Determination of the Mass Concentration of PCDDs/PCDFs (Stationary - PowerPoint PPT Presentation

Determination of the Mass Concentration of PCDDs/PCDFs (Stationary Source Emissions ) Department of Environment Islamic Republic of Iran (DoE)

Outline:  Department of Environment (DoE)- Iran  Dioxin / Furans (an overview)  Dioxins / Furans toxicity  Sources of Dioxins /Furans  Pathways of Human Exposures  Principle of the sampling procedure (EPA 23 & EN 1948)  Sampling devices and materials  Transportations and Storage, Sample Extraction and Clean-up techniques

Department of Environment (DoE) The DoE has established in 1971 and it’s responsible for matters related to protect the environment. The DoE is located in Pardisan Park, that is covering more than 270 hectares in the Northwest of Tehran. Currently, 66 Governmental Laboratories under the DoE and 285 the DOE-Trusted Laboratories are available in Iran.

Dioxin and Furans (PCDDS/PCDFS) Overview  Dioxins have two chlorinated benzene connected through a central ring with two oxygen atoms.  Furans have two chlorinated benzene connected through a central ring with one oxygen atom.  The chlorine atoms can be attached in 8 different places on the molecule. 135 pieces 75 pieces

Dioxins and Furans Toxicity Mono-, di-,tri- octa- chloro dioxins / furans show not really toxicity Most toxic of family are: 2,3,7,8-tetrachlorodibenzodioxin (TCDD) 2,3,7,8-tetrachlorodibenzofuran (TCDF) 1,2,3,7,8-pentachlorodibenzodioxin (PCDD) 2,3,4,7,8-pentachlorodibenzofuran (PCDF)  The toxicity of dioxins/ furans is calculated with the Toxicity Equivalence Factors (TEF) . In the report, PCDDS/PCDFS are added together form the value Toxicity Equivalent (TEQ). Cont.

PCCDs / PCDFs Toxic Equivalent Factors PCDD s Congeners I-TEFs PCDF S Congener I-TEFs Tetra-CDF 2,3,7,8 0.1 Tetra-CDD 2,3,7,8 1.0 Penta-CDF 1,2,3,7,8 0.05 Penta-CDD 1,2,3,7,8 0.5 2,3,4,7,8 0.5 Hexa-CDD 1,2,3,4,7,8 0.1 Hexa-CDF 1,2,3,4,7,8 0.1 1,2,3,6,7,8 0.1 1,2,3,6,7,8 0.1 1,2,3,7,8,9 0.1 1,2,3,7,8,9 0.1 2,3,4,6,7,8 0.1 Hepta-CDD 1,2,3,4,6,7,8 0.01 Hepta-CDF 1,2,3,4,6,7,8 0.01 Octa-CDD 1,2,3,4,6,7,8,9 0.001 1,2,3,4,7,8,9 0.01 Octa-CDF 1,2,3,4,6,7,8,9 0.001 TEF is a number assigned based on potency of the TCDD (the most toxic dioxin) .

Sources of Dioxins /Furans Anthropogenic Sources: As example: coal / oil and wood combustors, chlorine bleaching of paper, waste incinerators of all kinds, vehicle traffic, chemical production processes, accidental fires, most metal industries, specially sintering processes Natural Sources: As example: forest fires and volcano activities.

Emission of PCDDS/PCDFS from Combustion Processes Three general physicochemical pathways: 1. Contaminated feeding material 2. Molecular re-arrangement of precursor compounds 3. De-Novo- Synthesis of PCDDS/PCDFS Cont.

1. Contaminated Feeding Material  The first process occurs when the feed material going to the incinerator contains PCDDS/PCDFS and a fraction of these compounds persist in thermal breakdown mechanisms. This is not considered to account for a large volume of PCDDS/PCDFS released to the environment. 2. Molecular re-arrangement of Precursor Compounds  The second process is the formation of PCDDS/PCDFS from the thermal breakdown and molecular rearrangement of precursor compounds. The precursor compounds are such as chlorinated benzenes, chlorinated phenols and PCBs, which are resemblances to the PCDDS/PCDFS molecules. Cont.

3. De-Novo- Synthesis of PCDDS/PCDFS  The third process called De-Novo-Synthesis of PCDDS/PCDFS . In this mechanism , inorganic chloride compounds such as NaCI or HCI will form to chlorine (CI2) in the presence of oxygen and subsequently, Cl2 reacts with aromatic components. Therefore destruction of PCDD/PCDF depending on temperature and oxygen concentration.  The De-Novo-Synthesis is most active in a temperature range of 200 - 500 °C with a maximum at approximately 350 ° C.

Pathways of Human Exposures  Ingestion  Inhalation of vapors and particulates  Dermal contact Health Effects:  Acute symptoms/short term • skin darkening • liver dysfunction  Chronic symptoms/long term • diabetes • cancer • birth defects • physical deformities, • mental disabilities, etc.

