Assessment of Nitrous Oxide and Carbon Dioxide Emissions and the Carbon Footprint in an Aerobic Granular Sludge Reactor Treating Domestic Wastewater

Author(s):  
Gilberto Caye Daudt ◽  
Bruna Scandolara Magnus ◽  
Cássio Moraes Schambeck ◽  
Nelson Libardi ◽  
Rejane Helena Ribeiro da Costa
Author(s):  
Sara Toja Ortega ◽  
Mario Pronk ◽  
Merle K. de Kreuk

Abstract Complex substrates, like proteins, carbohydrates, and lipids, are major components of domestic wastewater, and yet their degradation in biofilm-based wastewater treatment technologies, such as aerobic granular sludge (AGS), is not well understood. Hydrolysis is considered the rate-limiting step in the bioconversion of complex substrates, and as such, it will impact the utilization of a large wastewater COD (chemical oxygen demand) fraction by the biofilms or granules. To study the hydrolysis of complex substrates within these types of biomass, this paper investigates the anaerobic activity of major hydrolytic enzymes in the different sludge fractions of a full-scale AGS reactor. Chromogenic substrates were used under fully mixed anaerobic conditions to determine lipase, protease, α-glucosidase, and β-glucosidase activities in large granules (>1 mm in diameter), small granules (0.2–1 mm), flocculent sludge (0.045–0.2 mm), and bulk liquid. Furthermore, composition and hydrolytic activity of influent wastewater samples were determined. Our results showed an overcapacity of the sludge to hydrolyze wastewater soluble and colloidal polymeric substrates. The highest specific hydrolytic activity was associated with the flocculent sludge fraction (1.5–7.5 times that of large and smaller granules), in agreement with its large available surface area. However, the biomass in the full-scale reactor consisted of 84% large granules, making the large granules account for 55–68% of the total hydrolytic activity potential in the reactor. These observations shine a new light on the contribution of large granules to the conversion of polymeric COD and suggest that large granules can hydrolyze a significant amount of this influent fraction. The anaerobic removal of polymeric soluble and colloidal substrates could clarify the stable granule formation that is observed in full-scale installations, even when those are fed with complex wastewaters. Key points • Large and small granules contain >70% of the hydrolysis potential in an AGS reactor. • Flocculent sludge has high hydrolytic activity but constitutes <10% VS in AGS. • AGS has an overcapacity to hydrolyze complex substrates in domestic wastewater. Graphical abstract


2008 ◽  
Vol 88 (2) ◽  
pp. 163-174 ◽  
Author(s):  
C F Drury ◽  
X M Yang ◽  
W D Reynolds ◽  
N B McLaughlin

It is well established that nitrous oxide (N2O) and carbon dioxide (CO2) emissions from agricultural land are influenced by the type of crop grown, the form and amount of nitrogen (N) applied, and the soil and climatic conditions under which the crop is grown. Crop rotation adds another dimension that is often overlooked, however, as the crop residue being decomposed and supplying soluble carbon to soil biota is usually from a different crop than the crop that is currently growing. Hence, the objective of this study was to compare the influence of both the crop grown and the residues from the preceding crop on N2O and CO2 emissions from soil. In particular, N2O and CO2 emissions from monoculture cropping of corn, soybean and winter wheat were compared with 2 -yr and 3-yr crop rotations (corn-soybean or corn-soybean-winter wheat). Each phase of the rotation was measured each year. Averaged over three growing seasons (from April to October), annual N2O emissions were about 3.1 to 5.1 times greater in monoculture corn (2.62 kg N ha-1) compared with either monoculture soybean (0.84 kg N ha-1) or monoculture winter wheat (0.51 kg N ha-1). This was due in part to the higher inorganic N levels in the soil resulting from the higher N application rate with corn (170 kg N ha-1) than winter wheat (83 kg N ha-1) or soybean (no N applied). Further, the previous crop also influenced the extent of N2O emissions in the current crop year. When corn followed corn, the average N2O emissions (2.62 kg N ha-1) were about twice as high as when corn followed soybean (1.34 kg N ha-1) and about 60% greater than when corn followed winter wheat (1.64 kg N ha-1). Monoculture winter wheat had about 45% greater CO2 emissions than monoculture corn or 51% greater emissions than monoculture soybean. In the corn phase, CO2 emissions were greater when the previous crop was winter wheat (5.03 t C ha-1) than when it was soybean (4.20 t C ha-1) or corn (3.91 t C ha-1). Hence, N2O and CO2 emissions from agricultural fields are influenced by both the current crop and the previous crop, and this should be accounted for in both estimates and forecasts of the emissions of these important greenhouse gases. Key words: Denitrification, soil respiration, rotation, crop residue


