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Journal of Environmental Management 91 (2009) 102–113

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Journal of Environmental Management

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Adoption of European Union’s IPPC Directive to a textile mill: Analysis of waterand energy consumption

A. Merve Kocabas, Hande Yukseler, Filiz B. Dilek, Ulku Yetis*

Middle East Technical University, Department of Environmental Engineering, Inonu Bulvari, 06531 Ankara, Turkey

a r t i c l e i n f o

Article history:Received 25 November 2008Received in revised form23 June 2009Accepted 15 July 2009Available online 15 August 2009

Keywords:Best Available TechniquesIPPC DirectiveTextileWater consumptionEnergy consumptionTurkey

* Corresponding author. Tel.: þ90 3122105868; faxE-mail address: uyetis@metu.edu.tr (U. Yetis).

0301-4797/$ – see front matter � 2009 Elsevier Ltd.doi:10.1016/j.jenvman.2009.07.012

a b s t r a c t

The present study was undertaken as part of the first application and evaluation of the BREF (BestAvailable Techniques; BAT Reference Document) Textile Document within the context of the EuropeanUnion’s Integrated Pollution Prevention and Control (IPPC) Directive to a large scale textile mill in Turkey.The BAT requirements for the denim manufacturing textile mill were selected in cooperation with thefactory management. Detailed mass balance calculations were conducted to evaluate the overall effect ofthe selected BAT options. The initial findings indicated that the adoption of the selected BAT optionsresulted in considerable savings in water and energy consumption in the mill. Besides the installation offlow meters and use of semi-counter current rinsing in the most water-intensive processes, minimizationof wash waters in the water softening plant, reuse of the concentrate stream from the reverse osmosisplant and compressor cooling waters provided a 29.5% reduction in the total specific water consumptionof the mill, reaching the lower limits suggested by the BREF Textile Document. In terms of energyconsumption, use of waste heat from finishing wastewater streams in heating up the wash waters, heatinsulation and maintenance applications in addition to BAT measures taken for water minimizationreduced specific energy consumption by 9% achieving the limits set by the BREF Textile Document.

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1. Introduction

In the European Union (EU) countries, industrial pollution hasbeen managed by ‘‘integrated’’ approach taking into account emis-sions to water, air and soil as a whole. This approach deals withpollution rising from industrial activities by considering the produc-tion phases rather than setting limit values for the discharges oremissions. In other words, the approach adopts ‘pollution prevention’rather than ‘end-of-pipe’ concept. Integrated Pollution Preventionand Control (IPPC) Directive (2008/1/EC), published originally in 1996by the EC, covers legal arrangements and requires the inspectingauthorities to give permits to the industrial facilities and to monitortheir environmental performances within this general approach. Inshort, the IPPC Directive requires an integrated approach to theenvironmental protection of air, water and land, through the appli-cation of Best Available Techniques (BAT), establishing operatingconditions and emission limit values in permits for installations.

According to the Directive, ‘‘certain measures designed toprevent or, where that is not practicable, to reduce emissions in the

: þ90 3122102646.

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air, water and land from the activities listed in Annex I, includingmeasures concerning waste are taken in order to achieve a highlevel of protection of the environment taken as a whole’’ (EC, 2008).In view of that, BAT Reference (BREF) Documents, published by theEuropean IPPC Bureau, are the basic tools to implement therequirements of the Directive.

Operators of industrial installations, where one or more activi-ties listed in Annex I of the IPPC Directive are carried out, arerequired to obtain an operating permit from the authorities. A widerange of industrial activities are listed in Annex I, categorized undersix topics: energy production, production and processing of metals,minerals, chemicals, waste management and others (EC, 2008). Thetextile industry listed among ‘‘others’’ is a water and energyintensive sector and production of textiles affords a great variety ofprocessing steps requiring use of large amounts of water andchemicals. Requiring large amounts of water for processing, textileindustry is also energy intensive as most of the energy consumed isto heat up the process baths (EC, 2003).

Instead of covering all textile manufacturing processes, BREFTextile Document specifies the activities to be covered as ‘‘plants forpretreatment (operations such as washing, bleaching, andmercerization) or dyeing of fibres or textiles where the treatmentcapacity exceeds 10 tones per day’’ (EC, 2003).

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Turkey, being a candidate country for full membership to the EU,is in the period of adopting legal requirements and sanctions of theUnion. Among many other environmental directives, the IPPCDirective is of priority as manufacturing industry is wide spread inTurkey and its implementation requires heavy investments.

This study is a part of the project for the first implementation ofthe IPPC Directive and BREF Document to an industrial facility inTurkey (‘‘Adoption of EU’s IPPC Directive to a Textile Mill in Turkey:BAT Applications’’ funded by the Turkish Scientific and Technolog-ical Research Council (TUB_ITAK) Project No. 105Y088). In theproject, all the aspects of the IPPC Directive including application ofappropriate preventive measures against pollution, wastemanagement, energy efficiency, prevention of accidents and risksand emissions to water, air and land have been studied. Hence,assessing water and energy consumption performances in thisstudy is a part of the abovementioned project.