Stockholm Convention: Iran signed the Stockholm Convention in May 2001 and ratified it in February 2006. Iran as well as other countries agree to reduce or eliminate the production, use or release of the 12 persistent organic pollutants (POPs) and PCDDS/PCDFS are in the list of POPs chemicals. Commonly used devices for controlling Air Pollution:  Dry Scrubbers Cyclones, Electrostatic Precipitators (ESP), Fabric Filters (bag houses),  Wet Scrubbers

Principle of Sampling Procedure (EPA 23 & EN 1948) Isokinetic Sampling To perform isokinetic sampling, it is necessary that the velocity and direction of the gas entering the nozzle is the same as the velocity and direction of the stack gas at the sampling point. 𝑗𝑡𝑝𝑙𝑗𝑜𝑓𝑢𝑗𝑑 𝑠𝑏𝑢𝑗𝑝 % = (Velocity at the nozzle / Velocity of the stack gas) ∗ 100 Isokinetic ratio during the sampling differs by more than 5% to +15% the measurement is not valid.

1- Velocity Calculation V = stack gas velocity (m/s) K = pitot tube velocity constant (34.97) C = velocity pressure coefficient (for S-type pitot=0.84) (dimensionless) ΔP = square root of differential pressure of stack gas (mmH20) T stack = stack temperature (ºC) M = molecular weight of stack gas, wet basis (g/g mole) P = absolute stack gas pressure (mm.Hg)

Molecular Weight The dry weight component (CO2, O2, N2) of the stack gas is calculated by: M= 0.44 (%CO2) + 0.32 (%O2) + 0.28 (%N2) M dry = dry molecular weight of stack gas (g/g mole) %CO2 = percentage CO2 in gas stream %O2 = percentage O2 in gas stream % N 2 = 100 – ( % CO 2 + % O 2 + % CO ) 44(g/g mole) = MW carbon dioxide 32(g/g mole) = MW oxygen 28(g/g mole) = MW carbon monoxide 28(g/g mole) = MW nitrogen

Traverse Points Minimum required number of traverse points for sampling sites which meet specified criteria 2- Volumetric flow rate in the stack Volumetric flow rate (m3/s)= Duct area (m2) x average velocity of stack gases (m/s)

Location of Sampling Port Sampling ports shall be located at least 8 times stack diameter down stream (B) and 2 times up stream (A) from any flow disturbance. Platform access shall be safe and easy access to the work platform and provided via caged ladder, stairway, or other suitable ways.

Sampling Procedure (EN 1948) Gas is sampled isokinetically in the duct. The PCDDs/PCDFs, both adsorbed on particles and in the gas phase, are collected in the sampling train. The collecting parts can be  Filter  Condensate flask  Solid adsorbent It’s possible to choose between three different methods:  Filter/Condenser Method  Dilution Method  Cooled Probe Method

Initial Checks before Sampling Temperature Profiles   Power Supply  Nozzle Selection  Safe Platform  Gas Oxygen  Sampling Ports (Correct Positions)  Moisture Contents  Gas Velocity Filter/Condenser Method (Sampling train) The sample gas is sucked through the nozzle, probe and filter (< 125 °C). Then the gas passes the condenser and the condensate flask and adsorbent by suction device.

Cleaning Sampling Devices: 1) Cleaning of the sampling equipment in the laboratory. Normally rinsing with water and detergent, followed by rinsing with solvent and/or treatment in a muffle oven for several hour (around 400 C). 2) Rinsing with solvent prior to sampling (can be done either in the laboratory or at sampling site). 3) Rinsing the equipment being in contact with the stack gas with solvents after the sampling. This rinsing solution is an important part of the sample (acetone or methanol followed by toluene or dichloromethane

Record keeping (at least every 15 min)  Gas velocity  Filter temperature (heated box)  Temperature profile in duct  Adsorbent temperature  Pressure data  Oxygen content  Flow rate Leakage Test A leak check shall be carried out before and after every sampling procedure. The sampling train is plugged nozzle (inlet) and the volume flow rate shall be less than 5 % of the normal flow rate.

Field Blank The field blank is taken at the operator’s site according the following procedure:  The probe is not inserted into the stack  No gas is drawn through the sampling train  A leak check is performed  A field blank procedure shall be performed at least before each measurement series.  The value of this field blank shall not exceed 10 % of the emission limit value and shall be reported with the corresponding measured values

After Sampling -The glassware and connections are rinsed with 100 ml each of acetone and dichloromethane -The rinsing solutions are combined with the condensate -The adsorbent (PU foam/ XAD2) is collected -All the parts are properly labelled Sample Storage The samples shall be stored in the dark not higher than room temperature (approx. 25°C).

PCDDs/ PCDFs Sampling Train (EPA 23) Front Half Back Half Front Half Probe Nozzle FH Filter Holder Back Half Filter Support BH filter Holder Condenser Transfer Line Cont.