Problems of advanced nitrogen removal from municipal wastewaters in Kharkov (Ukraine)

Abstract

Among the methods of nitrogen removal biological method is the most effective, economical and environmentally friendly. Deep removal of nitrogen compounds is carried out using microbiological nitrification, denitrification, the anammox process. The purpose of the work is to study composition of nitrogen pollution in wastewater, delivered into the Kharkiv WWTP, to determine the nitrifying capacity of activated sludge in aeration tanks and to demonstrate prospects of the treatment efficiency increase through an advanced nitrogen removal. Hydrochemical analysis of aqueous media was conducted via standard methods according to Ukraine standards demands The nitrifying capacity of activated sludge of treatment facilities was determined using the biochemical and the microbiological methods. It was found that in the municipal wastewater, entering the WWTP, organic nitrogen makes approximately 50 percent of the total nitrogen value. The total load of ammonium nitrogen and organic nitrogen on the treatment plants was extremely higher than the permitted level. It was determined that the concentration of nitrifying bacteria in the activated sludge and its enzymatic nitrifying activity were high enough for municipal wastewater treatment plants. The deep treatment process in the aeration tank with activated sludge includes deep nitrification, while anammox process and the denitrification process do not occur at all. N-NH 4 concentration after the treatment essentially decreases (up to 92.5%). The most perspective way to increase efficiency of the nitrogen compounds removal is to increase time of the aerobic treatment to allow advanced oxidation of organic compounds and to improve the nitrification process (decrease of residual ammonium nitrogen concentration) and organization of a denitrification process for deep removal of nitrites and nitrates.