The major goal of this study is to assess the water and energyconsumption performances of a textile mill in Turkey after theapplication of appropriate BAT measures for minimization of waterand energy consumption.

2. Background

Textile manufacturing is one of the oldest and most complicatedindustrial sectors among other manufacturing industries. Waterand energy are consumed in nearly every step of the process chainof textile manufacturing. However, in general, the majority of thoseresources are utilized in wet processes such as dyeing, sizing andfinishing. This fact has put efforts on the minimization of use of, andwhere applicable reuse of, raw materials, water and energy withinthe production steps.

The stringent environmental regulations for discharge today areforcing the dyers and finishers in the textile industry to examinethe potential for recycling the water from the waste stream bynewer technologies. In view of this fact, the BREF Textile Documentalso suggests many techniques related to process modifications,pollution prevention opportunities, use and optimization of waterand chemicals, control of raw materials, recovery, reuse and recycleoptions which in turn are experienced to result in significantreductions in terms of chemicals, water and energy without dis-torting the final product quality and hence improve productionefficiency, environmental and economic performance of the textilefactory.

Dulkadiroglu et al. (2002) indicated the importance of theimplementation of in-plant control techniques for textile industriesfor achieving significant reductions in water use, raw material andenergy consumption, wastewater production and in some caseseven wastewater load. Van Veldhuisen (1991) grouped in-plantcontrol applications under four headings: (i) water minimization(water conservation); (ii) wastewater recovery and reuse; (iii)chemical substitution and (iv) recovery of valuable substances(material reclamation). Significant reductions in water and energyuse can be achieved by preventing the unnecessary consumptionpractices in textile mills.

In particular, optimal use of water and energy should start frommonitoring of water, heat and power consumption of sub-units ofthe process and characterisation of the facility waste streams. Sincethe production may vary widely not only during a year (because ofseasonal changes and fashion) but even over a single day (accordingto the production programme), the resulting emissions are evenmore difficult to standardise and compare. The ideal approachwould be a systematic analysis of the specific processes, but dataavailability is very poor for many reasons, including the fact thatlegal requirements have tended to focus on the final effluent ratherthan on the specific processes (EC, 2003).

2.1. Textile industry in Turkey

Textile industry, being one of the most complicated and oldestindustries, plays a major role in Turkish economy. Exporting almosttwo thirds of the textiles produced, textile industry has a share of6–7% in total Turkish exports. In this share, EU market of Turkey isenlarged every year since Customs Union came into effect and is inthe front rank with 44:5% in Turkish textile exports (GSTAEU, 2007).Taking into account the share of textile industry in the Turkisheconomy, EU export of Turkish textiles is one of the most significantplayers of economy in Turkey. Therefore, the adoption of the IPPCDirective to textile industry is of utmost importance among otherindustrial activities in Turkey.

Meanwhile, throughout the EU, environmental concerns inmanufacturing industry have increased considerably with thepublication of the IPPC Directive. For that reason, many countriesthat import Turkish textiles (EU and the USA being the first) requirequality tests, covering environmental aspects, before, during andafter the production processes. Besides, those concerns are evendeclared as ‘non-tariff barriers’ in terms of exports inmanufacturing industry nowadays (SPO, 2007).

Being a water and energy intensive sector, in order to minimizeconsumption of these resources, the ‘‘Textile and Apparel SpecialistCommission Report’’ of the 8th Five Year Development Plan of theState Planning Organization stated that the current specific waterconsumption for textile industry being 131 L of water per kilogramfinished textile should be reduced to 80 L of water per kilogramfinished textile by using energy and water saving technologies(SPO, 2001). In the same report, the significance of energyconsumption and related expenses in textile industry are alsoemphasized. Additionally, target specific energy consumption isreported as 40 000 kJ/kg fabric.

From the foregoing discussion, it is clear that the adoption of theIPPC Directive to Turkish textile industry is of utmost importance.For this purpose, Ministry of Environment and Forestry (MoEF) ofthe Republic of Turkey has been conducting several projects for theadaptation and implementation of the Directive. Additionally, BREFTextile Document has been already translated into Turkish in theyear 2005 by the Turkish Textile Finishing Manufacturers Associa-tion which clearly shows that the manufacturers attach greatimportance to the adaptation process.

2.2. Water consumption in the textile industry

The textiles industry has always been regarded as a water-intensive sector. The main environmental concern is thereforeabout the amount of water discharged and the chemical load itcarries. Other important issues are energy consumption, air emis-sions and solid wastes and odours, which can be a significantnuisance in certain treatments.

In terms of ‘‘general good management practices’’ monitoringand recording water consumption at machine and process level isreported as vital in BREF Textile Document. Therefore, controllingwater consumption is stated as one of the key implementations foroptimizing water consumption. Additionally, reducing waterconsumption by improved working practices such as ‘‘well docu-mented production procedures and training of the staff’’ and byreducing liquor ratio in dyeing process is declared to be quiteimportant. Improving washing efficiency in both batch andcontinuous dyeing is reported as another way to reduce waterconsumption. By combining processes in a single step whereapplicable is indicated as another way to reduce specific waterconsumption in the facilities. Moreover, reuse of water is stated asthe third method to optimize water consumption in textile mills.Some examples of implementation of abovementioned measures

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are mentioned to result in 50–100 L of water per kilogram of fabricproduced in mills finishing of woven fabric consisting mainly ofcellulosic fibres in BREF Textile Document (EC, 2003).

