Evaluation of the application for a new alternative processing method for animal by‐products of Category 3 material (ChainCraft B.V.)
2018; Wiley; Volume: 16; Issue: 6 Linguagem: Inglês
10.2903/j.efsa.2018.5281
ISSN1831-4732
AutoresAntonia Ricci, Ana Allende, Declan Bolton, Marianne Chemaly, Robert Davies, Lieve Herman, Konstantinos Koutsoumanis, Roland Lindqvist, Birgit Nørrung, Lucy J. Robertson, Giuseppe Ru, Moez Sanaa, Marion Simmons, Panagiotis Skandamis, Emma Snary, Niko Speybroeck, Benno Ter Kuile, John Threlfall, Helene Wahlström, Rosina Gironés, Avelino Álvarez‐Ordóñez, John M. Griffin, Sandra Correia, Pablo Salvador Fernández Escámez,
Tópico(s)Meat and Animal Product Quality
ResumoEFSA JournalVolume 16, Issue 6 e05281 Scientific OpinionOpen Access Evaluation of the application for a new alternative processing method for animal by-products of Category 3 material (ChainCraft B.V.) EFSA Panel on Biological Hazards (EFSA BIOHAZ Panel), EFSA Panel on Biological Hazards (EFSA BIOHAZ Panel)Search for more papers by this authorAntonia Ricci, Antonia RicciSearch for more papers by this authorAna Allende, Ana AllendeSearch for more papers by this authorDeclan Bolton, Declan BoltonSearch for more papers by this authorMarianne Chemaly, Marianne ChemalySearch for more papers by this authorRobert Davies, Robert DaviesSearch for more papers by this authorLieve Herman, Lieve HermanSearch for more papers by this authorKonstantinos Koutsoumanis, Konstantinos KoutsoumanisSearch for more papers by this authorRoland Lindqvist, Roland LindqvistSearch for more papers by this authorBirgit Nørrung, Birgit NørrungSearch for more papers by this authorLucy Robertson, Lucy RobertsonSearch for more papers by this authorGiuseppe Ru, Giuseppe RuSearch for more papers by this authorMoez Sanaa, Moez SanaaSearch for more papers by this authorMarion Simmons, Marion SimmonsSearch for more papers by this authorPanagiotis Skandamis, Panagiotis SkandamisSearch for more papers by this authorEmma Snary, Emma SnarySearch for more papers by this authorNiko Speybroeck, Niko SpeybroeckSearch for more papers by this authorBenno Ter Kuile, Benno Ter KuileSearch for more papers by this authorJohn Threlfall, John ThrelfallSearch for more papers by this authorHelene Wahlström, Helene WahlströmSearch for more papers by this authorRosina Girones, Rosina GironesSearch for more papers by this authorAvelino Alvarez Ordoñez, Avelino Alvarez OrdoñezSearch for more papers by this authorJohn Griffin, John GriffinSearch for more papers by this authorSandra Correia, Sandra CorreiaSearch for more papers by this authorPablo Fernández Escámez, Pablo Fernández EscámezSearch for more papers by this author EFSA Panel on Biological Hazards (EFSA BIOHAZ Panel), EFSA Panel on Biological Hazards (EFSA BIOHAZ Panel)Search for more papers by this authorAntonia Ricci, Antonia RicciSearch for more papers by this authorAna Allende, Ana AllendeSearch for more papers by this authorDeclan Bolton, Declan BoltonSearch for more papers by this authorMarianne Chemaly, Marianne ChemalySearch for more papers by this authorRobert Davies, Robert DaviesSearch for more papers by this authorLieve Herman, Lieve HermanSearch for more papers by this authorKonstantinos Koutsoumanis, Konstantinos KoutsoumanisSearch for more papers by this authorRoland Lindqvist, Roland LindqvistSearch for more papers by this authorBirgit Nørrung, Birgit NørrungSearch for more papers by this authorLucy Robertson, Lucy RobertsonSearch for more papers by this authorGiuseppe Ru, Giuseppe RuSearch for more papers by this authorMoez Sanaa, Moez SanaaSearch for more papers by this authorMarion Simmons, Marion SimmonsSearch for more papers by this authorPanagiotis Skandamis, Panagiotis SkandamisSearch for more papers by this authorEmma Snary, Emma SnarySearch for more papers by this authorNiko Speybroeck, Niko SpeybroeckSearch for more papers by this authorBenno Ter Kuile, Benno Ter KuileSearch for more papers by this authorJohn Threlfall, John ThrelfallSearch for more papers by this authorHelene Wahlström, Helene WahlströmSearch for more papers by this authorRosina Girones, Rosina GironesSearch for more papers by this authorAvelino Alvarez Ordoñez, Avelino Alvarez OrdoñezSearch for more papers by this authorJohn Griffin, John GriffinSearch for more papers by this authorSandra Correia, Sandra CorreiaSearch for more papers by this authorPablo Fernández Escámez, Pablo Fernández EscámezSearch for more papers by this author First published: 06 June 2018 https://doi.org/10.2903/j.efsa.2018.5281Citations: 5 Correspondence: biohaz@efsa.europa.eu Requestor: European Commission Question number: EFSA-Q-2017-00619 Panel members: Ana Allende, Declan Bolton, Marianne Chemaly, Robert Davies, Pablo Salvador Fernández Escámez, Rosina Girones, Lieve Herman, Konstantinos Koutsoumanis, Roland Lindqvist, Birgit Nørrung, Antonia Ricci, Lucy Robertson, Giuseppe Ru, Moez Sanaa, Marion Simmons, Panagiotis Skandamis, Emma Snary, Niko Speybroeck, Benno Ter Kuile, John Threlfall and