Cellar waste minimization in the wine industry: a systems approach

Journal of Cleaner Production 15 (2007) 417e431 www.elsevier.com/locate/jclepro

Cellar waste minimization in the wine industry: a systems approach Ndeke Musee, Leon Lorenzen*, Chris Aldrich Department of Process Engineering, University of Stellenbosch, Stellenbosch, Private Bag X1, Matieland 7602, South Africa Received 21 June 2005; accepted 9 November 2005 Available online 27 December 2005

Abstract Waste minimization is slowly being adopted in the wine industry, owing to a combination of powerful drivers, which are either internally or externally motivated. However, these waste minimization practices in the wine industry are still carried out in an ad hoc fashion and have proven to be inefficient in many cases. The lack of a systematic methodology of synthesizing and targeting specific waste streams by the industry has been identified as a major cause of failure in realizing the full potential of waste minimization in the wine industry. This paper discusses a systems approach framework based on three fundamental concepts, viz. the identification of waste sources, detailed causative analysis of the wastes, as well as the derivation of feasible waste minimization alternatives based on the qualitative data and information obtained during process flowsheet evaluations. The application of the qualitative waste minimization methodology described in this study, led to the identification of 90 waste minimization strategies. Approximately 48% of the total number of strategies targeting intrinsic and extrinsic wastes falls in the category of process execution and management (operating practices). On the basis of these findings, waste minimization can yield considerable benefits to the wine industry on condition that it is incorporated as an integral part of the entire vinification process. Ó 2005 Elsevier Ltd. All rights reserved. Keywords: Wine industry; Vinification process; Waste minimization; Systems approach

1. Introduction Industrial wine production and its complementary products are accompanied by generation of large quantities of waste streams, namely the organic waste (solids, skins, pips, marc, etc.), wastewater, emission of greenhouse gases (CO2, volatile organic compounds, etc.) and inorganic wastes (diatomaceous earth, bentonite clay, and perlite). Waste minimization in the wine industry faces certain unique challenges. Firstly, the wine making process itself is more of an art than a science, as the industry was developed from artisanal activities. This limits the application of modern technologies to minimize waste in many wineries. Secondly, as a general rule in the wine industry many poor practices are often not classified as ‘poor’, but as common practices. This mindset renders the implementation of waste management in the wine industry

* Corresponding author. Tel./fax: þ27 21 808 2059. E-mail address: [email protected] (L. Lorenzen). 0959-6526/$ - see front matter Ó 2005 Elsevier Ltd. All rights reserved. doi:10.1016/j.jclepro.2005.11.004

a challenging task. Thirdly, the industrial operations are a mixture of both batch and semi-batch processes, and mostly characterized by intense processing campaigns lasting between a few weeks to several months. These uncontrollable variations adversely affect resources (both human and physical infrastructures) to the point where waste minimization is being compromised during actual production operations. These constraints offer an explanation as to why waste management is practiced as end-of-pipe (additive) technologies in numerous wineries, notably wastewater treatment and landfilling of solid wastes [1e3]. However, owing to rapidly growing global demand on manufacturing processes and final products to exert minimal or no environmental footprints [4], the wine industry has begun to experience legislative pressure to become more efficient [5e7]. Thus, the increasing demand for greening of industrial production processes and products, both from customers and legislative authorities, coupled with rising operational and waste treatment cost in the wine industry has started to move towards the adoption of integrated waste preventative approaches, as

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opposed to the traditional reparatory environmental engineering practices [8]. To effectively analyze waste generated in the wine industry, a systematic methodology was followed comprising of waste source identification, causative evaluation of waste and qualitative derivation of feasible waste minimization alternatives. Several generic methods for deriving waste minimization options at industrial scale have been discussed [9e11], and a case study on industrial food processing has been reported by Van Berkel [12]. In this study we propose a qualitative approach of seeking feasible waste minimization alternatives, owing to the lack of quantitative process data endemic to the wine industry. With this approach, waste minimization is addressed through the acquisition of process knowledge of winery operations. Knowledge acquisition can be achieved through regular observation of a variety of vinification processes and unit operations, interviewing personnel working in the wine industry (operators, wine makers, senior managers, and waste management experts in the wine industry), as well as literature surveys. This study concentrates on the entire vinification processes and considers comprehensive waste minimization strategies for each waste stream, process or unit operation. Secondly, the knowledge base developed from this work contains knowledge and information useful for decision-making with regard to effective waste management in the wine industry. Owing to the systematic character of the derived alternatives, a knowledge-based decision support tool was designed and developed using a fuzzy logic expert system [13e15]. Such tools have the potential of enhancing the performance of the wine industry with respect to safety, health of the workers and environmental concerns, in addition to improving the bottom line through minimization of resource consumption and pollution abatement costs. 2. Materials and methods 2.1. Scope of the study To address waste minimization problems in the wine industry, the scope and breadth of this study was unambiguously defined. It was established in this study that by casting the problem in terms of the definition of boundaries around the units of operation or processes as is the case in other process industries (e.g. chemical industry) in examining waste minimization alternatives would rule out numerous promising possibilities. Such a scope and breadth of a system boundary definition was found inadequate for two reasons. Firstly, many vinification processes are batch or semi-batch processes and are strongly seasonal dependent. Such a limitation implies that most alternatives are only applicable within a definite period and within localised equipment. Thus, management becomes a critical factor in effective waste minimization. Secondly, most significant wastes in the wine industry are linked to the nature of the raw materials used. Such wastes can only be handled sufficiently by other systems or processes outside the vinification process. Examples of these wastes are

leaves, skins, seeds and stems found attached to the grapes but cannot be removed before the start of the vinification process. Therefore, by defining expanded plant boundaries, these input wastes and those generated in the course of wine production could be readily accounted for. Cohen and Allen [16] classified the evolution of waste minimization according to three distinct generations. The first generation focused on good housekeeping, inventory control and minor changes in operating practices. The second generation was mainly concerned with the infusion of modern technologies in modifying existing units of operation and processes to improve effluent quality and reduce waste. In contrast, the third generation is envisioned to deal with highly selective separation and reaction technologies, specifically designed to tackle waste minimization challenges. In this study, the first and second phases of waste minimization techniques were adopted in deriving waste management alternatives for existing wine making plants. This approach reduces the problem to identify a retrofit solution that can be solved through process analysis and waste stream analysis [11,17]. This explicit identification of problem boundaries can have a profound impact on the viability of determining feasible waste minimization alternatives, particularly in the wine industry. 2.2. Evaluation methods Two approaches for evaluating process flowsheets to identify feasible strategies for achieve waste minimization in any industrial process have now been established [18]. The techniques are broadly classified as quantitative and qualitative approaches and the latter approach was employed in this study, owing to the general lack of reliable plant data in vinification processes. Secondly, a qualitative approach provided a feasible way of evaluating flowsheets of existing processes, unlike quantitative methods where large sets of data of high integrity are required to precisely determine feasible waste minimization alternatives. Thirdly, most data and information in the wine industry have been acquired through experience and qualitative techniques were found most suited in synthesizing process flowsheets for the identification of waste minimization opportunities. In that way, the adopted approach facilitated optimizing the entire vinification process mainly using heuristics based on the experience of plant operators and experts. A number of qualitative methods have been developed for identifying waste minimization opportunities in the process industries among them are the Douglas hierarchical procedure [19], onion diagram [20,21], 3E’s (3E stands for Energy, Environment and Economy) [22] and environmental optimization (ENVOP) [23,24]. Additionally, generic qualitative evaluation procedures have been published that are aimed at evaluating waste minimization options at industrial scale by the Environmental Protection Agency of USA (USEPA) [9], United Nations Environmental Programme (UNEP) [10], and Mulholland and Dyer [11]. In this study, the generic qualitative methods developed by USEPA, UNEP, and Mulholland and Dyer were applied in organizing data and information in the wine industry with respect to waste mitigation with a view

