FINAL REPORT NO- 01-90

AN AUTO RADIATOR REPAIR 8HOP

Presented by:

New Jersey Technical Assistance Program for

Industrial Pollution Prevention Hazardous Substances Management Research Center

New Jersey Institute of Technology Newark, New Jersey

April, 1990

DISCLAIMER

The statements and conclusions of this report are those of the New Jersey Technical Assistance Program and not necessarily those of the New Jersey Institute of Technology. The mention of commercial products, their source, or their use in connection with material reported herein is not to be construed as either an actual or implied endorsement of such products or their performance.

ACKNOWLEDGEKENT

The New Jersey Technical Assistance Program fo r Industrial Pollution Prevention is funded by a grant from the New Jersey Department of Environmental Protection's Division of Hazardous Waste Management; and by a grant from the New Jersey Hazardous Waste Facilities Siting Commission. NJTAP is an important part of fulfilling the mandate of those organizations to protect the environment by reducing the volume of hazardous and toxic wastes generated by New Jersey's industry.

ABOUT THE STAFF AT NJTAP

Mr. Alan Ulbrecht has over 18 years of experience with industry a5 a production manager, chemist and environmental compliance manager in the metal finishing industry, most recently with Nesor Alloy. He accepted a position with NJTAP in October, 1990.

Mr. Hanna Saqa is a mechanical engineer with over 30 years of project management and industrial process, design and troubleshooting experience with American Cyanamid's Lederle Laboratories. He became affiliated with NJTAP in October, 1990.

Mr. Kevin Gashlin managed environmental compliance, industrial liaison and pollution prevention programs for the past 12 years with the New Jersey Department of Environmental Protection before accepting the post as Director of NJTAP in March, 1990.

Summary of Findinss

After several visits to radiator repair shops and a review of

available literature, I have drawn the following conclusions:

1. There are several treatment options available to precipitate

metals from solution in the boil-out tank. However, there is no

affordable existing technology to effectively reclaim metals

generated by the boil-out tank degreasing/corrosion removal

procedure;

2 . Water conservation is a good option that can be undertaken

almost immediately with very little cost;

3 . ltoperationalgt changes, especially alternatives to the boil-

out tank for cleaning, not treatment, hold the most promise for

reducing the amount of hazardous waste generated; and,

4. It is impossible to quantify any costs and associated

benefits of equipment and/or operational changes until a thorough

review of such information is developed.

The enclosed report details how you can achieve your waste

reduction goals in the most cost-effective ways possible,-

assuming that you continue to use the boil-out method and given

the level of information and understanding that I have a b o u t vour

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operation. In order for you to evaluate and choose a proper

treatment alternative, you will want to evaluate the projected

overall cost and effectiveness. To do this you should develop an

accurate and complete accounting of existing costs. Among the

areas that need development are:

1. Cost for water each month or quarter.

2. Cost for sewage discharge each month or quarter.

3 . The volume of work passing through your shop per day, week,

month or quarter.

4 . The amount of caustic used per month and its costs.

5. The amount of boil-out sludge and waste water that was

generated in the past year. (approximate if you don't know)

6. The amount of test tank waste water and sludge generated in

the past year.

7. How are the radiators from the boil-out tank and test tank

rinsed. Is it a llstilllt or l1flow-throughIt rinse? Estimate

gallons of water discharged per month or quarter as a

result. "

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I

These costs should be developed as a monthly or quarterly

average or expenses over the past year.

8. Contact the vendors of treatment systems listed in the

appendix to the report and compare costs. Ask for

references. Contact the references. Go to the referenced

shop. See the system in action. Ask about discharges and

compliance with discharge standards. Take notes.

COMMENT - The treatment method you choose should allow the treated water to be discharged legally to the sewer. Otherwise

you will still have to dispose of it as a hazardous waste.

However, treatment systems with this ability are expensive and

will increase the amount of RCRA hazardous waste sludge you

generate. For this reason and other economic and environmental

reasons, I urge you to seriously consider substituting rodding,

mechanical cleaning and spot cleaning of radiators as a

substitute for using boil-out tanks for at least some of your

work. I strongly recommend that you contact Russell Burton,

President of Burton Auto Radiator in Somerdale, N.J. at 609-783-

1733. Mr Burton is an advocate of such an alternative and uses

it exclusively in his shop.

