COD Fractions in Sewage Flowing into Polish Sewage Treatment Plants

The paper presents the results of studies concerning the designation of COD fraction in raw wastewater. The research was conducted in three mechanical-biological sewage treatment plants. The results were compared with data assumed in the ASM models. During the investigation, the following fractions of COD were determined: dissolved non-biodegradable SI, dissolved easily biodegradable SS, in organic suspension slowly degradable XS, and in organic suspension non-biodegradable XI. The methodology fordetermining the COD fraction was based on the ATV- A 131guidelines. The real concentration of fractions in raw wastewater and the percentage of each fraction in total CODare different from data reported in the literature

The fate of nitrogen in the urban area – The case of Zielona Góra, Poland

The anthropogenic change of the nitrogen (N) cycle is strongly triggered by urban demand (such as food and meat consumption, energy demand and transport). As a consequence of high population density, impacts on human health through water and air pollution also concentrate on a city environment. Thus, an urban perspective on a predominantly rural pollution becomes relevant. Urban N budgets may be considered less intrinsically connected, so that separation of an agri-food chain and an industry-combustion chain is warranted. Results have been obtained for Zielona Góra, Poland, a city of 140,000 inhabitants characterized by domestic and transport sources and forest-dominated surroundings. In addition to food imports in Zielona Gora amounting to about 30 %, in the suburban area a significant share of N amounting to 41 % is related to fertilizer imports. The remaining imports are in fuel, electronics, textiles, plastics and paper. Most of the agri-food N (45 %) is denitrified in wastewater treatment. N associated with combustion (mainly NOx emissions from vehicles) represents a much smaller share than N entering via the agri-food system, amounting to 22 % of the total N imports. This overall picture is maintained also when specifically addressing the city center, with the exception of mineral fertilizer that plays a much smaller role, with just 7 % of N imports to the city

Urban nitrogen budgets: flows and stock changes of potentially polluting nitrogen compounds in cities and their surroundings – a review

Concepts of material flow and mass consistency of nitrogen compounds have been used to elucidate nitrogen’s fate in an urban environment. While reactive nitrogen commonly is associated to agriculture and hence to large areas, here we have compiled scientific literature on nitrogen budget approaches in cities, following the central role cities have in anthropogenic activities generally. This included studies that specifically dealt with individual sectors as well as budgets covering all inputs and outputs to and from a city across all sectors and media. In the available data set, a clear focus on Asian cities was noted, making full use of limited information and thus enable to quantitatively describe a local pollution situation. Time series comparisons helped to identify trends, but comparison between cities was hampered by a lack of harmonized methodologies. Some standardization, or at least improved reference to relevant standardized data collection along international norms was considered helpful. Analysis of results available pointed to the following aspects that would reveal additional benchmarks for urban nitrogen budgets: analysing the share of nitrogen that is recycled or reused, separating largely independent sets of nitrogen flows specifically between food nitrogen streams and fossil fuel combustion-related flows, and estimating the stock changes for the whole domain or within individual pools

Efektywność upłynnienia ChZT odpadów komunalnych w dezintegracji termicznej

This paper presents the content changes in the Chemical Oxygen Demand (COD) solubilised in hydrolisates obtained from thermally disintegrated municipal waste biofractions. A series of tests related to biowaste undergoing thermal treatment at the following temperatures: 55, 75, 95, 115, 135, 155 and 175°C were conducted for 0.5, 1 and 2 hours. The highest increase in COD solid fraction solubilisation (238%) was observed for the samples disintegrated at 175°C for 2 hours. The values of the reaction rate coefficient k20 = 0.6 d-1 and temperature coefficient θ = 1.023 were determined. Statistical analysis of the multiple regression (correlation coefficient R = 0.89) showed that the temperature has a greater impact on COD solid fraction solubilisation - determined β = 0.66. The multiple correlation coefficient for the treatment time was β = 0.61.W artykule omówiono zmiany udziału ChZT rozpuszczonego w hydrolizatach uzyskanych z dezintegrowanej termicznie bioofrakcji odpadów komunalnych. Wykonano serie badań, w których bioodpady poddawano obróbce w temperaturach 55, 75, 95, 115, 135, 155, 175°C w czasie 0,5, 1 i 2 godzin. Największy wzrost upłynnienia frakcji stałej ChZT (238%) uzyskano dla próbek dezintegrowanych w temperaturze 175°C w czasie 2 godzin. Wyznaczono wartość współczynnika szybkości reakcji k20=0,096 h i współczynnika temperaturowego θ=1,053. Analiza statystyczna wyników badań wykazała, że większy wpływ na efekt dezintegracji ma temperatura, niż czas obróbki