Another method to optimize water consumption is the appli-cation of counter-current washing systems. The counter-currentprinciple is explained as ‘‘reuse of the least contaminated waterfrom the final wash for the next-to-last wash and so on until thewater reaches the first wash stage, after which it is discharged’’ inBREF Textile document (EC, 2003). The technique is called as‘‘relatively straightforward and inexpensive and applicable forwashing after continuous desizing, scouring, bleaching, dyeing orprinting’’ (EC, 2003). However, it should be noted that in addition tothe methods to optimize–minimize water consumption explainedabove, many other techniques, generally complex in nature, aredescribed in the BREF Textile Document. It is also pointed out that,except investment in new equipments and major structuralmodifications (especially in segregating waste streams) theabovementioned principles are applicable with low cost (EC, 2003).

Smith (1989) claimed that, by the application of appropriatewater reuse and recovery options, a 10–30% reduction in water usecan be achieved without major investments in textile industry.Gleick et al. (2003) indicated that ‘‘the process water savings intextile industry can range from 20 to 50% in continuous dyeing bytaking simple measures such as counter-current washing tech-niques and use of automatic shut-off valves’’. Fresner (1998)pointed out that, 10% of process water could be saved by reusingcooling water as process water. He also mentioned water savings byapplying counter flow principle to the washing step. Additionally,he declared that 20% of water usage could be avoided by optimizingthe use of water through better process control, mainly in washingprocess (e.g. switching off the water supply when the equipment isnot used) in a textile mill applying mainly desizing. Consequently,Fresner (1998) resulted in a 30% reduction in the total water use.Likewise, Li Rosia et al. (2007) predicted a saving of 50% of freshwater consumption by the application of water reuse whereapplicable after suitable membrane treatment processes.

Kiran-Ciliz (2003) emphasized the significance of water mini-mization options such as reducing the liquor ratio of dyeingmachines, reusing of treated wastewater in certain processes (suchas pre-washing of printing screens) and optimization in theregeneration process for backwashing of the resins for the softeningof raw water in a textile mill. In their study, Kiran-Ciliz (2003)claimed that with the latter water minimization method, 6 m3 ofwater could be saved per day. Like Kiran-Ciliz (2003), Tana-pongpipat et al. (2008) studied the process modification in scouringprocess of textile industry by reducing the tank number to rinse thedesizing agent from the fabric and achieved a reduction ofapproximately 20% in wastewater discharged from the process.

Consequently, various methods are available to optimize and/orminimize water consumption in the textile industry, achieving upto 50% savings with no significant cost.

2.3. Energy consumption in the textile industry

In textile industry, energy efficiency is as significant as waterminimization and energy consumption is directly related to waterconsumption as most of the energy required is to heat up processbaths. Therefore, reduction in water consumption also results in thereduction of energy consumption.

Energy is consumed primarily in raising the temperature of thebaths (e.g. pretreatment, dyeing, etc.) and in drying and curingoperations. For this purpose, steam is produced on-site. Electricalenergy is required for driving the machinery. The productiontechniques, operating practices and the machinery employeddirectly affect water and energy consumption in a textile mill. For

example, batch dyeing processes generally require higher waterand energy consumption levels than continuous processes.

BAT starts from the monitoring of water and energy consump-tion in the various processes along with improved control ofprocess parameters. For the optimization of energy consumption,BREF Textile Document recommends several low technologymeasures which can easily be applied with minimum cost. Theseare, namely, heat insulation of pipes, valves, tanks, machines;optimizing boiler houses (reuse of condensed water, preheating ofair supply, heat recovery in combustion gases); segregation of hotand cold wastewater streams prior to heat recovery and recovery ofheat from the hot stream; installing heat recovery systems on wasteoff-gases; installing frequency-controlled electric motors; control-ling moisture content in the circulating air and on the textile instenters; proper adjustment of drying/curing temperature anddrying/curing time.

In Turkey, the textile industry has been reported as the thirdmost energy intensive sector after iron/steel and cement industries(Hepbasli and Ozalp, 2003). The 8th Five Year Development Plan ofTurkey also highlights that the cost of energy in textile processing is12% of the total cost. Thus, it is obvious that energy efficiencyshould be given of great importance in the textile industry and evenwith low technology measures considerable savings can beachieved.

