BS 16166:2021 pdf download – Soil, treated biowaste and sludge — Determination of adsorbed organically bound halogens (AOX)

BS 16166:2021 pdf download – Soil, treated biowaste and sludge — Determination of adsorbed organically bound halogens (AOX) 8 Sample storage and pretreatment 8.1 Sampling and storage For the sampling and storage of sludge samples, refer to existing standard, e.g. [2] and [3]. Samples shall be stored in suitable containers with an appropriate closure material such as PTFE. Samples to be frozen may be stored in aluminium containers pre-cleaned by heating to 450 °C for minimum 4 h or by rinsing with a non-chlorinated solvent. Samples shall be kept at a temperature of (5 ± 3) °C and in the dark. The sample pretreatment for sludge samples should take place within 24 h of sampling. Alternatively, samples can be frozen (−18 ± 3) °C) directly after sampling and kept frozen for a maximum of one month before sample pretreatment. 8.2 Sample pretreatment Pretreat the samples according to EN 16179 [8], if not otherwise specified. Cool the dried test sample in a desiccator, comminute and homogenize in an analytical mill or porcelain mortar (7.3.4) to a particle size of no more than 0,1 mm. Store the ground material in a desiccator or a tightly closed glass container. The homogenised wet sample portion may alternatively be freeze-dried, which in some cases makes homogenizing of the dried sample easier. 9 Procedure 9.1 General The test portion taken for analysis shall have an AOX value within the working range of the instrument. NOTE A typical working range is between 1 µg to 30 µg chlorine (absolute titrated amount). 9.2 Adsorption and inorganic halide removal Ensure that the dried, ground test sample is homogenized by stirring or shaking before taking the test portion. Prepare the test portion for combustion as follows: — Transfer a homogenized test portion of 10 mg to 100 mg depending on the expected AOX content to a conical flask or screw cap vial (7.2.3). — Add approx. 20 mg activated carbon (6.1) and 10 ml nitrate stock solution (6.7) to the sample. The amount of activated carbon shall be the same for all test samples, blank determinations, etc. — Shake for 1 h using a mechanical shaker (7.2.4). — Filter the suspension through a filtration apparatus (7.2.1) using nitrate washing solution (6.8). Wash the filter cake with small amounts of nitrate washing solution. Use a total volume of 25 ml to ensure complete transfer. — Transfer the moist filter and the...