The importance of assessment tools in promoting cleaner production in the metal finishing industry

Journal of Cleaner Production 14 (2006) 1612e1621 www.elsevier.com/locate/jclepro

The importance of assessment tools in promoting cleaner production in the metal finishing industry Arnesh Telukdarie a,*, Chris Buckley b, Michael Koefoed c a

Department of Chemical Engineering, Durban Institute of Technology, Durban 4001, South Africa b Pollution Research Group, University of Kwa-Zulu Natal, Durban 4001, South Africa c Cleaner MFI Production Project, 270 Stamford Hill Road, Durban 4001, South Africa Received 6 May 2004; accepted 9 November 2005 Available online 19 January 2006

Abstract Various cleaner production (CP) audits have been conducted in the South African metal finishing industry. These studies have been successful in effecting changes to the general status of the local metal finishing industry. In this paper, the initiatives undertaken by a Danish government sponsored project are detailed. The project included the conducting of in-plant assessments, using a tailor-made tool for CP benchmarking. Details on this tool’s operations and typical results are presented. Typical assessments indicated potential water savings of 78%, with chemical savings of approximately 30%. The plant modifications undertaken in order to achieve the CP objectives, are described. The affects of these initiatives on local municipal wastewater treatment works are detailed with specific reference to significant reductions in incoming wastewaterborne heavy metals. The main challenge for companies has been data retrieval for the tool and overcoming social barriers for implementing the improvement options. Recommendations include redesigning the assessment tool. Ó 2005 Elsevier Ltd. All rights reserved. Keywords: Cleaner production; Metal finishing; Environmental audits; South Africa

1. Introduction The services provided by the electroplating industry range from basic metal plating to a more advanced non metallic plating and pulse plating. The electroplating industry supplies a variety of products for various industrial/domestic sectors including the motor, clothing, building, aviation, electronic and military. The surface finishing industry consumes a range of chemicals that are considered harsh to humans and the environment. Like most other industries the chemicals used don’t always end up in the product being produced. This waste is sometimes released into the environment [1,2]. This has resulted in the belief that the electroplating industry is one of the most polluting industries worldwide [3e5].

* Corresponding author. Tel.: þ27 31 204 2415; fax: þ27 31 204 2285. E-mail address: [email protected] (A. Telukdarie). 0959-6526/$ - see front matter Ó 2005 Elsevier Ltd. All rights reserved. doi:10.1016/j.jclepro.2005.11.009

The waste generated is considered to be hazardous or toxic and ranges from volatile organics, acid/alkali fumes, hexavalent chrome, nickel, wastewater containing metal/cyanide, sludge with high metal contents, oil/grease, paint residue etc. In some instances these chemicals are treated and disposed off via wastewater treatment facilities to municipalities [6]. Most important to the profitability of the company is the fact that waste generated implies profit losses, which are mainly due to poor plant operations. The net result is the wastage of raw materials. This waste material then has to be treated at the wastewater treatment plant, resulting in further costs. It can be stated that the most effective means of dealing with waste is by curbing the production of waste. The application of CP principles to metal finishing processes can reduce or eliminate these factors. The net result of operating a plant without the application of CP [7,3] is the loss of toxic chemicals, higher financial implications, a higher risk environment for staff, reduced product quality and avoidable environmental releases.

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2. The metal finishing industry in South Africa

