The investigation of the sludge reduction efficiency and mechanisms in oxic–settling–anaerobic (OSA) process

2016 ◽  
Vol 73 (10) ◽  
pp. 2311-2323 ◽  
Author(s):  
Özlem Demir ◽  
Ayşe Filibeli
Keyword(s):  
Control System ◽  
Volume Index ◽  
Endogenous Respiration ◽  
Sludge Reduction ◽  
Capillary Suction ◽  
Term Operation ◽  
Effluent Quality ◽  
Conventional Activated Sludge ◽  
Reduction Mechanisms

This paper aims to provide a full understanding of the sludge reduction mechanisms in the oxic–settling–anaerobic (OSA) process and presents an evaluation of the sludge reduction efficiencies and sludge characteristics in this process compared to the conventional activated sludge process. Fifty-eight percent reduction in observed yield in the OSA process was achieved compared to the control system at the end of the operational period with no deterioration of effluent quality. The settleability of sludge in the OSA process was also found to be better than that of the control system in terms of sludge volume index. In long-term operation, capillary suction time and specific resistance to filtration values confirmed that the OSA process showed good filterability characteristics. The results of batch experiments showed that higher endogenous respiration in the systems might lead to lower sludge production and that energy uncoupling had only a limited impact on sludge reduction.

scholarly journals Sludge reduction via biodegradation of the endogenous residue (XE): experimental verification and modeling

2016 ◽  
Vol 75 (3) ◽  
pp. 561-570 ◽  
Author(s):  
Cheikh Fall ◽  
Ericka L. Millan-Lagunas ◽  
Carlos Lopez-Vazquez ◽  
Christine Maria Hooijmans ◽  
Yves Comeau
Keyword(s):  
Activated Sludge ◽  
Continuous Process ◽  
Synthetic Wastewater ◽  
Yield Reduction ◽  
Actual Behavior ◽  
Sludge Reduction ◽  
Conventional Activated Sludge ◽  
Retention System ◽  
Solids Retention

The feasibility of sludge reduction via the XE biodegradation process was explored both experimentally and through modeling, where the main focus was on determining the value of the bE parameter (first order degradation of XE) from a continuous process. Two activated sludge (AS) systems (30 L) were operated in parallel with synthetic wastewater during 16 months: a conventional activated sludge (CAS) system and a modified low-sludge production activated sludge (LSP-AS) process equipped with a side-stream digester unit (DU). First, the long term data of the CAS reactor (1 year) were used to calibrate the ASM model and to estimate the heterotrophic decay constant of the cultivated sludge (bH = 0.29 d−1, death-regeneration basis). Second, pre-simulations were performed to design the LSP-AS system and to estimate the DU volume required (40 L), to avoid XE accumulation in the process. Third, the LSP-AS process was built, put in operation and monitored for more than 9 months. This allowed assessment of the actual behavior of the quasi-complete solids retention system. Once calibrated, the modified AS model estimated the value of the bE parameter to be in the range of 0.003–0.006 d−1, satisfactorily describing the overall sludge yield reduction of up to 49% observed in the experiments.

Treatment of Oily Cafeteria Wastewater by Single-Phase and Two-Phase Anaerobic Filter

1990 ◽  
Vol 22 (3-4) ◽  
pp. 299-306 ◽  
Author(s):  
Keisuke Hanaki ◽  
Tomonori Matsuo ◽  
Katsuo Kumazaki
Keyword(s):  
Single Phase ◽  
Material Balance ◽  
Phase System ◽  
Two Phase ◽  
Term Operation ◽  
Effluent Quality ◽  
Anaerobic Filter ◽  
Phase Systems ◽  
Better Than

Cafeteria wastewater containing about 30% of lipid on COD basis was treated at 20°C by laboratory-scale anaerobic filter in single-phase system and two-phase systems. Stable COD removal (about 80%) was achieved in spite of large fluctuation in influent COD concentration (normal range of 1,300 - 2,500 mg−l) both in the single-phase system (hydraulic retention time (HRT) longer than 1.3 d) and in the two-phase system (HRT longer than 3.3 d). The single-phase system gave better effluent quality than the two-phase system because the former entrapped suspended solids better than the latter. However, material balance revealed that methane conversion from removed COD was higher in the two-phase system than the single-phase system. The single-phase system perhaps removed lipids by entrapment with filter media without biodegradation, and this might cause clogging problems in long-term operation. The two-phase system is recommended since it degrades lipids better than the single-phase system.

Biomass dewaterability, filterability and settleability in a membrane bioreactor operated with different sludge ages

2007 ◽  
Vol 2 (1) ◽  
Author(s):  
A. Pollice ◽  
G. Laera ◽  
C. Giordano ◽  
D. Saturno ◽  
G. Mininni ◽  
...  
Keyword(s):  
Steady State ◽  
Physical Properties ◽  
Membrane Bioreactors ◽  
Volume Index ◽  
Excess Sludge ◽  
Capillary Suction ◽  
Bench Scale ◽  
Conventional Activated Sludge ◽  
The Relationship