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to synthesize the knowledge into a format amenable for the development of a decision support system [13e15]. 2.3. Methodological approach To help frame the problem of waste minimization in wine production, two critical issues need to be clarified. On the one hand, it was important to establish an understanding of the product route from raw materials (grapes) to the final product (bottled wine). The wine production route was established through interviews, actual plant observations and reviewing the literature. The final waste matrix was found to be a combination of interactive factors. Examples of such factors are the type of technology used, reuse and recovery of useful byproducts and the operating practices within a given winery. On the other hand, different production scenarios were examined as they had a critical influence on the consumption of raw materials and effluent quantity and quality. 2.3.1. Product route determination Process flowsheets were evaluated from the inception of the raw materials (grapes) up to the packaging of the products (refined wine) ready for shipment to the markets. The visual representation of the flowsheets facilitated in the identification of critical points within the vinification processes, where major releases and discharges were likely to occur. This also helped to prioritize the waste streams in need of further investigation. A product route was established after visiting several wineries. It was also established that different process equipment were used in manufacturing the same product. While the vinification process was generic, a few exceptions were noted owing to the specificity of the product being made, the type of grapes used and the wine making philosophy of individual wine makers. The standard vinification process consists of destemming, crushing, cooling (storage), screening, fermentation, clarification (maturation), stabilization and bottling. However, various companies use different process routes, which significantly impact on waste management for both intrinsic and extrinsic wastes. Four illustrative examples of production matrixes identified are as follows:  route 1: destemmer / crusher / long pipes (horizontal) / basket filters / stainless steel tanks / bottling,

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 route 2: destemmer / crusher / short pipes (inclined) / vacuum press / cement tanks þ stainless steel tanks / stainless steel containers (no bottling line),  route 3: crusherestemmer / long pipes (inclined) / basket filters / stainless steel tanks / bottling line, and  route 4: crusherestemmer / short pipes (horizontal) / basket filters / cement tanks / bottling line. Note that a rigorous attempt in establishing all possible production matrix scenarios can give rise to an exponential combinatorial problem. In that sense, it is impossible to derive all feasible waste minimization strategies. Such a wide spectrum of process routes highlights the need for a systematic analysis to determine alternatives for eliminating or improving the handling of waste streams from the vinification processes. Furthermore, vinification being a batch process, the generation of wastes and emissions follows a recurrent pattern independent of the manufacturing process [25,26]. Establishment of the product route for the batch process also enhanced the understanding of fundamental reasons for generating waste. Table 1 illustrates how the type of technology employed in a given unit operation or process impacts on the generation of intrinsic or extrinsic wastes. 2.3.2. Campaign matrix determination In an attempt to find solutions of addressing intrinsic and extrinsic waste, a set of production campaign scenarios was investigated. The key principle was to determine how certain sequencing and scheduling of production processes had an impact on the quality and quantity of the waste, as well as the consumption of auxiliary feedstock, such as water and chemicals. For instance, effective sequencing of production processes influences the consumption of potable water and chemicals during cleaning and sanitization processes. Other scheduling and sequencing concerns focused on reducing the frequency of cleaning cycles of the equipment when the same line was used for the processing of different grape types or cultivars. Ripening of the grapes and hence the loads to be delivered in any given time, showed a strong dependency on climatic factors. Such factors are impossible to control and therefore could not be quantified in this study. Waste minimization was also investigated from a perspective of how different sequences of processes were executed, or how certain measures had been

Table 1 Some of the available technology choices for a given process and possible impacts on the quantity and quality of waste generated Process

Equipment

Waste type

Qualitative quantification of waste generated

Fermentation

Stainless steel tanks

Intrinsic, extrinsic

- Minimal spills of organic matter during removal from tanks. - Low/medium wastewater generated during cleaning owing to smooth surfaces. - Low chemical consumption during cleaning and sanitizing processes.

Cement tanks

Intrinsic, extrinsic

- High spills of organic matter during removal. - High water and chemical consumption.

Open hose pipes, high-pressure cleaners, clean in place (CIP)

Extrinsic

- High water and chemical consumption. - Low water and chemical consumption. - Very low water and chemical consumption with high levels of recovery for organic substrates and chemical cleaning agents.

Cleaning and sanitation

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implemented or not, again offered a clear understanding on the cause of waste generation. The insights gained from these investigations led to the identification of viable strategies to prevent or reduce waste generation. 3. Conceptual framework for waste minimization synthesis A conceptual framework was developed to derive strategies that can address waste management problems through the reduction, elimination or improved handling of vinification process wastes. At the onset of this study, different personnel such as operators, managers, and waste management experts who have extensive knowledge of the operations and working of the wine industry were interviewed. They provided heuristicbased insights that proved useful in reducing the complexity and size of the solution space for the problem under investigation. Thus, a systems approach facilitated the derivation of feasible waste minimization strategies through the optimization of the entire manufacturing process from a qualitative point of view. The framework entailed the evaluation of a broad range of processes (fermentation, crushing, filtration, etc.), production operations (cleaning and sanitization, storage, scheduling, etc.), raw materials (grapes, chemicals and water), waste tracking systems, and the management of inherently complex interactions between these components. The key concepts of the developed framework are discussed in the following subsections. 3.1. Inventory tools The identification and quantification of waste sources in the wine industry were accomplished using inventory tools [27,28]. The tools are classified as either product-oriented or process-oriented. In this study, the process-oriented tools, i.e. material mass balance and process flow chart methods were applied. At any process or unit operation, the material balances were carried out to identify the components of the waste streams generated during the vinification process. The process flow chart method facilitated the identification of all possible sources of waste generated at any stage of the vinification process. This process was carried out as follows. The vinification process was divided into unit operations. Note that a unit operation in this context refers to an area of the process, or a piece of equipment where input materials are processed and output material streams are generated, which could either be a product, a byproduct or waste. Every unit operation or process was drafted as a block and by connecting all the individual unit operations in the form of a diagram a vinification process flow chart was generated. An example of white wine production is schematically illustrated in Fig. 1. The qualitative mass balance method was used to establish the material flow at each level of production process or unit operation. As a result, the method enhanced the understanding of the relative significance of different sources and causes of waste, as well as clarifying the composition of wastewater