Table 2 Proportion of total toxic metal load from metal finishing industry

It is difficult to determine the size of the Metal Finishing Industry (MFI) in South Africa (SA) accurately [2]. Available data on the size and shape of the MFI in SA are difficult to obtain. Even the registration of enterprises by authorities provides only a partial picture of the size and distribution of the industry. A recent survey of the MFI indicates that there are 500e600 independent metal finishers in the country [2]. Many of these facilities operate from backyard facilities and are not officially registered [3]. A conservative estimate of the total number of firms with significant metal finishing operations is 1200 [2]. Information on processes employed, sizes and locations could only be obtained for a small proportion (25% maximum) of all enterprises involved in metal finishing. The survey is assumed to give a fair indication of the nature of this South African industrial sector [2]. The majority of companies were found to be located in Gauteng, followed by Kwa-Zulu Natal and the Western Cape, with very few located in the Eastern Cape, and no data were obtained for any of the other provinces. The results regarding metal finishing process types indicate that the processes in South Africa are similar to those in other countries [2]. Electroplating makes up the largest group (40%) in terms of total number of firms. Other significant sectors are anodising and galvanising, though they are much smaller in number (<10%), see Table 1. Zinc, nickel, copper and hard-chrome electroplating appear to be the most common types at 25, 21, 16 and 13%, respectively [2]. In South Africa and in other countries investigated, over 90% of the metal finishing shops are SMEs; the majority have less than 50 employees. Of these, 20% have <10 employees and 60% have <50 employees. Results so far indicate that there are a greater number of independent metal finishers than in-house metal finishers; however, the difference is not large. Unfortunately, due to outdated equipment and poor maintenance there are excessively high levels of water and energy consumption and unnecessarily large quantities of waste within these industries. Much of the problem lies with poor housekeeping often associated with inadequate worker education, training and skills. The most common areas of wastage are excessive water consumption and loss of chemicals due to drag-out and spillage; these problems are mainly a result of poor housekeeping practices [8]. The electroplating, anodising and chemical surface treatment processes have been found to be the most water-intensive amongst the metal finishing operations in South Africa. It was noted by Binnie & Partners Consulting Engineers [3] that water utilization was not optimal in most operations. The same study found that approximately 80% of the annual water intake of the metal finishing industry is used for rinsing.

Proportion of individual metal in total MFI waste streams (%)

Table 1 Survey of the metal finishing industry, South Africa Proportion of total (%) Electroplating 42 From [2].

Powder coating 29

Wet painting 18

Hot dip coating 13

Polishing

Anodising

12

7

Cadmium 2

Chromium 45

Copper 45

Lead 5

Nickel 72

Zinc 43

From [9].

Table 2 presents international figures for the individual metal load to the total load from metal finishing industries [9]. The rinsing process is the primary source of waste generated in metal finishing. The rinsing is necessary to remove the dragout from racks/parts after removal from the process baths shop [10], see Fig. 1. This results in process chemicals and heavy metal ions being dragged-in and discharged into the wastewater. Depleted process baths, which are periodically discharged, add to the wastewater. In order to comply with effluent discharge regulations, the metal finishing industries response has been the installation of end-of-pipe technologies, which generate toxic sludges that require careful disposal [11]. Wastewater treatment sludge is usually the major solid waste stream from metal finishing [4]. Conventional treatment systems consist of pH adjustments, oxidisation of cyanide and reduction of chromium bearing wastewaters, followed by hydroxide precipitation, clarification and sometimes filtration or solids dewatering. The generated hazardous sludge must be disposed off in an approved landfill [10]. A study undertaken on a number of metal finishing enterprises in the Johannesburg area has indicated that few actively practice effective effluent management, and that the rudimentary pre-treatment (where it exists) is usually not operated to comply with by-laws. This results in significant loads of heavy metal ions entering the sewerage system [12]. The heavy metal ions contained in industrial wastewater are, for a number of reasons, generally found to cause problems downstream at sewerage treatment plants. These problems include:
They are not easily removed from the wastewater streams and are present in the effluent discharged to waterways, causing adverse impacts on aquatic life;
Heavy metals inhibit the biological treatment processes at sewage treatment plants, thus reducing the treatment efficiency of the plants;
The high concentration of heavy metals, such as chrome and cadmium, which accumulates in sewage sludge limits the municipalities’ safe disposal and reuse options [9]. The sludge from sewage treatment plants in South Africa is traditionally used as a soil amendment on farmlands, but this is usually not possible due to this high heavy metal content. The alternate is sludge, which has to be disposed off in a welldesigned and properly managed landfill [13]. Governmental or privately owned treatment/disposal sites in South Africa are overloaded resulting in local authorities charging premium prices for disposal. Leaching and mobility rates of heavy metals in these landfills are accelerated by strongly acidic rainfall, a common occurrence in much of South Africa’s industrial heartland. With the shortage of engineered approved landfill

