Determination of TOC in Solid Waste Application Note · TOC Solid Analyzer

Introduction

Depending on the origin of the waste material its composition can vary considerably. There are also numerous utilization possibilities for waste. From simply dumping the waste to a landfill, burning it for energy production or the recycling of the material, various usages are employed and therefore numerous analytical techniques are applied to determine different parameters of interest. When depositing domestic or industrial waste, sewage sludge, contaminated excavated soil, road waste (containing bitumen and tar), rubble from building sites and many other materials the total organic carbon (TOC) content is an important measure for the waste classification. E.g. according to the European Landfill Directive among other parameters, the TOC concentration of waste determines the assignment to a landfill class. On dumping sites organic waste components are subject to microbial decomposition, which leads on one hand to the formation of landfill gases, causing a smell nuisance and contributing to the greenhouse effect. On the other hand, decomposition products such as organic acids contribute significantly to the mobilization of heavy metals by complexation reactions. This leads to their transfer into the lower soil layers and to serious seeping water or ground water contamination. To prevent this, waste materials with increased TOC content need to be treated differently.

The basics for the determination of the parameter TOC in solids are described in the DIN EN 15936 (also: EN 13137). Various techniques can be used, but all are based on a treatment of the sample with an inorganic non oxidizing acid as one step of the complete procedure. The carbonates react with the acid and form CO2, which is either quantitatively determined using the approach of the so-called indirect method (TOC = TC - TIC) or the CO2 is just eliminated from the sample with the aim to measure the TOC directly afterwards.