Membrane bioreactors (MBR) are designed to maintain high solid concentrations, thus limiting sludge production and the related operational costs of the process. Sludge physical properties strongly affect the operation of these systems, due to their influence on the filtration process and also on excess sludge handling. This study reports the physical characterization of a bench scale MBR biomass with different sludge ages and with complete sludge retention. The results span over a period of three years when a bench scale MBR was operated under the same conditions except for the sludge retention time (SRT). The main dewatering properties were measured over time and their steady state average values were related to the SRT. The capillary suction time (CST) and the specific resistance to filtration (SRF) showed similar decreasing trends during the transient phase and reached equilibrium values under steady state conditions, except in the case of complete sludge retention. Under all the tested conditions, the average equilibrium values of the CST, the SRF and the compressibility (s) of the MBR sludge were similar to those reported for conventional activated sludge, suggesting the adoption of the same dewatering technologies. In terms of settleability, the relationship between the diluted sludge volume index (DSVI) and the sludge age appeared weak for SRT higher than 20 days. Under the tested conditions, the best performances in terms of physical properties of the MBR excess sludge were obtained for sludge retention times between 40 and 80 days.

Extracellular polymers in partly ozonated return activated sludge: impact on flocculation and dewaterability

2006 ◽  
Vol 54 (9) ◽  
pp. 155-164 ◽  
Author(s):  
M.A. Dytczak ◽  
K. Londry ◽  
H. Siegrist ◽  
J.A. Oleszkiewicz
Keyword(s):  
Activated Sludge ◽  
Negative Impact ◽  
Kinetic Studies ◽  
Volume Index ◽  
Biological Nutrient Removal ◽  
Ozone Treatment ◽  
Batch Reactors ◽  
Strictly Aerobic ◽  
Capillary Suction ◽  
Term Operation

The purpose of this study was to evaluate the influence of partial ozonation of return activated sludge on settling properties and dewaterability of sludge. Sequencing batch reactors with two sets of aerobic and alternating anoxic/aerobic conditions were used. In each set, one reactor served as a control and the other was subject to the ozone treatment (doses in the range of 0.016–0.080 mg O3/mg TSS of initial excess sludge). The level of total suspended solids (TSS) in each reactor was controlled at 1,800 mg/l. To evaluate settleability and dewaterability, settling kinetic studies, sludge volume index (SVI) and capillary suction time test (CST) were used. For extraction and quantifying sludge biopolymers, thermal-ethanolic extraction was employed. The ratio of bound-to-total extracellular polymer substances (EPS) was higher for the strictly aerobic reactor than for the alternating anoxic/aerobic one, indicating the stronger structure of the aerobic flocs. After ozone treatment, the fraction of bound EPS was released and solubilized, increasing soluble EPS. Increased apparent food-to-microorganism (F/M) ratio favoured production of EPS in ozonated reactors, enhancing flocculation, which had potential to improve settling. Dewaterability, measured by CST test, was better in alternating anoxic/aerobic reactors than in aerobic ones, indicating that incorporation of an anoxic zone for biological nutrient removal leads to improvement in sludge dewatering. The negative impact of ozonation on dewaterability was minimal in terms of the long-term operation.

scholarly journals Renewal of the Control System and Reliable Long Term Operation of the LHD Cryogenic System

2015 ◽  
Vol 67 ◽  
pp. 77-82 ◽  
Author(s):  
T. Mito ◽  
A. Iwamoto ◽  
K. Oba ◽  
S. Takami ◽  
S. Moriuchi ◽  
...  
Keyword(s):  
Control System ◽  
Cryogenic System ◽  
Term Operation

Mechanical behavior of magnetorheological dampers after long-term operation in a cable vibration control system

2018 ◽  
Vol 26 (1) ◽  
pp. e2280 ◽  
Author(s):  
Wenxi Wang ◽  
Xugang Hua ◽  
Xiuyong Wang ◽  
Jiali Wu ◽  
Hongxin Sun ◽  
...  
Keyword(s):  
Control System ◽  
Mechanical Behavior ◽  
Vibration Control ◽  
Magnetorheological Dampers ◽  
Cable Vibration ◽  
Term Operation

scholarly journals The Detector Control System of the New Small Wheel for the ATLAS experiment

2021 ◽  
Vol 2105 (1) ◽  
pp. 012025
Author(s):  
Polyneikis Tzanis
Keyword(s):  
Control System ◽  
Continuous Monitoring ◽  
Automatic Processes ◽  
High Luminosity ◽  
Central System ◽  
Term Operation ◽  
Atlas Experiment ◽  
Data Rates ◽  
Detector Control System

Abstract The ATLAS Muon Spectrometer is going through an extensive Phase I upgrade to cope up with the future LHC runs of high luminosity of up to instantaneous luminosity of 7.5 × 1034cm−2s−1. The luminosity increase drastically impacts the ATLAS trigger and readout data rates. The present ATLAS Small Wheel Muon detector will be replaced with a New Small Wheel (NSW) detector which is expected to be installed in the ATLAS underground cavern by the end of the Long Shutdown 2 of the LHC. Due to its complexity and long-term operation, the NSW requires the development of a sophisticated Detector Control System (DCS). The use of such a system is necessary to allow the detector to function consistently and safely as well as to function as a seamless interface to all sub-detectors and the technical infrastructure of the experiment. The central system handles the transition between the probe’s possible operating states while ensuring continuous monitoring and archiving of the system’s operating parameters. Any abnormality in any subsystem of the detector triggers a signal or alert (alarm), which alerts the user and either adapts to automatic processes or allows manual actions to reset the system to function properly.

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