Helene Wahlström. Note: Parts of this output have been redacted to ensure compliance with their confidential status, granted by EFSA upon verification of the applicant's request. Adopted: 19 April 2018 AboutSectionsPDF ToolsExport citationAdd to favoritesTrack citation ShareShare Give accessShare full text accessShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL Share a linkShare onFacebookTwitterLinkedInRedditWechat Abstract EFSA received an application from the Dutch Competent Authority, under Article 20 of Regulation (EC) No 1069/2009 and Regulation (EU) No 142/2011, for the evaluation of an alternative method for treatment of Category 3 animal by-products (ABP). It consists of the hydrolysis of the material to short-carbon chains, resulting in medium-chain fatty acids that may contain up to 1% hydrolysed protein, for use in animal feed. A physical process, with ultrafiltration followed by nanofiltration to remove hazards, is also used. Process efficacy has been evaluated based on the ability of the membrane barriers to retain potential biological hazards present. Small viruses passing the ultrafiltration membrane will be retained at the nanofiltration step, which represents a Critical Control Point (CCP) in the process. This step requires the Applicant to validate and provide certification for the specific use of the nanofiltration membranes used. Continuous monitoring and membrane integrity tests should be included as control measures in the HACCP plan. The ultrafiltration and nanofiltration techniques are able to remove particles of the size of virus, bacteria and parasites from liquids. If used under controlled and appropriate conditions, the processing methods proposed should reduce the risk in the end product to a degree which is at least equivalent to that achieved with the processing standards laid down in the Regulation for Category 3 material. The possible presence of small bacterial toxins produced during the fermentation steps cannot be avoided by the nanofiltration step and this hazard should be controlled by a CCP elsewhere in the process. The limitations specified in the current legislation and any future modifications in relation to the end use of the product also apply to this alternative process, and no hydrolysed protein of ruminant origin (except ruminant hides and skins) can be included in feed for farmed animals or for aquaculture. Summary On 8 August 2017, the European Food Safety Authority (EFSA) received from the Netherlands Food and Consumer Product Safety Authority, Ministry of Economic Affairs (Competent Authority) an application (mandate and technical dossier) for the evaluation of an application of the company ChainCraft B.V. (hereinafter referred to as the Applicant) for the approval of an alternative method for treatment of Category 3 material, as foreseen in Article 20 of Regulation (EC) No 1069/2009. Category 3 of animal by-products (ABP) is the lowest risk category. It includes parts of animals that have been considered fit for human consumption in a slaughterhouse but which are not intended for human consumption for commercial or other reasons. Category 3 ABP also includes catering waste and products of animal origin, or foodstuffs containing products of animal origin which are no longer intended for human consumption for commercial reasons, or due to manufacturing, or packaging defects or other defects that do not pose a risk to public or animal health. The proposed alternative method consists of the hydrolysis of Category 3 material to short-carbon chains, resulting in a mixture of volatile fatty acids. The volatile fatty acids are fermented, together with ethanol, to medium-chain fatty acids (MCFA). The MCFA, which are present in their salt form, are separated from the fermentation broth and subsequently purified and dried to form the final product which will be used for animal nutrition. The data used in the assessment were provided by the Applicant as requested in Annex VII of Commission Regulation (EU) No 142/2011 and its amendment by Commission Regulation (EU) No 749/2011. A process flow diagram and a Hazard Analysis and Critical Control Point (HACCP) plan were attached to the application dossier. A report submitted by the Competent Authority, related to the application, was also considered. The feedstock used in the process is Category 3 material. According to the Applicant, materials referred to in Article 10 (o) of Regulation (EC) No 1069/2009 (i.e. adipose tissue) could be used as feedstock but, according to Article 14 d) (i), that type of material together with subcategories 10 (n) and (p) cannot be used for manufacturing feed for farmed animals other than for fur animals. The end use of the material from the ChainCraft B.V. process is animal feed and, in this case, a physical process, with ultrafiltration followed by nanofiltration to remove hazards, instead of a thermal or chemical inactivation process, is used. In a physical process based on filtration, all hazards present should be