scholarly journals Comparative Analysis for the Emission Amounts of Methane and Nitrous Oxide, and the Emission Characteristics with Operational Conditions of an Activated Sludge Process.

1998 ◽  
Vol 21 (12) ◽  
pp. 849-855 ◽  
Author(s):  
Motoyuki MIZUOCHI ◽  
Kazuaki SATO ◽  
Yuhei INAMORI ◽  
Masatoshi MATSUMURA
Keyword(s):  
Nitrous Oxide ◽  
Comparative Analysis ◽  
Activated Sludge ◽  
Emission Characteristics ◽  
Activated Sludge Process ◽  
Operational Conditions

The Performance of Microelectrolysis in Improving the Biodegradability Landfill Leachate

2013 ◽  
Vol 448-453 ◽  
pp. 1399-1402 ◽  
Author(s):  
Ling Zhao ◽  
Xiao Gu Cheng ◽  
Ping He Yin ◽  
Gang Lu ◽  
Jun Chang Suo
Keyword(s):  
Activated Carbon ◽  
Reaction Time ◽  
Activated Sludge ◽  
Landfill Leachate ◽  
Biological Treatment ◽  
Activated Sludge Process ◽  
Mass Ratio ◽  
Operational Conditions ◽  
A Value ◽  
Mature Landfill Leachate

The aim of this study was to check the effectiveness of microelectrolysis for the pretreatment of a municipal landfill leachate with the objective improving its overall biodegradability, evaluated in terms of BOD5/COD ratio, up to a value compatible with biological treatment. The best microelectrolysis operational conditions for achieving the desired COD values were: pH=2.0; granular activated carbon (GAC) =10 g/L; mass ratio of zero iron (Fe0)/GAC=2:1; reaction time=90 min. The BOD5/COD was significantly improved from 0.12 to 0.31, which allowed an almost 85% removal of COD by a sequential activated sludge process. The results show that the microelectrolysis is a promising technology to improve the biodegradability of mature landfill leachate.

Non-Filamentous Activated Sludge Bulking Caused by Zoogloea

1994 ◽  
Vol 29 (7) ◽  
pp. 301-304 ◽  
Author(s):  
L. Novák ◽  
L. Larrea ◽  
J. Wanner ◽  
J. L. García-Heras
Keyword(s):  
Activated Sludge ◽  
Wave Mode ◽  
Synthetic Wastewater ◽  
Activated Sludge Process ◽  
Volume Changes ◽  
Plant Operation ◽  
Operational Conditions ◽  
Bench Scale ◽  
Sludge Bulking ◽  
Previous State

An abundant growth of zoogloeal colonies was observed periodically during some experiments carried out on a bench-scale plant fed with a complex synthetic wastewater. The plant had a configuration with an enhanced regeneration-denitrification-nitrification (R-D-N) activated sludge process for low alkalinity wastewaters. Several operational changes were undertaken in order to suppress the excessive growth of zoogloeal colonies. They included: (1) changes in the wastewater composition, (2) volume changes in the compartmentalization of the anoxic selector, (3) increase of D.O. concentration in the regeneration and nitrification tanks. Conclusions from the plant operation observations give rise to a hypothesis that none of the operational changes provoked a significant restriction in the abundant zoogloeal growth. When a temporary improvement was observed, after acclimatization on the new operational conditions the microorganisms culture returned to its previous state and continued to grow in a wave-mode. The reason for the appearance of this type of sludge might be closely related to the composition of the synthetic wastewater.

Kinetic Model of Sequencing Batch Activated Sludge Process for Municipal Wastewater Treatment

1991 ◽  
Vol 23 (4-6) ◽  
pp. 1097-1106 ◽  
Author(s):  
H. Nakazawa ◽  
K. Tanaka
Keyword(s):  
Wastewater Treatment ◽  
Kinetic Model ◽  
Activated Sludge ◽  
Mathematical Models ◽  
Municipal Wastewater ◽  
Pilot Scale ◽  
Activated Sludge Process ◽  
Municipal Wastewater Treatment ◽  
Operational Conditions ◽  
Aeration Time

Mathematical models based on the kinetic aspect of the sequencing batch activated sludge process were developed to explain the characteristics of the process treating municipal wastewater. These models are a steady-state model dealing with the overall relationship between biomass concentrations in a reactor and operational conditions of the process, and a kinetic model dealing with the behaviors of biomass and substrate in a reactor within one cycle time of the process. Applying these mathematical models for the results of pilot-scale experiments for municipal wastewater treatment, reasonable parameters' values were obtained and the effects of operating strategies including the aeration time ratio and the solids retention time became clear for the process performance.

