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.

Sludge reduction and performance analysis of a modified sludge reduction process

2013 ◽  
Vol 69 (5) ◽  
pp. 934-940 ◽  
Author(s):  
Zhen Zhou ◽  
Weimin Qiao ◽  
Can Xing ◽  
Yingjun Wang ◽  
Chunying Wang ◽  
...  
Keyword(s):  
Activated Sludge ◽  
Nitrogen Concentration ◽  
Oxygen Demand ◽  
Reduction Process ◽  
Ammonium Nitrogen ◽  
Aeration Tank ◽  
Sludge Reduction ◽  
Oxidation Reduction ◽  
Solids Retention ◽  
And Performance

A modified sludge process reduction activated sludge (SPRAS) technology was developed by inserting a sludge process reduction (SPR) module, composed of an aeration tank and a settler, before the activated sludge system was proposed in this study. Compared with the anaerobic/anoxic/aerobic (AAO) process, the SPRAS resulted in a remarkable decrease in sludge production by 76.6%; sludge decay owing to lengthy solids retention time (about 121.5 d) could be the major cause. During the 217-day operation, the oxidation-reduction potential (ORP) (from 54 to −198 mV) and pH (from 7.8 to 5.0) at the bottom of the SPR settler gradually decreased, and low ORP and pH were in favor of sludge reduction in the SPRAS system. The insertion of the SPR module improved the removal efficiencies of suspended solids, chemical oxygen demand and ammonium nitrogen, and total nitrogen concentration in the effluent was reduced from 23.89 ± 4.82 to 14.16 ± 3.98 mg/L by 50% influent bypassing the SPR module. These results indicated that the SPRAS process could produce much less excess sludge and guarantee better effluent quality than the AAO process.

PACTTM process for treatment of kraft mill effluent

1997 ◽  
Vol 35 (2-3) ◽  
pp. 283-290 ◽  
Author(s):  
R. M. Narbaitz ◽  
R. L. Droste ◽  
L. Fernandes ◽  
K. J. Kennedy ◽  
D. Ball
Keyword(s):  
Activated Sludge ◽  
Oxygen Demand ◽  
Pulp Mill ◽  
Operating Conditions ◽  
Activated Sludge Process ◽  
Conventional Activated Sludge ◽  
Adsorbable Organic Halides ◽  
Organic Halides ◽  
Solids Retention ◽  
Year 2000

The PACTTM process (powdered activated carbon addition to the activated sludge process) was evaluated for the treatment of Kraft pulp mill wastewater in a series of bench scale experiments. Possibly due to the relatively low strength wastewater, the PACTTM process with carbon doses between 0.5 and 1.0 g/L of influent only performed marginally better than the conventional activated sludge process. Chemical oxygen demand and toxicity, evaluated with the Microtox® assay, were among the parameters monitored. For the operating conditions tested the solids retention time had no impact on performance. The main improvement was increased in adsorbable organic halides (AOX) removal, the magnitude of the improvement was dependent on the wastewater batch and the carbon dose. However conventional activated sludge treatment will meet Ontario's year 2000 AOX regulations. An empirical model from the literature described the data fairly well.

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 Fate of selected pharmaceutically active compounds in the integrated fixed film activated sludge process

2017 ◽  
Vol 75 (11) ◽  
pp. 2680-2691 ◽  
Author(s):  
K. J. Murray ◽  
W. J. Parker ◽  
L. M. Bragg ◽  
M. R. Servos
Keyword(s):  
Activated Sludge ◽  
Municipal Wastewater ◽  
Nitrification Rate ◽  
Process Conditions ◽  
Batch Reactors ◽  
Experimental Conditions ◽  
Conventional Activated Sludge ◽  
Fixed Film ◽  
Solids Retention ◽  
Biomass Activity

