar & Malcolm, 1997) as well as Sepacell (supplied by Osmonics, Minnetonka, MN, USA). ...
In existing processes, extraction and refining of glycoside based sweeteners from stevia leaves involves many process steps including extraction by organic solvents. The purpose of the present study was to develop a process of extraction and refining of sweeteners with reduced number of unit operations and minimization and/or elimination of chemical usage including organic solvents. It was found that water was very effective for extracting glycosides at selected pH and temperatures. It was also shown that a multi-stage membrane process was successfully able to concentrate the glycoside sweeteners. Based on the preliminary results, it appears that bitter-tasting components were washed out from the sweetener concentrate in the nanofiltration process. This work also has demonstrated that a membrane-based separation process for refining glycoside-based sweeteners could be viable and needs to be investigated further. Yes
Tubular membranes with fly ash as the primary precursor have been fabricated via extrusion process, which not only addresses the disposal issue of fly ash generated by thermal power plants but also aids in poultry slaughterhouse wastewater treatment. The fabricated membranes were characterized, and an optimum composition of 75% fly ash, 20% quartz and 5% calcium carbonate (Membrane K3) was fixed for the membranes to be used for separation processes. Membrane with the optimized composition has a pore size of 0.133 μm and porosity of 40.17% and offers outstanding chemical and mechanical stability. This membrane was further used for the treatment of poultry slaughterhouse wastewater, which is known to have high chemical oxygen demand (COD) and total suspended solids (TSS) content. The membrane successfully separated the organic matters present in the wastewater and the permeate water collected from the process satisfied the necessary environment protection norms regarding discharge and reusability. Hence, the inference can be drawn that the produced permeate water is completely reusable in poultry processing industries, which will help in mitigating the water scarcity problem prevailing nowadays.
The food processing industry is one of the most water intensive industries and has the highest contribution to the emissions of organic water pollutants. It differs from other industries in terms of water quality demands, as the microbiological food safety is a major criterion for the food industry. The current regulations permit the processors to reuse or recycle water unless the water poses a risk for the product safety and the wholesomeness of the product in its finished form. Two main focus areas for water management within the food industry are the efficient use of water, and the wastewater quality and management. The dairy, meat and poultry, and the fruit and vegetable processing sectors are the major water-intensive sectors within the food industry. A systematic approach for water management could lead to about 30?50 % decrease in total water use in the food processing industry.
This paper presents a series of works conducted to characterize humic substances in the environment and how they relate to organic waste. It introduces methods for quality assurance and quality control on waste sampling for environmental monitoring. In addition, the role that agricultural environmental auditing currently plays in ensuring compliance with certain production standards associated with quality marketing schemes, with the emphasis on agricultural pollution minimization policies and costs, is discussed.
Wastewater generated as a result of the fish brining process has a very high contamination load. Application of appropriate technologies of wastewater treatment in order to reuse it in the production process once the NaCl content has been supplemented can provide an alternative to its costly recycling. The experiment included ultrafiltration tests conducted on waste brine originating from food processing industry. The results of physicochemical tests indicated very high reductions of fat content (100%) and turbidity (99.8%). Reductions were also revealed in the case of other indicators, i.e., chemical oxygen demand, biochemical oxygen demand, protein and histamine content: by 24.4, 35.2, 27.6 and 22.7%, respectively. Furthermore, it was reported that the obtained permeate retained its quality and microbiological stability. The studied ultrafiltration (UF) process can be successfully used for recirculation of brine in salted fish processing, and at the same time constitute an easily monitored critical control point in the hazard analysis and critical control point ( HACCP ) system.
Practical Applications
Fish processing industry is characterized by very high water consumption for technological purposes and generates a considerable amount of wastewater burdened with organic matter and mineral compounds (mainly sodium chloride). Such wastewater is usually released to the common sewage system. An alternative solution would be to release it into a recirculation system. This solution can be made possible by membrane separation technologies. The application of the UF using ceramic membranes allows to obtain high‐quality brine which can be successfully reused in the production process after the NaCl content has been replenished. Moreover, introduction of the UF technology meets the requirements of the HACCP system.
