ARTICLE IN PRESS Journal of Environmental Management 84 (2007) 484–493 www.elsevier.com/locate/jenvman Cleaner production opportunity assessment for a milk processing facility A. Özbaya, G.N. Demirerb, a Social and Physical Infrastructure Department, State Planning Organization, Ankara, Turkey Department of Environmental Engineering, Middle East Technical University, Ankara, Turkey b Received 24 October 2005; received in revised form 21 June 2006; accepted 22 June 2006 Available online 1 September 2006 Abstract Possible cleaner production (CP) opportunities for a milk processing facility were examined in this study. The CP concept and its key tools of implementation were used to assess the potential CP opportunities in the facility studied. The general production process and its resulting environmental loads were investigated by taking possible CP opportunities as the basis of study. The methodology developed for CP opportunity assessment in the milk processing facility covered two major steps: preparation of checklists to assist auditing and CP opportunity assessment, and implementation of the mass-balance analysis. For mass-balance analysis, measurements and experimental analysis of the mass flows were utilized to determine the inputs and outputs. Prepared checklists were utilized to determine waste reduction options that could be implemented. Selected opportunities were evaluated considering their environmental benefits and economic feasibility. The results of the study indicated that 50% of the service water used, 9.3% of the current wastewater (WW) discharge, 65.36% of the chemical use and the discharge of 181.9 kg/day of chemical oxygen demand (COD) and 20.7 kg/day of total suspended solids (TSS) could be eliminated and 19.6% of the service water used could be recycled/reused. r 2006 Elsevier Ltd. All rights reserved. Keywords: Cleaner production; Waste reduction; Dairy; Milk processing facility 1. Introduction Cleaner production (CP) is an important tool that supports sustainable development by offering new opportunities for optimization and saving in business and complying with the environmental regulations (Ontario Ministry of Environment, 1993). It is a preventive strategy to minimize the impact of production and products on the environment. Compared with conventional end-of-pipe approaches, CP techniques and technologies use energy, raw materials and other input material more efficiently; produce less waste, facilitate recycling and reuse of resources and handle residual wastes in a more acceptable manner. They also generate less harmful pollutants. CP Abbreviations: CIP, clean in place; COD, chemical oxygen demand; CP, cleaner production; CPA, cleaner production audit; GHK, good house keeping; HTST, high temperature short time; TSS, total suspended solids; WW, wastewater Corresponding author. Tel.: +90 3122105861; fax: +90 3122101260. E-mail address: goksel@metu.edu.tr (G.N. Demirer). 0301-4797/$ - see front matter r 2006 Elsevier Ltd. All rights reserved. doi:10.1016/j.jenvman.2006.06.021 methods have significant financial and economic advantages as well as environmental benefits at the local and global level (RAC/CP, 2000). Although dairy processing occurs world-wide; the structure of the industry varies from country to country. The major pollutants in the dairy processing wastewater (WW) are organic materials, suspended solid waste (i.e., coagulated milk, particles of cheese curd, pieces of fruits and nuts), phosphorus, nitrogen, chlorides, heat and acid or alkali content of liquid wastes (UNEP and DEPA, 2000). These pollutants originate from the materials wasted, which are basically milk and milk products through the process, lubricants (primarily soap and silicone based) used in certain handling equipment, sanitary and domestic sewage, non-diary and milk by-products such as whey and sometimes buttermilk (Carawan et al., 1979) and cleaning chemicals. Typical water uses and effluent sources in a dairy factory are given in Fig. 1. Even though they are significant sources of environmental contaminants, there are a limited number of studies in the literature (Baskaran ARTICLE IN PRESS A. Özbay, G.N. Demirer / Journal of Environmental Management 84 (2007) 484–493 485 Fig. 1. Typical water uses and effluent sources in a dairy (Environmental Technology and Best Practice Program, 1999). et al., 2003; Nguyen and Durham, 2004) on CP for dairy food facilities. The aim of this study was to conduct a cleaner production audit (CPA) for the milk processing facility to identify the opportunities for CP, and corresponding environmental and economical benefits. During this assessment, comprehensive lists and checklists of opportunities for CP assessment in a dairy were prepared and applied. 