The response of nitrous oxide emissions to different operating conditions in activated sludge wastewater treatment plants in Southeastern Brazil

2017 ◽  
Vol 76 (9) ◽  
pp. 2337-2349 ◽  
Author(s):  
Renato P. Ribeiro ◽  
Rodrigo F. Bueno ◽  
Roque P. Piveli ◽  
Débora C. Kligerman ◽  
William Z. de Mello ◽  
...  
Keyword(s):  
Wastewater Treatment ◽  
Activated Sludge ◽  
Shock Loading ◽  
Wastewater Treatment Plants ◽  
N2o Emission ◽  
Operating Conditions ◽  
Nitrous Oxide Emissions ◽  
Southeastern Brazil ◽  
N2o Emissions ◽  
Continuous Measurements

Abstract The continuous measurements of N2O emissions from the aeration tanks of three activated sludge wastewater treatment plants (WWTPs) operated with biological nitrogen removal (BNR) and non-BNR were performed during the different operating conditions of several parameters, such as aeration, dissolved oxygen (DO) profiling and organic shock loading (with landfill leachate). The nitrification process is the main driving force behind N2O emission peaks. There are indications that the variation of the air flow rate influenced N2O emissions; high N2O emissions denote over-aeration conditions or incomplete nitrification, with accumulation of NO2− concentrations. Thus, continuous measurements of N2O emissions can provide information on aeration adequacy and the efficiency of complete nitrification, with major focus on DO control, in order to reduce N2O emissions. An additional concern is the observed propensity of WWTPs in developing countries to receive landfill leachates in their wastewater systems. This practice could have adverse effects on climate change, since wastewater treatment during periods of organic shock loading emitted significantly higher amounts of N2O than without organic shock loading. In short, non-BNR WWTPs are subject to high N2O emissions, in contrast to BNR WWTP with controlled nitrification and denitrification processes.

scholarly journals Effects of different operating conditions on total nitrogen removal routes and nitrous oxide emissions in a lab-scale activated sludge system

2018 ◽  
Vol 13 (2) ◽  
pp. 1
Author(s):  
Renato Pereira Ribeiro ◽  
Débora Cynamon Kligerman ◽  
William Zamboni de Mello ◽  
Denise Da Piedade Silva ◽  
Renatah Da Fonseca Correia ◽  
...  
Keyword(s):  
Nitrous Oxide ◽  
Organic Matter ◽  
Activated Sludge ◽  
Total Nitrogen ◽  
Shock Loading ◽  
Operating Conditions ◽  
Nitrous Oxide Emissions ◽  
N2o Emissions ◽  
Activated Sludge System ◽  
Sludge Waste

This study sought to determine the effects of different operating conditions, such as variable organic loading, different sludge retention times (SRTs) and airflow rates, limited dissolved oxygen (DO) concentrations and ammonium (NH4+) shock loading on total nitrogen (TN) removal routes and nitrous oxide (N2O) emissions in a lab-scale activated sludge system. Short SRT (5 days) combined with very low DO levels (0.5 mg L-1) were responsible for lower TKN oxidation efficiencies and, consequently, negligible NO2- accumulation rates. These results suggest that nitrification efficiency was hampered by the oxidation of organic matter, with a large part of TN removed by sludge waste process. As the SRT increased (from 5 to 10 days) and DO was set to 1.0 mg L-1, TKN oxidation rates and NO2- accumulation reached their maxima, which are thought to be the optimal conditions for both organic matter oxidation and partial nitrification. Under these conditions, gas transfer to the atmosphere became the preferential route for TN removal instead of incorporation into the sludge waste. However, N2O contribution is estimated as less than 5.6% (with respect to TN in the influent). Insufficient aeration and stress conditions (such as NH4+ shock loading) can cause limited DO conditions and NO2- accumulation, leading to higher amounts of emitted N2O. Therefore, the adequate control of DO concentrations is a key factor to avoid NO2- accumulation and consequently high N2O emissions.

scholarly journals The capacity of wastewater treatment plants drives bacterial community structure and its assembly