streams, and thus, the sources of pollutants. The sequence of defining the problem until all possible waste minimization alternatives has been identified and is presented in Fig. 2. 3.2. Waste reduction: methodological evaluation of waste minimization strategies Data were collected over a period of six months by focussing on different stages of the vinification process. At each stage, data from both personnel (operators, wine makers, senior managers, etc.) and documented sources (company historical data and published literature) were obtained and analysed to identify waste minimization opportunities. Some of the data obtained were comprised of flow rates of materials, the composition of generated waste effluent (in terms of pH, conductivity, TSS, COD, etc.), quantities of grapes crushed and volumes of wine produced as well as, operating conditions and practices in different processes. To ensure systematic identification of waste minimization strategies, a structured methodology was followed. The methodology comprised of three-step sequential approaches, namely waste source identification, qualitative evaluation of waste causes and finally the derivation feasible alternatives for waste minimization. 3.2.1. Waste source identification Optimal formulation of waste minimization strategies requires unambiguous identification of all possible sources of waste. Fig. 3 is schematic diagram of the inputs and consequent outputs from a given unit operation or process in order to trace material balances at each stage of the vinification process. Using waste classification proposed by [29,30], the winery wastes were classified as intrinsic (process) or extrinsic (utility). The intrinsic wastes are inherent in the fundamental process configuration, while on the other hand, the utility wastes are a function of auxiliary aspects of the operation [30]. Waste identification process was achieved through waste stream analysis and process analysis [11]. Note that, in the context of waste minimization and particularly in deriving the reduction strategies based on this classification, the two classes of waste types were found to be dependent on each other in the wine industry. In that sense, care was taken in understanding the interactions and interconnections between the two waste types to ensure that root causes of various waste streams were adequately established. For systematic identification of intrinsic waste sources, the vinification process was broadly divided into four categories as summarised in Table 2. After completion of each production stage, water and cleaning chemicals were used for a wide range of activities. These activities may include, but are not limited to cleaning, cooling, sanitizing of equipment and earth filtering. On the other hand, using the utility waste as basis of classification, the vinification process was grouped into four categories as presented in Table 3. Using the above classification scheme for the vinification process, different wastes, byproducts or product losses were identified from various unit operations and processes based

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Fresh Grapes

Weighing

Destemming & crushing

Solids/skins/pips

Wine juice, stems, juicy skins, pips

Separation Wine juice

Solids/skins/pips, wine juice

Pressing process Cold settling

Bitartrates, aqueous residues, dry skins Lees, bitartrates, grape colloids

Yeast, lactic bacteria

Filter aids, yeast, lees, aqueous residues

Fermentation Filter aids

Filtration

Bitartrates, bentonite aqueous residues, filter aids

Blending

Aqueous residues

Finings Bentonite, aqueous residues

Stabilization Filter aids

Filter press

Lees, bentonite

Filtration

Bitartrates, filter aids, aqueous residues

Bottling & packaging

Packaging waste, spilled wine

Purified wine

Bottled white wine Fig. 1. Schematic representation of standard white wine production.

on process flow path decomposition. Typical examples of wastes, byproducts or product losses identified in this case study are presented in Tables 4 and 5 for the intrinsic and extrinsic wastes, respectively. In most cases, the same kinds of wastes were generated at different unit operations and processes. Hence, to ensure consistent identification of viable waste minimization options for a specific waste or waste stream, each waste was coded with the same symbol. The wastes in solid, liquid and gaseous phases were coded S, L and G, respectively. 3.2.2. Causative analysis of waste In the first stage of the conceptual framework, waste inventories and characterization profiles provided valuable baseline data regarding the nature of pollutants generated in the wineries. However, before comprehensive strategies for waste reduction or minimization could be formulated, it was crucial to understand when, how and why different kinds of wastes were generated. Therefore, a causative analysis provided the understanding of the core influencing factors to the effluent quantity (in volume, mass or both) and quality (composition matrix), as well as the reasons for product and byproduct losses.

Thus, understanding of the causality formed a sound basis for the design of effective waste minimization strategies that had potential to yield the desired change. In addition, causality facilitated the grasping of cause-and-effect relationships that govern the vinification unit operations and processes that in reality are complex and multi-dimensional, and invariably influenced by diverse factors. It was not possible to provide definitive answers on causality and explicitly identify the differences that exist among various causes of waste. Therefore, in this model, the causes of waste generation were assumed to be independent. This approach rendered the process of evaluating causes of waste tractable for a given unit operation or process. To present causes of wastes in a format that lends itself to rapid identification of waste minimization options, possible causes of waste were broadly categorized as technology-oriented, process execution and management-oriented, input material characteristics-oriented, and waste recovery and reuse (recycling)-oriented. 3.2.2.1. Causes of waste related to input material characteristics. Generally in the process industries, the feedstock of any

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Start Problem definition Qualitative mass balance (material flow analysis) Identification of materials at input stream (every process/unit operation) Identification of waste stream(s) (at every process or unit operation) Perform causative analysis of each waste stream NO

All possible causes considered? Yes Derivation of detailed waste minimization alternatives

Yes

Other waste streams present in process? NO Stop

Fig. 2. Steps in waste minimization synthesis.

process or unit operation has certain properties. Examples of such properties are toxicity or non-toxicity, hazardousness or not, as well as other foreign bodies particularly for agriculturally-based raw materials such as leaves, stems and skins. On the basis of these properties, the input materials may require special handling to reduce waste generation or be substituted when they are toxic or hazardous. In the case of the wine industry, the key raw material is grapes, which are neither toxic nor hazardous. However, grapes have a high organic content and secondly, they contain tare and foreign bodies (e.g. stalks and leaves), which are an unwanted but nevertheless unavoidable component of the input material. Hence, to minimize or eliminate cross media pollution, grapes as raw materials require proper and effective handling. The same principle also holds in handling the inevitable byproducts (e.g. stalks, skins and seeds) and the high volumetric fluid product. In facilities where improper handling of the raw materials, intermediate products, byproducts or finished products (in this

Table 2 General categorization of intrinsic waste sources during the vinification processes

Raw Materials

Reuse/ Recycle

Waste Cleaning Solvents

case wine) occurs, the resultant effluent composition is characterized by high organic content, high conductivity and extremely low pH values. Such an effluent can be highly disruptive to the environment. On the other hand, certain cleaning and sanitizing chemicals are not environmentally benign, owing to their toxic and hazardous properties. For instance, while chlorine and ammonia solvents are effective cleaning and sanitizing materials, their toxicity and hazardousness have led to their substitution in certain wineries by more benign agents, such as hydrogen peroxide, ozone or hot steam. This also reduced the need for higher quantities of rinsing water to remove the chemicals. Other examples of non-benign cleaning agents are the sodium-based salts. Owing to their detrimental effects to soil, such agents are substituted with potassium-based cleaners. The alternative would be to treat the effluent before it is used for irrigational purposes, but that can be expensive. Based on the challenges discussed in the foregoing arguments, the

Finished Products

Vinification Process

Byproducts

Wastewater

Grape Solid Wastes

Fig. 3. Schematic diagram of waste source identification from any vinification process.

Process categories

Processes

Grouping factor

Grape reception and crushing area

Destemming, crushing

Successive batch operations within the area time interval between the two processes.

Transfer systems Pumping, piping

Waste generation due to wine, juice, and must transfers.

Separations

Screening, pressing, filtration

Product loss via separation of wine and solids.