Mechanizmy procesów biologicznych w przydomowych oczyszczalniach ścieków

The growing demand for solutions of household sewage treatment plants means that many new or improved technological solutions are available on the market. The implementation of these technologies is associated with the need to known the mechanisms of the unitary biological processes occurring when removing organic carbon, nitrogen and phosphorus from wastewater. Determining the optimal conditions for these processes will determine the correct operation of the household sewage treatment plant.Rosnący popyt na rozwiązania oczyszczalni przydomowych spowodował, że na rynku dostępnych jest wiele nowych lub ulepszonych rozwiązań technologicznych. Wdrażanie tych technologii wiąże się z koniecznością poznania mechanizmów jednostkowych procesów biologicznych zachodzących podczas usuwania ze ścieków związków węgla organicznego, azotu i fosforu. Ustalenie optymalnych warunków prowadzenia tych procesów decydować będzie o poprawnej eksploatacji przydomowej oczyszczalni ścieków

Influence of thermal disintegration on rate of organic waste biodegradation

Dezintegracja jest fizyczno-chemicznym upłynnianiem złożonych substratów organicznych do produktów w postaci cząsteczkowych cukrów, białek i tłuszczy oraz frakcji nierozkładalnych. W literaturze ten etap rozkładu najczęściej nazywany jest hydrolizą. W artykule przedstawiono wyniki badań na podstawie których wyznaczono stałą szybkości biodegradacji dla surowej biofrakcji odpadów komunalnych oraz po dezintegracji termicznej.Disintegration is the physical-chemical liquefaction of complex organic substrates to molecular products in the form of sugars, proteins and fats and persistent fractions. In the literature, this phase of degradation is commonly called hydrolysis. This paper presents the results of determining of the rate constant for the biodegradation of raw biofraction of mu-nicipal waste and thermally disintegrated fraction

Hydrolysis in biodegradation of organic waste

W artykule przedstawiono podstawowy opis matematyczny reakcji hydrolizy substratów organicznych. Zestawiono przykładowe wartości stałych hydrolizy enzymatycznej (kh) i biodegradacji (kb) dla osadów ściekowych oraz dla wybranych odpadów.The paper presents the basic mathematical description of the hydrolysis reaction of organic substrates. It was examples of enzymatic hydrolysis (kh) and biodegradation (kb) constant values for sewage sludge and for selected waste summarized

Cod balance in biological treatment of wastewater - part II - technical scale

W artykule sporządzono bilans ChZT dla układu technologicznego oczyszczalni ścieków w Sulechowie. Podstawy teoretyczne bilansowania oraz przykładowe obliczenia bilansów ChZT na podstawie badań przeprowadzonych w skali laboratoryjnej opisano w pracy "Bilans ChZT w biologicznym oczyszczaniu ścieków osadem czynnym - cz. I - skala laboratoryjna".In this article the balance of COD for wastwater treatment plant in Sulechow was prepared. The theoretical bases of COD balancing and the example calculations were in the work "COD balance in biological treatment of wastewater - part I - laboratory scale" described

Cod balance in biological treatment of wastewater - part I - laboratory scale

W artykule przedstawiono metodę bilansowania ChZT w układach oczyszczania ścieków osadem czynnym. Sporządzono bilans ChZT dla laboratoryjnych układów technologicznych. Potwierdzono, że zbilansowanie ChZT możliwe jest wyłącznie dla reaktorów tlenowych lub układów anoksyczno/tlenowych.In this article, the bases of COD balancing in aerobic, anoxic and anaerobic activated sludge systems were introduced. Literature data has been showing, that simulations of balances COD close 100% are possible for aerobic reactors or anoxic/aerobic systems. On systems including anaerobic zones the balance of COD is close maximally in 85%. It is suggested, that the "loss" COD, which becomes appointed in balances, is associated with the process of hydrolysis or the fermentation of organic matter. Inappropriate accepting the "loss" COD in modelling and optimization of activated sludge process, influences on the growth of aeration costs and quantity of sewage sludge