A second waste source to be concerned about is spray painting of

radiators. While it appears at this time that a suitable -

alternative to solvent based paint is unavailable, I will

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solids content. However, until that time it is essential that

the spray booth be used for the purpose and in the way that it

was designed. The radiator being painted must be in the spray booth so that the vent system draws the paint spray through the

exhaust system. This is important both environmentally and for

worker safety, especially because the paint is ignitable and

there are open flames in the shop. Vapor from the flammable

paint could be ignited by those flames if it is not controlled

properly. Also, because the overspray problem is related to the

spgay equipment used, I recommend that you look into equipment

that applies paint in a more exacting way. A partial list of

vendors is enclosed in the appendix. The vendors may also be a

good source of information about paint alternatives.

Finally, the following are the local limits for discharge

parameters and concentrations for the following constituents of

concern to the Trenton Sewage Authority. All units are m g / l

except for pH.

Oil+Grease Arsenic Cadmium Copper N/A N/A 5.5- 100 0.1 0.02 0.2

9.5

Chromium Cyanide Lead Mercury Nickel Silver 1.2 2 0.25 .Ol 0 . 4 0 . 6

Zinc COD Phenol 0.8 N/A 0.9

There may be other parameters as well. You should contacz the

sewage authority to discuss those materials that may be contained

in your waste water discharge.

E

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RCRA Annual Report - Keep this with our hazardous waste records. Use it when developing the annual report as evidence that you

have looked into waste minimization or pollution prevention

options.

Thank you for the opportunity to work with on these issues. I

hope this process has been useful. I will contact you in a few

months to follow up on this letter and attached report. I can be

reqched at 201 596-5864 if you would like to discuss any aspect

of my recommendations or report.

Appendices

Waste Reduction Options for the Radiator Repair Industry

(Other appendices were forwarded to you with earlier

correspondence).

RRShop. doc

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Waste Reduction Options for the

Motor Vehicle Radiator Repair Industry

Presented by

Kevin F. Gashlin Director

New Jersey Technical Assistance Program for

Industrial Pollution Prevention

New Jersey Institute of Technology Hazardous Substance Management Research Center

Advanced Technology Center Building 323 Martin Luther King Blvd

University Heights Newark, New Jersey 07102

May, 1990

1

This report presents results of a literature search, excerpts from previously published reports and observations from site visits. It offers suggestions for water consenration, reduction of spent caustic stripping baths and related metal sludges. Preceeding these recommendations is a protocal that can be followed for developing information needed for a successful technical and economic assessment of those options.

INTRODUCTION

Heated caustic stripping baths are used in numerous production and renovation industries for the removal of paints, coatings, oil and grease, dirt and other foreign materials from surfaces prior to refinishing. Wastes generated from these baths and associated downstream rinsing processes include rinse wastewater and a RCRA hazardous waste sludge, generally containing high concentrations of heavy metals. Treatment of rinse wastewater to meet discharge standards is complicated due to the extremely complex nature of the wastewater, which in addition to heavy metals contains high levels of solids, oil and grease, and other organic contaminants, is highly alkaline, and may also contain chelating agents and surfactants. Hence, treatment of this type of wastewater may require processes for solids separation, 'oil emulsion breakup, breakdown of chelating agents, and precipitation for metal removal. There is some evidence that copper, zinc and lead can be concentrated so as to make recovery by smelting economically viable (Leak, V . G . ) .

The radiator repair industry, which is comprised of over 8 , 0 0 0 facilities in the U.S. and Canada (ACJ, 1984), employs heated caustic stripping baths, and wastes generated from processes associated with the stripping operation in radiator repair shops are typical in nature to wastes generated by processes associated with stripping operations in other industrial categories. In addition to the challenge of treating a relatively complex wastewater, wastewater treatment to meet discharge standards for radiator repair shops is further complicated due to the relatively small scale of operation of the typical shop. Essentially no literature is available which addresses waste management issues at radiator repair shops (Walters, W.W. and Patterson, A.M., 1987).

GENERAL PROCESS DESCRIPTION

A block flow diagram depicting the unit opertions, sequence of work flow, and material flows in the radiator repair process is shown in Figure 1. The general process flow diagram show in Figure 1 and variations in operating practices and conditions discussed here are based upon observations made at a relatively high volume shop specializing in heavy equipment radiator repair as well as auto radiators.

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Radiator in Evaporation Evaporation

A

Radiator Out

""" ,"" P""""""" I I I 1 I I I I I I

r""

Physical Boilout Cleaning Tank

f

Makeup Water

Waste Oil and/or Radiator

Fluids

f Sludge

I""""" 1 r""""""" I I

I I I

I I I I I

.""