Tank farm

Fermentation, Extensive tank usage for storage/cooling, process execution. clarification, stabilization, blending

N. Musee et al. / Journal of Cleaner Production 15 (2007) 417e431 Table 3 General categorization of extrinsic waste sources during vinification processes Process categories

Processes

Grouping factor

Wetting Heat transfer

Cleaning, sanitization, cooling, earth filtering Heating, cooling

Gaseous handling

Sulphication

Packaging/loading

Grape reception, bottling, storage/store rooms

Extensive use of portable water. Use of energy for product quality enhancement. Gas usage and storage for quality enhancement. Waste sources from subsidiary support utilities.

characteristics of the input materials are viewed as a cause of waste cause and can be remedied through substitution or effective handling of the material. A comprehensive summary of causes of waste related to input materials is presented in Table 6. 3.2.2.2. Causes of waste related to technology. This category accounts for the causes of waste related to technological-based factors, such as the type of material used for equipment design, equipment sizes, piping layout, equipment efficiency among other, that influence the quantity or other characteristics of waste streams as a result of some equipment and/or unit operations changes. For example, low equipment efficiency or poor design, generally leads to increased waste generation. In addition, the technology used has a considerable impact on the effectiveness of managing and harnessing of useful, but inevitable byproducts generated at various unit operations and processes. For example, during the pressing process where skins and wine juice are separated, use of modern vacuum presses reduces wine losses significantly in comparison to traditional vertical pressing baskets. On the other hand, it was observed that the efficiency of equipment used for cleaning and sanitizing showed a strong correlation with the quantities of potable water and chemical demand in these operations. For instance, if open hosepipes were used, water and chemical consumption was found to be higher than in an operation where high-pressureelow-volume cleaners or cleaningin-place (CIP) systems were used. Table 7 presents a summary of technology-oriented causes and their relative impact on effluent volume, effluent quality, as well as the consumption of chemicals.

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3.2.2.3. Causes of waste related to process execution and management. In industrial chemical production processes, waste generation mechanisms can be regarded as functional variable depended (variable examples are pressure, temperature and composition) based on a model proposed by Lind [31]. The suitability of this functional model has been illustrated by Halim and Srinivasan [32] in identifying waste minimization alternatives in a chemical plant. In remarkable contrast, in the food and beverage industry, and particularly in the wine industry; procedural, administrative and institutional practices are the key causes of waste generation. These practices are simply good housekeeping and have a significant effect on waste profile in terms of volume, composition and dispersion to other environmental media. In this study therefore, the lack of or unsatisfactory execution of good housekeeping practices during the vinification process was viewed as a cause of waste generation. One distinctive feature of these practices is their requirement for relatively simple in-plant changes regarding the operating procedures or methods of handling wastes. Such changes lead to the reduced waste or concentration of the contaminants in a waste stream. While such measures are not always distinguishable from the technologically oriented process changes, their relatively low-cost distinguishes them from the rest. Numerous waste causing factors fall in this category and a few examples are presented in Table 8. Furthermore, most of these factors are generic in character (e.g. operation efficiency, equipment maintenance, resource management). In real winery plant operations, these causes account for a high percentage of what is regarded as waste in the wine industry. One unique feature of these causes is the difficulty of ascertaining how a certain ‘cause’ may influence the overall effluent quality and quantity. This is because multiple interactions among different causes lead into a potentially large combinatorial problem that could be difficult to solve. As an example, the inventory control of the raw materials, intermediate products, final products, and the associated waste streams is known to be a significant waste reduction technique. Thus, without doubt, lack of inventory control can be identified as a cause of waste. Closer scrutiny of this ‘cause’, established that the ‘cause’ was also influenced by other factors,

Table 4 Identification of intrinsic wastes (G e gas, L e liquid, S e solid) Process category

Raw/secondary materials

Air emissions and wastes Gaseous

Liquid

Solid

Raw material reception and crushing area Transfer system

Grapes/SO2/stalks

SO2 (G1)

Spilled wine juice (L1)

Skins/pips/solids (S1) Skins/pips/solids (S1)

Separation processes

SO2/wine/filter aids, suspended solids

SO2 (G1), VOCsa (G2)

Spilled/leaked wine (L1), must, wine juice (L2) Splashing wine (L3), aqueous residue (L4)

Tank-based processes

Wine juice/yeast

CO2 (G3), VOCsa (G2), ethanol (G4)

Aqueous residues (L4), grape colloids (L5), overflowing wine (L6)

a

Wine juice/must

VOCs: volatile organic compounds.

Skins/pips/solids (S1), filtration aids (S2), bitartrates (S3), filtration cake (S4) Lees (S5)/yeast (S6), bentonite (S7), bitartrates (S3)

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Table 5 Identification of extrinsic wastes (G e gas, L e liquid, S e solid) Process category

Raw/secondary materials

Wetting

Potable water, cleaning chemicals Energy, cooling water

Air emissions and wastes Gaseous

Heat transfer Packaging/loading

a b

Packaging materials, grapes from trucks, sticking glue

CFCsa (G5), ammonia (G6) VOCsb (G2), ethanol (G4), SO2 (G1)

Liquid

Solid

Wastewater (L7), used cleaning solution (L8) Cooling water (L9), ethylene glycol (L10) Spilled wine (L1), excessive glue (L11)

Dry skins and organic dust (S8)

Falling grapes (S9), residual packaging materials (S10)

CFCs: chlorofluorocarbons. VOCs: volatile organic compounds.

whose absence in the facility was termed as a cause of waste generation. For instance, lack of inventory in a given winery could be attributed to other factors, such as inadequate training or motivation of personnel on waste management, absence of drive to improve process operations, and maintenance of equipment among others. 3.2.2.4. Causes of waste related to recovery and reuse/ recycling. The degree of effectiveness in waste management depends on the nature of the industry under. This is due to the uniqueness of the feedstock materials as well as the specific nature of the products and the intermediate byproducts formed during the manufacturing process. The wine industry is not an exception to this rule and was found to experience unique waste management constraints that can only be addressed adequately through effective reuse, recycling or recovery. The best waste minimization strategy was to recycle the waste and byproducts, reusing them in other processes, recovering them in order to be sold, or used as input materials in other industries. The recycling should be done based on the understanding that byproducts and waste cannot be recycled in the process(es) generating them in an attempt to produce the same product or perform the same function. Secondly, high health standard requirements for food-based products as stipulated by the industrial food production act, render byproducts and recyclable wastes not easily reusable in the process(es) generating them owing to the risk and uncertainties associated with microbial contamination. From this perspective, products, byproducts and wastes recovery and recycling in other associated industries were viewed as the most feasible waste management alternative.

