Clean in Place – A Review of Current Technology and its Use in the Food and Beverage Industry
Report for general circulation
Clean in Place – A Review of Current Technology and its Use in the Food and Beverage Industry
October 2005 Report for general circulation
Clean in Place – A Review of Current Technology and its Use in the Food and Beverage Industry
Deakin Project Team Dr Laurence Palmowski A/Prof K. (Bas) Baskaran Dr Heidi Wilson Mr Brett Watson
October 2005
Project Contact Details Dr Laurence Palmowski School of Engineering and Technology Deakin University Geelong, VIC, 3217 Tel (03) 5227 2443 Fax (03) 5227 2167 Email:
[email protected]
Disclaimer This publication may be of assistance to you, but Deakin University and their employees do not guarantee that the publication is without flaw of any kind or is wholly appropriate for your particular purposes, and therefore disclaims all liability for any error, loss or other consequence which may arise from you relying on any information in this publication.
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Clean in Place – A Review of Current Technology and its Use in the Food and Beverage Industry
1 Introduction
EXECUTIVE SUMMARY The need to recycle water is becoming increasingly important. One of the main factors limiting the potential for water recycling is the high level of Total Dissolved Solids (TDS) found in treated water. Melbourne Water and City West Water, in their salinity reduction strategy for the Western Treatment Plant, have set a target of reducing TDS in treated water by 40% by 2009. Identified options to reduce TDS level in recycled water include end-of-pipe desalination technologies, segregation of salty streams at source, and TDS reduction and substitution at source. Following the waste hierarchy, TDS reduction and substitution at the source appear to be the best approaches as they avoid costly desalination technologies and the difficult handling of the segregated by-products. The food and beverage industries are among the main contributors of TDS loads to the sewer. A large source of TDS, and particularly sodium, in these factories is the cleaning chemicals used to maintain high hygienic and quality levels in the factories. Conventional cleaning agents used in the food and beverage industry are usually based on sodium hydroxide, and/or require strong acids or bases for neutralization. This results in high dissolved solids levels, especially sodium levels, being discharged in effluent streams from factories. Therefore, to reduce TDS loads discharged to the sewer it is necessary to review current industrial cleaning practices.
Project aims
The aim of this project was two-fold. The first aim was to identify cleaning chemicals that have the potential to replace traditional chemicals used in the food and beverage industry and that can reduce TDS in effluent discharged to the sewer. The second aim was to identify technologies that can be used to collect, treat and reuse cleaning solutions for subsequent cleaning cycles. This could lead to significant reduction in cleaning chemical usage. The tasks of the project were as follows:
Alternative cleaning chemicals
Conduct a critical desk-top review of CIP cleaning agents containing reduced levels of sodium or no sodium.
Undertake a desk-top review of CIP chemical recovery technologies via the trade and scientific literature.
There is a wide variety of cleaning agents currently available that could provide an alternative to sodium hydroxide. The alternative cleaning agents include built cleaning solutions (contain additives), low sodium alkaline cleaners, potassium hydroxide (KOH) based products, NaOH/KOH blends, biotechnology based
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Clean in Place – A Review of Current Technology and its Use in the Food and Beverage Industry
cleaners and further alternatives including plant based products. Alternatives to conventional acid cleaners were also identified. From this review, it was found that the use of built cleaning solutions can reduce cleaning times and/or cleaning chemical concentrations. The use of alkaline cleaners with medium and low sodium concentrations can lead to reductions in sodium discharge from CIP in the range of 78-99%. Even further reductions in sodium levels can be achieved by using KOH based products which do not contain sodium at all (almost 100% reduction in sodium discharge from CIP). However, the cost of KOH based cleaning agents is higher than that of NaOH, which is currently limiting its wide spread application in processing plants. Enzyme based cleaners have been shown to be very effective for cleaning purposes in the food and beverage industries. However, the application of enzymes is mainly restricted to cleaning membranes due to their operating temperature. Further alternatives to alkaline cleaning agents, including plant-based products were found to be rarely used in large scale applications. In addition, there is little information available on these chemicals. Alternative acid cleaners, which are mainly based on citric acid, have been shown to be effective for cleaning purposes but they have yet to become widely used in the food and beverage industries. Reuse and recovery of cleaning solutions
A number of different CIP systems are currently used in the food and beverage industries and can be categorised as follows: single use system, reuse system and multi-use system. A number of benefits and limitations are associated with each type of system. Reuse systems collect and reuse used CIP solutions for subsequent CIP cycles. As a result, reuse systems have lower running costs due to lower chemical requirements. However, they require trained operator and a centralised CIP infrastructure. Due to their simplicity, single use systems may be favoured over reuse and multi-use systems for certain applications. However, there will be situations where reuse and multi-use systems will be the better option. A table summarising the advantages and disadvantages of each system was produced to provide guidance for selecting the most appropriate technology for a specific application. While reuse systems increase the life of CIP cleaning solutions, leading to cost and environmental benefits, the use of recovery technologies can further extend the life of CIP solutions. By removing organic and inorganic contaminants from cleaning solutions, recovery technologies such as centrifugation or membrane separation can reduce chemical usage by up to 97%.
