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.

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.

Control of Activated Sludge Bulking: From the Lab to the Plant

1989 ◽  
Vol 21 (6-7) ◽  
pp. 717-726 ◽  
Author(s):  
R. Pujol ◽  
P. Boutin
Keyword(s):  
Wastewater Treatment ◽  
Activated Sludge ◽  
Wastewater Treatment Plants ◽  
Treatment Plant ◽  
Common Type ◽  
Test Method ◽  
Mixing Zone ◽  
Operational Conditions ◽  
Sludge Bulking ◽  
Technical Aid

Activated sludge bulking often occurs in French wastewater treatment plants. Precise identification of filaments and better knowledge of their ecophysiology helped to clarify their re1ations with the operational conditions of plants. Effective techniques were therefore developed for control. The “mixing zone” is suitable for many cases of bulking ocurring in extended aeration plants (the most common type in France). A test method was developed to provide the elements for dimensioning the system. Unreserved cooperation between the owner of the plant, the manager, the SATESE (Service of technical aid to wastewater treatment plant managers) and specialized laboratories is required to implement such measures. Some cases, about which CEMAGREF was consulted, were examined; three of them are detailed and reasons for success or fai1ure are analysed. Seeking funds for the works too often leads to excessive delays.

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.

A Knowledge-Based Framework for the Diagnosis of Sludge Bulking in the Activated Sludge Process

1991 ◽  
Vol 23 (4-6) ◽  
pp. 847-855 ◽  
Author(s):  
W. T. Chan ◽  
Lawrence C. C. Koe
Keyword(s):  
Expert System ◽  
Problem Solving ◽  
Expert Systems ◽  
Activated Sludge ◽  
Operating Conditions ◽  
Activated Sludge Process ◽  
Sludge Bulking ◽  
Qualitative Knowledge ◽  
New Generation ◽  
Problem Solving Behavior

Despite advances in the understanding of the activated sludge process for treating wastewater, the operation of an activated sludge process plant - in particular, the detection, diagnosis and remedy of operational problems - still involves a significant amount of qualitative knowledge derived from empirical observations. Expert systems can be of assistance to plant operators in problem diagnosis by automating the problem-solving behavior of human experts and retrieving the appropriate chunks of qualitative knowledge from a large collection of such knowledge as the context of the problem dictates. A new generation of expert systems shell delivers better performance by providing (i) an object-centred framework with interesting computational properties to organize the considerable amounts of information about the physical world, (ii) flexible, context-dependent and programmable inference strategies to better model the problem-solving behavior of human experts, (iii) a reliable means of integrating numeric and symbolic computation, and (iv) a means for the expert system application to couple its inference procedure with its ability to interact with events in the real world through sensors and actuators. A prototype expert system employing a new generation expert system shell has been developed for diagnosing the sludge bulking problem in the activated sludge process. The paper discusses the knowledge representation scheme employed in the prototype, which is general enough to be extended to cover other operational problems occurring in sewage treatment plants. A study was performed to validate the knowledge in the prototype by comparing the conclusions of a panel of human experts reported in the literature with those of the prototype in response to a wide range of operating conditions. The study shows close agreement between the two sets of conclusions.

Effectiveness of the membrane bioreactor in the biodegradation of high molecular-weight compounds

1996 ◽  
Vol 34 (9) ◽  
pp. 197-203 ◽  
Author(s):  
H. Winnen ◽  
M. T. Suidan ◽  
P. V. Scarpino ◽  
B. Wrenn ◽  
N. Cicek ◽  
...  
Keyword(s):  
Activated Sludge ◽  
Membrane Bioreactor ◽  
Municipal Wastewater ◽  
Extended Period ◽  
Membrane System ◽  
Pilot Scale ◽  
Synthetic Wastewater ◽  
Activated Sludge Process ◽  
Conventional Activated Sludge ◽  
Heterotrophic Microorganisms

The activated sludge process has been used extensively to treat municipal wastewater. The membrane bioreactor (MBR) process is a modification of the conventional activated sludge process where the clarifier is replaced with a membrane system for separation between the mixed liquor and the effluent. This paper presents the biological and physical performance data of a pilot-scale membrane bioreactor system, fed with a synthetic wastewater. At steady state, particularly high effluent quality was obtained and maintained for an extended period of time. Heterotrophic plate counting showed that the membrane retains heterotrophic microorganisms. Bacteriophage MS-2 was used to determine the retention of viruses. The membrane proved to retain the MS-2 virus.

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.

Potential of a Static Magnetic Field to Inhibit Filamentous Sludge Bulking in Activated Sludge Process

2019 ◽  
Vol 145 (3) ◽  
pp. 04019001 ◽  
Author(s):  
Nur Syamimi Zaidi ◽  
Khalida Muda ◽  
Johan Sohaili ◽  
Norelyza Hussein ◽  
Liew Wai Loan ◽  
...  
Keyword(s):  
Magnetic Field ◽  
Activated Sludge ◽  
Static Magnetic Field ◽  
Activated Sludge Process ◽  
Sludge Bulking

Performance evaluation of various aerobic biological systems for the treatment of domestic wastewater at low temperatures

2008 ◽  
Vol 58 (4) ◽  
pp. 819-830 ◽  
Author(s):  
N. Sundaresan ◽  
L. Philip
Keyword(s):  
Performance Evaluation ◽  
Activated Sludge ◽  
Fluidized Bed ◽  
Removal Efficiency ◽  
Biological Systems ◽  
Domestic Wastewater ◽  
Cod Removal ◽  
Synthetic Wastewater ◽  
Activated Sludge Process ◽  
Cod Removal Efficiency

Studies were undertaken on the performance evaluation of three different types of aerobic reactors, namely, activated sludge process, fluidized bed reactor and submerged bed reactor. Initially synthetic wastewater was used for stabilizing the system and later domestic wastewater of IIT Madras was used as the feed for the biological systems. The hydraulic retention time was maintained as 24 h. The seed sludge was collected from IIT Madras sewage treatment plant. The inlet COD to the reactors with synthetic wastewater was 1,000±20 mg/L and with real wastewater, it was 150 to 350 mg/L. The performance of the reactors was evaluated based on the soluble COD and nitrogen removal efficiency. The pH, temperature, dissolved oxygen (DO) and mixed liquid suspended solid (MLSS) concentration were measured periodically. The reactors were acclimatized at 35°C in batch mode and changed to continuous mode at 30°C. After the systems attained its steady state at a particular temperature, the temperature was reduced from 35°C to 5°C stepwise, with each step of 5°C. The start-up time for submerged bed reactor was slightly more than fluidized and conventional activated sludge process. The COD removal efficiency of the three reactors was higher with synthetic wastewaters as compared to actual domestic wastewater. Submerged bed reactor was more robust and efficient as compared to activated sludge and fluidized bed reactors. The COD removal efficiency of the reactors was relatively good until the operating temperature was maintained at 15°C or above. At 10°C, submerged bed reactor was able to achieve 40% COD removal efficiency whereas; the fluidized bed and conventional ASP reactors were showing only 20% COD removal efficiency. At 5°C, almost all the systems failed. Submerged bed reactor showed around 20% COD removal efficiency. However, this reactor was able to regain its 90% of original efficiency, once the temperature was raised to 10°C. At higher temperatures, the nitrification efficiency of the reactors was above 80–90%. As the temperature reduced the nitrification efficiency has reduced drastically. In summary, submerged bed reactors seems to be a better option for treating domestic wastewaters at low temperature regions.

Sign in / Sign up

Export Citation Format

Share Document