Two examples are provided to clarify the views expressed above. Firstly, while the wine industry waste(s) cannot replace the input feedstock streams, e.g. the skin residues from the grape berry cannot be reprocessed to produce table wine, however, they can be reused as inputs for spirits distillation. Note that the distillation is not part of the vinification process. A second example is the wastewater produced from cleaning and sanitizing of equipment which has come into contact with wine or wine residues. This renders the wastewater non-reusable for cleaning the equipment again, but can be reused on cleaning floor surfaces, grape bins or pre-rinse water for heavily equipment. Credible evidence [8] also indicates that where reuse and recycling is implemented ineffectively, or not at all, high effluent volumes are generated and the solids (e.g. skins, pips, lees, etc.) from various processes may result in odors, high organic content in the wastewater stream and other catastrophic environmental consequences, such as sodicity and salinity when the effluent is used for irrigation without proper handling. Other examples where reuse, recycling or recovery serve as the only feasible alternatives for waste handling in the wine industry have been discussed by Musee [15]. It is therefore clear from the examples presented above that recycling and reuse play a key role in reducing or eliminating what could be regarded as waste, based on the understanding of the input material and byproduct characteristics. Failure to practice recovery, reuse and recycling as discussed here can thus be regarded as a cause of waste generation. 3.2.3. Formulation of waste minimization strategies Within the context of a conceptual framework, the development of alternative strategies was aimed at eliminating,

Table 6 Examples of input materials giving rise to waste Process

Input material

Waste cause

Possible remedial actions

Crushing and destemming

Grapes

Grape composition, tare and foreign bodies

Cleaning and sanitization

Chlorine, ammonia, sodium

Filtration

Filtration aids

Inherent toxicity and hazardousness, its toxicity and salinity causing ability to the soils Use of filters (e.g. earth diatomaceous)

Effective handling of all materials with high organic matter. Substitution of the cleaning agent inputs. Substitute/replace filter requiring filtration techniques.

N. Musee et al. / Journal of Cleaner Production 15 (2007) 417e431 Table 7 A summary of waste causes related to technology Typical waste causes

Process design and unit layout Equipment efficiency (pressers, filters, and separators) Inadequate/non-existence of recovery installations Type of material used for equipment design The size and number of equipment used Inefficient/non-existing control and monitoring systems

Variables influenced by a cause Effluent volume

Effluent quality

Chemical volume

UUa UUU

UUU UUU

U UU

UU

UUU

UU

UU

UU

UU

UU

UU

UU

U

UU

U

a

The rating of possible impact of each cause on the variable is based on the scale: U ¼ low to moderate impact, UU ¼ moderate to high impact, UUU ¼ high to very high impact.

reducing, and controlling the causes of waste generation or segregating useful materials (e.g. products, intermediates, and byproducts) from the waste streams. This was guided by the identification and analysis of both waste streams and the processes giving rise to these streams [11] and consequently

Table 8 A summary of waste causes related to process execution and management Typical waste causes

Transportation of materials (raw materials, products and intermediates) Frequency of cleaning, spillages, leakages and shutdowns Level of personnel training and motivation on waste management Maintenance of equipment on schedule Equipment and resource management Inappropriate filling of vessels (e.g. tanks, barrels) Poor or lack of dosing control on chemicals Inadequate or lack of inventory and management of control procedures Losses owing to process disturbances (e.g. changeovers, malfunctions, pipe blockages, etc.) Communication failures (both written and verbal) a

Variables influenced by a causea,b,c Effluent volume

Effluent quality

Chemical volume

U

U



U

U



U

U

U













U

U







U





U



U









Note that most ‘causes’ have no direct link to a certain output variable, however, it may trigger another cause that impacts one or more variables. b U Indicates that the variable is directly affected by given waste cause. The ‘cause’ effect on a variable is continuous ranging from lowest to the highest level as a function of practices in a given winery. c  Indicates that a variable is not directly affected by the ‘cause’ but it experiences its effect through a chain of events.

425

establishing their true causes through systematic causative analysis. Alternative strategies were derived from personnel expertise and information from technical literature. The information and knowledge from this causative analysis are crucial in identifying viable waste minimization strategies. On the other hand, data and information from waste source identification were used in targeting waste sources in unit operations and processes characterized by high volume, toxicity or hazardousness. To expedite the identification of waste minimization options, the causative categories were grouped (see discussions in Section 3.2.2) in a manner matching the corresponding waste minimization option based on the pollution prevention techniques proposed by Van Berkel [27,28]. However, in this study, the option of product modification was not considered. The waste minimization techniques were classified in the following categories: technological modifications, input substitution, operational practices, and waste/product recovery and reuse/recycling (WPR and RR). Some of the minimization strategies derived from this work, and others reported in the literature are presented in tabular form, but by no means are comprehensive. Note that the strategies derived for a waste stream, operation or process do not imply that they are applicable to every winery, and in certain cases the information and knowledge presented here are inappropriate to some of the current practices in the wine industry. However, such strategies can be viewed as a roadmap to future possibilities for improving and sustaining sound waste management.

4. Case study: the vinification process To illustrate the application of the considered in conceptual framework in Section 3 for waste minimization in the wine industry, the standard vinification process schematically presented in Fig. 1 was used as our case study. Extensive descriptions of processes and unit operations as well as mechanisms by which wastes are generated in the wine industry have been presented by Musee [15]. Furthermore, to simplify presentation, a strategy was either classified as generic or specific. A ‘generic’ strategy in this case refers to a waste minimization alternative which is applicable to different wastes generated in different unit operations or processes. An example of a generic strategy is the effective recovery of organic matter for reuse as an input for manufacturing compost or fertilizer. On the other hand, a ‘specific’ strategy refers to a unique option that is only applicable to a particular unit operation or process. Thus, the strategy only addresses a waste or byproduct generated by specific equipment or unit operation during the vinification process. An example would be the dedication of crusher lines to a particular grape or cultivar type aimed at reducing the number of cleaning cycles or elimination of cross product contamination. Such a strategy would only be applicable within the crushing unit in the entire vinification process.

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By using the type of waste generated as a unit of classification, three distinct waste minimization classes were identified, viz:  Strategies for minimizing intrinsic waste. The intrinsic waste could be addressed by both generic and specificoriented strategies.  Strategies for minimizing extrinsic waste.  Strategies for odor elimination and improvement of effluent quality. In the last two classes, the strategies were found to be mostly generic. To ensure consistency in the identification of waste minimization based on the hierarchy comprised of waste elimination or source reduction, and recycling, reuse or recovery, a set of guidewords was used [23,24,33]. Table 9 presents the variables and guidewords used in this study for the derivation of waste minimization strategies. The guidewords can be applied to every unit operation, process or piece of equipment as a means to derive waste minimization alternatives. 4.1. Strategies for minimizing intrinsic waste As is the case in any process industry [30] including the wine industry, intrinsic waste poses the greatest challenge to eliminate or reduce. This is because most waste minimization alternatives with the capability of achieving a reasonable reduction or elimination of intrinsic waste ought to be technologybased. As a result, high capital investment is required for the acquisition, installation and operating costs of the equipment. Nevertheless, the merits of reducing waste generation are manifold such as reduction of waste treatment costs as well as increasing the yield per unit throughput. By applying the conceptual framework for waste minimization discussed in Section 3, generic waste reduction strategies Table 9 List of guidewords used for generating waste minimization strategies using heuristics Elements

Variable

Guideworda

Materials

Quality Impurity Quantity Toxicity Inventory Hazardousness Geometry Configuration Flow rate Efficiency Size Stream Operating conditions Training Flow rate Inventory Stream Flow rate Operating procedures

Reduce Minimize Eliminate Improve Change Replace Modify Increase Decrease Segregate Install Recover Recycle Optimize Avoid Substitute

Technology

Operational practices

WRP and RR

a

The guidewords are applicable to all elements and variables.