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Metals Brighteners Energy

Metal Parts

Energy Caustic

Acids

Cleaning

Pickling

Spent Plating Plating

Waste Energy Drag - out

Spent Cleaning

Spent Cleaning

Water

Metals/Salts

Water

Rinsing

Treatment

Passivation

Spent Passivation

Treatment

Rinsing

Effluent Finished Product

Sludge

Fig. 1. Electroplating process including inputs and wastes [10].

sites, disposal methods used for industrial wastes will be increasingly closely monitored, and the costs involved will, to a much greater extent, take into account the environmental burdens of the wastes to be buried in them. 3. The Cleaner Metal Finishing Industry Production Project, South Africa In 2000 the Danish Cooperation for Environment and Development (DANCED) launched a three-year demonstration project in South Africa to assist the metal finishing industry to significantly reduce its negative impacts on the environment [7]. The objectives and outputs included: Project objectives:
CP processes implemented in metal finishing companies;
Develop sustainable and accessible capacity in the metal finishing industry;
Increase environmental awareness among people in companies and regulators.

The primary target group of the Cleaner Metal Finishing Industry Production Project was the metal plating and the hot dip galvanising industries in South Africa. However, many of the project activities and results can be applied in other sectors of the metal finishing industry. 4. Benchmarking cleaner production The dedicated Benchmarking Cleaner Production Tool (BCPT) was developed by Dahl [14] as a cornerstone of the Cleaner Metal Finishing Industry Production Project [15]. The model is based on the unit operation/mass balance principle, which is taught in most waste minimisation clubs [13] and is also, applied as one of the most common general approaches to CP assessments. The model addresses all the unit operations in metal plating (see Fig. 1) and describes the CP profile of a metal plating plant by eight parameters (see Fig. 2). The Focus on OHS

Items input

Spent baths

Chemicals

Project outputs comprise:
Perform training of consultants, metal plating managers and plating staffs;
Perform CP benchmarking assessments of metal finishing companies;
Perform feasibility studies on CP options;
Perform 20 demonstration CP programs in MF plants;
Enhance CP capacity of the metal finishing industry and within the sustainable metal finishing trade organisations.

Metal finishing process

Chemical waste

Water Focus on operation procedures

Chemical waste Outlet water quality

Items output Wastewater

Wastewater treatment Chemicals

Fig. 2. The benchmarking cleaner production tool environmental profile.

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review evaluation is conducted by obtaining detailed plant data in the eight key areas of the plant. The data are inputted into the Benchmarking tool. The tool then generates outputs with a summary graph as illustrated in Fig. 2. The eight key areas are:









Occupational health and safety; Operational practice at the wastewater treatment plant; Chemical consumption at the wastewater treatment plant; Waste minimisation; Water savings; The state of the rinsing system; Maintenance of the process baths; Consumption of process chemicals [14].

The efficiency of the unit processes is calculated as consumed metals, chemicals, water, wastewater and sludge produced per production unit. The results are benchmarked in the model by built-in goal values representing Best Available Technology (BAT). These target values are predetermined values provided by Dahl [14]. This enables the company to compare its CP to best performance among companies anywhere in the world, see Fig. 3. By repeating the benchmarking exercise, the company can measure the improvement of its CP as required by most environmental management systems certifications e.g. ISO 14000 series [16]. 4.1. Implementation of Flemming’s model The first stage in the review process entailed a plant visit/ walk through by the reviewer. This visit was intended to be a qualitative indication of potential areas for improvement. The reviewer is to identify areas for improvement based on his experience of CP. A walkthrough report was intended to illicit the companies interest by illustrating the areas of potential savings. The next stage of the audit commenced with the pre-review document. The pre-review document was used to obtain basic plant operations data. The document was to be circulated to the companies two weeks prior to the review. It was comprised of seven pages with a total of nine tables to be completed. The manager of the company under review was expected to complete the document prior to the review process. BENCHMARKING LEVEL

MARKETS

Best Available Technology (BAT)

Trendsetter

BAT Not Exceeding Excessive Cost (BATNEEC) Global International Standards

SA Metal Finishing Industry

National

Previous Environmental Productivity Performance of Company

Local

Fig. 3. Environmental benchmarking levels [16].