Booth

Makeup Water

T 'I

Rinse Wastewater and

Sludge

Makeup Water

f Solids and

Periodic Tank Dump

Figure 1. General Process Block Flow Diagram of the Radiator Repair Process.

Evaporation Fresh

LMakeup Makeup Makeup 3 1 . Makeup Water

z . 'I 1

Boilout Rinse Dragout Test

I Tank Booth Tank Tank &

Treatment Treatment iL

Sludge 'I Sludge Dewatering Figure 2. Water Management Strategy for

Radiator Repair Shops Employing Water Reuse and Dragout Recovery. 1 Solids to Disposal

A generalized process diagram of the repair process is shown in Figure 1. The normal repair procedure involves submerging the radiator in a a bath containing a caustic solution (often referred to as the boil-out tank) which is heated to 140 to 200 OF. The radiator is soaked in the bath for 15-60 minutes to soften and/or remove deposits, scale, corrosion and other foreign materials. Newer boilout tanks may also be equipped to enable ultrasonic cleaning, a technique which significantly improves cleaning efficiency (Walters, W. W. and Patterson, A.M., 1987). However, the ultrasonic cleaning does such a good job that it may actually cause or worsen leaks. After soaking, the radiator is withdrawn and to varying extents the contents are drained back into the boilout tank. The effort put into draining the radia- tors varies and with it varies the amount of drag out contaminat- ing subsequent rinse and test tanks.

The radiator is then rinsed using roughly 5 to 10 gallons of water per radiator in a rinse tank. The primary purpose here is to remove the caustic coating and loosened scale from the inside aqd outside of the radiator. Rinsing is accomplished using either fresh tap water in a once-through system, wash water from a wash tank recirculation reservoir or treated wastewater. The rinsed radiator is then leaked-tested in a test tank. Leak- testing involves hooking up one end of the the radiator to a compressed air line, plugging the other end, and submerging the radiator in the test tank. Any leak which is identified by visual detection of air bubbles is repaired typically by applying muriatic (hydrochloric) acid and/or flux followed by soldering. While repairs are being made, the radiator is usually supported by a rack that is mounted directly over the test tank. Once the radiator has been repaired, it is painted using a solvent based black enamel and reinstalled.

The boilout solution is approximately 4 0 - 50% NaOH. In the particular shop assessed in developing this report, no chelating agents or surfacants are used in conjunction with the NaOH solution, a practice employed in some shops. This omission somewhat simplifies the design needs of a pretreatment system.

Wastes generated from the radiator repair process include rinse wastewater from the rinse booth, and sludge which must be periodically removed from the boilout tank.

In addition to these production wastes, shops also need to dump the boil-out and test tanks periodically. The boilout tank is dumped based on the buildup of sludge in the bottom of the tank. This is related directly to the volume of work that a shop has. Test tanks may be dumped as often as once per month owing to the buildup of suspended solids which cause turbidity in the water and interferes with the leak-test process.

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INFORMATION COLLECTION

Collecting information on waste generation, operation procedures, and process chemicals and materials is essential to assessing the technical and economic feasibility of waste reduction options. General information should be collected on where, how, and why the waste is generated, and more specific data is needed on volume of the waste and its composition. Data should be collected over a representative period of time in order to take into account any variations in production. The information can then be analyzed to identify ways to reduce waste generation and develop cost-effective waste management options. The types and sources of information which should be collected for a radiator repair shop include:

o The sources, quantities, and composition of all waste generated, including the volume of continuous flows such as rinse water, and irregular discharges such as dumps of process baths, waste motor oils, spent coolants, spent or excess process chemicals, scrap metal/radiators, etc. Also, keeping records of all waste generated along with infomation on why it was generated (i.e. why a test tank had to be dumped) will help pinpoint specific problem areas.

0 The complete composition of all chemicals and materials used in repairing radiators. This includes cleaners, solder, flux, test tank solution, caustic solution, etc. This will help to identify products containing chemicals which are adding to the contaminant load, such as metals, or which may cause management problems later on, such as chelating agents.

0 Diagram the exact steps used in the repair process including any which are infrequently used. This will help to identify practices which are generating too much waste (i.e. not draining the radiator well) or steps which might generate a very hard-to-manage waste.

o Compile purchasing records and water usage rates. This will indicate if, for some reason, too much material or water is being used (Hunt, G. 1986).

Waste Characterization & Analysis

The following are results of a sample analysis taken from 2 4 earlier case studies (Walters, R.W. and Patterson, A. N. 1987). These results are consistant with waste analysis provided by the shop cooperating in this study.