3. Methodology

3.1. Study approach

Prior to the initiation of the studies, a site visit was carried out tothe pilot plant in order to get familiar with the processes involved inthe production chain with types, production amounts, the majorwaste streams and recipes and to collect necessary information bya walk through in the plant with the accompany of the mill staff. Inthe BREF Textile Document, it is indicated that information collectedshould be composed of types, quantities, composition and sources ofall waste streams. Furthermore, the significance of collection ofinformation on the volumes of water consumed in every installationwithin the mill is emphasized. Process specific data is mentioned tobe vital in order to give priority to the processes in terms of pollutionprevention options (EC, 2003). In this respect, initially, a detailedprocess analysis was conducted in order to collect information onthe abovementioned categories. Additionally, information on theamount of water and energy consumed in every installation withinthe mill was collected and water and energy consumptions weremonitored till the end of the study. The major intention for collectinginformation on water and energy consumption was to conducta mass balance analysis for the pilot plant. However, the productionprogramme in textile industry varies according to seasonal changesand fashion not only during a year, but even over a single day (EC,2003). Therefore, it was difficult to standardise and compare theemissions of processes in the mill. The ideal approach is indicated as‘‘a systematic analysis of the specific processes’’ (EC, 2003). For thatreason, the most water and energy intensive processes were selectedand the influence of BAT measures on the consumption levels of theprocesses and the selected mill was analyzed.

3.2. Selected mill

In the present study, a denim producing textile mill which isamong the World’s leading denim manufacturers was selected asthe pilot plant. The selected mill, with a production capacity of75 tons per day, is in the scope of the IPPC Directive. The plantstudied produces denim textile starting from raw cotton. Textileproduction starts with fibre manufacturing, continues with sizing,

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dyeing, weaving and ends up with finishing among which sizing,dyeing and finishing are the wet processes. The plant extracts waterfrom wells; softens through ion exchanger and reverse osmosisfacilities and discharges its biologically treated wastewaters intothe sewer line that ends up with a municipal wastewater treatmentplant. In the mill, hard water is generally required for cleaningpurposes; whereas, the majority of the processes are carried out bysoftened water. Thus, a portion of the extracted groundwater issoftened in ion exchangers. The softened water from the ionexchangers is diverted to the processes. In addition to this, almost40–50% of softened water from ion exchangers is transferred to thereverse osmosis system to produce deionised ultra pure water to beutilized in the cogeneration plant for steam generation. Softenedwater diverted to the processes is mostly used in dyeing, sizing andfinishing steps which are the major wet processes.

The energy utilized in the mill comes from a cogeneration plantand a boiler house consuming natural gas. The mill produces20 000 tons of cotton fibre and 45 million meter of denim fabricper year. Before the implementation of the project, the total dailywater consumption was about 5000–7000 tons. Fig. 1 presents theproduction chain and the water flow in the selected mill.

The IPPC Directive, besides its other requirements, states that‘‘Member States shall take the necessary measures to provide thatthe competent authorities ensure that installations are operated insuch a way that energy is used efficiently’’ (EC, 2008).

In this context, a detailed energy balance analysis is necessary formonitoring energy consumption in addition to the assessment ofenergy consumption performance in the mill. In the selected mill,the major energy source is natural gas. Natural gas is consumed inthe cogeneration plant for the generation of electricity and steam tobe used in the production processes and also for other purposes inthe mill campus. Furthermore, natural gas is required in someprocesses such as singeing and drying. On the other hand, apart fromproduction processes, natural gas is also consumed for heating ofcompany dwellings and staff canteen. When the electricity produc-tion of the cogeneration plant is insufficient for the mill, electricity ispurchased from the central electricity network. In addition to elec-tricity and natural gas, steam is also a significant energy sourcerequired in the production processes. Steam is produced in cogen-eration unit and boilers then directed to the processes. Steam is anessential energy source consumed as the majority of steam isconsumed in wet processes for heating up the process baths.

Cogeneration units, also known as Combined Heat and Power(CHP), produce electricity and heat in one single process byconsuming fuels. The efficiency of CHP systems can reach up to 90%which cannot be underestimated as most advanced conventionalelectricity generation systems can convert 55% of fuel into usefulenergy. The system saves 15–40% of energy when compared withthe separate production of electricity and heat. Moreover, cogene-ration reduces CO2 emissions significantly (UNEP Energy Tech-nology Fact Sheet on Cogeneration).

In the selected mill, CHP system includes two steam turbineswith a capacity of 5 MW. In cogeneration unit, natural gas andwater enter into the steam turbines and electricity is produced. Theresulting steam at a temperature of 500 �C is directed to the by-passstacks. However, an economizer system is present in order torecover the steam and send to the processes to be consumed.Therefore, the temperature of the flue gas is reduced to 130–140 �C.On the other hand, if economizer system is not utilized (i.e. whenproduction is much less) flue gas is wasted at a temperature ofaround 500 �C. In addition to the cogeneration unit, boilers alsoprovide steam for the processes by consuming natural gas. Thesystem is put into service when the steam production in cogene-ration facility is not sufficient to meet the demand. In the mill, thereare three steam boilers with a capacity of 15 tons each.

Fig. 2 presents the energy flow in terms of steam and natural gasconsumption in the selected mill for the year 2005, which is beforethe implementation of the project.

According to the initial findings, water and energy consump-tions were observed to mainly stem from dyeing and finishingprocesses. These processes are responsible for 50% of the totalwater consumption and consumption of 75% of the total steamproduced. Moreover, the wastewater originating from those twoprocesses is responsible for 80% of the total wastewater directed tothe on-site wastewater treatment plant.

