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Piotr Maciołek*, Beata Janowska**, Kazimierz Szymański**
*Miejskie Wodociągi i Kanalizacja Sp. z. o. o. w Koszalinie; **Politechnika Koszalińska

Abstract
Discharge of raw wastewater which contains nutrients (nitrogen and phosphorus) can be hazardous for environment, due to its potential to cause eutrophication, oxygen reduction, and also toxicity in water bodies. Thus, it is needed to treat polluted water in terms of nutrient removal before discharging in environment. The study was conducted in the municipal wastewater treatment plant in Koszalin. It is one of the largest facilities in the Middle Pomerania. The planned flow capacity is about 40000 m3 per day. The average daily flow rate entering the plant is 20 500 m3 per day. This wastewater treatment plant operates with activated sludge systems. It utilizes high efficiency system for carbon, nitrogen and phosphorous removal from municipal wastewater. Currently, the total nitrogen content in the treated wastewater is approx. 10 mg N/dm3. In order to improve the efficiency of N removal within the existing capacities, the denitrification process can be enhanced by adding external carbon sources. The article presents the technological solutions aiming to improve the quality of treated wastewater. The research has proven that the use of an external carbon source, which was a commercial product KEM-CARBO GCM95, resulted in approx. 23% reduction in total nitrogen concentrations in treated wastewater. Preparation was dosed into the chambers of the denitrification a yield of 22 dm3/h. The results of studies were conducted in 2014. External carbon source was dosed at three different times – in April, June and late August. In 2015 were repeated. The ratio of organic pollutants in wastewater COD/BOD5 was approx. 2.0. On the other hand, the high ratio of BOD5/Nog ratio > 7.0 (the entire study period), indicating good susceptibility of wastewater on biological nitrogen removal in the process of denitrification. The use of preparation KEM-CARBO GCM 95, resulted in approx. 23% reduction in total nitrogen concentrations in treated wastewater. One of the practical methods to obtain required concentration of total nitrogen in treated wastewater is to increase the degree of internal recirculation. The practical method to obtain proper concentration of total nitrogen in treated wastewater is to increase the degree of internal recirculation and uniform distribution of wastewater on biological rectors.

Słowa kluczowe
ścieki komunalne, azot ogólny, zewnętrzne źródło węgla organicznego

Removal of Nitrogen from Municipal Wastewater Using an External Carbon Source

Key words 
municipal wastewater, total nitrogen, external carbon source

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