2. Methodology A CPA helps the dairies to explore the CP opportunities, address the most important pollution sources and develop a list of feasible corresponding CP opportunities for implementation. The methodology of the CPA used in this study was prepared by compiling and reorganizing different manuals and checklists developed by several leading institutions in the field of CP (UNEP and DEPA, 2000; Technical Pollution Prevention Guide, 1997; Environment Protection Authority, 1997; Sustainable Business Associates, 1998; New York State Department of Environmental Conservation Pollution Prevention Unit, 2001). The CPA methodology adopted was based on the massbalance approach. During implementation of the methodology, the outline borders were drawn as the milk processing facility, which can be divided into two main procedures namely: raw milk intake and pasteurization. To quantify the inputs and outputs to the mass balance, measurements and experimental analyses were performed to determine pollution loads from different steps of operation. Chemical oxygen demand (COD), total suspended solids (TSS), alkalinity and pH analysis of the apparent WW sources were conducted by using standard methods (APHA, 1995). Measurements were made for every major mass flow for quantifying flow rates of discharges or raw material use. The outline of the methodology followed is presented in Table 1. After obtaining the management commitment and selecting team members in the pre-assessment phase, background information was compiled to develop the facility profile to give an overview of the production facility and related environmental aspects. In the assessment phase, an environmental review was conducted to both determine the waste streams and their sources and to determine the processes to be focused on. Therefore, the facility data were first compiled by establishing a preliminary mass balance of the raw materials, products, byproducts and losses, wastes and emissions. Later, a detailed site inspection was performed to ensure the correctness of mass balances and flow diagrams. In the stage of identification of CP opportunities, which were gathered from different case studies, innovative ideas suggested by the interviewed experts and operators were listed in worksheets. After determining different alternatives, they were organized and the unfeasible ones were excluded. Finally, options suitable for implementation were selected by conducting a simple technical and economic feasibility analysis since the benefits of most of the opportunities were obvious at the feasibility and assessment phase. ARTICLE IN PRESS A. Özbay, G.N. Demirer / Journal of Environmental Management 84 (2007) 484–493 486 Table 1 The methodology used in the study Step Task Sub-task description 1. Planning and organization Establishing and organizing a CPA Program (A) Obtain management commitment (B) Select team members to develop cleaner production plan 2. Pre-assessment (qualitative review) 3. Assessment (quantitative review) Compilation of background information Conducting environmental review (A) Develop facility profile (A) Compile facility data (B) Conduct site inspection (C) Identify cleaner production options (D) Organize cleaner production options 4. Evaluation and feasibility study Conducting feasibility assessment (A) Conduct feasibility assessment Clarifier CW T Raw milk 1 FM Filter Balance Tank Filter Raw Milk Tank Cooling Plates Raw Milk Storage Tanks Clarifier Sludge (A) Raw Milk Intake Process HW Pasteurization 1 HW Cream Odor FM Balance Tank CW Separator CW Homogenizator Deodorization Separator sludge Channel Pump Glass Packaging Not always in operation Mixing Holding Pipes (B) Pasteurized Milk Storage Tanks Milk Pasteurization Cartoon Packaging FM Flow meter T Check valve with time control Piston Fig. 2. Flow diagram of the milk processing facility. 3. Results and discussion 3.1. Pre-assessment The investigated milk processing facility is a dairy products processing plant where about 18 million liters of milk is processed yearly into several products. Since there is no WW treatment facility, WW is directly discharged into the Ankara River. Therefore, minimization of the pollution load by CP techniques was not only an urgent necessity but also a very significant opportunity. Milk processing can be divided into two main process stages namely: raw milk intake and pasteurization (Fig. 2). Raw milk is received by tanker trucks, each of which has three tanks with 5-ton capacity. Three–four trucks of milk is bought daily. After removal of coarse particles in a steel filter, milk is pumped to a 650 L pool for flow equalization. From the equalization basin, raw milk is pumped to a clarifier where milk is agitated at 1800 rpm. Coarse particles are collected at the sides and are swept up by water. The resulting milk sludge is