The potential for integrated fixed film activated sludge (IFAS) processes to achieve enhanced transformation of pharmaceuticals relative to conventional activated sludge (CAS) processes was assessed. Previous studies have focused on direct comparisons of parallel reactors with and without fixed film carriers and little information is available on the impacts of how varying operating parameters impact the differences in observed pharmaceutical compound (PC) transformation capabilities between CAS reactors and those equipped with both an activated sludge (AS) and fixed film carriers. The testing was carried out using bench scale sequencing batch reactors fed with authentic municipal wastewater and operated at selected combinations of temperature and solids retention time (SRT). PC transformation efficiencies were assessed in a 22 factorial design that employed the IFAS and CAS processes, operated in parallel under identical process conditions. Nitrification rate testing that was conducted to obtain insight into the biomass activity demonstrated that IFAS consistently had improved nitrification kinetics despite lower mixed liquor volatile suspended solids levels thereby demonstrating the contribution of the biofilm to nitrification. Increased transformation of atenolol (ATEN; ranging from 10–60%) and trimethoprim (TRIM; ranging from 30–50%) in the IFAS equipped reactors relative to their respective activated sludge (AS) controls was observed under all experimental conditions. Negligible transformation of carbamazepine was observed in both reactors under all conditions investigated. More than 99% of acetaminophen was transformed in both configurations under all conditions. There was no correspondence between nitrification activity and TRIM removal in the control AS while conditions that stimulated nitrification in the control AS also resulted in enhanced removal of ATEN. The results of this study indicate that the integration of biofilms in AS processes enhances transformation of some PCs.

Biodegradation and toxicity of melamine at high activated sludge concentrations in a membrane bioreactor

2017 ◽  
Vol 77 (4) ◽  
pp. 979-987 ◽  
Author(s):  
Shengnan Xu ◽  
Minghao Sun ◽  
Allen Thompson ◽  
Zhiqiang Hu
Keyword(s):  
Activated Sludge ◽  
Membrane Bioreactor ◽  
Hydrolytic Enzymes ◽  
Biomass Concentration ◽  
Batch Studies ◽  
Conventional Activated Sludge ◽  
Low Mass ◽  
Removal Efficiencies ◽  
Low Mass Ratio

Abstract Melamine is recalcitrant and toxic to bacteria in conventional activated sludge systems. In this study, we investigated the degradation and toxicity of melamine in a membrane bioreactor (MBR) system operated at high activated sludge concentrations (∼8.5 g TSS/L). Melamine was dosed at 3 mg/L for about 100 days. The average melamine removal efficiency in the MBR system was 20 ± 11%. Meanwhile, batch studies showed the acclimated sludge from the MBR had higher removal efficiencies after the depletion of readily biodegradable substrate (acetate) while non-acclimated sludge did not remove any melamine. As acclimated sludge had removal efficiencies ranging from 33 ± 6% (by 1.7 g TSS/L biomass) to 41 ± 10% (by 8.5 g TSS/L biomass), microbial specialists with unique hydrolytic enzymes in the acclimated sludge were likely responsible for melamine degradation. Since bacteria prefer to use readily biodegradable substrates for growth in the MBR, the population of microbial specialists capable of degrading melamine or the capability of cometabolism appeared not to increase with an increase in biomass concentration. Nevertheless, because of high sludge concentrations and thus low mass ratio of toxic melamine to biomass in the MBR, the long-term melamine exposure did not affect MBR activated sludge performance.

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.

Long-term performance of side-stream deammonification in a continuous flow granular-activated sludge process for nitrogen removal from high ammonium wastewater

2015 ◽  
Vol 71 (8) ◽  
pp. 1241-1248 ◽  
Author(s):  
Babak Rezania ◽  
Donald S. Mavinic ◽  
Harlan G. Kelly
Keyword(s):  
Activated Sludge ◽  
Retention Time ◽  
Biomass Concentration ◽  
Granular Sludge ◽  
Operating Conditions ◽  
Activated Sludge Process ◽  
Conventional Activated Sludge ◽  
Wide Range ◽  
Nitrite Oxidizing Bacteria ◽  
Solids Retention

An innovative granular sludge deammonification system was incorporated into a conventional-activated sludge process. The process incorporated an internal baffle in the bioreactor for continuous separation of granular biomass from flocculent biomass, which allowed for controlling the solids retention time of flocculent sludge. The process was evaluated for ammonium removal from municipal digested sludge dewatering centrate under various operating conditions lasting over 450 days. The process successfully removed, on average, 90% of the ammonium from centrate at various ammonium loading reaching 1.4 kg/m3d at 20 hours hydraulic retention time. Controlling the retention time of the flocculent biomass and maintaining low nitrite concentration were both found to be effective for nitrite oxidizing bacteria management, resulting in a low nitrate concentration (below 50 mg/L) over a wide range of flocculent biomass concentration in the bioreactor.

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