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Operational Chanaes

The types of changes which can be made generally fall into the following categories:

o Changes in the way the radiators are handled, cleaned, and repaired to ensure minimum waste is generated. A good example is discontinuing the use of boil-out methodology and substituting high pressure water together with manual reaming oraeroddingal. Another example is not repairing (soldering) over the test tank where excess solder and flux can fall into the tank, causing sludge build-up and contaminated water (Burton R. personal communication).

o Substitution of the process chemicals (i.e. cleaners, test tank solution, flux, etc.) used to reduce levels of contaminants in the wastes and to ensure that compounds in the process chemicals will not cause any treatment/ management problems later on. Examples: using a flux . that does not contain zinc and using a lead-free solder.

o Segregation of waste to ensure that non- or lightly- contaminated wastes are not mixed with highly-contaminated wastes. For example, keeping test tank water segregated from rinse and boil-out tank water.

o Modifications to the process equipment to ensure minimum waste generation. For example, using a counter current water use system rather than a flow through system saves water and concentrates waste.

These types of changes will basically help to keep the maxiumum amount of process chemicals in the process tanks and out of the waste water. For example, the frequent dumping of a test tank due to its becoming llcloudyal may indicate too much solids are being introduced into the tank. This can be corrected by improving the rinsing of the radiator before it is placed in the test tank and/or by filtering or settling the solids from the solution instead of dumping it.

Based on these four waste minimization categories, a number of simple reduction methods can be identified. Examples of the types of methods which can be used are discussed below:

Potential - for Water Reuse - and Dropout Reduction

Water reuse appears to be an attractive option for reducing costs in this industry. This is so for several reasons:

1. Expense of treating/disposing of wastewater:

2. Acceptability of low quality waster for rinsing; and,

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3 . The high evaporative loss of water from boilout tanks. ..

ShoD Water Balance

The principal components of water use in radiator repair shops include the usage of fresh tap water to replenish evaporative losses from the boilout tank and test tank, as well as water used for rinsing purposes. For shops which employ once-through rinsing, rinse wastewater represents the largest use of water even through relatively samll volumes are used. Typical daily rinse water usage data are presented in Table I (as rinsewater flows). These data show that even the largest of the shops surveyed use only about 700 gallons of rinse water per day. Evaporation from the heated boilout tank represents the primary consumptive use of water at shops which employs a recirculating rinse booths. these losses were found to range from 20 gallons per week (especially for ultrasonic boilout tanks which are significantly smaller than other tanks) to as high as 60 galllons pe'r day (Walters, R.W. and Patterson, A.M. 1987) . The basic philosophy of water reuse is to treat rinse wastewater only to meet reuse quality requirements, as opposed to more stringent discharge standards, and to apply dragout minimization techniques employed extensively in the electroplating industry (Kushner and Kushner, 1981). In particular, the management strategy involves: (1) using relatively low-quality water for primary rinsing, where the objective is to remove caustic material from the radiator via scouring as opposed to clean rinsing, ( 2 ) dragout recovery in the form of a still rinse tank following rinsing, where the objective is to accomplish cleaner rinsing and to prevent dragout from contaminating the test tank and ( 3 ) implementation of sequential water replenishment in a direction countercurrent to the work flow (see figure 2 ) . In this scheme, water lost from the boil-out tank due to evaporation would be replenished using rinse wastewater. Rinsing wo'uld be accomplished in either recirculation or once-through system using rinse water generated by periodic (e.g., overnight) treatment of rinse wastewater. In the recirculating system, the rinse booth reservior would be filled with treated rinse water and would be recirculated until it was no longer suitable for rinsing. At this point, rinse wastewater in the reservior would be collected for future treatment and the reservior replenished with treated rinse water (Walters, R.W. and Patterson A.M. 1987).

In the once-through rinsing mode, all rinse wastewater would be collected for treatment. Water removed from the rinsing system to compensate evaporate losses from the boil-out tank would be replenished using water from the dragout tank. The dragout tank would be replenished with fresh water, supplemented if necessary with test tank water. Use of test tank water would also help purge the test tank from contaminants which enter this tank via dragout and/or which are concentrated by evaporation. Fresh makeup water would be used to replenish the test tank. Also, use

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Table 1. Summary of Field Sample Characterization Results for Twenty-Four Radiator Shops in Maryland.