derived for the intrinsic waste are presented in Table 10. Note that most common alternatives are in the category of ‘operating practices’. For certain equipment, unit operations or processes, specific waste minimization alternatives were derived and the results are presented in Table 11. The majority of specific waste minimization alternatives derived was classified under the technology modifications category. This implies that, technology related alternatives have the greatest potential for reducing intrinsic waste or enhancing the effectiveness of handling unavoidable waste. 4.2. Strategies for minimizing extrinsic waste Extrinsic waste is generated in large quantities in the wine industry (e.g. wastewater, used cleaning solvents, etc.) and have a negative impact on the environment, though in many instances little attention is given to this. Extrinsic wastes are generated from various auxiliary processes such as cleaning, cooling or packaging. However, waste handling and treatment in the wine industry, e.g. in terms of energy required for cooling purposes, treatment of large quantities of wastewater, purchasing of cleaning and sanitizing chemicals and their associated impact on the environment. Through the application of the conceptual framework discussed in Section 3, 42 alternatives for reducing, eliminating or re-using extrinsic waste were identified, as presented in Table 12. It should also be noted that several alternatives have the potential of also improving the wastewater. However, it was noted that the effluent quality mainly depended on the handling of intrinsic waste. In that sense, if the yield per given batch throughput was high and unavoidable process waste handling was adequate, the effluent quality was found most likely to be high and a considerably low effluent volume generated as well. This shows that acceptable effluent quality and quantity can be achieved through the implementation of integrated waste and production management strategies. 4.3. Odor elimination and effluent quality improvement In the wine industry there are two other problems related to the manner in which extrinsic and extrinsic wastes are handled. The problems are odor generation from wastewater reservoirs and the poor quality of the effluent. In this study, it became quite clear that neither of the above problems can be addressed exclusively under the classification of extrinsic or intrinsic wastes. In addition, it was noted that these problems can be viewed as indicators of effectiveness in the handling, elimination or reuse and recovery of both intrinsic and extrinsic wastes during the vinification process. Effluent quality is influenced by the presence of organic matter, chemicals and nutrients in the wastewater stream. Offensive odors are generated when organic matter remains in the liquid effluent for a period of time, under anaerobic conditions. In that sense, the effluent quality and odor formation exhibit a cause-and-effect relationship. Overall, odor elimination and effluent quality improvement can be viewed as benefits derived from the adoption of integrated production premised

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Table 10 Generic waste minimization strategies for managing intrinsic wastes Waste type generated

Type of WM practice

Waste minimization strategies

S1, S3, S4, S5, L1, L2

Operating practices

Avoid spillage or leakage of organic matter waste on floor surfaces or wastewater streams. Optimization of organic material recovery from all unit operations e.g. tanks, vacuum presses, crushers for compost and fertilizer manufacturing or for responsible disposal. Institutionalization of operational procedures to reduce waste dispersion between media. Segregate various solid waste for easy recycling, or recovery of useful products (consider all possible reusable or recycling possibilities before landfill option). Embark on progressive training of personnel on the significance of integrated approach to waste and product handling, to mitigate against waste dispersion and product loss. Improve storage and handling of solids, e.g. by use of impermeable base layer or keeping or isolating them away from drainage system. Improve system surveying and maintenance to reduce or avoid spills and leakages either incidentally or accidentally. Installation of drip pans under equipments to collect leaked process materials. Increase process controllability to reduce spillages, incidentals and accidents. Ensure bulk packaging of material purchased for both auxiliary and utility processes to reduce the disposal of packaging and dusty bags. Explore/test new markets for the process byproducts and other wastes to increase revenue.

Technological modification

Use of dry recovery techniques of solids from surfaces, floors, equipments e.g. using brooms, brushes and pneumatic devices. Change of vessel bottoms designed to increase access to residues, thus improving the removal and effectual segregation of the organic matter sources from entering liquid effluent streams. Installation of containment systems in case of incidents and accidents to recover product and avoid its loss to the waste streams or for ensuring responsible waste disposal.

Technological modification Waste/byproducts recovery

Improve the internal surface smoothness of tanks to enhance the recovery of byproducts.

S3, S5, S6, S7

Consider recovery of useful materials e.g. tartrates, grape seed oil etc. using possible recycling and reuse options before land fill techniques are employed for solid disposal.

on the principle of preventing cross media waste transfers. The strategies for addressing effluent quality and generation of odor in the wine industry are presented in Table 13. 5. Results and discussions By applying a systematic qualitative methodology to analyze the entire vinification process, we were able to identify and diagnose all feasible sources of waste accurately and isolate their possible causes. In this study, 11 liquid-phased and 10 solid-phased waste streams were identified. In comparison to the number of waste streams generated in the petrochemical process industries [34], wine industry produces far less intermediate waste. The properties of various waste streams posed unique challenges in an attempt to eliminate, reduce or manage them effectively. Waste minimization analysis was carried out on the entire vinification process by targeting the following environmental aspects: (1) the reduction of auxiliary feedstock mainly water as well as cleaning and sanitizing chemicals, (2) reduction of wastewater volume, (3) possibility of improving the quality of effluent and (4) ensuring improvement in the handling of wine industry wastes. As can be seen from the results tabulated in Table 2 through Table 9, the methodology was successful in identifying all waste streams, their respective sources as well as possible causes. Using data, information and heuristics suggested by the personnel working in the wine industry, comprehensive and appropriate waste minimization alternatives were derived. Each waste minimization strategy was classified in a single category with a graphical distribution of the results presented in Fig. 4. Graphical representation highlights the distribution of the waste minimization alternatives across the

four categories of process execution and management, technological modifications, waste/product reuse and recycling/recovery and input substitution. The results in Fig. 4 show that 48% of the strategies derived address challenges related to process execution and management, 30% fall under technological modifications, 14% target better winery environmental performance via waste/product recovery and reuse/recycling, and approximately 8% accounts for input substitution. Thus, the large number of alternatives which fall in the process and execution management category is an indication that active participation and involvement of personnel at all levels in waste minimization program present wineries with a low-cost choice of improving their environmental performance. Note that approximately 54% (49 alternatives) of the total identified strategies target intrinsic wastes, where 33% can be classified as ‘‘generic’’, while 67% fall can be considered ‘‘specific’’. The large number of alternatives being specific in this category is an indication of the difficulty of applying a given strategy in addressing the intrinsic waste problems in various processes and operations during vinification. These results confirm the idea that involvement of the workforce is an effective strategy for reducing effluent and preserving resources. Consequently, many of these alternatives require no or relatively low-cost investments and can be rapidly implemented in many wineries without the need for detailed quantitative analysis. Such undertakings exhibit the potential for improvement by reducing waste quantities, improving waste composition and lowering the consumption of resources. A total of 47 alternatives were identified specifically in an endeavor to improve the handling and reducing of intrinsic

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Table 11 Specific waste minimization strategies for managing intrinsic wastes Process operation unit

Waste type generated

Type of WM practice

Waste minimization strategies

Destemming/ crushing trucks

S1

Technological modification

Installation of crusherestemmer system that does not break seeds. Fit ‘‘crusher lips’’ to reduce spilling over of grapes during unloading from trucks/grape bins and loading on crushers and destemmers. Conveyor belts and other solids handling equipments to be modified to reduce or avoid their spillage into the liquid effluent stream. Use of high quality grapes to reduce quantity of solids and improve yield per unit throughput. Dedication of crushers for a given grape type to reduce product contamination and frequency of cleaning cycles. Improve site communication during unloading of grapes from trucks, grape bins and loading on the crushers to avoid spillages. Optimize scheduling of grape deliveries to minimize start-up and shut down waste generation and energy consumption.