2012 ◽  
Vol 610-613 ◽  
pp. 2120-2128 ◽  
Author(s):  
Jun Xia Peng ◽  
Liang Huang ◽  
Yu Bo Zhao ◽  
Pan Chen ◽  
Lu Zeng ◽  
...  

Input-output model on cement plants were established. Carbon dioxide emissions of key steps and carbon footprint of products were calculated and predicted using the input-output model. The results showed that CO2 emission in the plant (the production of the plant is 1320000t a year) reached 910000 t a year and CO2 emission per ton product is 0.689 ton. Over 80% of the total CO2 was emitted during the process of firing,so the firing process is the key step for reducing CO2 emission in the cement plant. Carbon footprint of three kinds of cement products including ordinary portland cement, portland pozzolan cement and portland blast furnace slag cement are 0.76, 0.59, 0.72 respectively.


2009 ◽  
Vol 2009 ◽  
pp. 249-249
Author(s):  
H Prosser

The work of the UK Climate Change Commission (UKCCC) in recommending targets and options for reducing emissions of greenhouse gases is focusing attention on what agriculture and land use can contribute to deliver these targets. Although overall the major issue is the reduction of carbon dioxide emissions from energy use, agriculture and land use are significant emitters of methane and nitrous oxide. UKCCC has identified three main routes by which emissions can be reduced• Lifestyle change with less reliance on carbon intensive produce -eg switching from sheep, and beef to pig, poultry and vegetables.• Changing farm practices – eg to improve use of fertilisers and manures• Using new technology on farms – eg modifying rumen processes, anaerobic digestion.


2020 ◽  
Vol 305 ◽  
pp. 122961 ◽  
Author(s):  
Riccardo Campo ◽  
Sara Sguanci ◽  
Simone Caffaz ◽  
Lorenzo Mazzoli ◽  
Matteo Ramazzotti ◽  
...  

2018 ◽  
Vol 98 (3) ◽  
pp. 389-398 ◽  
Author(s):  
K.P. Edwards ◽  
C.A. Madramootoo ◽  
J.K. Whalen ◽  
V.I. Adamchuk ◽  
A.S. Mat Su ◽  
...  

Irrigation practices change the soil moisture in agricultural fields and influence emissions of greenhouse gases (GHG). A 2 yr field study was conducted to assess carbon dioxide (CO2) and nitrous oxide (N2O) emissions from surface and subsurface drip irrigated tomato (Solanum lycopersicum L.) fields on a loamy sand in southern Ontario. Surface and subsurface drip irrigation are common irrigation practices used by tomato growers in southern Ontario. The N2O fluxes were generally ≤50 μg N2O-N m−2 h−1, with mean cumulative emissions ranging between 352 ± 83 and 486 ± 138 mg N2O-N m−2. No significant difference in N2O emissions between the two drip irrigation practices was found in either study year. Mean CO2 fluxes ranged from 22 to 160 mg CO2-C m2 h−1 with cumulative fluxes between 188 ± 42 and 306 ± 31 g CO2-C m−2. Seasonal CO2 emissions from surface drip irrigation were significantly greater than subsurface drip irrigation in both years, likely attributed to sampling time temperature differences. We conclude that these irrigation methods did not have a direct effect on the GHG emissions from tomato fields in this study. Therefore, both irrigation methods are expected to have similar environmental impacts and are recommended to growers.


2013 ◽  
Vol 77 (3) ◽  
pp. 817-829 ◽  
Author(s):  
Xiaobin Guo ◽  
Craig F. Drury ◽  
W. Daniel Reynolds ◽  
Xueming Yang ◽  
Ruqin Fan

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