Determination of TKN in Water, Waste Water and Sludge by Kjeldahl Method (CAT#: STEM-EA-0050-ZJF)

Introduction

Nitrogen ends up in the environment mainly through agricultural processes, and thereby also ends up in water. The main source of nitrogen compounds in water are inorganic fertilizers that mainly contain nitrates, but also ammonia, ammonium, urea and amines. After fertilization, crops take up a relatively small part of added nitrogen compounds, namely 25-30%. The residue ends up in groundwater and surface water through soil. Organic fertilizers (such as guano) mainly contain nitrogen as proteins, urea or amines, which have different mechanisms of absorption. Nitrogen compounds are also applied in several different industries. Thereby other nitrogen compounds, such as nitrous oxide applied in anaesthetics, can be produced. Nitric acid, urea, hydrazine and amines are other products from nitrogen industries. Nitrogen compounds are by-products of colouring and synthetic agent production. From an analytical point of view, the properties of water, waste water and sludge samples can vary considerably depending upon their source; in unpolluted waters, low nitrogen levels make it necessary to use large sample volumes, whereas high concentrations of surface active agents in some waste waters can also cause foaming during the initial step of the digestion so the volume required by the analysis is lower.