Thus, it is clear that the application of the preventive measuresincluded in sector specific BREF Document is essential in order toimplement water and energy management in the selected mill.Initially, all the production processes were analyzed in depth by theproject team and an initial BAT screening was made. Then a set ofpreventive measures were suggested to the industrial facility. Thefacility adapted the appropriate BAT measures suggested whichwere considered to be technically and economically feasible.Subsequently, in the present study water and energy consumptionsof the mill are analyzed in order to investigate the effects of theapplied BAT measures that were determined in cooperation withthe managerial authorities of the mill.

4. Results

4.1. Analysis of water consumption

During the water mass balance analysis, it was found that waterconsumption is highly variable in the plant due to variations in theproduction scheme and should be closely monitored. More than 50%of the total extracted water is used for dyeing and finishing processes;and the rest being used for other purposes such as sizing, steamgeneration, good housekeeping, etc. Moreover, dyeing and finishingprocesses are responsible for 80% of the total wastewater generated.Therefore, water reuse in dyeing and finishing processes is essentialfor minimization of water consumption. For this reason, a systematiccharacterisation of the quality and the quantity of various processstreams is crucial. In the selected mill, the segregated wastewaterstreams were characterized at first to identify the pollution profilesand to evaluate possible reuse alternatives. The possible BAT optionsfor the minimization of water consumption were identified based oncomparison with the BREF Textile Document. The applicability ofthese options at the plant scale was discussed and evaluated with thefactoryadministration. Also, additional water minimization strategiesthat were not covered by the BREF Textile Document were developedby the mill staff considering their technical and economical viability.The identified BAT options were:

1. Installation of flow meters in dyeing and finishing processes –installation of flow meters on the individual machines utilizedin different processes enables flow control in processes.Furthermore, flow meters are utilized in order to documentwater use and evaluate improvements and hence help inmonitoring the water consumption.

2. Semi-counter current rinsing in dyeing and finishing processes –reuse of the least contaminated wash waters in final wash untilthe water reaches the first wash stage quality. After reachingthis quality stage the water is discharged to effluent channel.This application improves washing efficiency.

3. Reuse of dyeing and finishing wash waters after a treatmentscheme (advanced oxidation, membrane filtration, etc.) –washwaters with chemicals and dyestuffs are treated in order toremove the impurities; and, if reuse criteria for textile industryare met, these waters are reused in the processes and hence

Fig. 1. Water flow in the selected mill (as of year 2005).

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minimize total water consumed by eliminating the extractionof water from the wells.

4. Recovery and reuse of sodium hydroxide from mercerization washwaters in the finishing process – after sodium hydroxiderecovery from wash waters of mercerization, water is re-circulated into the process to be reused and hence washingefficiency is improved along with reduced chemical cost.

5. Reuse of concentrate stream of reverse osmosis plant – the use ofconcentrate stream for cleaning purposes (e.g. toilets) in the millimproves the total water consumption performance of the millby eliminating the extraction of water for cleaning purposes.

6. Minimization of wash water consumption in the water softeningplant (reuse of wash waters from regeneration of ion exchangers) –elimination of excess water consumption in regeneration of ionexchangers improves water consumption performance of themill, reducing the amount of total extracted water.

7. Reuse of compressor cooling waters in production processes –reuse of softened cooling waters of compressors in productionprocesses reduces the amount of water extracted from thewells and thus increase total water consumption performanceof the mill.

Among BAT measures listed above, 1, 2, 5–7 were implementedduring the project period. Installation of flow meters in wetprocesses was completed by April’06. Additionally, semi-countercurrent rinsing systems in dyeing and finishing processes werecompleted by April’06 and August’06, respectively. Meanwhile,concentrate reject streams of reverse osmosis process have beenreused in the processes since mid-2006. Furthermore, waterconsumed for rinsing after regeneration of ion exchangers isreduced nearly at the same time. Compressor cooling waters arealso reused in the processes since July’06.

4.1.1. Total water consumption in the millInitially, in order to get an overall picture of the water

consumption in the mill, annual consumption trends wereanalyzed starting from the year 2002 including the year 2007. Itshould be noted that the IPPC implementation project started in theyear 2005 and ended up in January 2008.

As can be seen from Table 1, the total specific water consump-tion of the facility reduced from 78 to 55 L/kg during the projectimplementation period, which makes a 29.5% reduction. Thisreduction was achieved by the implementation of the

Fig. 2. Energy flow in the selected mill (as of year 2005).

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abovementioned BAT measures. The effect of BAT options imple-mented on the overall reduction in specific water consumption canbe better assessed from Fig. 3.

According to Fig. 3, total specific water consumption in the millhas reduced sharply around mid-2006 when the implementation ofthe BAT measures was completed. These achieved reductions areimportant both from environmental and economical point of view.Moreover, by achieving a consumption value of 55 L/kg, waterconsumption in the mill is considered to be efficient enough, as thisvalue is very close to the lowest end of achievable specific waterconsumption level of 50–100 L/kg reported in the BREF TextileDocument for finishing of woven fabric consisting mainly ofcellulosic fibres (EC, 2003).

Table 1Total water consumption in the mill.

Year Total water consumption(tons/day)

Specific water consumption(L/kg fabric)

2002 6903 1062003 6089 1012004 7419 902005a 6070 782006 4813 712007 4845 55

a Start of the project.

