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SAMPLE COLLECTION BOTTLE

BASELINE MONITORING UNDER VACUUM - CLINIC 5-LR

Sample bottle holds 20 liters. It is vacuum rated and made of polypropylene.

Wastewater from operatories enters via white line on left.

Wastewater passes through a vacuum filter prior to sampling (wastewater normally passes 

through a vacuum filter before going to the liquid-ring vacuum pumps).

Only air leaves the sample bottle, and then goes to the tandem liquid-ring vacuum pumps, 

at right. 

Valves above sample bottle are set to direct flow into sample bottle.

Valves would be reset to change bottle, while still maintaining vacuum at the operatories.

Union fittings are located just below valves. This is point where bottles are disconnected.

All piping and bottle are under vacuum during the time that wastewater is being collected.

Piping near valves is clear to allow viewing of flow. Person can wait until there is no flow 

passing through system, before changing bottle.

Sample bottle placed in a plastic tub in case of leaks.
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SAMPLE COLLECTION BOTTLE

BASELINE MONITORING UNDER VACUUM - CLINIC 6-LR

Sample bottle holds 20 liters. It is vacuum rated and made of polypropylene.

Wastewater from operatories enters via white line on right.

Wastewater passes through a vacuum filter prior to sampling (wastewater normally passes 

through a vacuum filter before going to the liquid-ring vacuum pump).

Only air leaves the sample bottle, and then goes to the liquid-ring vacuum pump at left. 

Valves above sample bottle are set to direct flow into sample bottle.

Valves would be reset to change bottle, while still maintaining vacuum at the operatories.

Union fittings are located just below valves. This is point where bottles are disconnected.

All piping and bottle are under vacuum during the time that wastewater is being collected.

Piping near valves is clear to allow viewing of flow. Person can wait until there is no flow 

passing through system, before changing bottle.

Sample bottle placed in a plastic tub in case of leaks.
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SAMPLE COLLECTION BOTTLE, CLOSE-UP VIEW - CLINIC 6-LR

20 liter polypropylene, vacuum rated sample bottle.

Valves above sample bottle are set to direct flow into sample bottle.

Valves would be reset to change bottle while still maintaining vacuum at the operatories.

Union fittings are located just below valves. This is point where bottles are disconnected.

All piping and bottle are under vacuum during the time that wastewater is being collected.

Sample bottle placed in a plastic tub in case of leaks.
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REBEC MODEL 2000 E AND SAMPLE COLLECTION BOTTLE - CLINIC 6-LR

The 2000 E system and the sample collection bottle are under vacuum while the vacuum 

pump is on.

The liquid-ring vacuum pump is located at right.
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PURE WATER DEVELOPMENT LLC – METASYS GROUP ECO II

AND SAMPLE COLLECTION BOTTLE - CLINIC 6-LR

Wastewater passes through a vacuum filter before entering the ECO II.

The vacuum filter, ECO II, and the sample collection bottle are all under vacuum while 

the vacuum pump is on.
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REBEC MODEL 2000 EL AND SAMPLE COLLECTION BOTTLE - CLINIC 7-T

Wastewater originates from operatories above, turns diagonally down white pipe, and 

enters the Rebec Model 2000 EL.

Wastewater is retained in the 2000 EL system until the vacuum pump is turned off. 

(There is a check-valve between the upper chamber and the settling/filtration container.)

Wastewater then passes through the settling/filtration container, to the sample bottle.

The settling/filtration container and the sample bottle both are not under vacuum, even 

when the vacuum pump is on, due to the check-valve.

The line leaving the sample bottle is routed to the drain. This would only carry wastewater 

if the bottle overflowed. The sample bottles were changed prior to filling completely.

The bottles were changed using the union fittings located on the bottles.

Only air leaves the Rebec 2000 EL, through the grey line (below the white diagonal line).

The white tank at the right is the clinic’s preexisting air/water separator tank, which is part 

of the turbine (dry) vacuum pump system (basically nonfunctional during this testing).
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DURR CENTRIFUGE AND AIR/WATER SEPARATOR - CLINIC 5-LR

The air/water separator is the square container mounted on the wall. This separator was a 

preexisting component of the liquid-ring vacuum pump system.

Wastewater (from the operatories and the city tap water that is routed through the tandem 

vacuum pumps, which mix in the pumps) is routed to the right side of the air/water 

separator, behind the centrifuge.

Air leaves the air/water separator via the white vent pipe at the top of the separator.

Wastewater leaves the bottom of the separator, and is normally routed to a drain (see 

disconnected white line just above sink). During the study, the wastewater was routed to 

the rear, bottom of the centrifuge. 