2019 ◽  
Vol 9 (1) ◽  
Author(s):  
Young Kyung Kim ◽  
Keunje Yoo ◽  
Min Sung Kim ◽  
Il Han ◽  
Minjoo Lee ◽  
...  
Keyword(s):  
Wastewater Treatment ◽  
Community Structure ◽  
Bacterial Community ◽  
Activated Sludge ◽  
Community Assembly ◽  
Bacterial Communities ◽  
Wastewater Treatment Plants ◽  
High Capacity ◽  
Operating Conditions ◽  
Rrna Gene

Abstract Bacterial communities in wastewater treatment plants (WWTPs) affect plant functionality through their role in the removal of pollutants from wastewater. Bacterial communities vary extensively based on plant operating conditions and influent characteristics. The capacity of WWTPs can also affect the bacterial community via variations in the organic or nutrient composition of the influent. Despite the importance considering capacity, the characteristics that control bacterial community assembly are largely unknown. In this study, we discovered that bacterial communities in WWTPs in Korea and Vietnam, which differ remarkably in capacity, exhibit unique structures and interactions that are governed mainly by the capacity of WWTPs. Bacterial communities were analysed using 16S rRNA gene sequencing and exhibited clear differences between the two regions, with these differences being most pronounced in activated sludge. We found that capacity contributed the most to bacterial interactions and community structure, whereas other factors had less impact. Co-occurrence network analysis showed that microorganisms from high-capacity WWTPs are more interrelated than those from low-capacity WWTPs, which corresponds to the tighter clustering of bacterial communities in Korea. These results will contribute to the understanding of bacterial community assembly in activated sludge processing.

Modelling and simulation of the steady-state of secondary settlers in wastewater treatment plants

2001 ◽  
Vol 43 (7) ◽  
pp. 39-46 ◽  
Author(s):  
I. Queinnec ◽  
D. Dochain
Keyword(s):  
Fluid Dynamics ◽  
Computational Fluid Dynamics ◽  
Wastewater Treatment ◽  
Steady State ◽  
Activated Sludge ◽  
Parameter Identification ◽  
Wastewater Treatment Plants ◽  
Operating Conditions ◽  
Sensitivity Studies ◽  
Activated Sludge Processes

This paper discusses the steady-state modelling of thickening in circular secondary settlers of activated sludge processes. The limitations of the solid flux theory basic models to represent steady-state operating conditions serve as a basis to introduce more sophisticated models derived from computational fluid dynamics. Parameter identification and sensitivity studies have been performed from lab-scale continuous experiments.

scholarly journals Evaluation of the Nitrous Oxide Emission Reduction Potential of an Aerobic Bioreactor Packed with Carbon Fibres for Swine Wastewater Treatment

Energies ◽  
2019 ◽  
Vol 12 (6) ◽  
pp. 1013 ◽  
Author(s):  
Takahiro Yamashita ◽  
Makoto Shiraishi ◽  
Hiroshi Yokoyama ◽  
Akifumi Ogino ◽  
Ryoko Yamamoto-Ikemoto ◽  
...  
Keyword(s):  
Nitrous Oxide ◽  
Wastewater Treatment ◽  
Wastewater Treatment Plant ◽  
Wastewater Treatment Plants ◽  
Treatment Plant ◽  
Treatment Method ◽  
N2o Emission ◽  
Swine Wastewater ◽  
N2o Emissions ◽  
Carbon Fibres

Nitrous oxide (N2O) is a potent greenhouse gas that is emitted from wastewater treatment plants. To reduce emissions of N2O from swine wastewater treatment plants, we constructed an experimental aerobic bioreactor packed with carbon fibres (ca. 1 m3 bioreactor) as an alternative to conventional activated sludge treatment. The N2O emission factor for the aerobic bioreactor packed with carbon fibres (CF) was 0.002 g N2O-N/g TN-load and the value for the typical activated sludge (AS) reactor was 0.013 g N2O-N/g TN-load. The CF treatment method achieved more than 80% reduction of N2O emissions, compared with the AS treatment method. The experimental introduction of a CF carrier into an actual wastewater treatment plant also resulted in a large reduction in N2O generation. Specifically, the N2O emission factors decreased from 0.040 to 0.005 g N2O-N/g TN-load following application of the carrier. This shows that it is possible to reduce N2O generation by more than 80% by using a CF carrier during the operation of an actual wastewater treatment plant. Some bacteria from the phylum Chloroflexi, which are capable of reducing N2O emissions, were detected at a higher frequency in the biofilm on the CF carrier than in the biofilm formed on the AS reactor.