retained by the barrier imposed by the membrane depending on their physical characteristics. Therefore, the efficacy of the process has been evaluated based on the ability of that physical process to remove potential biological hazards present in the material. The level of agent risk reduction published in 2005 EFSA 'Opinion on the safety vis-à-vis biological risks of biogas and compost treatment standards of animal by-products (ABP)' was used for this particular case to consider if the process was equivalent to the processing standards laid down in Regulation (the process applied for treatment shall be capable of reducing the concentration of the relevant pathogenic bacteria by at least 5 log10 and the infectious titre of the relevant viruses by at least 3 log10). Specific information on the size and physical properties of the various hazards that could be present in the feedstock was not provided by the Applicant. Taking into account their size and considering the filtration properties, viruses and bacterial toxins are the most relevant hazards to be taken into account. The possible presence of small bacterial toxins that could be introduced during the fermentation steps cannot be avoided by the nanofiltration step and this hazard should be controlled by a Critical Control Point (CCP) elsewhere in the process. The ultrafiltration membrane used in the process has a mean pore size of 30 nm according to the technical description provided by the Applicant and probably small viral particles may pass through, e.g. Parvovirus and Circovirus (18–26 nm) and Picornavirus (around 30 nm). Small viruses passing the ultrafiltration membrane will be retained at the nanofiltration step, which represents a CCP in the process. The nanofiltration step of this application has not been validated after inoculation of bacteria or viruses to assess the effectiveness of the process. Nonetheless, the ability of nanofiltration to remove viruses when they are artificially inoculated into laboratory models that mimic industrial-scale nanofiltration conditions has been shown. This CCP requires the Applicant to provide validation and certification for the specific use of the nanofiltration membranes used, in addition to conducting continuous monitoring and membrane integrity tests as control measures described in the risk assessment plan. The end product mainly contains MCFA, but may also contain up to 1% of hydrolysed protein (polypeptides, peptides and amino acids). The limitations specified in the current legislation and any future modifications in relation to the end use of the product also apply to this alternative process, and no hydrolysed protein of ruminant origin (except ruminant hides and skins) can be included in feed for farmed animals or for aquaculture. The ultrafiltration and nanofiltration techniques are able to remove particles of the size of viruses, bacteria and parasites from liquids. If used under controlled and appropriate conditions, the processing methods proposed should reduce the risk in the end product to a degree which is at least equivalent to that achieved with the processing standards laid down in the Regulation (EC) No 1069/2009 for Category 3 material. 1 Introduction 1.1 Background and Terms of Reference as provided by the Dutch Competent Authority On 8 August 2017, the European Food Safety Authority (EFSA) received from the Netherlands Food and Consumer Product Safety Authority, Ministry of Economic Affairs (Competent Authority) an application (mandate and technical dossier), under Regulation (EC) No 1069/20091 and Commission Regulation (EU) No 142/20112, for the evaluation of an application of the company ChainCraft B.V. (hereinafter referred to as the Applicant). An evaluation of the application by the Competent Authority was also submitted to EFSA. The Applicant submitted an application for the approval of an alternative method for the treatment of Category 3 ABP material as foreseen in Article 20 of the Commission Regulation (EC) No 1069/2009. This alternative method consists of the hydrolysis of Category 3 material to short-carbon chains, resulting in a mixture of volatile fatty acids. The volatile fatty acids are fermented, together with ethanol, to medium-chain fatty acids (MCFA). The MCFA, which are present in their salt form, are separated from the fermentation broth and subsequently purified and dried to form the final product. The application of the final product is animal nutrition. Category 3 ABP is defined in Article 10 of Regulation (EC) 1069/2009 as the lowest risk category. It includes parts of animals that have been considered fit for human consumption in a slaughterhouse but which are not intended for consumption for commercial or other reasons. Category 3 ABP also includes catering waste and products of animal origin, or foodstuffs containing products of animal origin which are no longer intended for human consumption for commercial reasons or due to manufacturing or packaging defects or other defects that do not pose a risk to public or animal health. Under Commission Regulation (EU) No 142/2011, catering waste means all waste food, including used cooking oil originated in restaurants, catering facilities and kitchens, including central kitchens and household kitchens. 