discharged automatically to a WW collection channel every half hour. Service water is introduced to collect the sludge formed and the excess is discharged to the channel continuously. In addition, there is a loss of water from valves. Milk received in excess of daily production capacity is cooled in cooling plates from 4–5 to 2 1C by water at 0 1C flowing between the plates. After cooling, milk is stored in four tanks, two ARTICLE IN PRESS A. Özbay, G.N. Demirer / Journal of Environmental Management 84 (2007) 484–493 of which have 15,000 L capacity, while the other two have a 11,250 L capacity. The pasteurization system covers the processes starting from the high-temperature short-time (HTST) pasteurization up to the pasteurized milk storage tanks. The HTST pasteurizer is composed of parallel plates where milk flows along one side of the plates, while water (cold/hot) flows along the other side without being mixed. Since the pasteurization system and the raw milk storage tanks are connected manually, there is a loss of milk due to spills and milk foam remaining at the bottom of the tanks. Before the start of pasteurization, the HTST pasteurizer is heated to 90 1C with hot water, which is discharged to the channel afterwards. Before pasteurization, milk is pre-heated and flown to the separator for separation of cream. After processes of separation, deodorization and homogenization, milk flows to the HTST pasteurizer to be heated to 89–90 1C by water at 90 1C. Water used at this stage is heated with steam. Condensed steam is discharged to the channel. Milk heated to 90 1C passes through holding pipes to keep its temperature constant for some time and then cooled to 6 1C by water at 0 1C. Cooling water is recycled to the cooling tower. Pasteurized milk flows to three pasteurized milk storage tanks. The separator used for cream separation works with a similar process as the clarifier where milk fat is expelled from the top. Separator sludge is discharged to the channel every half hour. The excess water from the collection of sludge is discharged to the channel continuously using two separate hoses. In the deodorization process, milk coming from the separator is subjected to vacuum to expel any odor compounds. In this unit, while cooling water is recycled to the cooling tower, heating water is discharged to the channel. There was a loss in the cooling water return pipe due to a hole in the pipe. In the homogenization unit, the fat and liquid content of the milk are homogenized under pressure. Due to a torn hose, there was a continuous loss of cooling water. Milk collected in pasteurized milk storage tanks flows to packaging. Cases of filled boxes are carried manually to the storage area. The door of the cold-storage area is kept open for about 3 h per day. In bottle packaging, milk is bottled automatically and carried to cold storage by a belt conveyor. During this process, milk from the uncapped or fissured bottles is collected in vessels to be used in other products. Some of the milk is sold to the state offices in 40 L steel vessels as unpacked. During all these packaging processes, some amount of milk is lost due to spills from broken packages, overflow in vessel filling, milk foam remaining at the bottom of storage tanks and milk washed off by the first rinse during cleaning. At the end of each production day, all the equipment, system and tanks are cleaned. In the pasteurization system milk left is washed off the system by rinsing and all milky rinse water is discharged to the channel. After this first step 487 of cleaning, chemical solutions are used. All the manual washing processes result in milky WW from the first rinse. After the first rinse, caustic or detergent containing WW is discharged to the WW collection channel. Lastly hot and cold rinse waters are discharged to the WW collection channel. Manually pre-rinsed vessels are introduced to a washing machine or mechanical washing which is composed of three tanks namely, caustic wash, warm rinse and cold rinse. During mechanical cleaning, the major cleaning agent is NaOH. Nitric acid (HNO3) is only used in cleaning of the pasteurization system after the caustic wash and the acidic solution is discharged to the sewer. Table 2 illustrates the WWs from the cleaning processes. Sources of information for facility data were mainly measurements, facility records of purchase and operation, and interviews with the facility engineers. By measuring the flow rates of discharges, the amounts of raw material use were determined. Flow rates were mostly measured by determining the time required to fill a known volume of vessel. Details of the plant data compilation program are tabulated in Table 3. Chemical characterization (COD, TSS, alkalinity and pH) of the streams had to be done for determining raw material losses and pollution loads to the environment. 