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The document requires various pieces of data under the different plant categories. The first table to be completed requires information about the production rate of the plant. This production rate was the square meterage of materials plated at the facility over the period of the year to date. This was difficult to obtain, as electroplating companies did not keep or use this type of data. All companies charged their clients based on mass or number of items to be plated. This was due to the complex sizes and the multitude of shapes encountered. The companies reviewed did not have the skills level or the time available to complete the task of determining the surface area of components plated. The companies plated anything from 10 components to thousands of components per year and found it impossible to keep statistics of the surface area. For the purpose of the environmental review, the auditor, together with a manager from the company, had to obtain the surface area required. This was done by obtaining records on the components plated over the year together with the number of components. The surface area was estimated from these data. This proved a challenge as the exact components were not usually on hand and records of the exact number plated were not always available. The process of estimating the surface area plated by the company, usually required a time investment of between 4 h and a day, depending on the variety of components plated. Another crucial input for the Flemming model was the plating thickness. The company was required to enter the layer thickness plated. The companies depended on random samples by the chemical suppliers for surface thickness analysis, as this analysis required trained personnel as well as expensive equipment. The company’s plating was based on time in the electroplating tank and it was assumed that the surface plated was sufficient. The companies depended on a final visual inspection to ensure coverage of the plated surface. The companies were not equipped to complete such tests across the range of components plated. It has to be remembered that plating thickness is dependent on the shape of the component. Once these data were obtained the remainder of the tables could then be completed. 4.1.1. The chemical and water consumption tables The company was to complete the sections on the actual chemical consumption (see Table 3). The data sheet required the annual consumption of the different components of each tank. The electroplating companies managed their process based on the information received from their chemical suppliers. Weekly dosing usually occurred, based on supplier tank analysis. To complete this, the company had to obtain the annual consumption figures from their stores department or their purchasing department. Companies with large stock reserves found it difficult to obtain data and actual audits had to be carried out to determine the year to date chemical consumption. Some chemicals were difficult to measure as consumption was not directly measurable. A typical example was: the anodes were replaced after extended periods and had to be proportioned according to consumption within a specified period.

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Table 3 Typical review table to be completed be auditor Thickness in mm

Chemicals Process bath

Type

kg/yr

Zinc line Degreasing bath Sulfuric acid pickling HCl pickling Electrolytic cleaner Acid dip Zinc bath Zinc bath Zinc bath Zinc bath Zinc bath Deoxidizer Chromating, blue Chromating, blue Chromating, yellow

Chemaline 05 Sulfuric acid, 96% HCl, 32% Chemaline 26 Chemacid 33 Zinc anodes NaOH NaOH Brightener Sodium sulphate Nitric acid Concentrate Nitric acid Concentrate

2250 4520 13,700 3100 175 11,190 4250 8100 6425 200 4537 238 1713 838

18,585 3345 18,073 26,536 4022 91,534 73,738 12,960 89,757 1080 5036 3506 3323 6101

61,236

357,596

Sum Operation time: h/yr

R/yr

Calculated

7.1237586

4400

4.1.2. Maintenance of the process baths The third table that required completion was the maintenance of all the process baths. The typical data required here were the tank capacity and exact chemical breakdown of each process tank. The company enters various codes on the present practice of bath management. It was found that the chemical supplier usually completed this table as the suppliers managed the tank chemistry. The suppliers completed the analysis of the baths on a weekly basis. 4.1.3. The rinse tables The audit required details about the hardware of the rinse system; this included the tank configuration and flow patterns, the sources of raw water etc. The Flemming system depends on statistics in order to determine the operation efficiency. This component of the rinse system was reasonably simple to complete but the challenge was in quantifying the exact amount of water required for each individual process. The company had to enter the exact amount of water flowing to each tank. If these data were not on hand, the company had to use the bucket and stop watch method to determine the consumption. This section of the questionnaire was excluded by the company and when the auditor got to site these data had to be determined. 4.1.4. Hazardous waste and waste water treatment The company had to provide data on the amount and composition of hazardous waste generated. This included the steps for the treatment process and the costing associated with the waste treatment and disposal. The hardware and calibration of hardware associated with the waste water treatment facility had to be identified. The exact chemical composition of the waste was required for the audit. The chemical formulation of the treatment chemicals was also required.

