1. CE 510 Hazardous Waste Engineering
Department of Civil Engineering
Southern Illinois University Carbondale
Instructor: Jemil Yesuf
Dr. L.R. Chevalier
Lecture Series 4: Source Analysis

2. Course Goals
Review the history and impact of environmental laws in the United States
Understand the terminology, nomenclature, and significance of properties of hazardous wastes and hazardous materials
Develop strategies to find information of nomenclature, transport and behavior, and toxicity for hazardous compounds
Elucidate procedures for describing, assessing, and sampling hazardous wastes at industrial facilities and contaminated sites
Predict the behavior of hazardous chemicals in air, surface impoundments, soils, groundwater and treatment systems
Assess the toxicity and risk associated with exposure to hazardous chemicals
Apply scientific principles of hazardous wastes management, remediation and treatment

3. Fundamental Concepts Covered
Materials Balance/Waste Audits
Hazardous Waste Site Assessments
Source Sampling: Statistics

4. Materials Balance/Waste Audits
Industrial Facility
Losses:
Incorporated into Product
Volatilization
Spillage
Water treatment chemicals
Laboratory chemical wastes
Catalyst
Spent Chemicals
Lubricating Oils
Spent and dirty filters
Maintenance Material
Waste Oil
See Figure 4.2 p. 214

5. Materials Balance/Waste Audits
Overall Strategy
Convert to mass
Convert to mass flux
Cannot add concentrations
Mass In – Mass Out + Rxn = Accum.

6. Problem 4.2 in Text
The following records are available for a small company that manufactures semi-conductors. The chemical used most at the plant is TCA, and the primary loss mechanism is volatilization. Using the following data, estimate the maximum volatilization rate.
Note: S.G. of TCA = 1.339
Acquisitions:
RCRA Manifests:
Date
Vol. (L)
Purity (%)
Waste No.
Vol.(L)
C (%)
8-Jan
208 92
28-Feb
F001
1140 22
6-Feb
833 95
20-Apr
386 13
26-Feb
416 88
21-May
462 45
15-Mar 97
30-May
1287 36
11-Apr 90
2-May
625
Discharges:
Wastewater characteristics: 18.9 x 106 L/day (5 MGD) at 0.5 mg/L TCA

7. Solution Acquisitions: (208 L)(1.339 kg/L)(0.92) + . . . = 3122 kg
2. Wastewater discharges
= (18.9 x 106 L/day)(143 days)(0.5 mg/L)
(1kg/106 mg) = 1351 kg
3. RCRA Manifests:
= (1140 L)(1.339 kg/L)(0.22)
= 1302 kg

8. Solution Total Mass of TCA leaving the facility: = 1351 kg + 1302 kg
5. Total TCA volatilized:
= 3122 kg – 2653 kg = 469 kg
6. Volatilization rate:
= (469 kg)/(143 days) = 3.3 kg/day
......end of example

9. Problem 4.3 in Text
A plastic formulation facility receives one of its synthetic chemicals, dimethyl phthalate, by steady flow through a supply pipe at a flow rate of 200 L/day. The dimethyl phthalate is used in synthesis reactors for making a plasticized polymer at a rate of 0.8 moles/min. Partially reacted polymers are precipitated from specific reactions containing fluids with 1200 mg/kg (dry wt.) dimethyl phthalate. If 30,000 kg of the sludge (with an average water content of 85%) are generated each day, how much dimethyl phthalate is unaccounted for?
Note: S.G. = 1.191, MW = 194 g/mole

10. Solution 1. Mass balance: In – Out + Rxn = Accum. If Out = 0 then
In + Rxn = Accumulated
2. Determine the mass of dimethyl phthalate supplied
(200 L/day)(1.191 kg/L) = kg/d

11. Solution 3. Determine the mass lost due to the reaction
(0.8 moles/min)(194 g/mol)(60 min/hr)(24 hr/d)
= kg/d
In + (-Rxn) = – = 14.7 kg/d
4. Determine the mass of dimethyl phthalate in the sludge
(1200 mg/kg)(30,000 kg/d)(0.15) = 5.4 x 106 mg/d
= 5.4 kg/d
5. Mass unaccounted for:
14.7 kg/d – 5.4 kg/d = 9.3 kg/d
......end of example

12. Hazardous Waste Site Assessments
Phase I
Paper research (background search)
Chemical inventory evaluation
Interviews with current and former personnel
Interviews with community
Regulatory agency record searches
Title searches
Areal photographs
Permits and violations
If suspicions of hazardous waste contamination are confirmed, Phase II is warranted

13. Hazardous Waste Site Assessments
Phase II
Finalizing any searches that were incomplete in Phase I
Detailed evaluation of pathways and potential receptors
Random sampling and analysis
If contamination occurred, Phase III

14. Hazardous Waste Site Assessments
Phase III
Determine the extent of contamination
Area, volume, concentration
With appropriate sampling designs, contaminant concentration data over depth and area
Provides sufficient information to assess the site hazard (need for site cleanup)
Provides criteria for the design of remedial process

15. Source Sampling: Statistics
Homogeneous source
Aqueous waste in a drum
No concentration gradients
No layering from density difference
One sample represents the waste
Most hazardous waste is heterogeneous
Sludges
Soils
Lagoons
Characterization of the waste is expensive
Reliable analysis with sophisticated instrumentation
Quality Assurance
Report preparation

16. Source Sampling: Statistics
Two fundamental statistical concepts for sampling plan:
Accuracy
How close a measured value is to the true value
Error allowed, a
Corresponding parameter is the confidence level (1-a)
Precision
Measure of the variability between samples
D, deviation from the true value – precision requirement

17. Source Sampling: Statistics
Population
True value of global data
A number that describes a population is called a parameter
Parameters include
Mean, m; Variance, s2 ; Standard deviation, s
Sample
Data set collected from population
A number that describes a sample is called a statistic
statistics include
Average, x; Sample variance, s2 ; Sample Standard deviation, S.