3.2. Assessment: site inspection A detailed site inspection was performed at this step. During this task, processes were analyzed in detail to determine the mass inflow and outflows to be included in the mass balances which would be the basis for CP opportunities evaluation (Table 4). 3.3. Assessment: input–output analysis by mass balance Since the bookkeeping system was not working well, for the requirements of this study, the whole mass balance had to be based on measured flow rates of inputs and discharges. Table 5 presents results of the mass-balance study that covered the major resources used in the process and discharges both in production and cleaning stages. As seen from Table 5, raw milk, water and steam constituted most of the mass input categories while packed milk, WW, water spills and losses and discharge water were the main mass outputs from the process. Note that the overall mass balance included over 100 inputs and outputs. Therefore, only the summary results are provided below. Full details may be found in Özbay (2003). By the assessment of CP alternatives during the processes of milk production, it was determined that water discharges that can be reused for cleaning in other steps of the process are 9458.4 kg/day (Tables 6 and 7). Service water, steam condensate, the discharge from the separator and heating water were the sources of potential reuse. It was observed that 361 kg/day of reusable milky waste (milk sludge, spills and milk foams) is discharged (Table 5). Furthermore, water discharge sources that could be ARTICLE IN PRESS A. Özbay, G.N. Demirer / Journal of Environmental Management 84 (2007) 484–493 488 Table 2 Cleaning process discharges Source Type of cleaning First rinse discharge Cleaning agent Final discharge Tanks on trucks Steel vessels Raw milk storage tanks Pasteurization system Manual Manual+mechanical Manual Manual Milky hot water Milky-caustic hot WW Milk foam+milky WW Milk remained in system that is purged by rinsing+milky WW — Hot and cold rinse WW Cold rinse water Hot and cold rinse Pasteurization area floor Pasteurized milk storage tanks Manual Manual — Milk foam+warm milky WW — Caustic WW Detergent Caustic solution Second rinse of caustic solution Acidic solution Detergent Caustic solution Warm rinse WW Warm rinse WW Cold rinse WW Bottle washing (Both in morning and at end of day) Mechanical Milky WW Caustic Solution Bottle case washing Bottle packaging washing Box packaging cleaning Mechanical Manual Mechanical (CIP system) — Milky WW — Detergent Caustic WW Warm rinse WW Cold rinse WW Cold rinse WW Cold Rinse WW Warm Rinse WW Cold rinse WW (in morning wash) Table 3 Plant data compilation program Facility-specific information Dairy products processed and/or manufactures Volume of dairy products processed and/or manufactured General shipment schedule Active ingredients or components of concern Unloading Spillage control system Operating schedule/periods Site cleanup method Process unit operation Spillage control system Wastewater generation rate Quantity of spillage Site cleanup method Wastewater treatment/disposal method Operating schedule Storage Storage method Fuel, lubricants, chemicals Quantity of materials Spill prevention and cleanup method Wastewater management practices Quantity of wastewater Wastewater management method Environmental permit requirements Position of the firm with respect to wastewater discharge limits on regulations Data sources Raw materials Facility records and interviews Process unit operation and storage Equipment list and specifications Equipment layouts and logistics Operating manuals and process description Operator data logs Fuel, lubricants, chemicals Purchasing records Interviews with operators and engineers Wastewater Interviews with operators and engineers Waste materials (solids) Interviews with operators and engineers Visual inspection of the wastes Environmental permit requirements Interviews with engineers ARTICLE IN PRESS A. Özbay, G.N. Demirer / Journal of Environmental Management 84 (2007) 484–493 489 Table 4 Site inspection guidelines adopted Pre-inspection activities  Evaluate data compiled along with mass balance calculations and flow diagrams to gain familiarity with the targeted processes and to identify additional data requirement.  Review existing documents such as operators’ manuals and purchasing and shipping records.  Prepare an inspection agenda that identify the targeted processes and the data requirement.  