4.1.2. Water consumption in the dyeing processIn the mill, dyeing is applied to the non-weaved products, i.e.

yarn dyeing is taking place. In the dyeing process more than 400recipes are being used. A small portion of the water is consumed indye preparation kitchens; whereas, the majority of water isconsumed in dyeing baths with a variety of dyestuffs and chemicalsthroughout the process. In the dyeing line, there are four dyeingmachines composed of pretreatment, pre-rinsing, dyeing, post-rinsing, softening and drying processes. Both soft and hard watercan be used for the rinsing operations. In the kitchens, for thepreparation of the dyeing recipes, softened water is being used.Hard water is mainly used for cleaning purposes. As of July’06, dueto the reuse of compressor cooling waters within the mill, generallysoft water is being used for rinsing operations.

By the beginning of 2006, flow control of the dyeing process wasfully automated. That’s why the consumption figures before 2006were disregarded in the analysis of the affect of BAT options taken onthe overall performance. The studies regarding semi-counter currentwashing also started by the beginning of 2006 and in April’06 thissystem was implemented in three dyeing machines. Studiesregarding the implementation of a full scale membrane system forthe reuse of wash waters from dyeing process are underway.

At this point, it should be noted that, for evaluating the perfor-mance of water consumption in the dyeing process, the recipeeffects should also be taken into consideration. This is because,dyeing of darker shades requires consumption of more waterduring the process. Here, it should be noted that, in denim

Fig. 3. Specific water consumption pattern in the selected mill.

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manufacturing or in the mill studied, there is no pre-bleachingstep applied before dyeing and the most water-intensive steps arethe pre- and post-rinsing stages in the dyeing process. Thus,the parameter ‘‘% dyeing’’ is used to reflect the recipe effect in theoverall water consumption. It is the ratio of the dye stuff utilized tothe amount of yarn dyed. When Table 2 is analyzed, it is clear that,although the % dyeing is increased in the year 2007 as compared to2006, the specific water consumption has decreased. This clearlyhighlights the fact that although darker shades were used in theyear 2007, water consumption did not increase, although it shouldbe higher, as compared to 2006. This is due to the BAT measurestaken within the process which optimizes the water consumptionin the process.

Fig. 4 presents the specific water consumption in the dyeingprocess for the period 2006–2007. In the mill, specific waterconsumption reduced from around 40 to 20 L of water per kg ofdyed yarn from the beginning of 2006 to the last months of 2007,respectively. Moreover, in this period, % dyeing increased from 5.7to 8. This variation is simply based on different recipes applied tothe yarns to obtain different shades of end products throughout thespecified period.

As can be seen from Table 2, 22.2% reduction was achieved in thespecific water consumption for the period January’06–December’07,as a result of the BAT measures taken in the dyeing process regard-less of increase in the % dyeing in this period. Consequently, in theyear 2007, uniform and lower water consumption was achieved inthe dyeing process. As mentioned above, the adoption of BATmeasures regarding the reuse of wash waters is underway. Thismeasure, once applied, will definitely result in high amounts ofsavings in the water consumption of the dyeing process.

Table 2Water consumption in the dyeing process.

Year Dyed yarn(kg)

Total water consumed(tons)

Specific water consumption(L/kg yarn)

%Dyeing

2006 1 218 830 31 942 27 6.32007 1 446 598 30 767 21 7.0Average 1 332 714 31 355 24 6.6

4.1.3. Water consumption in the finishing processIn the selected mill, different types of finishing processes, dry

and wet, are being applied to the woven fabric. As dry processes aregenerally applied by mechanical or physical means, wet processeswhich are applied by hot water baths saturated with variouschemicals are of concern in the water consumption analysis.Throughout the process, softened water is consumed. Wet finishingprocesses have chemical treatment and rinsing stages requiring useof large quantities of chemicals and water. Regarding differentrecipes being applied, the utilization of machines and chemicalsvary widely. Hence, average production amounts of machines varyalso. There are 8 different machines utilized for wet processing inthe finishing line of which two of them are responsible for theconsumption of 40% of the water in the whole process.

By April’06, fully automated flow control system was imple-mented in the finishing process. Additionally, at the same time,semi-counter current rinsing system was installed in one of themachines responsible for the majority of water consumption.Afterwards, the same system was installed to the other machine inAugust’06. Furthermore, for caustic recovery from finishingwastewaters, a pilot scale membrane system was installed inAugust’07, after optimization of the treatment scheme at the labscale. Studies on further optimization of the pilot membranesystem are ongoing. This application is expected to further reducewater consumption by reusing the rinsing waters and also reducethe chemical cost by reusing the recovered caustic in the process.

As can be seen from Table 3, while fabric production increasedalmost 30%, the total water consumption increased only 10.9%during the indicated period. Accordingly, almost 16% reduction wasachieved in the overall specific water consumption in the finishingprocess. In Fig. 5, it is clearly seen that specific water consumptionreduced sharply by May’06 despite the continuous increase infabric production. Additionally, water was consumed more effi-ciently during the indicated period as specific water consumptionreduced more while fabric production increased over 6 millions ofkilograms. Consequently, specific water consumption of finishingprocess reduced by 15.8% in total, achieving a lower and moreuniform water consumption trend. It is for sure that upon the use of

Fig. 4. Specific water consumption and % dyeing pattern in the dyeing process.