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Clean in Place – A Review of Current Technology and its Use in the Food and Beverage Industry
CIP optimisa tion
Recommendations
Several optimisation methods can be implemented to help minimise the consumption of cleaning chemicals, thereby reducing the TDS load of the effluent. Some of these methods are the review of cleaning frequency, the use of mechanical action (pigging systems, high pressure sprayers and floor scrubbers) and CIP monitoring. Increased intervals between cleaning cycles have been found to have little or no negative impact on product quality and hygienic requirements in certain applications. Pigging systems are effective at removing product from pipes prior to chemical cleaning while high pressure spray and mechanical floor scrubbers can enhance the removal of biofilms from equipment. CIP monitoring systems can be used to fine-tune and optimise the cleaning operations of factories. Further work is recommended including laboratory evaluation of alternative cleaning chemicals, followed by factory trials. Pilotscale trials of reuse and recovery systems in factories are suggested. Of high priority is also the training on CIP practices and optimisation as well as the transfer of technology and knowledge to industry.
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Clean in Place – A Review of Current Technology and its Use in the Food and Beverage Industry
2 TABLE OF CONTENT 1
EXECUTIVE SUMMARY................................................................................ 2
2
TABLE OF CONTENT ................................................................................... 5
3
ACRONYMS ................................................................................................. 7
4
INTRODUCTION ........................................................................................ 10 4.1 CLEANING AND CIP......................................................................................... 10 4.1.1 Key factors for cleaning .....................................................................................................10 4.1.2 The benefits of CIP vs. manual cleaning ............................................................................12 4.1.3 Typical CIP cycle................................................................................................................13 4.2 AIM AND OBJECTIVES ..................................................................................... 13 4.2.1 Background.........................................................................................................................13 4.2.2 Aim and Objectives.............................................................................................................14 4.2.3 Scope of the project ............................................................................................................15
5
IDENTIFICATION OF REDUCED SODIUM AND NON-SODIUM CLEANERS..... 15 5.1 INTRODUCTION ............................................................................................... 15 5.2 BUILT NAOH OR BUILT KOH............................................................................ 16 5.3 ALKALINE CLEANERS WITH MEDIUM OR LOW SODIUM CONCENTRATIONS ................... 16 5.4 POTASSIUM HYDROXIDE (KOH) BASED PRODUCTS ................................................ 17 5.5 SODIUM AND POTASSIUM BLENDS ...................................................................... 18 5.6 ENHANCED CLEANING CHEMICALS ..................................................................... 19 5.7 BIOTECHNOLOGY CLEANING AGENTS .................................................................. 20 5.7.1 Enzyme-based cleaners.......................................................................................................20 5.7.2 Bacteria-based cleaners .....................................................................................................26 5.8 ALTERNATIVES TO ALKALINE CLEANING AGENTS INCLUDING PLANT-BASED CLEANERS .. 27 5.9 ALTERNATIVE ACID CLEANERS ........................................................................... 29 5.10 ALTERNATIVE SANITISERS ............................................................................. 