Source: Walters, R.W. and Patterson, A.M. 1987

Concentration. ma/L

Flow, gallons cu Pb 7n Der dav

Boilout Tank X 370 7900 1300 S 490 5900 1900 n 20 20 20 max 2200 18000 7700 min 1.5 7.7 1.76 range 30-700 1000-18000 120-2000

Test Tank X 18 150 990 S 30 530 1600 n 28 27 28 max 2200 18000 7700 mi n 0.99 2.2 12 range 1-34 2-57 12-2400

Rinse Wastewater X 55 270 260 440 S 120 320 610 200 n 13 13 13 15 max 460 520 21 00 71 0 min 4.0 10 2.9 32 range 4-62 10-520 3-60

"""""""""""""""""

Xtmean concentration; %standard deviation: ntnumber of samples; max and min are maximum and mtnumum concentrations observed, respectively; and range indicates the general range of concentrations of most (90°/o) of the samples excluding unusually low or high outliers.

washwater as makeup to the boil-out tank.

Increasing the temperature at which the tank operates will increase the evaporation rate thus allowing for the return of more water. For example, increasing the temperature of a rinse from 140 degrees F to 160 degrees F will increase evaporation by 50% (Hunt, G. 1986). Of course, fuel consumption and cost must be taken into account as well.

0

0

0

0

0

0

0

Boil-out Tank

It has been established that a boil-out tank is unnecessary to the repair of radiators (Burton, R. personal communication) Substitute with high pressure recirculating water, manual rodding and spot cleaning.

Use compressed air to blow out any residual alkaline solution, especially from the oil-cooling section, left in the radiator after it is taken out of the boil-out tank. This should be done over the boil-out tank or in a manner so that the ‘material can be collected and returned to the boil-out tank.

Carefully monitor the boil-out tank and only add the minimum required types and quantity of chemicals. Some auxiliary chemicals can buildup over time and shorten the life of the bath, while other materials, such as chelating agents, can cause waste management problems.

When the process tanks have to be dumped, first remove the liquid to a tank and trap the solids, using filtration (such as a bag filter), drying (see following section on sludge management) or gravity settling. Then return the liquid portion to the process tank. Accumulate and dispose of solids in accordance with RCRA.

Use a smaller process tank, such as an ultra-sonic cleaning unit, to reduce the volume of waste generated (Hunt, G. 1986).

” Test Tank

Do not solder over the test tank, letting excess solder fall into the process solution. This will result in a zinc and lead buildup in the solution. Instead, solder over a seperate area or in such a way that any solder can be caught before it falls into the tank.

Do not dump the process solution because it becomes llcloudylr. If there is a solids problem, filter the solution ( a simple bag or cartridge filter can be used), or let the solids settle out by gravity (Hunt, G. 1986).

Treatment and Recvclinq of Rinse Water

Once waste has been reduced to the maximum -degree possible the waste remaining can be treated and reused or discharged. The

7

water from the rinse tank will be the best candidate for reuse. This waste water is the major source of volume and concentration of metals (lead levels alone can reach over 600 ppm) . There are basically three types of water recycling techniques: filtration, simple chemical/physical treatment and advanced chemcial/physical treatment. Some suppliers of such recycling systems are listed in Table 2 along with the capability of the treatment. Descriptions follow below.

Filtration

The simplest recovery technique is gravity settling and filtration to remove solids and some oil from the contaminated rinse water. In such a system the largest particles are first settled out and the waste water is then run through a series of successively finer filters to remove the remaining suspended solids. The treated water can be reused for rinsing or as makeup for the boil-out tank. Over time, caustics, oils, metals, and dissolved solids will build up, but since the water is not discharged, the level will not matter from a discharge permit stpndpoint. However, if the levels of contaminants build up too much it could cause operational problems. This can be avoided if enough of the treated water is removed for use as makeup in the boil-out tank and replaced by fresh water. This will allow the concentration of dissolved solids to stay at an acceptable level. Identifying and maintaining this operating condition will be the key to the successful performance of the system. Any buildup in caustic over time can be corrected by acid addition as needed (Hunt, G. 1986).

Chemical/Phvsical treatment

A simple chemical/physical treatment system can also be used to remove oil, metals, and solids from the waste waster so that it can be reused. Such a system would consist of adjusting the pH with acid (such as hydrochloric acid) , adding an inorganic flocculent (such as ferric chloride) or polymer, and letting the solids settle and the oil float to the surface. The treated wash water can than be stored for reuse as rinse water, or as makeup to the boil-out tank. Such a system can remove metals down to about 10-30 mg/l. Metal levels cannot be reduced much further due to chelating/complexing agents in the rinse water. Also, this system could be used to treat any batch dumps of the process tanks. The cost of such a unit will depend on the unit's capacity as well as if it is built in house or bought from a vendor (Hunt, G.1986) .