1.2 Interpretation of the Terms of Reference EFSA evaluated the alternative method proposed by the Applicant under the frame of Article 20 of Regulation (EU) No 1069/2009. 1.3 Additional information During the assessment for the evaluation of the alternative method, as set out in Article 20 of Regulation (EU) No 1069/2009, it was deemed necessary to request additional information and data from the Applicant on certain technical aspects of the dossier. In particular, the Applicant was asked about some specific parameters (temperature and time) related to the evaporation and drying process steps. The Applicant replied with a general description of the process without detailed specifications. 2 Data and methodologies 2.1 Data The data used in the assessment were provided by the Applicant as requested in Annex VII of Commission Regulation (EU) No 142/2011 and its amendment by Commission Regulation (EU) No 749/20113. A process flow diagram and a Hazard Analysis and Critical Control Point (HACCP) plan were attached to the application dossier as well some technical specifications of the membranes systems and of the analysis certificates. The report submitted by the Competent Authority (CA) related to the application was also considered. Relevant scientific papers provided by experts of the Working Group (WG) were considered during the assessment. 2.2 Methodology The EFSA Panel on Biological Hazards (BIOHAZ) evaluated the ChainCraft B.V. process by following the steps set out in the 'EFSA Scientific Opinion on the format for applications for new alternative methods for ABP' (EFSA BIOHAZ Panel, 2010). These steps are: full description of the process; full description of the material to be treated; hazard identification; level of risk reduction; HACCP plan; risk associated with interdependent processes; risk associated with the intended end use of the product. The Applicant is required to document as fully as possible the different aspects of each of these steps and according to the CA, the application meets the requirements as laid down in the above mentioned EFSA Opinion. As set out in Article 20 of European Union Regulation (EC) No 1069/2009, EFSA is required to assess whether the method submitted ensures that the risks to public or animal health are: 'controlled in a manner which prevents their proliferation before disposal in accordance with this Regulation or the implementing measures thereof; or reduced to a degree which is at least equivalent, for the relevant categories of animal by-products, to the processing methods laid down pursuant to point (b) of the first subparagraph of Article 15(1).' In essence, point (b) above means that the proposed processing method must reduce the risk to a degree that is at least equivalent to that achieved by the processing methods that have already been approved for the same category of ABP. This requirement for applications is elaborated in the Commission Regulation (EU) No 142/2011 implementing Regulation (EC) No 1069/2009 and amended by Commission Regulation (EU) No 749/2011. According to point 2(d), Chapter II, Annex VII of Commission Regulation (EU) No 142/2011, any application for the evaluation of alternative methods shall 'show that the most resistant biological hazards associated with the category of materials to be processed are reduced in any products generated during the process, including the waste water, at least to the degree achieved by the processing standards laid down in this Regulation for the same category of animal by-products. The degree of risk reduction must be determined with validated direct measurements, unless modelling or comparisons with other processes are acceptable'. The validation requirements are further elaborated on in the 2010 EFSA Opinion. According to the Opinion and to section 2, Chapter III, Annex V of Commission Regulation (EU) No 142/2011 (point 1 (c)), the 'validation of the intended process can be performed by measuring the reduction of viability/infectivity of: endogenous indicator organisms during the process, where the indicator is: consistently present in the raw material in high numbers, not less resistant to the lethal aspects of the treatment process, but also not significantly more resistant than the pathogens for which it is being used to monitor, relatively easy to quantify and relatively easy to identify and to confirm; or a well-characterised test organism or virus introduced in a suitable test body into the starting material.' The Opinion states that 'results should be accompanied by evidence'. Such evidence 'includes, for measurements, information on the methodology used, nature of samples that have been analysed and evidence that samples are representative (e.g. number of samples, number of tests performed