Reference method for PCDDs and PCDFs in pulp and paper mill effluents: appendix A

1.0 Introduction

It is important to ensure that representative samples are collected which are free from outside contamination, and are properly preserved. The following is proposed as a means of collecting representative samples, and minimizing sample contamination and degradation.

Two 1-L composite samples should be collected for each final effluent and combined bleach plant effluent as defined in the following sections and at the frequencies specified in Schedules I and II of the Pulp and Paper Mill Effluent Chlorinated Dioxins and Furans Regulations. These samples may be prepared by using either manual or automatic sampling techniques as described in Section 3 of this Appendix.

2.0 Sample Contamination

There is the potential for contamination in every step of collection, preservation, shipping, and handling of dioxin/furan samples. Some sources of potential contamination include improperly cleaned sample containers, tubing, etc., poor handling, not using or improper use of latex gloves, and dirty conditions at sampling sites. Amber glass bottles with Teflon-lined caps are the best sample containers for dioxin/furan samples. Samples should never come into contact with plastic other than Teflon, except at autosampler pump heads where minimal lengths of surgical silicone tubing are acceptable. All sample containers (bottles, graduates, etc.) should be washed with standard laboratory-grade detergent, followed by rinsing with aliquots of deionized water, acetone, hexane, and dichloromethane. Containers should be air-dried in a contaminant-free area and then capped or foil-covered before use. Precleaned and proofed bottles are commercially available.

It is recommended that all sampling devices and equipment, their containers and all tubing, valves and contact components be dedicated to a particular sampling site in order to minimize the possibility of cross-contamination. It is the user's responsibility to demonstrate that the sampling equipment is clean, free from contamination, and suited for sampling and analysis needs. Generally, the cleaning and preparation of any relocated equipment should include hot water, phosphate-free detergent washing, hot water rinse, acetone rinse, hot and cold water rinses, distilled water rinse. Contact openings of cleaned equipment should be foil-covered in transit.

It is also recommended that new non-talc latex gloves be put on just before handling the sample aliquot bottle at each site, after any dirty work is completed. This precaution minimizes opportunity for cross-contamination.

3.0 Sampling of Final Effluent

Final effluent samples should be collected in the stream discharging to receiving waters, downstream of all on-site wastewater treatment devices. If there are multiple points of discharge, then each discharge stream must be sampled, to be composited later into a single final effluent. Samples can be collected by either a manual or automated method. With either method, it is essential to collect at a point of thorough mixing.

3.1 Manual Sampling Method

The sample can be collected by using simple field equipment, including buckets, funnels, and suitable lengths of chain or dip poles. The equipment must be suited to the sampling and analysis being performed, and should generally be dedicated to the sampling site. Special procedures for cleaning of relocated equipment are defined in Section 2 of this Appendix.

This approach is less rigorous than continuous automated sampling, and requires manual sampling of the effluent stream at regular intervals over a 24-hour period, in order to obtain a representative sample.

Manual sampling can be conducted using an automated sampler in manual mode in cases of automatic mode failure.

3.1.1 Detailed Sample Collection Procedure

The sample shall be obtained by taking manual grab samples in precleaned 500-mL aliquot bottles at a frequency of one grab sample at least every three hours (over a 24-hour period) from a representative point in the final effluent stream.

The following procedure should be undertaken during sample collection.

  1. Open sampling valves and/or sewer covers.
  2. Put on latex gloves.
  3. Remove cap from a precleaned aliquot bottle.
  4. Place cap liner up on a surface away from potential sources of contamination.
  5. Place the bottle in a reaching-assist device (if necessary) and place in the flow. If not possible, use a pre-washed, stainless steel bucket to collect the sample.
  6. Rinse the aliquot bottle (or bucket) twice with the sample to be collected.
  7. Fill the aliquot bottle with the sample.
  8. Rinse the cap by pouring about 10% of the contents of the aliquot bottle over the cap.
  9. Refill the aliquot bottle to the top.
  10. Place the bottle on a solid surface.
  11. Screw the cap onto the aliquot bottle.
  12. Identify all aliquot bottles as to their contents, location and time of sampling.
  13. Place the aliquot bottle into a cooler (kept at 1 to 5°C).
  14. Close all sampling valves and sewer covers.
  15. At the end of the 24-hour period, transport the aliquot bottles to the laboratory in the cooler.
  16. From each aliquot bottle, transfer the required volume [see (q)] into each of two precleaned l-L sample bottles, as follows:

    • rinse a 500-mL precleaned graduated cylinder, specific for the effluent stream;
    • for rinsing, shake the aliquot bottle and pour 10 mL into the 500-mL graduated cylinder. Ensure all inside surfaces are thoroughly rinsed. Pour the rinsing volume out, and repeat the rinse with another 10 mL;
    • shake the aliquot bottle again and pour the required volume [see (q)] into the 500-mL graduated cylinder;
    • pour this volume into one of the 1-L sample bottles; and,
    • repeat the shake and pour sequence for the second 1-L bottle.
  17. The required volume from each aliquot bottle is 1 L divided by the number of aliquot bottles (for a time-proportional sample). For a flow-proportional sample, this volume is multiplied by the ratio: flow at aliquot collection/24-hour average flow.
  18. Tightly cap both I -L bottles with precleaned Teflon caps, and identify as to contents, location and date.