Advanced Treatment

The final type of system using advanced treatment methods is able to reduce the metal concentrations down to levels which will meet discharge limits, for example 0 . 5 mg/l or less of lead. Such systems use special treatment chemicals and/or oxidation techniques to break up chelating/complexing agents and precipitate metals (Hunt, G . 1986). A list of selected Publicly

8

Owned Treatment Works (POTWs) in New Jersey and their current discharge parameters and limits is included in the appendix of this report.

One commercially available unit uses a chemical oxidizer, chlo- rine, and an ultra-violet lamp to break up metal complexing/chelating agents, followed by standard chemical/physi- cal treatment processes to remove the remaining metals and sol- ids. In any of these systems the treated water can then either be reused or discharged. Depending upon the treatment used, these systems can cost $15,000 or more to purchase. The chemical costs for operating such a system will be several hundred dollars a year (Hunt, G. 1986).

Before any of these systems are installed, a treatability study must be conducted to determine that the technology will work and what concentration and type of treatment chemicals must be used. Once the system is installed and properly operating, changes in the materials used in the repair process must not be made. If changes are made, a test must be conducted to determine if the n&w compounds will have any effect on the treatment/recycle system (Hunt, G. 1986).

Volume Reduction throuuh Drvinq

There are a number of techniques available to remove excess water from the sludge, thus reducing its volume. This will, in turn, reduce disposal costs. Most of these techniques will depend on filtering the solids out of the sludge and/or air drying the sludge.

If the solids in the sludge are of a high enough concentration when they come out of the treatment system, then they can be put directly into a drum and let air-dry over time. The addition of a heat source, such as an electric band drum heater will speed up the drying process and produce a drier material.

If the sludge is very ttwatery't then a gravity filtration system can be used first to increase the solids concentration. There are a number of different designs and configurations for such a system. The simplest system would be a paper cloth filter placed on a holder over a drum. The sludge can then be pumped or gravity-fed onto the filter material. The water will drain through the filter and be collected in the drum. The sludge can then be dried and the-water returned to the treatment system. Vendors of this type of equipment are listed in Table 2 (Hunt, G. 1986).

Dewatering and/or drying of the sludge for purposes of reducing wastes may or may not be permitted at both the federal and state level, particularly depending upon the individual state hazardous waste regulations. Federal regulations generally favor recycle, and would allow dewatering if it is performed so as to recover boil-out tank water from the sludge reuse. Further dewatering by

9

drying may be considered treatment and thereby impermissible, thoush radiator repair shops generate such small sludge volumes that they are generally exempt from federal regulations which require facilities to be licensed to treat a hazardous waste. Inquiries regarding treatment permits should be directed to the appropriate state environmental program officials.

Theoretically, evaporation could be accomplished utilizing your existing equipment. It is simply a matter of raising the temper- ature of the bath. Be aware however that this option may require either a water treatment, hazardous waste or air emission treat- ment permit in. In New Jersey you should contact NJDEP (Division of Water Resources at (609)984-4428, Air Quality Information at (609) 292-6716, and Hazardous Waste Engineering (609) 292-9880 to discuss this matter.

Tests were conducted using caustic sludge from the boil-out tank to evaluate thickening and drying. Sludge used in these studies had an initial suspended solids concentration of 36 g/L and a bulk density of 1400 g/L (concentrations of Cu and Zn were 8.6 aqd 1.0 mg/g dry solids, respectively) . Sludge settling charac- teristics are shown in Figure 3 , which shows a comparison of settling hot sludge from the boilout tank (14O0F) versus sludge which is allowed to cool overnight to room temperature. Room temperature settling was found slightly more effective for sludge thickening. Thickened-sludge results and drying characteristics show that room temperature air drying under still or ventilated conditions are roughly comparable, and are capable of reducing sludge mass by 25% over a period of five days of drying or long- er. Drying in an oven achieves 50% reduction in sludge mass in one day. Though oven drying may not be feasible on a practical scale, this provides perspective to the air drying data, suggest- ing that roughly half of the water occluded in the sludge is likely to be evaporated. Figure 4 compares drying rates of sludge under various scenarios.