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.

Reduction of excess sludge production using mechanical disintegration devices

2006 ◽  
Vol 54 (5) ◽  
pp. 69-76 ◽  
Author(s):  
G.W. Strünkmann ◽  
J.A. Müller ◽  
F. Albert ◽  
J. Schwedes
Keyword(s):  
Activated Sludge ◽  
Nitrogen Removal ◽  
Activated Sludge Process ◽  
Operational Parameters ◽  
Excess Sludge ◽  
Operational Conditions ◽  
Mechanical Disintegration ◽  
Conventional Activated Sludge ◽  
Removal Capacity ◽  
Sludge Production

The usability of mechanical disintegration techniques for the reduction of excess sludge production in the activated sludge process was investigated. Using three different disintegration devices (ultrasonic homogeniser, stirred media mill, high pressure homogeniser) and different operational parameters of the disintegration, the effect of mechanical disintegration on the excess sludge production and on the effluent quality was studied within a continuously operated, laboratory scale wastewater treatment system with pre-denitrification. Depending on the operational conditions and the disintegration device used, a reduction of excess sludge production of up to 70% was achieved. A combination of mechanical disintegration with a membrane bioreactor process with high sludge age is more energy effective concerning reduction of sludge production than with a conventional activated sludge process at lower sludge ages. Depending on the disintegration parameters, the disintegration has no, or only minor, negative effect on the soluble effluent COD and on the COD-removal capacity of the activated sludge process. Nitrogen-removal was slightly deteriorated by the disintegration, whereas the system used was not optimised for nitrogen removal before disintegration was implemented.

Reducing nitrous oxide gas emissions from fill-and-draw type activated sludge process

1995 ◽  
Vol 29 (6) ◽  
pp. 1607-1608 ◽  
Author(s):  
Takashi Osada ◽  
Kazutaka Kuroda ◽  
Michihiro Yonaga
Keyword(s):  
Nitrous Oxide ◽  
Activated Sludge ◽  
Activated Sludge Process ◽  
Gas Emissions

State and Coefficients Estimation for the Activated Sludge Process Using a Modified Kalman Filter Algorithm

1991 ◽  
Vol 24 (6) ◽  
pp. 235-247 ◽  
Author(s):  
E. Ayesa ◽  
J. Florez ◽  
J. L. García-Heras ◽  
L. Larrea
Keyword(s):  
Activated Sludge ◽  
Identification Algorithm ◽  
Activated Sludge Process ◽  
State Variables ◽  
Operational Conditions ◽  
Kaiman Filter ◽  
Modified Kalman Filter ◽  
On Line ◽  
Kalman Filter Algorithm ◽  
High Degree

An advanced identification algorithm is proposed for the on-line estimation of the non-measurable state variables and coefficients of the IAWPRC biodegradation dynamic model for the Activated Sludge process. The new algorithm employs real-time measurable data. This paper represents a first step in a mathematical methodology which intends to improve the present techniques used for model calibration and validation. The algorithm is based on a recursive non-linear extended Kaiman filter and it has been verifiedrby using simulated values of the measurable data. These simulations describe the behaviour of a specific physical configuration of the AS process under steady and transient operational conditions. When the coefficients are assumed to be known, the algorithm estimates the state rapidly and accurately even when the measurements are affected by a very high degree of noise and the initial estimates are very far from the real values. The speed of convergence of the algorithm decreases when neither the states nor the coefficients of the model are known.

Influence of operational conditions on the performance of a mesh filter activated sludge process

2005 ◽  
Vol 39 (5) ◽  
pp. 803-810 ◽  
Author(s):  
W. Fuchs ◽  
C. Resch ◽  
M. Kernstock ◽  
M. Mayer ◽  
P. Schoeberl ◽  
...  
Keyword(s):  
Activated Sludge ◽  
Activated Sludge Process ◽  
Operational Conditions
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