Schedule the inspection to coincide with operations of the targeted processes. On-site inspection activities  Monitor the raw materials handling process from the point where bulk materials enter the plant site to the point where          Post-inspection activities finished products and wastes exit. Identify all wastewater discharges including leaks and spills. Monitor the process unit operations to identify unmeasured or undocumented releases of products and wastes. Make necessary measurements to identify flow rates of specific discharge sources. Make necessary experiments to characterize wastewater sources where there are obvious CP opportunities or high pollution loads to environment. Interview the operators in the targeted dairy products processing areas to identify operating parameters, wastewater generation and spill reduction opportunities. Evaluate the general conditions of the processing equipment. Examine housekeeping practices throughout the facility. Check for spillage and leaks at the equipment/valve vehicle maintenance area. Check waste storage area for proper waste segregation.  Update mass balance calculations and flow diagrams with new or corrected information.  Conduct follow-up site inspections to collect additional data or to clarify questions identified during data analysis. Table 5 Mass flow of milk processing and cleaning (AOC, 2002) Quantity (kg/day) Source of mass flow in Raw milk Service water Steam Caustic Detergent Acid Total 33,985.8 94,661.1 2677.9 142.2 2.4 10 131,479.6 Source of mass flow out Packed milk 33,527.1 Cream 119 Recycled milk to other products 271.2 Wastewater 69,827.1 Water spill and cooling water loss 15,911.4 Clean discharge water 11,747.5 Milk and milk foam loss by spill and due to cleaning 302.6 Milk sludge 58.4 Total 131,764.3 completely eliminated by good house keeping (GHK) opportunities, i.e., repairing of equipment, amounted to 4137.1 kg/day (Tables 6 and 7). If the CP alternatives in the cleaning procedures are considered, the amount of milky WW discharged to the channel that could be prevented or reduced by using it in other products or processes as ingredients was 843.9 kg/ day. The chemicals used in cleaning processes which could be reduced by applying CP opportunities amounted to 152.1 kg/day. During all cleaning procedures, unnecessary water use which could be eliminated or replaced by other sources is 27003.2 kg/day. Finally, WW or water use sources that could be reduced by applying CP opportunities add up to 52589.3 kg/day. The details of these CP opportunities are presented in the next section. 3.4. CP opportunities 3.4.1. Opportunities for the milk processing Clean water recycles: The excess service water used by the clarifier and separator for equipment cleaning and the steam condensate have service water quality. These streams are currently being discharged to the WW channel. These sources (9458.4 kg/day) may be recycled and reused in separator or cleaning operations. GHK/repair: Repairing valves of the clarifier, HTST pasteurizer fittings, and leaks in the cooling water line in deodorization and changing of the damaged hose in the homogenization unit would eliminate discharge of 2037.3 kg/day of service water. Off-site reuse/milk sludge: In clarification and separation, the main issue in terms of organic load is the milk sludge discharged to the sewer. Actually, it is a very valuable source of animal feed due to its nutritional value. The investigated facility also feeds cattle. Therefore, milk sludge can be used in their feeding or it may be used in the fodder industries, some of which are found in the vicinity of Ankara. For this purpose, collected sludge may be kept in refrigerated storage for weekly transfer to the fodder industry. Off-site reuse/milky water: The water from the first rinsing can be collected in a tank and used for cattle, as in the case of milk sludge. Due to the organic content of this ARTICLE IN PRESS A. Özbay, G.N. Demirer / Journal of Environmental Management 84 (2007) 484–493 490 Table 6 The proposed CP opportunities and corresponding pollution prevention that could be obtained upon implementation for milk processinga Opportunity Eliminated discharge (kg/day) Clean water recycle GHK/repair Off-site reuse/milk sludge Off-site reuse/milky water GHK/small equipment Change/water and milk GHK/operating Practices/milk Total Reduced recycling (kg/day) Recycled water (kg/ day) Reduced COD (kg/ day) Reduced TSS (g/ day) 9458.4 2037.3 55.8 6.9 2100 45.2 Water Milk 102.8 4245.3 102.8 9458.4 5.7 9.1 1.7 792.5 1704.9 413.6 11.1 2627.7 27.7 5538.9 a In plant although raw milk intake system works 360 day/yr, pasteurization system works 308 day/yr. Values are calculated as if raw milk intake system worked 308 days/yr, and iterated accordingly. Table 7 The proposed CP opportunities and corresponding pollution prevention that could be obtained upon implementation for the cleaning operations Opportunity Eliminated water use (kg/ day) Eliminated discharge (kg/ day) CIP system Off-site reuse/ milky rinse as animal fooda Shut-off