Metal Removal/Recoverv

Due to the complex nature of the waste water and sludge and the relatively low value and concentration of metals, it is not believed to be economically practical to recover metals on site. It may be cost effective however to send concentrated sludges to secondary smelters or other reusers directly or through a waste exchange. This can save on disposal cost and recycles a re- source. There is evidence that non-electrolytic metal recovery utilizing ammonium cabonate efficiently leaches ionic copper from caustic sludge at a rate of much as 800:1, and that all metals with the exception tin, can be precipitated from ultrasonic boil- out tank solution using sodium sulfide, the resulting product of which could be acceptable for metal recovery via secondary smelt- ing (Leak, V . G . ) . A list of known metal sludge users is included as an appendix to this report. You can contact the Northeast Industrial Waste Exchange at (315) 474-4201 to market your sludge to potential users.

10

I 4

References

AWWA Research Foundation (1987). "Reuse Strategy for Wastewater from Caustic Stripping Operations: A Case Study of Radiator Repair Shops." Walters, R. W. and Patterson, A. M. August 2-7 1987, Denver, Colorado

APHA (1985). Standard Methods for the Examination of Water and Wastewater, 16th ed., American Public Health Association, Washington, D.C.

ACJ (1984). "American Pollution Controls Introduces System, "Automotive Coolins Journal, March, 10-14, Harleysville, PA.

Burton, Russell, Personal Communication, 1990.

Huht, Gary (1986). IlWaste Reduction Options: Radiator Service Firms", Pollution Prevention Pays Program, North Carolina Dept. of Natural Resources and Community Development, Raleigh, North Carolina . Kushner, J.B., and Kushner, A.S. (1981). "Water and Waste Control for the Plating Shop'@, 2nd Ed., Gardner Publications, Cincinnati, Ohio.

Leak, V. G. "Metal Removal/Recovery Using Non-Electrolytic Metal Recoveryg1, Universtiy of Minnesota-Duluth, Natural Resources Institute.

11

Amendix

1. Radiator Repair Fact Sheet, Minnesota Technical Assistance Program

2. Hazardous Waste Reduction Checklist, California Dept. of Health Services

3. List of Users of Metal Bearing Solutions & Sludges

4. Supplies of Waste Water Recycle Systems, North Carolina Pollution Prevention Pays

5. Partial list of Paint

Program

Spraying Equipment Manufacturers, NJTAP (,*,.$" ,. r ' , .. L- ;{ 1

0416901.KG

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I 1

RADIATOR REPAIR/ENGINE REBUUgING INDUSTRIES; W % N

Introduction, This Minnesota fact sheet is intended for persons in the radiator repair business, engine rebuilders, parts remanufacterers and other industries using caustic cleaners. These industries commonly use caustic liquids to

0 dean vehicle radiators, 0 ciean vehicie engine blocks. 0 clean other vehicie pans, o degrease other metal parts, or o remove/strip paints from metal surfaces.

These activities generally invoive dipping items into a tank containing a heated caustic solution and then rinsing them off. The wastes produced are hazardous because they are caustic (pH more than 12.5) AND because they contain hazardous levels of lead or other toxic elements. 'Qpical wastes include:

A. Caustic, lead-containing tank solutions: B. Caustic, lead-containing tank sludge; C. Caustic, lead-containing rinse water; D. Caustic liquid paint wastes; and E. Caustic paint sludge,

k v amount of anv of these wastes are hazardous waste Venera- tors" and must follow the r e a m e r 7045, To obtain a brief summary of these requirements, call the Minnesota Pollution Control Agency (MPCA) at 612/296-7790 ana ask for the fact sheet titled "Who's a Generator?" or the "Hazardous Waste Compliance Guide". Minn. Rules Chapter 7045 can be-purchased for about S15.00 from the Depanment of Admini- stration, Documents Division (612/297-3OOO).

The remainder of this fact sheet covers

above, and I. Proper handling and disposal of the caustic hazardous wastes listed

II. Options for reducing the volume of these hazardous wastes.

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Tnere are four options for handling used caustic tank soiution. Tncy XC:

Discharge it to the sanitaq sewer p-stern. T h e 1IPCX STROSGLS DISCOLXAGLS this disposal practice You "MUST no& h e l o c i sewage rrcamxx plant operaror

set 'by the rrearment piant or local ordinances. Tne MPC.4 Disciosur: Lait O r rk t appropriate metropolitan couny oficials should ais0 be no~iiied.

BEFORE YOU sewer am, ind~srriai w&. Y O U discba~gi mu1 not exceed any iiz;;ts

d j I f vour comDanv is not connected to a sanitalv sewer svstern, o follow option 4.a) or 4.b) above, o connect your shop to the local sanitary sewer, OR o obtain written pennission from the local treatment plant operator for a ii-

censed hazardous waste transponer to discharge caustic solutions from your containers directly into the sanitary sewer system.