29 5.10.1 Alternative chemical sanitisers...........................................................................................30 5.10.2 Non-chemical sanitisers .....................................................................................................31 5.10.3 Combined acid detergent + sanitiser .................................................................................33 5.11 COMPARISON OF CLEANING CHEMICALS ........................................................... 33 5.11.1 Comparison on cleaning performance ...............................................................................33 5.11.2 Comparison of cleaning efficiency for membrane cleaning ...............................................34 5.11.3 Comparison of cleaning efficiency for biofilm removal......................................................36 5.11.4 Comparison of cleaning chemicals through life cycle assessment .....................................36 5.12 DESK-TOP REVIEW OF THE IMPACT OF IMPLEMENTATION OF ALTERNATIVE CHEMICALS 37 5.12.1 Residue risk, OH&S and corrosion issues..........................................................................37 5.12.2 Sodium discharge reduction ...............................................................................................38
6
REVIEW OF CIP RECOVERY TECHNOLOGIES ............................................ 40 6.1 INTRODUCTION ............................................................................................... 40 6.2 SINGLE USE SYSTEMS ...................................................................................... 41 6.3 MULTI-USE SYSTEMS ....................................................................................... 42 6.3.1 Benefits of multi-use systems ..............................................................................................42 6.3.2 Case studies ........................................................................................................................43 6.4 CIP REUSE SYSTEMS ...................................................................................... 44 6.4.1 General remarks .................................................................................................................44 6.4.2 Straight reuse vs. treatments...............................................................................................45 6.4.3 Reuse after gravity separation............................................................................................45 6.4.4 Reuse following physicochemical treatments .....................................................................48 6.4.5 Reuse following membrane separation...............................................................................49 6.5 REVIEW OF POSSIBLE IMPLEMENTATION OF CIP RECOVERY TECHNOLOGIES .............. 57
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Clean in Place – A Review of Current Technology and its Use in the Food and Beverage Industry
6.5.1 6.5.2 7
Single use vs. reuse systems................................................................................................57 Selection summary of reuse treatment technologies ...........................................................58
OPTIMISATION OF CLEANING TOWARDS REDUCED CHEMICAL USAGE ..... 60 7.1 FREQUENCY OF CLEANING ................................................................................ 61 7.2 MECHANICAL ACTION TO SUPPORT CLEANING ....................................................... 62 7.2.1 High pressure spray and mechanical scrubber ..................................................................62 7.2.2 Pigging systems ..................................................................................................................62 7.3 CIP MONITORING ........................................................................................... 63 7.4 CASE STUDIES ............................................................................................... 63
8
RECOMMENDATIONS FOR FUTURE WORK ................................................ 64
9
ACKNOWLEDGMENTS ............................................................................... 66
10
REFERENCES......................................................................................... 67
APPENDICES Appendix A - Summary and classification of alternative chemicals
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Clean in Place – A Review of Current Technology and its Use in the Food and Beverage Industry
3
ACRONYMS
BSA
Bovine Serum Albumin
CAPEX
Capital Expenditure
CIP
Cleaning-In-Place
COD
Chemical Oxygen Demand
CSCCO
Combined Simultaneous Caustic Cleaning and Oxidation