nozzle use GHK-change operating practices Chemical change Alkaline water reuse in cleaning bottle cases 26,110.3 3262.7 1581.2 Total 47,329.7 a Eliminated chemical use (kg/day) Recycled water (kg/day) Reduced COD (kg/day) 4.2 23.7 11,727.8 259.4 7 53.5 9178.5 94.1 Reduced TSS (g/day) 1566.2 2153 126.2 11,469 154.1 15,188.2 Reduced alkalinity as CaCO3 (kg/ day) 40.1 9178.5 4843.9 101.1 9178.5 40.1 In the proposed case 1364.2 kg/day of waste rinse water would be collected as animal feed. stream, animals fed with this source would have higher milk production efficiency. To prevent milk spills on the floor, raw milk storage tanks can be connected to a single pipe, which could be connected to the pasteurization unit. This will prevent the milk spills on the ground and make the flow from the raw milk storage tanks manually controllable. Moreover, the milky first rinse water from the washing of storage tanks could be collected from the new pipe installed. GHK/small equipment change/water and milk: During operation of the separator, excess water used for liquefaction of sludge overflows from the tank and is disposed to the channel. If a level control is affixed to the tank in which service water is stored for the separator sludge, this discharge (2100 kg/day) could be eliminated. The function of the level control should be to close the incoming service water line when the tank is full. Furthermore, 45.2 kg/day of milk spills on the floor due to leaking valves and overfilling during filling of the vessels that are going to be sold as unpacked milk. If a valve with level control is used, this spill would be prevented. GHK/operating practices/milk: Milk which is spilled due to defective packaging (box/bottle) and remains in the pipe is already collected in vessels and sent to the beginning of the process. If defective packaging is minimized with better management practices, the amount of return milk would be reduced. This would prevent the use of chemicals, energy and water once again for the same amount of milk. If box packages were stored in better conditions and purchase policy was rearranged to avoid excessive buying of raw materials, it is assumed that defective carton packaging could be reduced by 40%. In the bottle line, defective packaging is mostly due to uncapped bottles. If they could immediately be capped manually, this milk would not be spilled and contaminated. Also, milk remaining in the tank at the end of the day may be filled into bottles and capped manually. By these measures, it is assumed that 70% of return milk could be avoided ARTICLE IN PRESS A. Özbay, G.N. Demirer / Journal of Environmental Management 84 (2007) 484–493 (Personal interview with Mr. Sahin Durna, Process Engineer of the facility, March 2003). Opportunities for improvement in the box and bottle packaging are expected to reduce the milk return by 102.8 kg/day. If all the proposed CP measures are implemented, the corresponding pollution prevention that would be obtained is depicted in Table 6.     3.4.2. Opportunities in cleaning operations The outcomes of the mass-balance analysis indicate that the major environmental load in market milk production facilities originates from cleaning procedures since there is an extensive use of chemicals and water. The main reason for this is the use of manual procedures for cleaning instead of effective systems like clean in place (CIP) (Fig. 3). Water use in cleaning procedures could be reduced significantly by eliminating unnecessary water use and by using CP opportunities. These could be achieved with better management practices, CIP use, etc. This would be a significant achievement since water discharged due to cleaning adds up to 48,738.2 kg/day. Change of technology—CIP system: The CIP system suggested covers the cleaning of the pasteurization unit, pasteurized milk storage tanks and glass bottle filling. The proposed system has three tanks (1-ton each) that serve for rinsing, alkaline solution and acid solution; a dosing system for chemicals based on conductivity measures of solutions; a heating system for increasing the effectiveness of solutions and a pumping system for recycling in the closed system. The first investment cost of such a CIP system is 19,750 Euro (http://www.cleantechindia.com/eicnew/guidelines/Dairy1.htm 1.8.2002). By using this system, manual and separated rinsing procedures are combined and use a water volume of 1000 L. Furthermore, the repeated cleaning solution preparation and detergent use is prevented by recycling alkaline and acidic solutions through the whole system. This new system results in water savings both due to rinsing and cleaning solution preparation as well as final rinsing. Total water savings come from:  491 rinsing of bottle packaging, caustic solution preparation for