DO NOT allow a septic tank pumping service to remove hazardous waste of a n y kind from your shop unless they have been issued a hazardous waste transDorter License by the Minnesota Department of Transponation (MNDOT).

DO NOT discharge caustic tank wastes to a septic tank or drainfield system.

B, Caustic Tank Sludges. After step A3., the hazardous sludge in the first tank bottom should be dewatered or dried as much as possible and put in containers resistent to

. caustics. Waste containers must be o anaiyzed before shipment, o properly marked and labeled, o picked up by a licensed hazardous waste rransponer, a x o delivered to a permitted hazardous was12 ytorage. treatrznt or disposai company.

"A Checklist for Selecting a Hazardous Waste Transponer", "Choosing a Hazardous Waste Recuest the fact sheets "Labeling Hazardous Waste", "Hazaraous Waste Storage",

Management Facility", and lists of hazardous waste transporters and disposal firms.

C . Caustic &we Watm Caustic rinse water from spraying off radiators, engines or engine parts should also be collected. If solids are filtered out in the process, the solids should be combined with the tank sludge in I.B. Save the rinse water and reuse it for rinsing or as the "make-up" water in new batches of caustic tank solution. As a iast resort. rinse water which cannot be reused may be discharged to the local s a n i t a r y sewer E

o the local sewage treatment plant operator has been notified, o rinse water does not exceed any limits set by the treatment plant or local ordinances.

o either MPCA's Hazardous Waste Disclosure Unit or the appropriate metropolitan

-

and

county hazardous waste officials have also been notified.

DO NOT discbarge caustic rinse waters into a septic tank or drainfieid system.

. . D, Caustic Q m d P- Wastm Hazardous caustic paint stripping waste must be handled. picked up and disposed of by licensed companies. See A4.b) and B. above. Paint strim

Pine rinse mta should be handled and disposed of as in C. above.

11. Waste Reduction/Minimization. A. Minimizinp the amount of caustic leadcontaininp waste vou eenerate.

1. Substitution. If possible, substitute physicai methods for the caustics that remove paint. grease and dirt from vehicle radiators, engine blocks, etc..

o Can plastic bead or steel shot blasting be used to remove paint? o Can grease and/or paint be "baked" off using a high-temperature oven? o Can radiators etc. be pmidy-cieaned using steel brushes?

NOTE: Waste from these processes may ais0 be hazardous. 2. Pre-cleanins Remove as much grease and dirt from radiators, engines etc. 3s possible

BEFORE putting them in your caustic dip tank. Do this by using a high-pressure. hot detergent spray. This detergent waste water can be discharged to a sanitary sewer or septic tank and drainfield system.

3. Chemical Savings, Use as small a tank as possible to meet your company's needs. An . ultrasonic cleaning unit may require less cleaning soiution. 4. Efficient ODerations. Use caustic tank solution efficientiy.

a) Use the minimum amount of caustic soda needed to make up new tank solution. b) Avoid using chemicals which contain complexing agents. They prevent lead from

forming a sludge when the waste solution is neutralized. c) use the caustic tank solution over and over again by

o periodically neutralizing the tank soiution to pH 5-9, o letting the solution stand and settie for 48 hours, o syphoning it into a second holding tank, o removing the hazardous tank sludge from the first tank and disposing of it as

o filtering the contents of the second tank back into first tank (perhaps using fine

o adding only the needed amount of caustic soda to captured hazardous rinse

hazardous waste,

mesh screen), and

water to make the solution up to its on@ strength.

sariiy (once per year should be adequate for most shops).

o Drain radiators or other parts thoroughly before transferring them from one

o Dewater hazardous sludges as much as possible before wosing of them. o Do not solder radiators over test tanks.

d) Do not dispose of waste caustic tank solution or make up new caustic solution uneces-

5. Other. Test tank solutions may also become hazardous for lead. To avoid this:

tank to another.

For questions on hazardous waste rules, contact the MPCA at 612/296-7790. For advice on waste reduction, call the Minnesota Technical Assistance Program at 612/625-9471 or 1/800-247-0015.

This fact sheet was contributed by the SmaU Quantity Generator Assistance Group, composed of Minnesota Pollution Controi Agency Twin Cities Metropolitan County Officials Minnesota Business and Industry Representatives Minnesota Technical Assistance Program