CTAB
Cetyle-Trimethyl-Ammonium Bromide
CWW
City West Water
DEH
Department of the Environment and Heritage
EDTA
Ethylene Diamine Tetra Acetic Acid
EO
Electrolysed Oxidizing
EPA
Environment Protection Authority
ETBPP
Environmental Technology Best Practice Program
H3PO4
Phosphoric acid
HCl
Hydrochloric acid
HNO3
Nitric acid
KMS
Koch Membrane Systems
LCA
Life Cycle Assessment
LPS
Lactoperoxidase System
MF
Microfiltration
NaOH
Sodium hydroxide
NF
Nanofiltration
NFESC
Naval Facilities Engineering Service Center
OH&S
Occupational Health and Safety
PLC
Programmable Logic Controller
PPM
Parts Per Million
PVC
Poly Vinyl chloride
RO
Reverse Osmosis
RWPC
Reconstituted Whey Protein Concentrate
SDS
Sodium Dodecyl Sulphate
SME
Small and Medium Enterprise
SPC
Standard Plate Count
SS
Suspended Solids
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Clean in Place – A Review of Current Technology and its Use in the Food and Beverage Industry
TAZ
Terg-A-Zyme
TOC
Total Organic Carbon
TDS
Total Dissolved Solids
TVC
Total Viable Count
UF
Ultrafiltration
UK
United Kingdom
UNEP
United Nations Environment Programme
UV
Ultraviolet
Glossary
Caustic or caustic soda
Other name for sodium hydroxide
Diafiltration
Water is added during the filtration process to reduce the concentration of a component in the retentate or permeate (Wagner 2001)
Fouling
Product residues, scale and other unwanted deposits. Word used interchangeably with “Soil”
Flux
Flow rate through a membrane divided by membrane surface area
Membrane recovery
Defined as the volume of permeate obtained per total volume of stream processed
Permeate
Stream passing through a membrane
Recirculation
In most CIP cycles, there is a step where cleaning solutions are recirculated, i.e. pumped in closed loop through the equipment until an acceptable cleaning level is reached
Recovery
Collection of cleaning solutions followed by treatment and subsequent use in following cleaning cycles
Recycling
In this report, this term is limited to the recycling of water
Retentate
Stream not passing through a membrane
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Clean in Place – A Review of Current Technology and its Use in the Food and Beverage Industry
Reuse
Collection of cleaning solutions and subsequent use in following cleaning cycles
Soil
Product residues, scale and other unwanted deposits (Romney 1990a)
Specific energy
Energy required in a membrane process per volume of permeate obtained
Volume retention ratio (VRR) Volume of retentate solution treated
over
volume
of
Symbols
)
Symbol for a case study Symbol for a scientific research outcome
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Clean in Place – A Review of Current Technology and its Use in the Food and Beverage Industry
4
INTRODUCTION 4.1 Cleaning and CIP
Trägårdh (1989) defined cleaning as “a process where material is relieved of a substance which is not an integral part of the material.” In the food and beverage industry, cleaning is an essential procedure in the operation of a factory to achieve the following objectives (Garrick and Schiekowski 1980; Dresch et al. 2001):
Maintain the high hygienic levels required;
Remove soil (or fouling) to restore process performance (heat transfer, pressure drops). Soil is defined as product residues, scale and other unwanted deposits (Romney 1990a);
Maintain product quality.
4.1.1 Key factors for cleaning Cleaning is a combination of physical and chemical action, in which the following aspects play an important role (Australian Standards 2001):
Contact time. The contact time between the chemical and the soil is important and needs to cover the following phases: o Diffusion of the cleaning chemical into the soil layer o Swelling of the soil o Mass transfer phase from the soil layer into the liquid o Transport away from the surface, flush
Temperature o Cold: below 30ºC o Warm: 30 - 50ºC o Hot: 50 - 80ºC o Very hot: above 80ºC Temperature influences diffusion, mass transfer and fluid characteristics, the various parameters are thus inter-linked.
Turbulence and resulting shear forces acting on deposits
Type of soil (Romney 1990a; Prasad 2004c) o Organic soil: mainly of plant or animal origin, depending on the industry. Organic soil is usually cleaned by alkaline detergents, amongst which sodium and potassium hydroxide are the most common. o Inorganic soil: mainly of mineral origin. It is mostly cleaned by acidic detergents, including inorganic acids (e.g.