scholarly journals Methodology for Energy Optimization in Wastewater Treatment Plants. Phase I: Control of the Best Operating Conditions

2019 ◽  
Vol 11 (14) ◽  
pp. 3919 ◽  
Author(s):  
Ana Belén Lozano Avilés ◽  
Francisco del Cerro Velázquez ◽  
Mercedes Llorens Pascual del Riquelme
Keyword(s):  
Wastewater Treatment ◽  
Control System ◽  
Activated Sludge ◽  
Phase I ◽  
Wastewater Treatment Plants ◽  
Energy Optimization ◽  
Industrial Process ◽  
Operating Conditions ◽  
Process Conditions ◽  
Real Time Control

Most purification systems work correctly from the point of view of water quality; purification, like any industrial process, must also be carried out efficiently with a minimization of costs. The overall project examined the potential benefits of using a recommended methodology for process evaluation and energy optimization in the aeration stage of activated sludge in the biological reactor at wastewater treatment plants (WWTP), which accounts for more than 44% of total operating costs. This energy control methodology encompasses the process, the installation and the control system. These three phases are examined in separate articles to make it easier to guide the user in the arduous task of optimizing energy efficiency of the WWTP from start to finish. This article focuses on Phase I of the methodology, the stage in charge of selecting the correct variables to control the best process conditions in the activated sludge system of the WWTP. Operating conditions that are a function of the recommended sludge age are influenced by exogenous factors such as temperature. The implementation of a real-time control system of the selected process variables, adapted to the needs, achieves reductions in the overall energy consumption of the installation, in this phase alone, of more than 15%, by reducing the oxygen requirements of the system and the recirculation ratios.

scholarly journals Unwanted mainstream nitritation-denitritation causing massive N2O emissions in a continuous activated sludge process

2021 ◽  
Author(s):  
A. Kuokkanen ◽  
K. Blomberg ◽  
A. Mikola ◽  
M. Heinonen
Keyword(s):  
Nitrous Oxide ◽  
Wastewater Treatment ◽  
Activated Sludge ◽  
Nitrogen Removal ◽  
Municipal Wastewater ◽  
Nitrous Oxide Emissions ◽  
N2o Emissions ◽  
Activated Sludge Process ◽  
Municipal Wastewater Treatment ◽  
Activated Sludge Processes

Abstract Nitrous oxide emissions can contribute significantly to the carbon footprint of municipal wastewater treatment plants even though emissions from conventional nitrogen removal processes are assumed to be moderate. An increased risk for high emissions can occur in connection with process disturbances and nitrite (NO2−) accumulation. This work describes the findings at a large municipal wastewater treatment plant where the levels of NO2− in the activated sludge process effluent were spontaneously and strongly increased on several activated sludge lines which was suspected to be due to shortcut nitrogen removal that stabilized for several months. The high NO2− levels were linked to a dramatic increase in nitrous oxide (N2O) emissions. As much as over 20% of the daily influent nitrogen load was emitted as N2O. These observations indicate that highly increased NO2− levels can occur in conventional activated sludge processes and result in high nitrous oxide emissions. They also raise questions concerning the risk of increased greenhouse gas (GHG) emissions of the nitritation-denitritation processes – although the uncontrolled nature of the event described here must be taken into consideration – and underline the importance of continuous monitoring and control of N2O emissions.

Swine wastewater treatment technology to reduce nitrous oxide emission by using an aerobic bioreactor packed with carbon fibres

2016 ◽  
Vol 56 (3) ◽  
pp. 330 ◽  
Author(s):  
Takahiro Yamashita ◽  
Makoto Shiraishi ◽  
Ryoko Yamamoto-Ikemoto ◽  
Hiroshi Yokoyama ◽  
Akifumi Ogino ◽  
...  
Keyword(s):  
Nitrous Oxide ◽  
Wastewater Treatment ◽  
Activated Sludge ◽  
N2o Emission ◽  
Swine Wastewater ◽  
Water Volume ◽  
N2o Emissions ◽  
Carbon Fibres ◽  
Treatment Technology ◽  
Total N