3.2 Autosampling Method

Final effluent samples may be collected by using automated sampling equipment. The autosamplers must be mechanically and electrically suited to the environment in which they will serve, and should be easily accessible for routine inspection and maintenance. Ability to obtain a representative sample, material composition, and temperature stability are the three most important characteristics of automated sampling equipment.

It is essential that the autosampler take its sample from a location in the final effluent stream that will provide a representative point of thorough mixing. The material composition characteristics can generally be met through consistent use of materials such as stainless steel, Teflon and glass. Minimal lengths of surgical grade silicone rubber tubing may be used at peristaltic pump heads.

The temperature stability is best monitored with a continuous temperature recorder and documented in a sampler-specific log book that is kept close to the sampler. This log book should also incorporate repair, inspection, routine use, and maintenance records.

The detailed automatic sampling procedure recommended by the automatic sampling equipment suppliers should be followed.

Two 1-L 24-hour composite samples of the final effluent shall be collected during a period of 24 hours by:

  1. taking a continuous sample of the final effluent at a constant or flaw-proportional rate;
  2. compositiog final effluent aliquots of equal volume (taken at least every three hours); or,
  3. compositiog final effluent aliquots of equal volume (taken at least every three hours) in a quantity proportional to flow at the time of aliquot collection.

The autosampler should be programmed, if possible, to utilize the purge function. It should produce sufficient or more than sufficient volume at the end of 24 hours. If it fills a single container only, the sample should be split into two 1-L sample bottles at the end of the sampling period, while stirring with a precleaned glass rod, leaving a slight headspace. If it fills one or more series of separate aliquot bottles, transfer to two 1-L sample bottles as described in Subsection 3.1.1(p), or by direct shaking and pouring if volumes are equal to those required.

3.3 Compositing of Multiple Discharges

If there are multiple discharges, separately sampled, then a flow-proportional composite sample must be prepared. The method described in Subsection 4.3 of this Appendix is followed to produce two 1-L composite sample bottles.

4.0 Sampling of Combined Bleach Plant Effluent

A combined bleach plant sample is produced for each bleach plant. It includes all seal tank overflows that leave the bleach plant, excluding any recycle flows that are reused within the bleach plant. It also excludes any lime mud or other additions from outside the bleach plant. It will usually be necessary to obtain the sample manually, as a flow-proportional composite of acid and alkaline filtrates or acid and alkaline sewers. Results should be reported with associated total effluent flows for each bleach plant

4.1 Manual Sampling

4.1.1 Detailed Sample Collection Procedure

In the case of acid sewer or acid bleach filtrates, the following additional procedure should be taken for each sampled stream.

  1. Before beginning sampling of each aliquot: obtain the residual chlorine reading from the bleach plant operator.
  2. The procedure (j) as described in Subsection 3.1.1 should be followed by: adding Na2S03, proportional to the amount shown in Table A.1 (based on the residual chlorine reading) to the aliquot bottle.
Table A.1: Sodium sulphite requirements for acide sewer or acid bleach filtrate aliquot bottles
Chlorine Residual (mg/L) Amount of Na2SO3 Required for Each 500-mL Aliquot Bottle (mg)
1 - 100 95
101- 200 191
201- 300 287
301- 400 382
401- 500 478

4.2 Automatic Sampling

Procedures follow those described in Subsection 3.2, with the additional requirement for acid streams of pre-charging autosampler bottles with Na2S03. The amount is determined from Table A.1, considering the autosampler bottle volume and the expected limit of chlorine residual.

4.3 Compositing Techniques for Bleach Plant Effluent

The combined bleach plant effluent sample is prepared by flow-proportional compositing of the individual effluent samples. Flows for the individual bleach plant effluent streams may be estimated by mass balance. The flow data for each effluent shall be obtained before preparing the final composite at the end of the 24-hour period.

The procedure for flow-compositing at the end of the 24-hour sampling period is applied to each of the two 1-L samples as follows.

  1. Rinse a 500-mL precleaned graduated cylinder specific for each composite required.
  2. For rinsing, shake the 1-L bottle representing the largest flow, and pour 10 mL into the 500-mL graduated cylinder. Ensure all inside surfaces are thoroughly rinsed. Pour the rinsing volume out, and repeat the rinse with another 10 mL.
  3. Shake this bottle again and then pour the required volume (see Note 1) into the 500-mL graduated cylinder.
  4. Pour this volume into the precleaned 1-L composite sample bottle.
  5. Repeat the compositing procedure with all remaining samples contributing to the final composite.
  6. Tightly cap the composite bottle, with a precleaned Teflon cap, and identify as to contents, location and date.

Note 1: The required volume to be retained from each contributing effluent is 1 L times the ratio: average flow of contributing effluent/total of average flows for all contributing effluents.

5.0 Shipping and Storage of Samples

All samples should be kept at 1 to 5°C during collection and shipping to minimize the potential for degradation. Shipping coolers will be equipped with a suitable number of ice packs to ensure that the samples are kept cold. Individual bottles in the cooler should be separated by protection sleeves and any large empty spaces in the cooler should be filled. Automatic samplers should have their own cooling system.

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