pasteurized milk storage tanks and pasteurization system, rinses of pasteurization system and pasteurized milk storage tanks, elimination of rinses in morning washes, acidic solution preparation for pasteurization system and its rinse water, water eliminated in manual cleaning of bottle packaging, eliminated losses due to overflows and hoses remaining open. These savings would eliminate 26,110.3 kg/day of water use. Furthermore, they eliminate the discharge of 3262.7 kg/day of reusable water or solution since it is a closed system. Off-site reuse/milky rinse as animal food: If the rinsed water from the cleaning of the truck tanks is collected for the first 1 min, this milky water may be used for cattle. This rinse water would contain milk solids from the first rinse of pasteurization, pasteurized milk storage and bottle packaging cleaning. The design of the system for water collection includes piping work, a tank and a small pump for pumping of this water to the truck. By this implementation, 1581.2 kg/day of water would be prevented from being discharged to the sewer, while 1364.2 kg/day of rinse water is reused for cattle watering. Change equipment/shut-off nozzle use: An important opportunity for reducing the use of water in manual washing practices is assembling shut-off spray nozzles at the ends of hoses. This would pressurize water and increase water use efficiency. This equipment may be used in cleaning tanks on trucks, rinse of return and unpacked milk vessels, floor cleaning in vessel washing areas, surface and floor cleaning in the pasteurization area, surface cleaning of pasteurized milk storage tanks and their morning surface wash and surface cleaning of packaging areas. By increasing the effectiveness of water use, this equipment would bring a saving of 11,727.8 kg/day of service water, which is a very significant amount. Fig. 3. A multi-use CIP system (http://www.ea.gov.au/industry/eecp/case-studies/pauls1.html). ARTICLE IN PRESS 492 A. Özbay, G.N. Demirer / Journal of Environmental Management 84 (2007) 484–493 GHK-change in operating practices: During the initial manual rinsing of returned milk vessels, an NaOH solution is used in each vessel. If the solution used in a vessel could be reused for five vessels, both chemical and water consumption would be reduced. During the cleaning of box packaging equipment, a CIP system is used. Although water should be recycled by using the CIP tank, the rinsing is done by fresh water which amounts to 3 times the volume of the tanks. If management changes the rinsing procedure so that the first water is recycled for 2–3 min, a final rinse with one tank (250 L) of fresh water is expected to be sufficient. Thus, by changing the operation procedure, it is possible to eliminate the use of 259.4 kg/day of water and 7 kg/day of NaOH. Chemical change: In the alkaline tank of the CIP system, P3-mip CIP, an alkaline product designed for cleaning closed systems may be used instead of NaOH. This product provides better cleaning at lower concentrations (1–2%) at temperatures of 60–80 1C (http://www.dioxide.com/Services/Chemical_Dosing_Systems/CIP/cip.html), whereas for preparation of acidic solutions P3-horolith flüssig may be used, which is an acidic cleaning agent that contains nitric acid, phosphoric acid and inhibitors. This chemical is used in concentrations of 1–2% at 50–60 1C (http://www.cleantechindia.com/eicnew/guidelines/ Dairy1.htm; 1.8.2002). Although synthetic chemicals are 3–4 times more expensive than the current chemicals, their use is still economically feasible since the amount required is 80 times less for the alkaline and 20 times less for the acidic chemical, respectively. It has to be underlined here that no trials have been run in this factory and the results might not be the same as in the reference given. For the mechanical washing of steel vessels, cleaning solution could not be used for more than 1 week due to the chemical characteristics of NaOH. Alternatively, if P3asepto is used together with a dosing system, the alkaline wash solution would last for 1 month. This would however require that the hot and cold rinsing water tanks be changed weekly (http://www.cleantechindia.com/eicnew/ guidelines/Dairy1.htm; 1.8.2002). In bottle washing, the main environmental concern is the highly alkaline solution (3.75% concentration) used and discharged to the sewer weekly. The addition of P3-stabilon WT in concentrations of 0.2% doubles the efficiency (http://www.cleantechindia.com/eicnew/guidelines/Dairy1.htm; 1.8.2002). Therefore, if this chemical was used together with a dosing system, NaOH usage would decrease by 50%. If the above-stated opportunities are implemented, there is a potential to eliminate use of 94.1 kg/day of chemical most of which is NaOH. Reuse-alkaline water reuse in cleaning bottle cases: In the mechanical washing, the overflow alkaline water is continuously discharged to the channel. On the other side, during the process of case washing, service water is sprayed on cases continuously. Also prior to mechanical washing, dirty bottles are filled with water. If overflow water from the mechanical washing is collected in a small equalization tank and pumped continuously, it could be reused to wash bottle cases and fill dirty bottles at the end of the day. Through this opportunity, 9178.5 kg/day of highly alkaline water may be reused. If all the proposed CP measures are implemented, the resulting pollution prevention opportunities are depicted in Table 7. 