18. Source Sampling: Statistics
Why sample the source material (population)?
Sampling errors and analytical errors?
Which one is greater and why?
If we take a sample and calculate a statistic, we often use that statistic to infer something about the population from which the sample was drawn.
Why sample:
- a census may not be cost effective
- there may not be enough time to obtain more than a sample
- a carefully obtained sample may be more accurate than census
- sometimes a census is impossible due to large (infinite) population.
Therefore, an effective sampling scheme that fully characterizes the site or facility in an efficient and economical manner is necessary to assure the quality of the analytical results.

19. Source Sampling: Statistics
Degrees of freedom:
A parameter used in statistical distributions that represents the sample size minus the number of parameters being estimated
df = n-1

20. Source Sampling: Statistics
Sampling procedures
Search sampling (historic information)
Using prior knowledge of the site
Probability sampling
Designed so that samples which have an equal chance of being chosen are collected
Simple random sampling
Stratified random sampling
A series of simple random sampling stacked on top of one another
Others

21. Probability Sampling Based on the t-distribution
A probability density function that is used to evaluate sample means when the population variance (σ2) is not known but can be estimated by S2.
This value is found in tables.
Need to know the size of the sample set and the confidence level desired.
i.e., t = (df, α)
See Appendix E.

22. Determining sampling points
Divide source area into a grid of sampling units (blocks)
Assign a number to each block of the grid
Use a random number generator to determine sampling points

23. Determining the number of samples
Initial or previous data
Determine average and S2
Determine the student’s two sided t with n-1 degrees of freedom for a confidence level of (1-a)%
Determine the regulatory threshold, RT (e.g. toxicity characteristic leaching protocol (TCLP))

24. Confidence Interval (CI)
This parameter is needed to determine whether or not a hazardous chemical is present at concentrations which are measured below RT.

25. Procedure for the Simple Randomized Sampling of RCRA Hazardous Waste Sources
Collect a 3-6 random samples to obtain preliminary estimates of the average and variance
Estimate the minimum number of samples using a specified confidence interval
Using a sampling grid and random number assignments, collect and analyze at least the minimum number of samples from the waste source

26. Determine the average and variance from the detailed sampling plan
Procedure for the Simple Randomized Sampling of RCRA Hazardous Waste Sources
Determine the average and variance from the detailed sampling plan
If the sample mean is ≥ the regulatory threshold (RT), the compound is present in hazardous concentrations
If the sample mean is ≤ RT
Determine the confidence interval
If the upper CI < RT, the compound is not present

27. Class example from Text:
A drying bed holding sludge from an electroplating process is to be sampled for cadmium content. The dimensions of the drying bed are 6 m X 6 m, and the sample volume will require an area 40 cm X 40 cm. Five preliminary samples were collected randomly with the following results: 25, 36, 49, 28, and 48 mg/kg Cd. Based on this information, develop a simple randomized sampling scheme. Determine (1) number of samples required for 95% confidence limits within 5 mg/kg of the sample mean, and (2) the location of the samples in the sludge bed.

28. Solution
For the five preliminary samples,

29. Solution
From the Student’s t table (Appendix E), for df =n-1=4, and using α = 0.025, t95% = Note that 2α=5%, error level for 95% confidence level).
The number of samples (n) is:

30. Solution The number of sampling units in both directions is:
8 m/0.4 m = 20 unit, and
6 m/0.4 m = 15 units
Total sampling units is 20 x 15 = 300.
Then select 38 random number between 1 and 300.
MS Excel has a built-in function RANDBETWEEN().
RANDBETWEEN(1, 300) at 38 cells will generate 38 sampling locations in the 20x15 grid.
spreadsheet
......end of example

31. Stratified Random Sampling
Strategy involves dividing a site into layers or strata (subpopulations)
Strata are evaluated separately
Increases sampling precision for the entire population
For soils, the strata are simply horizontal layers at different depths

32. Stratified Random Sampling
Mean for each strata is determined by:
The mean over all strata is:
where
L = total number of strata
Nh = total number of sampling units in the hth stratum
N = total number of sampling units in all strata

33. Stratified Random Sampling
Sample variance within each stratum:
Variance of the sample mean over all strata:

34. Summary of Important Points and Concepts
Waste audits, which are based on materials balance, can be used to determine losses from volatilization, spillage, authorized removals to secure landfills or incineration, or improper management.
Waste audits also serve as a basis for waste minimization and pollution prevention plans.
Assessment of contaminated sites is based on a multi-step approach, with each phase characterized by succeeding complexity. (Phase I, II, and III)

35. Summary of Important Points and Concepts
Source materials, such as soils and sludges, are most effectively sampled using probability sampling.
Simplified random sampling is used in system which there is no gradient in contaminant concentration with depth. It is also the basis for probability sampling.
Stratified random sampling is used to sample systems where different strata contain a range of concentrations.