Input substitution Operating practices

Sulphiting

G1

Input substitution Operating practices

Technological modification Fermentation

G2, G3, G4

Technological modifications

Operating practices S6

L6

Input substitution Waste recovery/ product Operating practices Technological modifications

Replace gaseous SO2 with liquefied form or solidified pellets to eliminate its dispersion thus reducing air pollution and negative health impact on personnel. Ensure that the gas storage is outdoor or in a well ventilated room to ensure minimal air pollution or chances of suffocating the personnel in case it leaks. Sulphur dioxide to be handled by trained personnel only to avoid accidents. Limit leaks and exposure periods to personnel. Put emergency plans and simple procedures in place in cases of accidents. Installation of sensors to detect SO2 concentration or presence before exceeding the recommended lethal levels to staff. Installation of efficient ventilation systems to ensure no accumulation of greenhouse gases in tanks and buildings. Installation of sensors for CO2 and VOCs for health and safety reasons for the personnel. Use of carbon absorption technology for controlling ethanol and other VOCs concentration to prevent the killing of yeast cells which may cause sluggish fermentation. Use of centrifugal fans to blow clean air into tanks to enhance the removal of heavy gases at the bottom to reduce risks to staff. Establish procedural measures to determine CO2 and VOCs levels in tanks before personnel enter into them for maintenance or cleaning purposes. Use tested commercial wine yeast strains to avoid stuck fermentation process. Reclaim the yeast cells and sell them to pharmaceutical or food companies or send them for recycling (as they are a high source of protein and vitamin B). Fill tanks appropriately to avoid spillages during the fermentation process. Installation of sensors to control filling procedures of empty tanks to eliminate overfilling.

Piping and transfer

L2

Operating practices Technological modifications

Ensure adequate maintenance of pump seals and pipes to reduce spills and leakages. Modify fixed piping systems which are laid horizontally to inclined elevations to enhance product flow under gravity to minimize product and energy losses. Reduce transfer line length to reduce spillages, water, energy and chemical during cleaning and sanitization processes. Install welded piping instead of screwed connections to facilitate pigging process in order to reduce product loss.

Filtration

S2, S

Technological modifications Waste/product recovery

Installation of effective separation technologies e.g. use of membranes. Installation of hoppers to charge all filtration cakes (reduces waste dispersion from solid to liquid media). The filter aids can be used as compost/fertilizer in vineyards and also for the suppression of weed growth. Using the press, wring the filters of wine and materials for their reuse in the filtration process (reduces material purchases and disposal costs). Reduce the use of diatomaceous earth for filtration by using centrifuges and optimal capture techniques as alternatives.

Operating practices Pressing

S1, L4

Technological modifications

Old inefficient pressers should be replaced with modern vacuum presses to reduce wine losses that result in getting into the effluent waste stream. Ensure newly acquired pressers have removable bottoms for easy discharge of pressed dry skins or pips.

wastes. Sixty eight percent of these opportunities were specific in nature, that is, each option identified was only applicable to a particular unit operation, process or piece of equipment. The batch character of the vinification process rendered the handling and prevention of intrinsic waste dispersion to other waste streams to be mainly effective source through technological modifications. This explains why of the 68% of strategies in this category, about 47% are classified as technology modifications. Owing to the large number of alternatives identified in this study, it is imperative that justification for implementing any

given strategy takes into account economic returns as well as non-monetary rated benefits, such as environmental performance, ease of implementation, safety and hazard reduction, feasible payback periods, etc. This makes it essential to use multi-criterion decision analysis in ranking the alternatives. 6. Conclusions The wine industry is facing serious environmental challenges comprised of internally driven factors, such as rising costs of production and non-value adding expenditures on

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Table 12 General waste minimization strategies for extrinsic wastes from vinification process Unit operation

Waste type generated

Type of WM practice

Waste minimization strategies

Cleaning and sanitization

Wastewater, used cleaning solvents

Input substitution

Use of steam to reduce water and chemical usage. Use of high quality water for cleaning equipments (reduces biofouling of equipments and the quantity of water and chemicals used). Substitute chlorine hazardous based-cleaning agents with non-hazardous or non-toxic agents such as hydrogen peroxide and ozone. Replace low efficient cleaning equipment (e.g. hosepipe) with high-pressureelow-volume ones to reduce water and chemical quantity consumptions. Installation of high-pressure rotary nozzles inside tanks to ease the cleaning process (reduces water volume used). Installation of water meters to monitor water use at different user points. Improve internal smoothness of tank surfaces to reduce water and chemical demand. Install CIP systems to reduce water and chemical consumption as well as improving the byproduct recovery. Apply modern dosing equipments and techniques to reduce quantities of used during the cleaning and sanitization processes. Fix-flow restrictors in taps and other water fixtures to avoid or minimize water wastage after the completion of use. Training of staff to view water and chemicals as highly valuable resources in order to achieve attitude change thus improving how they are handled. Develop strategies for reducing spillages and leakages of wine from pipes and equipment to minimize number of cleaning cycles. Optimize the batch operations through scheduling of production processes to reduce cleaning sessions (conserves water and chemical usage). Ensure closing of all taps when not in use to conserve water. Segregate various streams to enhance water and cleaning chemical recovery. Ensure correct chemical concentrations for cleaning and process chemicals by measuring the quantities before use. Use mechanical techniques to remove organic sources in equipment and surfaces to reduce water and chemical consumption. Practice effective pre-cleaning of equipments and floor surfaces to remove soiling thus reducing water and chemical demands. Emergency and clean up procedures should be developed and communicated via training to contain cases of chemical spills or accidents. Use of adsorbent to clean up wine and chemical immediately after spills occur to reduce high usage of cleaning water and organic loading on wastewater stream. Segregation of chemicals which are incompatible to avoid explosions and contamination both in usage and storage periods. Limit the quantities and inventories of chemicals purchased to control wastage via expiry (use the thumb rule first in, first out). Apply counter cleaning technique during cleaning sessions to minimize the quantities of water required per cleaning cycle. Use de-ionized water for preparing cleaning solutions. This minimizes quantities of chemicals used due to water hardness. Pump fixed amount of cleaning/sanitizing solutions to equipments and surfaces to reduce overall chemical required. Immediate cleaning of equipment and surfaces after each operation to reduce water and chemical demands. Reuse of high quality wastewater as first rinse for the next cleaning cycle. Recycle cleaning agents before they are sent for their recovery (on/off site). Reuse of the cleaning solutions till they are saturated (avoid once through use). Reuse of non-contact cooling water for cleaning floor surfaces. Reuse of storm water for cleaning of floor surfaces or as a first rinse for the highly soiled processing equipment.

