SPECTROPHOTOMETRIC METHOD FOR ANALYSIS OF TOTAL NITROGEN IN BIOTREATED MUNICIPAL SOLID WASTE PRODUCTS

摘要

The present work aims at developing an express methodology to determine the amount of total nitrogen in products from biologically treated municipal solid waste, an opportunity the spectrophotometry offers. This will help to promptly obtain information about the quality of the products and will further facilitate composting in taking a significant role in diverting bio-waste from landfills and reduce greenhouse gas emissions (CH_4).Nitrogen in the tested samples is mainly contained in the form of insoluble organic nitrogenous substances. To apply the spectrophotometric method for analysis it is necessary for them to be in water-soluble form. For this purpose, the source samples are previously subjected to oxidation with H_2O_2 in sulphuric acid medium, where the organic carbon is converted to CO_2 and the organic nitrogen turns into a water-soluble form. For the spectrophotometric analysis the soluble form of the nitrogen is required to be free NH_3. The results from the research give reason to draw the following conclusions: (i) the optimum conditions for the conversion of insoluble organically bound nitrogen to a water soluble form (free NH_3) have been determined; (ii) as a consequence the methodological error which was due to incomplete course of the analytical reaction has been corrected.