and selection of measuring points). If several treatment steps are involved, an assessment should be performed on the degree to which individual titre reduction steps are additive, or whether early steps in the process may compromise the efficacy of subsequent steps. In any case it is necessary to provide the sensitivity and specificity of the detection methods applied. Data on the repeatability and statistical variability of the measures obtained during the experiments should also be presented.' It states also that 'Generally, the level of risk reduction for human and animal health which can be achieved by the process should be evaluated on the basis of direct measurements (validation).' Should 'no direct measurements of the risk reduction be available (i.e. no validation as defined above is feasible), modelling or comparison with other processes may be acceptable if: the factors leading to the risk reduction are well known; the model of risk reduction is well established; and continuous direct measurements of the factors leading to the risk reduction are provided for the full-scale process which demonstrate that these factors are homogeneously applied throughout the treated batch.' The standard processing methods are described in Chapter III, Annex IV of Commission Regulation (EU) No 142/2011. The degree of risk reduction achieved by these methods is not specified and no definitive standards have been set down in relation to risk reduction for alternative methods dealing with Category 3 materials. The 2010 EFSA Opinion states that the 'standard already approved for validation of composting processes for Category 3 ABPs can be used as a benchmark for other treatment processes for comparable input material and potential end use.' In the present assessment, the same rationale for agent risk reduction published in the 2005 EFSA Opinion is used: the process applied for treatment shall be capable of reducing the concentration of the relevant pathogenic bacteria by at least 5 log10 and the infectious titre of the relevant viruses by at least 3 log10 (EFSA, 2005a). The end use of the material from the ChainCraft B.V. process is animal feed and a physical process based on filtration is used to remove biological hazards. In a filtration process all hazards present should be retained by the barrier imposed by the membrane depending on their physical characteristics (size, charge, membrane affinity, etc.). Therefore, the efficacy of the process has been evaluated based on its ability to remove potential biological hazards, irrespective of the levels of hazards present in the raw material. The Applicant describes the raw material as Category 3 material and the final product as MCFA that may contain up to 1% of hydrolysed protein. Therefore, the following Regulations concerning the raw materials and the end use of these final products have been considered in the assessment: Regulations (EC) No 1069/2009, Commission Regulations (EU) No 142/2011 and Regulation (EC) No 999/2001 and their amendments. 3 The new process as provided by the Applicant The description presented in the current chapter has been extracted verbatim from the application, with minor editorial changes for clarity purposes. The 'alternative method consists of the hydrolysis of Category 3 material', e.g. food waste, 'to short-carbon chains, resulting in a mixture of volatile fatty acids. The volatile fatty acids are fermented, together with ethanol, to MCFA. The MCFA, which are present in their salt form, will be separated from the fermentation broth and subsequently purified and dried to the final product. The application of the final product is animal nutrition.' 'ChainCraft developed a platform technology in order to produce chemical building blocks that are now being produced from crude palm kernel oil or petrochemical sources. This unique patented technology can be integrated into the existing infrastructure of the agri-food industry and uses different types of organic product streams, including Category 3 material, as feedstock. The process can be divided into seven important steps. The first step is the pre-treatment of Category 3 material. When former foodstuffs are used as feedstock, the products are unpacked. Subsequently the particle size of the feedstock is reduced. In the second step the organic feedstock is hydrolysed and acidified by a mixed culture of bacteria. During the hydrolysis and acidification phase, long carbon chains in the biomass are biodegraded into short chain fatty acids. At the end of the second step, solid particles are removed. In a third step the short chain fatty acids are coupled with ethanol via fermentation to longer chains: the MCFA. At the end of this step, the product is filtered by ultrafiltration. The product is then concentrated by reverse osmosis. In the next step, the product passes through a nanofiltration membrane, which guarantees that all molecules have a molecular weight below 10,000 dalton and no microorganisms and proteins can be