Estimated

5

Key figures: kg chemicals/1000 m2

Production 2

2

m /yr

m /h

220,000 220,000 220,000 220,000 220,000 220,000 220,000 220,000 220,000 220,000 220,000 132,000 132,000 88,000

50 50 50 50 50 50 50 50 50 50 50 30 30 20

Calculated 10.2 20.5 62.3 14.1 0.8 50.9 19.3 36.8 29.2 0.9 20.6 1.8 13.0 9.5 290.0

Goal

Score, 1e5

25 50 75 25 10

1 1 1 1 1

32 39 7

1 1 5

5 2

5 1

5

2 2

Score: 1 ¼ good, 5 ¼ unsatisfactory

This entire questionnaire was to be completed by the company as a pre-audit questionnaire. It was found that the response time from companies ranged from one week to three weeks to complete the data sheet for the pre-audit. This depended on the availability of information and on the organisation of the data in the available format. While conducting the review, it was found that two visits had to be made to the companies under consideration to explain the requirements for these data sheets. 4.2. The company visit and audit The application of Flemming’s model required the completion of the data tables with a comprehensive set of guidelines. The data tables were Excel based. Table 3 illustrates a typical data sheet. There were a total of nine tables to be completed. Appendix A2 contains a guideline for the completion of these tables. The guideline document contains 16 pages of details on the methods to be followed in completing the excel tables. The completion of the excel tables by the auditor was carried out at the company concerned as detailed process information was required. Table 3 is an example of a typical table. From Table 3 it can be seen that accurate plant data were required for the review process. Table 3 is a table of chemical consumption at the company. The annual chemical consumption is required together with details such as plated thickness. The company also needs to provide the exact surface area plated in order for the spreadsheet to calculate the chemical consumptions. If the surface area is not available or cannot be estimated, the entire review process is compromised. Each excel table requires what Flemming’s terms support values. The support values are either default values or values that need to be inputted based on the guideline document. The main inputs for the support tables are values like the drag-out, the dilution factors, surface area, production hours, equipment operations details etc. These values have to be

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metal finishing industry in South Africa during the period June 2001eJune 2002. This introductory visit before starting the CP benchmarking assessment resulted in:

determined by the auditor with reference to the guideline document. The entire review process, and the results obtained were reported to the company with estimated potential savings. Fig. 4 is the final graph indicating potential improvements under the different categories for the plant.


Increases in the motivation of management towards CP;
Increases in the amount and reliability of data input to BCPT. This was verified by cross checking a part of the benchmarking tool.

5. BCPT application in South Africa

In the period September 2000eMay 2002, the Cleaner Metal Finishing Industry Production Project benchmarked 32 companies. The assessment team was comprised of a consultant who worked in conjunction with company representatives. A detailed review was conducted, as described above. The review entailed completing detailed data sheets on consumptions and operations. This process usually took a month to complete. The review report detailed precise potential savings in water, chemicals and on waste generation. Typical key indicators are presented in Fig. 2 and can be summarised as:

The BCPT was developed for CP assessments in industrialised countries like Denmark, Germany and newly industrialised countries like Thailand, where detailed data of production load measured as surface area of the products produced and consumption of metals, chemicals and water were available [17]. The benchmarking exercise in South Africa showed some interesting lessons regarding seeking to obtain such data:
Few manufacturing companies with metal plating plants have the necessary data;
No metal plating job shops had production load data or consumption data;
The comprehensiveness of the tool and its data requirements are big barriers for its application as an initial CP assessment tool (a screening process).