The centrifuge treats the wastewater, and it is routed to the drain.

The centrifuge does not operate under vacuum. Therefore, when using a liquid-ring 

vacuum pump, the centrifuge is connected to the air/water separator outlet.
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STAINLESS STEEL SAMPLE COLLECTION TANK

This 27 liter sample collection tank was used in Clinic 2-PLR.

(A similar, 14 liter stainless steel sample collection tank was used in Clinic 1-PLR.)

Tank operates under vacuum. 

Same valve arrangement as the interchangeable polypropylene sample collection bottle 

used in the other clinics (Clinics 3-7).

Tank shown as it would look when draining the tank into a jug to transport the wastewater 

samples. (Multiple 9 liter jugs, made of high-density polyethylene, were used to collect 

full sample.)

Port on top of tank would be opened to allow air into tank for draining and to allow a 

pressure sprayer wand inside to rinse tank after draining.

Tank is lined with a white, epoxy paint made for tank interiors.

More detailed information on the tank is given in Section III. D. 2 of the report.
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PRESSURE SPRAYER

Pressure sprayer used to rinse solids out of stainless steel sample collection tanks.

(For this function, a straight wand was used, and the tip cover was removed to allow for a 

“right-angle” spray out of the end of the wand.)

Pressure sprayer was also used to deliver a jet of low-volume water to rinse the solids off 

of the sidewalls of the wastewater sample settling tanks (see next picture).

All volumes of rinse water used with such a sprayer were accounted for.
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WASTEWATER SETTLING TANKS AND ISCO DECANTING PUMP

Settling tanks used to settle wastewater collected from dental clinics.

Tanks shown held 42 liters (if upright). 

Tanks were made of high-density polyethylene.

Tanks positioned in racks, tilted forward and turned sideways, to maximize the settling of 

solids to one corner of tank.

After wastewater was allowed to settle, subsamples of the liquid layer were collected with 

a ladle as the liquid was decanted by an ISCO pump, shown at center, and routed to the 

sink drain at right.

Banding around each tank is colored tape to code the tanks for each of the clinics. Each 

clinic (4-T, 5-LR, 6-LR, and 7-T) had their own, dedicated settling tank. Similar color 

coding tape was also used on dedicated sample collection bottles. (Other dedicated 

wastewater sample settling tanks were used for the other three clinics; not shown here.)

Clipboards hanging below each tank held the “Clinic Sample Collection Log” for each 

sample (see form in Appendix E).

Sink at right is custom sink installed to wash settling tanks between samples.

More detailed information on sample processing is given in Section III. D. 1-4 of the 

report.

Tanks were kept covered during settling periods and when empty.
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OVERVIEW OF PROCESSING BEAKERS WHICH CONTAIN SOLIDS

Section III. D. 1-4 of the report discusses methods used to prepare samples for analysis.

Included in this photograph are: (1) pipette used to subsample liquid from beakers that 

have been allowed to settle, (2) pump, hose, pipette tip that are used to decant settled 

liquid from beakers, (3) beakers containing solids from one of the types of amalgam 

removal equipment, and (4) Parafilm® used to cover beakers. (Pump also shown below.)

Decanted liquid, after settling and sampling, was routed to sink drain at left.
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BEAKERS CONTAINING SOLIDS FROM CENTRIFUGE CASSETTE - CLINIC 4-T
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DIGESTION OF SOLIDS ON HOT PLATES IN LABORATORY HOOD

TRANSFER OF “PREDIGESTATE” FROM BEAKERS TO VOLUMETRIC FLASKS

After solids were digested in beakers, on a hot plate, the resulting “predigestate” was 

transferred into volumetric flasks.

The predigestate was poured through a coarse paper filter as part of the transfer procedure, 

to protect the analytical instrument, which would be used later. (The filter would retain 

material that did not dissolve during the digestion process, such as dental hygiene 

polishing compound.)

More detailed information is given in Section III. E. 1-3 of the report.
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TRANSFER OF “PREDIGESTATE” FROM BEAKERS TO VOLUMETRIC FLASKS
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VOLUMETRIC FLASKS CONTAINING PREDIGESTATE

500 milliliter flasks containing predigestate after analysis.

Each flask contains the predigestate of five beakers from the processing of the solids 

removed from the Rebec 2000 E settling/filtration container used in Clinic 6-LR.

Although not visible in a black & white photograph, the color of the predigestate was 

often blue or green, with darker shades indicating higher levels of mercury.

The amount of mercury shown here for each flask is in milligrams. This was determined 

by the analysis (concentration) multiplied by the volume (0.5 liters). See Appendix C.