The effect of caffeine, metronidazole, and ibuprofen on continuous flow activated sludge process

BACKGROUND: The aim of this work was to study the biological treatment of a synthetic wastewater containing emerging contaminants. The 95-day experiment was conducted in an 81 L continuous flow conventional activated sludge apparatus consisting of anoxic and aerobic reactors with internal recycling, and a clarifier with activated sludge recycling. Real activated sludge from the municipal wastewater treatment plant in the Nur-Sultan city was used. The degradation efficiencies of caffeine, metronidazole, and ibuprofen in the synthetic wastewater were studied either separately or in combination. RESULTS: When treated separately at the concentration of 30 mg/L, the degradation of caffeine and ibuprofen was up to 100%, while the degradation of metronidazole was in the range of 12–27%. Caffeine and ibuprofen inhibited the nitrification process, while the presence of metronidazole in the system suppressed the activity of denitrifying microorganisms. The biological treatment of the synthetic wastewater containing all three compounds (at the concentration of 10 mg/L each) resulted in degradation of caffeine and ibuprofen up to 100%, and 56% in the case of metronidazole. As both nitrification and denitrification processes were affected, the total nitrogen removal was significantly reduced from 53% to 22%. CONCLUSION: Complete degradation of caffeine and ibuprofen, and partial degradation of metronidazole were observed in a synthetic wastewater using the activated sludge process. As the presence of emerging pollutants in a wastewater affects the general efficiency of the wastewater treatment plants, other physical or chemical pre-treatment should be utilized to minimize the harmful effect of contaminants on the biological processes

EVALUATION OF DECOUPLING OF GDP, ENERGY, AND CO2 EMISSIONS IN EU-15

Global warming, which is a consequence of the rapid increase of CO2 emissions, has attracted the world’s attention. Usually, the growth of economy occurs in parallel with the increase in energy demand, which in turn would lead to the high levels of GHG emissions. Decoupling provides reduction of environmental pressure without deterioration of economic growth of a country. In this study, decoupling relationship between GDP and CO2 emissions from public electricity and heat generation sector was investigated for EU-15 for the period from 1990 to 2014. The decoupling assessment was performed by using two methods: the Tapio decoupling elasticity method and OECD decoupling factor method. Based on results of both of those methods the decoupling states were defined. The results demonstrate that the decoupling states between GDP and CO2 emission intensity (CO2 emissions from public energy and heat production sector) fluctuated to a significant extent during the entire study period 1990-2014 for EU-15. Thus, no clear patterns for decoupling states were observed. Nevertheless, almost in all countries strong and weak decoupling were mostly occurred between GDP and CO2 emission intensity. In comparisons, the Tapio results represented more comprehensive picture of decoupling relationship between chosen indicators compared to the OECD method. Under the Kyoto Protocol, EU-15 countries were committed to reduce their GHGs emissions to 8% below the 1990 levels between 2008 and 2012. According to EEA, total EU- 28+Iceland emissions were below 1990 levels in 2014. It has been found that Austria, Denmark, Luxembourg and Spain produced significantly higher levels of emissions than their initial targets committed under the first commitment period 2008–2012 of Kyoto Protocol respect to 1990 levels. However, this tend to be not correlate with decoupling performance of countries in a specific sector. Among all countries of EU-15, only in Luxemburg the GDP strongly decoupled from CO2 emissions from public energy and heat production sector for almost the entire period 1990-2014, although Luxemburg did not reach its emission reduction target. According to results, the decoupling states tend to be dictated by the rate of change of GDP and CO2 emission intensity, which in turn depend on different factors. It was found that in general, decreasing the use of solid and liquid fuels, transition to nuclear power, shifting to more efficient technologies and growing shares of renewable energy sources in public electricity and heat production would promote decoupling of GDP from CO2 emission intensity in EU-15 member countries. Furthermore, our investigation has shown that the 2008-2009 global financial crisis had affected the economy and public energy and heat production sector of countries. As a result, the decoupling states of countries switched to strong negative decoupling state, which is the least desired state, during the crisis period and after it. Many researchers found that the population growth can significantly increase CO2 emissions in a country. Since significant population increase had not been observed for the period of our study in EU-15, effect of this factor can be considered less significant, except for France and Spain. Because the human population remained fairly stable during 1990-2014 for almost all EU-15 member countries. In the future, decoupling analysis should be combined with the decomposition technique to confirm which factors has significant effect on decoupling trends