All assessed plating lines environmental performance could be improved (average ‘‘Fair’’);
The largest potential improvements were in water savings and process bath maintenance (state often ‘‘unacceptable’’);
There were significant potential improvements in parameters: occupation health and safety (OHS), operational practice of wastewater treatment plant, state of rinsing systems, process chemicals consumption and savings of chemicals in wastewater treatment plants.

After the first unsuccessful application of the BCPT, an introductory company assessment called a walk through, was performed. This qualitative assessment is a plant visit, during which the plating manager and the consultant follow the production flow of raw materials through the plating plant until the final packaging and distribution [18]. The walkthrough report briefly describes the company’s history and its production. Rough data for consumption of raw materials, water and energy are presented. The main company challenges (or problems) are listed with reference to the plating manager. A flow sheet of the plating plant is annexed to the report. The state of the company wastewater treatment plant and its operation is briefly commented on. The walkthrough report recommendations include initial zero cost or low cost CP actions and highlight the need for further assistance or assessments. More than 40 walk throughs were completed in the

A summary of the recommendations are (the percentage indicates the number of companies receiving this recommendation from the total companies reviewed):
Process bath treatment (oil skimming, ultra filtration and centrifuges for cleaning baths) 50%;
Process chemical substitution (cyanide 30% and substitution high to low concentration baths 25%);
Reuse of collected chemicals from process baths (cleaners 30%, nickel bath 30% and chrome baths 30%);
Optimising rinse systems 88%;

Occupational health and safety

50

Operational practice of WWTP

50

Chemical savings for WWTP

64

Possibilities for waste minimisation

59

Required water savings

20

State of rinsing system

48

Maintenance of process baths

33

Consumption of process chemicals

55 0

10

20

30

40

50

60

70

80

90

100

Score

Fig. 4. Potential improvements in the different categories. Legend: 0e20, unacceptable; 20e50, poor; 50e80, fair; 80e100, good.

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Flow control 88%; Counter current rinse flow 84%; Improve static rinse (‘‘drag-out’’) 72%; Spray rinse 60%; Water reuse after ion exchanger 60%; Reuse of purified wastewater 60%; Chemical savings in wastewater treatment plant 44%; Waste recovery 44%.

More specifically the following systems were considered in the review process and detailed in the company review report for improvements. 5.1. Improved housekeeping Good housekeeping implies the practice of minimizing raw material losses and thus preventing unnecessary waste generation. Good housekeeping also implies improved operating environments and reduced accident potential. For the metal finishing industry good housekeeping includes [3]:
Segregation waste e all waste is not treated together. E.g., chrome-containing waste has to be reduced in pH, treated and then the pH has to be increased. If this were done collectively, with all the waste collectively, then the treatment chemical requirements would be larger than single streams;
Monitoring of dosing chemicals e this would ensure optimum dosing;
Production based on surface area measurement e plant production needs to be determined by surface area as compared to mass of components;
Lengthen drag-out times e reduces the losses of process chemicals by allowing for longer drip-off times above the tanks;
Position pieces so as to optimize dripping e optimum liquid run off can be facilitated by ensuring components are hung properly;
Ensure adequate training of staff e this ensures awareness on all operations and need for operating efficiently;
Optimum temperature regulation e prevent excessive vaporization of chemicals and ensure optimum chemical efficiency.

Evaporation

DI Water Process plating tank

Rinse tank 1

Rinse tank 2

Rinse tank 3

Fig. 5. Illustration of low flow counter current rinse.


The rinse water from the acid system can be re-used as a reactive rinse in the degreaser section. The quality of the treated wastewater may be sufficient for reuse in areas of the plant. 5.3. Process optimisation Process optimisation implies changes to the process to ensure the efficient operations of the various units. Typical process optimisations includes [3,19,20]:
Optimum bath chemistry ensures that anode and cathode efficiency are maintained according to the supplier’s specifications;
Optimum mixing and dilution of rinse water by agitation, inlet/outlet location and prevention of back mixing e this ensures that the components are effectively cleaned in the rinse tanks;
Maintaining optimum chemical concentrations for all processes will ensure product quality and production efficiency;
Optimum measurement and dosing of wastewater ensures optimum chemical usage and reduces the risk of fines due to irregular releases;
Regulation of water flow into the process ensures minimum water usage; optimum process tank temperatures ensure efficient cleaning/plating while maintaining sufficient evaporation for closed circuit operations. 5.4. Optimum use of resources

