Verification of TIE Protocol with Target

2.2 Phase I Studies Using Prepared Solutions

3.2.3 Verification of TIE Protocol with Target

Compounds

The four target compounds used to evaluate the Phase I

TIE protocol were processed according to two different test

schemes as explained in this section. The objective was to

determine if any of the TIE tests in the EPA protocol

produced either false negative or false positive results.

For example, if Cu is the target compound, then the only

test that should reduce toxicity is chelation. A reduction

in toxicity produced by any other test(s) would be

considered a false positive.

TIE Scheme for NPE-9 and 1-MN

EPA's first draft protocol for the Phase I

Characterization Tests (Anderson-Carnahan & Mount, 1987) was

used as a starting point to design a test scheme for NPE-9

and 1-MN in evaluating the Phase I tests. Figure 3-1 shows

the TIE scheme proposed in this EPA draft protocol. The TIE

scheme used for these target compounds is presented in

Figure 3-2. The ET50 was used for the toxicity tests as

recommended by EPA. Comparison of Figures 3-1 and 3-2 shows

that the (light/dark) Degradation Test was deleted and that

Baseline

Toxicity

Tests

Toxic Effluent Sample

Degradation

Test

Ai r Stripping

Test '

Acid Rase Neutral

Filtration Test Reducing Agent Test Chelation Test

Cig Solid Phase

Extraction Test Acid Base Neutral

Figure 3-1 Initial EPA Draft Procedure for Phase I Effluent Characterization Tests (Anderson-Carnahan &

TARGET COMPOUND SPIKED SOLUTION

DAY 0 B^SEUNB AERATION

pH3

AERATION

pHl

OOARSERUIR 1.2 um. AERATION

pHll

1 WEEK GAC ADSORRION RNE FILTER [02 urn.)

Cia SPE

OOLUMN 0«,F£]XiaiON

low cone. _{high cone.}

FINE FILTER 0.2 um. 2 WEEKS 3 WEEKS EDTA low cone. EDTA mod .CQDc. EDTA high cone TIME-DEGRADATION TEST

Figure 3-2

_{Test Scheme Used to Evaluate Phase I Characterization Tests Using Target}

Compounds NPE-9 and 1-MN

Degradation Test were added. The Light/dark Degradation

Test, intended to indicate the presence of photodegradable toxicants, was not relevant for these target compounds. The GAC Adsorption Test was added because adsorption removes a broader spectrum of organic chemicals than the C18 SPE

column. The Time-Degradation Test was added because earlier tests with wastewater effluents showed disappearance of

toxicity with time even though samples were stored at 4°C. In addition to the above changes, the Chelation Test was placed after the Filtration Tests. This scheme

separates filterable from non-filterable metals. Had the toxicant been unknown, it would have been interesting to compare the results of this test with the results of a parallel Chelation Test on the unfiltered whole sample. That is, a greater reduction in toxicity with chelation

after filtration would show that metals sorbed to solids

cause toxicity. However, this test result would be valid

only if EDTA is a strong enough chelating agent to remove

the metals from the solids. Although NPE-9 and 1-MN are clearly not chelatable metals, it is regrettable that chelation before filtration was omitted from the test

scheme.

A control to measure survival of the test species in

non-toxic control water was prepared using water from Botany

Pond, Chapel Hill, N.C.

Time-Degradation Test

Multiple aliquots of the stock solution spiked with the target compound were set aside and stored at 40C in

containers with no headspace (to prevent volatilization). At approximately weekly intervals, each aliquot in turn was subjected to toxicity testing by bioassay to note any change in ET50 through time.

Filtration Tests

The target compound solution was filtered first through a 1.2 um filter and subsequently through a 0.2 um membrane. Aliquots of filtrate were taken at both points for toxicity testing.

EDTA Chelation Test

The three different concentrations of EDTA used in

performing the Chelation Test were those that would have

been used for an unknown sample from Westside WWTP at High

Point, NC based on the range of reported values of metals

concentrations found in the effluent from that plant.

Corresponding control samples were prepared using the

unspiked background wastewater to check for toxicity caused

by the EDTA itself.

Aeration Test

Air stripping was performed at pH 3, original pH of the

Aliquots were returned to original pH before bioassay

testing. To check the effect of acid and base addition on the aliquots stripped at altered pH, two controls drawn from the target compound solutions raised to pH 11 and lowered to pH 3 respectively were neutralized but not air stripped.

Oxidant Reduction Test

This test treats two aliquots of the target compound solution with low and high concentrations of sodiiua

thiosulfate (Na2S203) respectively. The goal is to cover

the range of 20 reducing agent additions proposed in the EPA protocol (Anderson-Carnahan & Mount, 1987) with only two representative concentrations. The full range of additions recommended in the manual for WWTP effluent samples is based on the average residual chlorine concentration. Thus, the average residual chlorine concentration found in the High Point WWTP effluent background (0.3-0.4 mg/L) indicates a

range of twenty Na2S203 additions: 0.05 mL (one drop) of

10~3 N reagent per 5.0 mL sample to 0.95 mL (19 drops) of

10~2 N reagent per 5.0 mL sample. Two concentrations—the

mid-range addition and the highest addition—were chosen for

treating the target compound solution. Corresponding

controls were prepared using the background non-toxic wastewater to check for toxicity caused by the reagent

itself. Any anomaly in the results could be re-examined

GAC Adsorption Test

GAC was crushed to the size range between 100 and 200 U.S Standard Sieve which corresponds to diameters ranging

from 0.149 mm. to 0.074 mm. (Weast, 1962). The GAC was not

washed to remove fines. The dosage was 200 mg per 100 mL of

target compound solution. The GAC-containing solution was placed on a rotating shaker apparatus for at least five hours. The aliquot was filtered through a 0.2 um membrane to remove the GAC before toxicity testing.

C18 SPE Column Test

The target compound solutions were passed through the C18 SPE (octadecyl solid phase extraction) column. Post- column effluent samples were taken for toxicity testing after 100, 500, 750, 850, and 950 mL had passed through the column. The column sorbent was then eluted eight times by