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Clean in Place – A Review of Current Technology and its Use in the Food and Beverage Industry
phosphoric, nitric and hydrochloric acids) and to a smaller extent organic acids (e.g. hydroxyacetic and citric acid) o Combined organic/inorganic common type
soil,
which
is
the
most
o Biofilms, which develop on equipment if soils are not removed frequently enough. Biofilms can lead to hygiene issues as well as adverse technological effects (Kumar and Anand 1998)
Concentration and type of cleaning chemical
A wide variety of detergents are used in the food and beverage industry. They can be classified according to their functions and applications (Australian Standards 2001). Brief descriptions of the different detergents commonly used in the food and beverage industry are given below. The following section has been taken directly from Australian Standards (2001). Multi-purpose detergents – Multi-purpose detergents are intended primarily for use in manual, pressure or foam cleaning of all types of surfaces, in all areas. Heavy-duty alkaline detergents – Heavy-duty alkaline detergents are intended for the removal of proteins, fats and other strongly adherent organic soils from surfaces. Enzyme-assisted detergents – Enzyme-assisted detergents are detergent formulations which contain enzymes, which are intended to break down and solubilize otherwise difficult-to-remove food soils using relatively mild detergents and cleaning conditions. Acidic detergents – Acidic detergents are used to remove mineral soils and other soils resistant to neutral or alkaline detergents. Oil-lift detergents – Oil-lift detergents are detergents, typically containing water soluble solvents and surfactants, intended for the removal of accumulated grease and oil from walls and floors. Smokehouse detergents – Smokehouse detergents are designed primarily for the removal of fats and tar from walls, floors and equipment in smokehouses. It is common practice to add additives to pure cleaning chemicals such as NaOH to improve specific attributes of the chemicals. The attributes that a detergent should ideally have are described in the following section, which has been taken directly from Romney (1990a). Dispersing and suspending power – to bring insoluble soils into suspension and prevent their redeposition on cleaned surfaces.
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Clean in Place – A Review of Current Technology and its Use in the Food and Beverage Industry
Emulsifying power – to hold oils within the cleaning solution. Sequestering power – the ability to combine with calcium and magnesium salts to form water-soluble compounds and to aid detergency. Wetting power – to reduce surface tension and thus aid soil penetration. Rinsing power – the ability to rinse away clearly and completely without leaving any trace of soil or the detergent chemical on the cleaned surface. In membrane cleaning for example, surfactants perform a wide range of roles: they help to wet surfaces, facilitate soil removal, suspend materials, stabilize foam, adsorb on surfaces to amend properties of the surface and act as biocide (D'Souza and Mawson 2005).
4.1.2 The benefits of CIP vs. manual cleaning Over the last few decades, the use of Cleaning-In-Place (CIP) systems has brought more reliability in equipment cleaning. CIP is defined as “the cleaning of complete items of plant or pipeline circuits without dismantling or opening of the equipment and with little or no manual involvement on the part of the operator. The process involves jetting or spraying of surfaces or circulation of cleaning solutions through the plant under conditions of increased turbulence and flow velocity” (NDA Chemical Safety Code, 1985). The use of CIP shows numerous advantages compared to manual cleaning, including improved cleaning efficiency, shorter cleaning cycles, improved Occupational Health and Safety (OH&S) and reduced environmental impact (DEH 2003).
) As an example, Cascade Brewery applied, extended and automated the reticulation of cleaning solution throughout their brewery and beverage plants. As a result, a 60% reduction in cleaning agents was achieved in the brewery, while the reduction reached up to 80% in the cider section of the beverage plant (DEH 2003).
) The introduction of CIP systems in a Small and Medium Enterprise (SME) can also show economic and environmental benefits. At Food Spectrum, which produces ingredients for the food manufacturing industry, it is estimated that 20% of cleaning water can be reused by introducing a $50,000 CIP system, with a pay-back period of 3 years (Prasad et al. 2004). It was also reported that the CIP system has the potential to increase water reuse to 50%, leading to increased water savings and reduced payback period (EPA 2003).