4. Conclusions The CPA study applied to the facility investigated in this study revealed several significant CP opportunities. The implementation of these opportunities would lead to prominent pollution prevention and economical savings especially in terms of water and chemical use if they are properly executed. Water use and the milk losses in the milk production facility constitute major CP opportunities that can be implemented without very high cost or technical difficulty. Furthermore, repairing of the equipment and fittings, installation of small process controlling equipment and changing of current operating practices were suggested as the GHK opportunities. In addition, recycling of the clean water of service water quality, off-site reuse of the milk sludge and milky rinse water for cattle and reuse of alkaline water for cleaning of other equipment are recommended. In the context of technological change, the use of a CIP system for automation of the cleaning system and the use of shut-off spray nozzles for increasing the effectiveness of water use are suggested. Finally, alternative cleaning chemicals were proposed to the facility. Tables 6 and 7 summarize all the CP opportunities developed and proposed to the facility as well as the corresponding pollution prevention that could be obtained upon implementation. When the values in Table 5 are compared with the mass flow of the whole facility, it can be seen that:   50% of the service water used, 9.3% of the current WW discharge, 65.4% of the chemical use and the discharge of 181.9 kg/day of COD and 20.7 kg/ day of TSS could be eliminated, 19.6% of the service water used could be recycled/ reused. Finally, the CPA methodology which was put together by using different CP manuals and checklists of the leading institutions in the field was based on the mass-balance approach. Even though it was one of the simplest tools of CP, it proved to be sufficient to reveal the CP opportunities for the facility investigated. References AOC, 2002. Facility Records. APHA, 1995. Standard Methods for the Examination of Water and Wastewater, 19th Ed. Washington, DC. ARTICLE IN PRESS A. Özbay, G.N. Demirer / Journal of Environmental Management 84 (2007) 484–493 Baskaran, K., Palmowski, L.M., Watson, B.M., 2003. Wastewater reuse and treatment options for the dairy industry. Water Science and Technology: Water Supply 3, 85–91. Carawan, R.E., Chambers, J.V., Zall, R.R., 1979. Water and wastewater management in food processing. Extention Special Report no. AM18B, North Carolina State University, Cornell University, Purdue University. Environment Protection Authority, State Government of Victoria, Australia, 1997. Environmental Guidelines for the Dairy Processing Industry. Environmental Technology and Best Practice Program, 1999. Reducing Waste for Profit in the Dairy Industry, England. http://www.cleantechindia.com/eicnew/guidelines/Dairy1.htm. http://www.dioxide.com/Services/Chemical_Dosing_Systems/CIP/ cip.html. New York State Department of Environmental Conservation Pollution Prevention Unit, 2001. Environmental Self-Assessment for the Food Processing Industry. 493 Nguyen, M.H., Durham, R.J., 2004. Status and prospects for cleaner production in the dairy food industry. Australian Journal of Dairy Technology 59, 171–173. Ontario Ministry of Environment, 1993. Pollution Prevention Planning, Guidance Document and Workbook. Özbay, A., 2003. Cleaner Production Opportunity Assessment for Market Milk Production. M.Sc. Thesis, Middle East Technical University, Department of Environmental Engineering, Ankara, Turkey. Regional Activity Centre for Cleaner Production, 2000. Minimization Opportunities for Environmental Diagnosis. Sustainable Business Associates, 1998. Good House Keeping Guide for Small and Medium-Sized Enterprises. Technical Pollution Prevention Guide for the Dairy Processing Operations in the Lower Frazer Basin, 1997 Environment Canada Environmental Protection Fraser Pollution Abatement North Vancouver. UNEP and Danish Environmental Protection Agency, 2000. Cleaner Production Assessment in Dairy Processing.