From a global warming perspective it is important to control emissions of methane (CH4) and nitrous oxide (N2O) from excreta and manure management. To mitigate emissions of N2O during swine wastewater treatment, we examined aerobic treatment technologies that use carbon fibre carriers as an alternative to conventional activated sludge treatment. We used scaled-up experiment equipment (water volume, 700 L) to evaluate the treatment performance. The N2O emission factor was 0.008 g N2O-N/g total N load in an aerobic bioreactor packed with carbon fibres (CF reactor), compared with 0.021 gN2O-N/g total N load in an activated sludge reactor (AS reactor). The CF treatment reduced N2O emissions by more than 60% compared with the AS treatment. Combined CH4 and N2O emissions from the CF reactor were 504 g-CO2 eq/m3.day, whereas those from the AS reactor were 1333 g-CO2 eq/m3.day. Interestingly, N2O emissions from the CF reactor were reduced even when nitrate and nitrite accumulated.

scholarly journals CONTROLLING FACTORS OF NITROUS OXIDE EMISSIONS FROM A CONVENTIONAL ACTIVATED SLUDGE WASTEWATER TREATMENT PLANT

Engevista ◽  
2015 ◽  
Vol 17 (3) ◽  
pp. 375 ◽  
Author(s):  
Renato Pereira Ribeiro ◽  
Jaime Lopes da Mota Oliveira ◽  
Débora Cynamon Kligerman ◽  
Renata Barbosa Alvim ◽  
Samara Almeida Andrade ◽  
...  
Keyword(s):  
Nitrous Oxide ◽  
Wastewater Treatment ◽  
Activated Sludge ◽  
Wastewater Treatment Plant ◽  
Treatment Plant ◽  
Nitrous Oxide Emissions ◽  
Aeration Tank ◽  
N2o Emissions ◽  
Air Stripping ◽  
Conventional Activated Sludge

Nitrous oxide emissions were determined in three campaigns in the aeration tank of a full scale conventional activated sludge wastewater treatment plant. During these experiments, the carbonaceous organic matter (BOD and COD) removal was high and rather constant (97-98% and 93-96%). The results indicate that the concentration of total nitrogen in the influent wastewater, especially NH4+, and the aeration flow rate are key controlling factor of N2O emissions from the aeration tank. Nitrification was the major source of N2O, suggested by the behavior of DO concentrations, NO3-/NH4+ ratio and pH values along the six interlinked zones of the aeration tank. Excessive air flow intensified N2O transfer from the liquor to the atmosphere by air stripping.

Removal of selected non-steroidal anti-inflammatory drugs (NSAIDs), gemfibrozil, carbamazepine, b-blockers, trimethoprim and triclosan in conventional wastewater treatment plants in five EU countries and their discharge to the aquatic environment

2004 ◽  
Vol 50 (5) ◽  
pp. 253-260 ◽  
Author(s):  
N. Paxéus
Keyword(s):  
Wastewater Treatment ◽  
Activated Sludge ◽  
Aquatic Environment ◽  
Wastewater Treatment Plants ◽  
Removal Rate ◽  
Average Concentration ◽  
Operating Conditions ◽  
Removal Rates ◽  
Eu Countries ◽  
Acidic Drugs

The removal of commonly used pharmaceuticals (ibuprofen, naproxen, diclofenac, gemfibrozil, carbamazepine, atenolol, metoprolol and trimethoprim) and a biocide (triclosan) in operating wastewater treatment plants in five EU countries has been studied. Under normal operating conditions the acidic drugs and triclosan were partially removed with removal rates varying from ca. 20 to >95%. The highest removal rate was found for ibuprofen and triclosan (>90%) followed by naproxen (80%), gemfibrozil (55%) and diclofenac (39%). Ibuprofen undergoes an oxidative transformation to corresponding hydroxy- and carboxy- metabolites, which contributes to its high removal rate. Disturbances in the activated sludge process resulted in lower removal rates for all acidic drugs, mostly for diclofenac (<10% removed) but also for ibuprofen (<60% removed). The treatment of wastewaters by activated sludge usually did not result in any practical removal (<10%) of neutral carbamazepine or basic atenolol, metoprolol and trimethoprim. The removal rates of the investigated drugs and triclosan are discussed in terms of mechanisms responsible for their removal. Discharges of carbamazepine, diclofenac, gemfibrozil, naproxen, triclosan and trimethoprim from WWTPs to the aquatic environment, expressed as the average concentration in the effluent and the daily discharged quantity per person served by WWTPs were assessed.

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