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Clean in Place – A Review of Current Technology and its Use in the Food and Beverage Industry
4.1.3 Typical CIP cycle A typical CIP cycle is presented in the sequence below (Romney 1990a; Australian Standards 2001). It is important to note that this cycle will differ from one site to another and from one process to another at the same site. 1. Product flush to remove product residuals. This is often carried out using water but is not a necessity 2. Pre-rinse to remove any loosely-adherent residuals (and microorganisms attached to these residuals). This is usually performed with water (or slightly alkaline solution) and reduces the amount of soil, which the main cleaning step has to remove. 3. Main cleaning step to lift the soil from the equipment surface. The soiling compounds will be suspended or dissolved in the cleaning solution. This step, which is responsible for removing most of the soil and micro-organisms attached to surfaces, can be subdivided into sub-steps to allow for various cleaning chemicals to be used. For example: a. Caustic cleaning, followed by b. Intermediate rinse, and c. Acid cleaning step (when required) 4. Final rinse to remove residuals of cleaning solutions 5. Disinfection/sanitising step to reduce the number of microorganisms from previously cleaned surfaces 6. Post-rinse might be necessary to remove residuals of sanitisers Each food and beverage industry type has different CIP requirements. Furthermore, each area of a food and beverage factory can have different CIP requirements. For example, the CIP requirements differ in open systems (e.g. vessels) and in closed systems (e.g. pipes). The CIP performance in the former is easier to assess visually.
4.2 Aim and Objectives 4.2.1 Background The need to recycle water in industry is becoming increasingly important. There is also a growing need to reduce sewer loadings to achieve a higher quality of trade waste discharges and of treated water. Total Dissolved Solids (TDS) levels in treated water have been identified as a key factor limiting water recycling due to their significant impact on soil productivity (DSE 2004). In the Western Melbourne metropolitan
13
Clean in Place – A Review of Current Technology and its Use in the Food and Beverage Industry
region, almost half of the TDS in treated water is produced by industry and commerce. The government has shown its commitment to work with industry and water authorities to improve industrial water management. Urban water authorities are currently working with industrial and commercial customers and the Environment Protection Authority (EPA) to develop cleaner production programs and to reduce TDS discharges. In particular, Melbourne Water and City West Water in their salinity reduction strategy for the Western Treatment Plant have set a target of reducing the TDS content of recycled water by 40% by 2009 (DSE, 2004). Identified options to reduce TDS content in recycled water include endof-pipe desalination technologies, segregation of salty streams at source, and salt reduction and substitution at source. Following the waste hierarchy, salt reduction and substitution at the source appear to be the best approaches as they avoid costly desalination technologies and the difficult handling of the segregated by-products. The food and beverage industry, which represents 22% of the total Victorian manufacturing turnover (ABS 2005), is a significant contributor to trade waste and TDS discharges. It is estimated that approximately 50% of the sodium found in trade waste from some of the food and beverage industries originates from CIP practices. The reason for this is that conventional cleaning agents used in CIP systems are usually based on sodium hydroxide, and/or require strong acids or bases for neutralization. This results in high dissolved solids levels, especially sodium levels, being discharged from factories in trade waste. 4.2.2 Aim and Objectives The aim of this project was two-fold. The first objective was to identify CIP chemicals that have the potential to replace traditional CIP chemicals used in the food and beverage industry to reduce TDS in trade waste. The second aim is to identify the technologies that can be used to collect, treat and reuse cleaning chemicals for subsequent cleaning cycles. The tasks of the project were as follows:
Conduct a critical desk-top review of CIP cleaning agents containing reduced levels of sodium or no sodium. To conduct this review, published literature, available case studies, and chemical suppliers have been consulted.
Undertake a desk-top review of CIP chemical recovery technologies via the trade and scientific literature. Technology suppliers have also been contacted for additional information.
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Clean in Place – A Review of Current Technology and its Use in the Food and Beverage Industry
4.2.3 Scope of the project The main focus of this report is on factories in the food and beverage sector, which are major contributors of TDS within the CWW boundary. Some information related to the utilisation of alternative chemicals and technologies has also been found from other industry sectors and has been included in the report. All assessments have been made based on published literature, available case studies and information provided by suppliers of alternative chemicals and/or technologies. No experimental work was undertaken at this stage of the project.