The dairy industry is among the most polluting of the food industries in volume in regard to its large water consumption. The present work was related to investigations about practices of water management of 11 dairy plants. Treatment of the process water produced in the starting, equilibrating, stopping and rinsing processing units was proposed to produce water for reuse in the plant and to lower the effluent volume. Reverse osmosis of such wastewaters, collected in dairy plants, was performed after a prior check of their stability during storage. Filtration performances were focused on permeate flux versus water recovery and on water quality (TOC, conductivity). Reverse osmosis water similar to available vapour condensates (produced in drying processes) can be achieved allowing this water to be reused for heating, cleaning and cooling purposes. A 540 m2 RO unit is required to treat 100 m3/d of wastewater with 95% water recovery.
In dairy plants the process waters generated during the starting, equilibrating, interrupting and rinsing steps contribute to the production of effluents. They correspond to milk products (milk, whey, cream) diluted with water without chemicals. The treatment of these dairy process waters by nanofiltration (NF) or reverse osmosis (RO) operations was proposed to concentrate dairy matter and to produce purified water for reuse in the dairy plant. The study reports one-stage and two-stage (NF + RO and RO + RO) spiral-wound membrane treatments with five model process waters representative of the main composition variations observed in dairies. Performances (permeate flux, milk components rejection, purified water characteristics) of the different operations were compared. Discussion was focused on the comparison between quality of produced waters and vapour condensates (from product drying and evaporation processes) reused in dairy plants. Accordingly, both total organic carbon (TOC) and conductivity of water treated by a single RO or NF + RO operations were convenient for reuse as heating, cooling, cleaning and boiler feed water. With the two-stage RO + RO process, a more purified water complying with the TOC drinking water limit was achieved.
Electrical current in combination with a salt was evaluated as a method to destroy Salmonella typhimurium in poultry chiller water. Chiller water from a poultry processing plant was mixed with a salt, sodium chloride (NaCl), sodium nitrate (NaNO3), sodium carbonate (Na2CO3) or trisodium phosphate (Na3PO4), inoculated with S. typhimurium at 1 × 104 CFU/mL, and then treated at 4°C for 60 min using pulsed electrical signals at 10 mA/cm2 current. 1 kHz frequency, and 50% duty cycle. Samples taken at different time intervals were serially diluted, plated on xyclose Iysine desoxycholate (XLD) agr, and incubated at 37°C for 18 to 24 h before the colony forming units (CFU) were counted. To detect injured cells, samples were pre-enriched in buffered peptone water at 37°C for 4 to 5 h and then were plated. The results showed that the bacterial death rate, the decimal reduction time or the time required to destroy 90% of S. typhimurium in chiller water, was 2.7 to 3.1 min with 0.15 M NaCl or 0.015 M Na3PO4, 4.7 min with 0.015 M NaCl, and 9.3 to 10.4 min with 0.15 and 0.015 M NaNO3 or 0.015 M Na2CO3. The bacterial death time of S. typhimurium in the treatments with NaCl decreased as salt concentration or electrical current increased.
About 97% of Escherichia coli strains produce β-glucuronidase, but almost all other Enterobacteriaceae lack this enzyme. A D-glucopyranosiduronic acid (glucuronide) possessing a readily detectable β-linked aglycone should, therefore, constitute a specific reagent for the detection of this organism. For this purpose, the title compound has been synthesized for the first time. The synthesis proceeds in eight steps from readily available D-glucuronolactone, anthranilic acid, and chloroacetic acid and can be carried out on a large scale. The compound has the predicted properties: when included in the standard membrane filter test for the analysis of water, indoxyl-β-D-glucuronide allows specific detection of E. coli through the formation of blue colonies that are the result of rapid conversion of the liberated aglycone to indigo. The recovery of E. coli is easily measured and almost quantitative.
Reverse osmosis separations of polyethylene glycol (PEG) solutes PEG-6000, PEG-9000, PEG-15000, and PEG-20000 in aqueous solutions in the concentration range 50 to 5000 ppm of solute have been studied using porous cellulose acetate membranes in the operating pressure range 25 to 100 psig. On the basis of the analysis of all experimental results, the necessary physicochemical data and practical techniques have been generated for predicting membrane performance (both solute separation and product rate) for reverse osmosis separations of different PEG solutes in aqueous solutions from only a single set of experimental data for a reference feed solution system such as one involving a dilute solution of PEG-6000.