present. Subsequently, ammonia is removed by stripping, after which the product flow will pass an evaporation step and drying step, in which the product is dried to a solid powder of fatty acid salts. The application of the final product is animal nutrition. According to Regulation (EC) No 767/2009, the product can be considered as feed material, suitable for all animal species.' The process with its main seven steps can be visualized in Figure 1 below. Figure 1Open in figure viewerPowerPoint Process flow diagram of a new alternative processing method for Category 3 ABP material (ChainCraft B.V.) 3.1 Pre-treatment of Category 3 material 'Category 3 material is used as feedstock. Initially, ChainCraft will process former foodstuffs (as described in Article 10(f) of Regulation (EC) No 1069/2009). All subcategories of Category 3 material, other than materials referred to in Article 10(m), (n), and (p) of Regulation (EC) No 1069/2009, may be used as feedstock. The category 3 material is supplied by vendors who are authorized according to Regulation (EC) No 1069/2009. The former foodstuffs are unpacked and the particle size of the Category 3 material is reduced with a hammer mill or other suitable milling equipment. Unpacking and milling can be done by the supplier. The particle size after the pre-treatment is usually smaller than 12 mm.' 3.2 Hydrolysis, acidification and solid/liquid separation 'The Category 3 material is hydrolysed and acidified by an anaerobic mixed culture (mesophilic or thermophilic) fermentation. Naturally occurring endogenous microorganisms are used (no specific bacterial culture is added to the process). Recycled water coming from the reverse osmosis and/or evaporation step is added. Sodium hydroxide is added for acidity/pH control. Mixing in the reactors occurs via stirring or nitrogen bubbling. The resulting main process flow is a fermentation broth containing water and mainly dissociated volatile fatty acids (VFA) and some ethanol. The resulting gas flow from the fermentation contains nitrogen, hydrogen sulphide, hydrogen, methane and carbon dioxide. This gas is treated by a scrubber where the hydrogen sulphide is removed by activated carbon. The remaining gas will be burned in the steam engine for steam production or will be flared, all within permit boundaries. Periodically, the used activated carbon will be reactivated by the supplier. The remaining solids and liquids in the main process flow are separated from each other by a centrifuge decanter and/or disk bowl centrifuge. The solids, which are considered as untreated Category 3 material, will be disposed of via one of the routes described in the application' (see Section 4.5.1). 'Characteristics of the main process flow: ■■■■■ ■■■■■ • Temperature: mesophilic or thermophilic • Pressure: atmospheric • Exposure time: up to 8 days ■■■■■ ■■■■■ • Particle size after solid/liquid separation: maximum 0.5 mm' 3.3 Fermentation and Ultrafiltration 'The dissociated VFA in the main process flow will be fermented, together with ethanol, to dissociated medium-chain fatty acids (MCFA).' According to the Applicant, 'the fermentation is mesophilic and the dominant prevailing fermenting organism is Clostridium kluyveri. Natural occurring endogenous microorganisms are used (no specific bacterial culture is added to the process). Sodium hydroxide is added for acidity/pH control. The resulting main process flow is a fermentation broth containing mainly water, dissociated MCFA, and sodium ions. The remaining solids and liquid in the main process flow are separated from each other by membrane filtration (ultrafiltration).' The Applicant claims that 'the ultrafiltration will remove all microbiological species, viruses and parasites. The membranes have a pore size of maximum 30 nm' (according to the technical annex provided by the Applicant, membranes have a mean pore size of approximately 30 nm). 'The permeate fraction is the main process flow. The retentate is the flow containing the solids. This stream is a Category 3 material that will be disposed of following one of the routes described in the application' (see Section 4.5.1). 'The resulting gas flow from the fermentation contains nitrogen, hydrogen sulphide, hydrogen, methane, and carbon dioxide. This gas is treated by a scrubber where the hydrogen sulphide is removed: the remaining gas will be burned in the steam engine for steam production or will be flared, all within permit boundaries. The used activated carbon will be periodically reactivated by the supplier. Characteristics of the main process flow: ■■■■■ ■■■■■ • Temperature: mesophilic • Pressure: atmospheric • Exposure time: maximum 2 days ■■■■■ ■■■■■ • Particle size after ultrafiltration: maximum 30 nm' 3.4 Concentration via reverse osmosis 'The remaining main process flow will be split via reverse osmosis (R.O.) into a permeate flow containing clean water and a concentrated retentate. The major part of the process water will be used for recirculation. The surplus is was
Referência(s)