5
IDENTIFICATION OF REDUCED SODIUM AND NONSODIUM CLEANERS 5.1 Introduction
One of the main purposes of this project was to identify alternative CIP chemicals and processes to those currently used in the food and beverage industry with the intention of reducing TDS in effluent discharged to the sewer. Sodium hydroxide or caustic soda (NaOH) is the most widely used alkaline detergent in the food and beverage industry, due to its low price and high cleaning efficiency for fatty-type and protein soils. The most commonly used acidic detergents are nitric acid and phosphoric acid. These conventional cleaning chemicals contribute significantly to the TDS and sodium levels discharged by food and beverage industries. As a result of high TDS and sodium concentrations, the recycling of treated water is restricted to avoid any damage on soils and vegetation. Therefore, there is a clear need to identify alternative chemicals to reduce the use of traditional chemicals throughout the food and beverage industry. The range of alternative cleaning chemicals can be classified as follows:
Built NaOH or built KOH. These chemicals contain additives which enhance the performance of the sodium and/or potassium hydroxide. As a result, lower salt/sodium concentrations can be used.
Low sodium alkaline cleaners
Potassium hydroxide (KOH) based products
NaOH/KOH blends
Biotechnology based cleaners, mainly consisting of enzyme-based cleaners
Alternatives to alkaline cleaning agents, including plant-based cleaners
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Clean in Place – A Review of Current Technology and its Use in the Food and Beverage Industry
Alternative acid cleaners
Alternative sanitisers, including non-chemical based sanitisers
All these options, which offer a possible reduction in TDS and/or sodium in trade waste, are discussed in more detail below. Available case studies and literature references have been included. A complete list of all alternative chemicals can be found in Appendix A. It should be noted that some of the chemicals listed are currently not available in Australia and would need to be introduced if interest was shown. Following this presentation of the alternative chemicals, a desk-top assessment of the possible reduction in sodium discharged to trade waste, as a result of the change over from traditional cleaning chemicals, is presented.
5.2 Built NaOH or built KOH As discussed in the introduction to this report (section 4.1.1), additives (or builders) are often added to cleaning solutions to improve their properties and cleaning efficiency. Cleaning solutions containing additives are called “built” cleaning solutions. The use of built cleaning solutions can reduce cleaning times, rinse water consumption and/or cleaning chemical concentrations. This can therefore lead to improved trade waste discharges. Typical additives include:
Dispersing and suspending agents
Emulsifiers and surfactants
Sequestrants
Wetting agents
Rinsing agents
As an example, sequestrants are widely used to remove hardness from water. Prasad (2004c) reported that “hard water can result in scale build-up, which affects the capacity of detergents and sanitisers to contact the surface and can lead to excessive scaling in boilers and cooling towers.” Therefore, hard water may need some treatment such as ion exchange or the use of detergents and sanitisers containing specially formulated additives (Prasad 2004c).
5.3 Alkaline cleaners with medium or low sodium concentrations While the sodium concentration in chemical cleaners can reach 52% (pure or bulk caustic – see Appendix A for examples of these chemicals)), chemical manufacturers have developed products with lower sodium concentrations. Table 1 presents alkaline cleaners with medium sodium concentrations, while Table 2 shows alkaline cleaners
16
Clean in Place – A Review of Current Technology and its Use in the Food and Beverage Industry
with low sodium levels. The sodium concentration corresponds to the sodium concentration in the cleaning solution, after dilution. This has been calculated using the sodium content of the chemical and its range of recommended concentration. More details about these chemicals and their applications can be found in Appendix A. Table 1: Alkaline cleaners with medium sodium concentration Name
Chlorozolv
Suma Ilam L1.8
Composition 20% w/v as sodium hydroxide Active chlorine Stable chelating and dispersing agents Na content ≥ 11.5% Sodium Hydroxide < 30% Sodium Hypochlorite < 4% available chlorine Na: 12.6% w/w Scale inhibitors
Na level in ready-to-use cleaning solution [gNa/kg cleaning solution]
1.7 – 2.9
0.63 – 1.89
Table 2: Alkaline cleaners with low sodium concentration Name
Diverwash VC24
Flowsan
Glide
Composition Na: 1.8%w/w Wetting agents, buffering agents, sequestrants & dispersants Sodium hydroxide 5-15% Sodium hypochlorite 5-15% Chlorine-based bleaching agents 5-15% Polycarboxylates
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