5.2. Chemical/water reuse/recycle/recovery Wastewater that is used in the process is usually treated before being released into municipal waste collection systems. The reuse of chemical and water included the following considerations [19,20]:

The raw materials such as water and chemicals must only be used as required in the process [21,22]. Excess chemicals must be recovered for reuse. Chemicals designed for process usage must not be lost to the wastewater. 5.5. Improved product quality


Usage of low flow, counter current rinses throughout the plant. This implies that the process liquid that has been dragged out can be recovered through the rinse system (see Fig. 5);
The acid/degreaser can be stored and used as dosage chemicals for the wastewater treatment facility;

The plant product quality is a result of optimum operations. Optimum operations ensure improved product quality. Typical quality issues are [21,22]:
Optimum cleaning ensures proper adhesion of coating;

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6.2. Case study 2 e manufacturer of electrical appliances Kwa-Zulu Natal [23]

Table 4 Savings measured relative to pre-cleaner production Water

Effluent

Chemicals

Electricity

30%

33%

15%

20%


Measurement of plated thickness on a regular basis ensures quality of finished product and reduces the wastage of raw expensive materials;
Optimum temperatures and chemical dosages reduce the risk of exposure of operators to chemicals;
Improved staff training results in motivated, effective and efficient workforce. 5.6. Chemical substitution Toxic and hazardous chemicals must be replaced with environmentally friendly chemicals [2,5]. These include the replacement of cadmium, cyanide and hexavalent chrome. 6. Results of the study Various companies implemented significant modifications based on the audit processes. Two case studies are briefly described followed by a summary table of 14 companies (see Table 5). These results indicate actual savings achieved after implementation of the CP strategies listed above. 6.1. Case study 1 e job shop Kwa-Zulu Natal [13] A small electroplating shop situated in Durban, 20 years old, employs 50 staff. Recorded savings include metals, chemicals, electricity, water and effluent charges totaled R200,000 per year. Savings measured relative to pre-CP conditions (Table 4).

The company produces electrical appliances and is considered to be an in-house plater. The old nickel chrome plating plant operated with huge consumption and waste of metals, chemicals and water. The plating plant was rehabilitated in 2001e2002. Local and international consultants (from the Cleaner Metal Finishing Industry Production Project) assisted in the redesign of the plant e.g. by adding rinse tanks and changing the jig design. The cost of the CP equipment was approximately R400,000, equal to 25% of the total investment (R1.4 million). The preliminary records from three months of plant operation after the changes were made revealed savings of water (80%) and chemicals (45%). The plant has since doubled its production whilst maintaining water savings, as compared to the original facility, in excess of 80% (Table 5). 7. The metal finishing industry of South Africa Since the June 2000 beginning of the Cleaner Metal Finishing Industry Production Project, many conditions for the metal finishers in South Africa have changed in the following ways:
The South African Metal Finishing Association (SAMFA) has been established with three regional centres;
A centre for CP research and development in metal finishing has been established at a local university;
SAMFA has hosted two national conferences on plating;
SAMFA has established various information dissemination tools including a quarterly plating magazine and training courses;
Trade organisations have emerged and today a total of 165 companies are members of the metal finishing organisations, equivalent to an organisation rate of approximately 35%;

Table 5 Savings achieved in the electroplating industries Company name

Process description

Aberdare cables Anodising systems Cascolor Defy appliances Durban wire Euro industrials Fascor Federal mogul Frontier metal processing Malben engineering MPS/AES Natal electroplaters Pinetown EP Pinclip Industries

Tin plating copper wire Aluminium anodising Chrome plating Nickelechrome Zinc phosphating Nickelechrome Zinc and nickel Hard chrome plating Copper plating

617,880 134,600 245,040 384,000 205,806 183,250 383,740 320,566 226,000

75,000 67,300 49,008 75,000 41,161 75,000 75,000 64,112 45,200

Alkaline zinc plating Alkaline zinc plating Nickelechrome nickel, chrome Pre-treatment (degreasing)