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the pilot membrane system effectively, higher reductions in waterconsumption will be achieved in the finishing process.

Table 3Water consumption in the finishing process.

Year Fabricproduction(m)

Fabricproduction(kg)a

Waterconsumption(tons)

Specific waterconsumption(L/kg fabric)

2006 3 371 171 2 056 414 34 047 16.92007 4 359 226 2 659 128 37 742 14.2% change þ29.3 þ10.9 �15.8

a 1 m of fabric is 0.61 kg (Kocabas, 2008).

4.2. Analysis of energy consumption

During the energy balance analysis, it was found that energyconsumption is also highly variable in the plant due to highlyvariable water consumption patterns. This result was also sup-ported by the BREF Textile Document highlighting that ‘energy ismostly consumed in heating up process baths in textile industry’(EC, 2003). Therefore, it is considered that most energy intensiveprocesses are finishing and dyeing which are the most waterdemanding processes.

The possible BAT options for the minimization of energyconsumption were identified based on comparison with the BREFTextile Document. The applicability of these options at the plantscale was discussed and evaluated with the factory management.The identified BAT options were:

1. Use of waste heat from finishing and dyeing wastewater streamsin heating up the washing waters: instead of consuming energyto heat up process baths, heat of wastewater streams origi-nating from finishing machines is recovered by water–waterheat exchangers. This reduces the total energy consumption ofthe specific machine.

2. Heat insulation of pipes, valves, tanks, machines: heat insulationis the general principle of good housekeeping practice thatshould be applied at the general level in all processes. Heatinsulation of the machinery equipment eliminates losses inenergy streams and can save up to 9% of energy consumption(EC, 2003).

3. Maintenance of heating systems and stenters: periodical main-tenance of the heating systems and stenters eliminates lossesto a considerable extent.

4. Heat recovery from hot air discharges in finishing line: addi-tionally, exhaust heat can be recovered by air-to-water heatexchangers to be used in dyeing or finishing processes. Those

measures result in reduction in total energy consumption ofthe mill.

5. Optimization of stenter frames: if the water content of theincoming fabric is minimised by using mechanical dewateringequipment, considerable amount of energy saving can beachieved.

By the end of the year 2005, waste heat from hot wastewaterstreams was recovered by heat-exchanger systems installed in thefinishing process. On the other hand, heat insulation and mainte-nance applications could not be scheduled as those measures areapplied periodically during the project period. Additionally, studiesfor items 3 and 4 in the list above are underway and hence they arenot implemented yet. On the other hand, BAT measures imple-mented for water minimization are considered to be as effective asBAT measures taken for energy minimization. By the application ofsemi-counter current rinsing system, as wasted wash waters withrelatively high temperatures are reused, it is not necessary toincrease the temperature of wash waters for the next washing cycleand hence, energy is saved. Additionally, reusing compressorcooling waters which are higher in temperature than groundwaterprovides energy savings as energy is not required to increase thetemperature of process waters as much as it was before imple-mentation of this measure. As a result, BAT measures taken forwater minimization are considered to have a major effect on energyminimization also.

Fig. 5. Specific water consumption in the finishing process.

A.M. Kocabas et al. / Journal of Environmental Management 91 (2009) 102–113110

4.2.1. Total energy consumption in the millInitially, in order to get an overall picture of the energy

requirement in the mill, annual consumption trends were analyzedfor the project period, i.e. 2005–2007, as given in Table 4.

As can be seen from Table 4, although fabric productionincreased from 2.36 to 2.66 millions of kilograms (about 13%increase), the total specific energy consumption of the facilityreduced by 9% reduction during the period 2005–2007.

Fig. 6 shows the overall reduction in energy consumption in themill as a result of BAT options taken. As can be seen from Fig. 6, thetotal energy requirement of the mill has reduced by mid-2006 asa result of implementing measures regarding maintenance andinsulation applications and other process specific BAT options.Although reduction in energy consumption is not as high as it wasin water consumption, Fig. 6 indicates that the sharp decrease isobserved within the same period. This result also clearly shows thatwater and energy consumption patterns are closely related.

4.2.2. Energy consumption in the dyeing processIn dyeing process, the major energy sources required are steam

and electricity. Electricity is consumed in order to run the dyeingmachines plus for lightening and air conditioning. Furthermore, inrope openers where warp yarns are folded onto, electricity isrequired. Additionally, steam is required in order to heat up theprocess baths. As can be seen from Fig. 7, specific energy

Table 4Monthly energy requirement in the mill.

Year Natural gas Electricity Fabric production Specific energy

Sm3 Gcala kWh Gcalb kg Gcal/kg

2005 2 690 808 23 141 530 221 456 2 355 909 0.01002006 2 460 523 21 160 409 831 352 2 056 414 0.01052007 2 746 648 23 621 599 886 516 2 659 128 0.0091

a 1 Sm3 natural gas is equivalent to 0.0086 Gcal.b 1 kWh¼ 0.00086 Gcal.

requirements reduced whereas warp yarn production increasedgradually in the indicated period. Especially by April’06 it is seenthat specific energy requirement reduced whereas production ofwarp yarn increased. Application of semi-counter current rinsing(April’06) in dyeing process and reuse of compressor cooling waters(July’06) in addition to maintenance and insulation measuresresulted in the reductions observed.