Technological modifications

Operational practices

Recycling/reuse

Energy transfer

G5, G6

Operational practices

Input substitution Recycling/reuse Packaging

S10

Recycle/reuse

S11

Operating practices

Prevent leaks through constant and periodical maintenance of the cooling systems to avoid emissions and high water consumption. Reduce the levels of releases when performing maintenance in all cooling systems. Emergency procedures should be instituted in event of accidents and accidentals to control the extent of feasible damages and losses. Substitute the environmentally harmful refrigerants with benign ones such as ozone, hence the cost of replacement and quantities released to the atmosphere during refilling process. Recycle the refrigerants effectively in the cooling system. Send paper, cardboards and other recyclable solids back to the suppliers to minimize accumulative solid wastes from outside sources. Request that deliverables be shipped in returnable containers and reuse boxes. Packaging and office paper can be shredded and reused as packing material saving costs on disposal as well as purchase of new packing materials. Avoid excessive use of glue as it makes recycling of bottles very difficult. Prevent glue spillages as they may result to wastewater stream thus deteriorating the effluent quality.

effluent treatment. Likewise, externally-oriented drivers like the dynamic evolution of an onerous regulatory regime on process waste handling and disposal, and a rapidly rising demand for wines produced in an ecologically responsibly way add to

these problems. A satisfactory solution to these multifaceted challenges calls for an integrated approach in order to achieve effective waste management in the wine industry. In this paper, a systematic methodology for qualitative waste minimization

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Table 13 Waste minimization strategies for eliminating or reducing odor and improving effluent quality Problem

Cause

Feasible odor and effluent quality elimination/improvement strategies

Odor generation

Rotting organic wastes in wastewater

Adopt effective organic separation from the liquid waste streams to ensure low BOD, SS, COD values in the wastewater stream. Ensure spent diatomaceous earth is covered while in storage after use or in containers and for periods not beyond three weeks or spread it as compost in vineyards. Locate compositing sites for grape marc away from residences, cellar buildings and highways (at least should be 200 m from such facilities). Untreated wastewater should not be stored in open lagoons or ponds for periods exceeding 72 h especially in areas where there are residences in the neighbourhood. Mechanically aerate the wastewater in lagoons and ponds to achieve BOD reduction, thus off setting odor generation. Improve operational practices where organic sources are mechanically removed from surfaces and equipment before beginning wet cleaning process. During irrigation using wastewater on the vine farms ensure that the irrigating rate is approximately equal to the filtration rates to avoid residence of organic matter that can generate odors while pending on the soils.

Effluent quality

Presence of organic matter chemicals and nutrients in wastewater.

Avoidance/elimination of spillages and leakages of product and wine juice into the wastewater streams. Use pigging of pipes technique to avoid cleaning water coming into contact with residue wine. Improve removal of all organic solids mechanically from surfaces and equipment before beginning wet cleaning wet processes. Effectively segregate effluent streams from cooling and ion exchange operations in order to reduce the impact of chemicals on the wastewater quality. Recovery of organic solids from water streams as soon as possible using screens or the sedimentation process. Use closed cooling systems to ensure that refrigerants and cooling water does not enter into wastewater streams (segregation to be done during the bleeding process). Ensuring extra storage containers are available during peak vintage season so that excess wine or byproducts are not damped into the wastewater streams. Segregating chemical solutions from laboratory wine testing works and ion exchange operations from entering into the wastewater streams. Recycling used cleaning solutions till they are saturated such that their pH is reasonably below 10.

and the derivation of feasible strategies has been proposed. The methodology is applicable to any winery regardless of its size and production philosophy. The conceptual framework is based on systems approach aimed at optimizing the entire vinification process. The tangible benefits of implementing the derived alternatives include eliminating, reducing or minimizing waste generation, reducing costly effluent treatments in the wine industry or even improving the handling of intrinsic and extrinsic wastes. In addition, data, information and knowledge gaps existing in

the wine industry with regard to waste management have been addressed. These alternatives were automated to enhance decision-making with regard to waste minimization in the wine industry via the development of a knowledge-based decision support system [15]. The results of this systematic methodology for qualitative waste minimization through waste stream and process analysis, led to the derivation of 90 alternative strategies. On the basis of pollution prevention techniques [27], the strategies were classified into four broad categories: process execution and

Input Substitution (IS) 9% Intrinsic (specific) 43% Extrinsic 57% Intrinsic (general) 8% Intrinsic (specific) 23%

IS

Intrinsic (generic) 26%

WPR&RR PEM

Extrinsic 69%

Waste/Product Recovery & Reuse/Recycling (WPR&RR)

Process Execution and

Extrinsic 48% Management (PEM) 48%

TM Extrinsic 26%

Intrinsic (generic) 15%

Technological Modifications (TM) 30% Intrinsic (specific) 59%

Fig. 4. Distribution of waste minimization strategies across pollution prevention categories.

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management (PEM), technological modifications (TM), waste/ product recovery and reuse/recycling (WPR and RR), as well as input substitution (IS). From this study, the majority of the derived strategies belonged to the process execution and management category, thus requiring minimal or no evaluation before adoption in a given winery. However, in circumstances where rigorous evaluation of the alternatives is required, the multiple alternatives identified can be screened using any of the multi-ranking criteria as discussed by Balik and Koraido [34], Smith and Khan [35], and Saaty [36]. This is to ensure that the ‘‘best’’ waste minimization strategies are selected and implemented to meet the set objectives and goals of a particular company and to adhere to legal requirements governing effluent disposal standards. Acknowledgments The financial contributions of National Research Foundation (NRF), Winetech, Prolor Techpros (Pty) and the University of Stellenbosch during this project are acknowledged. References [1] Recault Y, editor. Proceedings of the second international specialized conference on winery wastewaters, 5e7 May, Bordeaux, France; 1998. [2] Marais D. The development of an audit procedure and treatment technologies for Rupert and Rothschild Vignerons’ Winery Wastewater. Masters thesis, Department of Chemical Engineering, University of Stellenbosch; 2001. [3] Shepherd HL, Grismer ME, Tchobanoglous G. Treatment of highstrength winery wastewater using subsurface flow constructed wetland. Water Environmental Research 2001;73(4):394e402. [4] Wackernagel M, Rees W. Our ecological footprints. Gabriola Island, BC: New Press Publishers; 1996. [5] Mu¨ller AM. Government of South Africa gazette no. 20526.8, October, 1999. Government notice, Department of Water Affairs and Forestry. Section 21 (e); 1999. [6] Katsiri A, Dalou F. Wine and distillery effluents in Greece: main results of the SPRINT AQUANET program. In: Proceedings of international specialized conference on winery wastewaters, 20e22 June, Narbonne, France 1994. p. 25e30. [7] Massette M. Wineries facing regulation. In: Proceedings of international specialized Conference on Winery Wastewaters, 20e22 June, Narbonne, France 1994. p. 13e8. [8] Lorenzen L, Hayward DJ, Bezuidenhout S, Barnardt N, Prozesky V, Trerise M, et al. The development of an integrated management plan for the handling, treatment and purification of effluents in the wine, spirit and grape juice industries. Research report to Winetech, IRSOT; 2000. [9] United States Environmental Protection Agency (USEPA). Waste minimization opportunity assessment manual. Cincinnati, OH: US EPA Hazardous Waste Engineering Research Laboratory, Centre for Environmental Research Information; 1988. EPA-625/7-88/003. [10] United Nations Environment Programme (UNEP). Audit and reduction manual for industrial wastes. Paris, France: UNEP Industry and Environment Office/UNIDO; 1991. Technical Report Series No. 7. [11] Mulholland KL, Dyer JA. Process analysis via waste minimization: using DuPont’s methodology to identify process improvement opportunities. Environmental Progress 2001;20(2):75e9.

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