395,000 395,744 192,960 226,150 347,000 4,257,736

Total savings

Total CP investment

CPMFI Project subsidy

Total savings

Payback period (months)

Chemical savings per year

%

Rand

667,204 70,732 86,125 329,050 165,766 93,057 234,047 321,150 165,024

11 23 34 14 15 24 20 12 16

41 37 36 45 57 25 33 89 26

546,690 57,460 75,695 282,394 132,252 91,580 178,452 307,555 159,144

99 79 91 91 98 57 78 75 58

120,514 13,272 10,430 46,656 33,514 1477 55,595 13,595 5880

75,000 75,000 75,000 75,000 68,560

240,000 181,569 91,506 80,767 126,180

20 26 25 34 33

82 26 30 71 89

234,960 160,957 90,460 77,743 123,655

60 98 84 90 40

5040 20,612 1046 3024 2525

935,341

2,852,177

22

49

2,518,997

78

333,180

%

Rand

Water savings per year

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Four waste minimisation clubs comprising 120 members have been established. Participation is equivalent to approximately 15% of the industry;
Bylaws were promulgated in Kwa-Zulu Natal in 1999 as a result of negotiations between the MFI and Ethekwini Metro [24];
The metal finishing industry’s guidelines have been developed by Ethekwini Metro Waste & Wastewater Department in collaboration with MFI representatives;
The prices of chemicals, metals and water have increased by approximately 80% during the period 1999e2005;
Water costs have increased from R2.50eR5.60/m3. 8. Benchmarking impacts of usage of the cleaner production tool Since the start of the Cleaner Metal Finishing Industry Production Project, the heavy metal load to the Central Effluent Treatment Plants (CETPs) in Durban Metro has been reduced significantly [25] illustrated by the chrome reduction of 68% and cadmium reduction of 80% as shown in Fig. 6. Many factors contribute to this reduction [17,2] of heavy metal load, as described in Section 5, and although causee effect analysis is complex it is not impossible. This is a direct indication of CP systems, typical systems implemented at companies for chrome reduction include:
Closed loop operation of the chrome plating system resulting in almost zero discharge of chrome;
Substitution of chrome-based passivates with chrome-free passivates;
Optimum usage of chrome chemicals to prevent wastage;
Separation and optimum treatment of chrome. Interviews with Ethekwini Municipality officials, metal platers and Metal Finishing Associations show that the Cleaner Metal Finishing Industry Production Project including the Benchmarking Cleaner Production Tool have significantly contributed to obtaining such reductions in environmental impacts [6]. 9. Conclusions and future work The successes achieved by the initiatives, to date, have resulted from targeting a fraction of the total surface treatment

Concentration mg/kg Sludge

Municipal treatment plant sluge metal Concentration 500 450 400 350 300 250 200 150 100 50 0

Cadmium

2001

2002

2003

2004

Chrome

2005

Year Fig. 6. Heavy metal concentration at the sewage treatment facilities [24].

companies. It would be ideal to extend the lessons learned to other companies. The South African Metal Finishing Association (SAMFA) has since been formed. SAMFA focuses on:
Dissemination of case studies as illustrations of potential savings;
Hosting of industrial theatres;
Auditing and plant improvements;
Training and staff development;
International links for technology transfer, such as the American Electroplating and Surface Finishing Association;
Research and development projects on improved processes. The data requirements for the review process have been identified as a problem. Environmental assessments in industry require intensive data, which seldom exist. There is a need for developing environmental assessment tools with user-friendly data input approaches [26]. The Water Research Commission and the National Research Foundation have together funded the development of an artificial intelligence based review tool. The tool is currently being tested. The impact of the regulating authorities should not be underestimated as reductions in metro limits assist in redirecting the company to adopt CP systems. Local municipalities are represented in SAMFA and have requested CP audits for current company permit renewals. Further, the key to reaching out to the smaller companies would be for them to achieve cost savings and reductions in time requirements to carry out their audits. Future work could be focussed upon these issues.

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