4.2.3. Energy consumption in the finishing processFinishing is the major water consuming process in the selected

mill. Since energy consumption is directly related with waterconsumption in the process, the energy efficiency of the finishingprocess is of utmost importance regarding the overall energyconsumption pattern in the mill. Furthermore, the dry processesapplied in the finishing line are also responsible for considerableenergy consumption.

In the finishing process, the energy sources consumed aresteam, natural gas and electricity. Electricity is consumed to runfinishing machinery equipment plus for lightening and air condi-tioning purposes. On the other hand, steam is consumed to heat upprocess baths. Natural gas is directly utilized in some machines fordry processing.

Fig. 8 indicates that specific energy requirement in the finishingprocess was variable during the period of 2006–2007 despite thefact that annual average specific energy requirement decreased by2.8%. In assessing specific energy requirement of the finishing line,energy source requirements should be handled separately asnatural gas, electricity and steam are not required in everymachine. Thus, the detailed energy requirement analysis is madebased on each finishing machine; however, only the overall trendfor the finishing line is given in this paper.

4.3. Cost analysis

In order to achieve the abovementioned reductions in theoverall water consumption, the major investment was made toinstallation of flow meters to dyeing and finishing processes. The

Fig. 6. Energy requirement pattern of the selected mill.

A.M. Kocabas et al. / Journal of Environmental Management 91 (2009) 102–113 111

installation of flow meters to the plant cost EUR 45 000 in total. Onthe other hand, by reducing the overall specific water consumptionof the selected mill from 78 to 55 L/kg fabric, the mill saves EUR300 000 per year on average due to the reduction in the amount ofwater pumped. Therefore, it is clear that the return period of initialinvestment is less than a year and the cost of flow meters isinsignificant when compared to the savings. Besides, as waterconsumption has decreased significantly, wastewater generationhas also decreased. The reduction in water consumption not onlyreduced the payments for discharge of wastewaters into themunicipal sewer system but also the operational costs of the

Fig. 7. Specific energy requirement

wastewater treatment plant. Since, currently the installation ofmembrane processes to dyeing and finishing processes isunderway, water extraction from the wells will further decrease inline with installation and operation of the membrane processes.Thus, a detailed cost assessment shall be made after this stage.

As regards to energy savings, the major issue was to use the hotdischarged finishing wastewaters in heating up the washing watersvia the liquid–liquid heat exchangers that were already installed inthe plant. Thus, a new investment was not made. Insulation andmaintenance measures needed were not plenty. Regarding heatrecovery from hot air discharges, the studies are still underway. The

pattern of the dyeing process.

Fig. 8. Specific energy requirement pattern of the finishing process.

A.M. Kocabas et al. / Journal of Environmental Management 91 (2009) 102–113112

initial findings have shown that, once the measure is taken,a considerable energy saving will be achieved in the plant.

The amount of savings in terms of energy costs is calculated to bealmost EUR 687 000 on annual basis by assuming that the cost of1 Sm3 of natural gas is EUR 0.24 (Kocabas, 2008). This estimation isbased on the fact that energy requirement of the mill has reducedfrom 10 to 9.1 Mcal per kilogram of fabric produced in the period ofJanuary’05–December’07. The reduction in energy requirement interms of Mcal corresponds to 0.104 Sm3 per kilogram of fabricconsidering the fact that 1 Sm3 of natural gas is 0.0086 Gcal. Thisamount of reduction is then converted to total amount of natural gassaved which is 2 854 800 Sm3 on annual basis by considering thefabric production which is 45 000 000 of meters (i.e. 27450 000 kg)per annum. The amount of savings in terms of energy costs is thencalculated by multiplying the unit cost of natural gas with the totalamount of natural gas saved on annual basis.

5. Conclusions

In this study, a large scale textile mill was selected as a pilotplant for the implementation of the BREF Textile Document underthe IPPC Directive. The results of the study clearly indicated that theapplication of BAT measures is essential to reduce water and energyconsumption. The adaptation of the BAT options to the selected millcaused significant changes in terms of water and energyconsumption as listed below:

� 29.5% reduction in total specific water consumption in theselected mill for the period January’05–December’07

B 22.2% reduction in specific water consumption in thedyeing process,

B 15.8% reduction in specific water consumption in the fin-ishing process,

� 9% reduction in total specific energy requirement in theselected mill for the period January’05–December’07

B 2.8% reduction in specific energy consumption in thedyeing process,

B 27% reduction in specific energy consumption in the fin-ishing process,

For the abovementioned savings in water and energy, a roughestimation of total amount of investment and total savings is to beEUR 45 000 and 987 000, respectively.

Acknowledgements

This study was conducted as a part of the project ‘‘Adaptation ofEU’s IPPC Directive to a Textile Mill in Turkey: BAT Applications’’funded by The Scientific and Technological Research Council ofTurkey, Project No. 105Y088.

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