Bench-scale study on zero excess activated sludge production process coupled with ozonation unit in membrane bioreactor

2008 ◽  
Vol 43 (11) ◽  
pp. 1325-1332 ◽  
Author(s):  
Zheng Wang ◽  
Lin Wang ◽  
Bao Z. Wang ◽  
Yi F. Jiang ◽  
Shuo Liu
Keyword(s):  
Activated Sludge ◽  
Production Process ◽  
Membrane Bioreactor ◽  
Bench Scale ◽  
Sludge Production

Modelling the degradation of endogenous residue and ‘unbiodegradable’ influent organic suspended solids to predict sludge production

2013 ◽  
Vol 67 (4) ◽  
pp. 789-796 ◽  
Author(s):  
Mathieu Spérandio ◽  
Marc-André Labelle ◽  
Abdellah Ramdani ◽  
Alain Gadbois ◽  
Etienne Paul ◽  
...  
Keyword(s):  
Activated Sludge ◽  
Membrane Bioreactor ◽  
Suspended Solids ◽  
Municipal Wastewater ◽  
Modified Model ◽  
First Order ◽  
Degradation Rates ◽  
Solids Retention ◽  
Activated Sludge Models ◽  
Sludge Production

Activated sludge models have assumed that a portion of organic solids in municipal wastewater influent is unbiodegradable. Also, it is assumed that solids from biomass decay cannot be degraded further. The paper evaluates these assumptions based on data from systems operating at higher than typical sludge retention times (SRTs), including membrane bioreactor systems with total solids retention (no intentional sludge wastage). Data from over 30 references and with SRTs of up to 400 d were analysed. A modified model that considers the possible degradation of the two components is proposed. First order degradation rates of approximately 0.007 d–1 for both components appear to improve sludge production estimates. Factors possibly influencing these degradation rates such as wastewater characteristics and bioavailability are discussed.

Optimal sludge retention time for a bench scale MBR treating municipal sewage

2008 ◽  
Vol 57 (3) ◽  
pp. 319-322 ◽  
Author(s):  
A. Pollice ◽  
G. Laera ◽  
D. Saturno ◽  
C. Giordano ◽  
R. Sandulli
Keyword(s):  
Activated Sludge ◽  
Membrane Bioreactor ◽  
Municipal Wastewater ◽  
Operating Conditions ◽  
Municipal Sewage ◽  
Process Conditions ◽  
Physical Parameters ◽  
Municipal Wastewater Treatment ◽  
Bench Scale ◽  
Conventional Activated Sludge

Membrane bioreactors allow for higher sludge concentrations and improved degradation efficiencies with respect to conventional activated sludge. However, in the current practice these systems are often operated under sub-optimal conditions, since so far no precise indications have yet been issued on the optimal operating conditions of MBR for municipal wastewater treatment. This paper reports some results of four years of operation of a bench scale membrane bioreactor where steady state conditions were investigated under different sludge retention times. The whole experimental campaign was oriented towards the investigation of optimal process conditions in terms of COD removal and nitrification, biomass activity and growth, and sludge characteristics. The membrane bioreactor treated real municipal sewage, and four different sludge ages were tested (20, 40, 60, and 80 days) and compared with previous data on complete sludge retention. The results showed that the the biology of the system, as assessed by the oxygen uptake rate, is less affected than the sludge physical parameters. In particular, although the growth yield was observed to dramatically drop for SRT higher than 80 days, the biological activity was maintained under all the tested conditions. These considerations suggest that high SRT are convenient in terms of limited excess sludge production without losses of the treatment capacity. Physical characteristics such as the viscosity and the filterability appear to be negatively affected by prolonged sludge retention times, but their values remain within the ranges normally reported for conventional activated sludge.

Production of Sludge in a Submerged Membrane Bioreactor and Dewatering Aspects

2007 ◽  
Vol 5 (1) ◽  
Author(s):  
Watsa Khongnakorn ◽  
Christelle Wisniewski
Keyword(s):  
Activated Sludge ◽  
Water Reuse ◽  
Membrane Bioreactor ◽  
Operating Conditions ◽  
Good Prediction ◽  
Activated Sludge Process ◽  
Conventional Activated Sludge ◽  
Sludge Dewaterability ◽  
Conventional Activated Sludge Process ◽  
Sludge Production

In wastewater treatment, the membrane bioreactor (MBR) holds the potential to become one of the new generation processes, ensuring effluent quality and disinfection of sufficiently high levels to allow water reuse and recycle. Furthermore, the possibility to operate with high biomass concentrations (2 to 5 times higher than in conventional activated sludge process, CAS) allows to impose high solid retention times(SRT) that can be beneficial to a sludge production reduction and so to a reduction of disposal costs. These non-conventional operating conditions (high SRT) can also induce different sludge characteristics and dewatering aptitude, which are essential parameters for the optimization of the sludge post-treatment, like mechanical dewatering. The objective of this work was to study the performances of a complete sludge retention membrane bioreactor, in terms of organic removal efficiency, sludge production and sludge dewaterability. The adaptability of Activated Sludge Model 3 (ASM3) to provide good prediction results of high SRT-MBR was studied. Typical parameters adopted to describe sludge dewaterability were quantified and compared with the conventional activated sludge process (CAS).

The innovative Osmotic Membrane Bioreactor (OMBR) for reuse of wastewater

2011 ◽  
Vol 63 (8) ◽  
pp. 1557-1565 ◽  
Author(s):  
E. R. Cornelissen ◽  
D. Harmsen ◽  
E. F. Beerendonk ◽  
J. J. Qin ◽  
H. Oo ◽  
...  
Keyword(s):  
Activated Sludge ◽  
Membrane Fouling ◽  
Membrane Bioreactor ◽  
Membrane Separation ◽  
Economic Assessment ◽  
Laboratory Scale ◽  
Membrane Area ◽  
Bench Scale ◽  
Draw Solution ◽  
Osmotic Membrane Bioreactor

An innovative osmotic membrane bioreactor (OMBR) is currently under development for the reclamation of wastewater, which combines activated sludge treatment and forward osmosis (FO) membrane separation with a RO post-treatment. The research focus is FO membrane fouling and performance using different activated sludge investigated both at laboratory scale (membrane area of 112 cm2) and at on-site bench scale (flat sheet membrane area of 0.1m2). FO performance on laboratory-scale (i) increased with temperature due to a decrease in viscosity and (ii) was independent of the type of activated sludge. Draw solution leakage increased with temperature and varied for different activated sludge. FO performance on bench-scale (i) increased with osmotic driving force, (ii) depended on the membrane orientation due to internal concentration polarization and (iii) was invariant to feed flow decrease and air injection at the feed and draw side. Draw solution leakage could not be evaluated on bench-scale due to experimental limitation. Membrane fouling was not found on laboratory scale and bench-scale, however, partially reversible fouling was found on laboratory scale for FO membranes facing the draw solution. Economic assessment indicated a minimum flux of 15 L.m−2h−1 at 0.5M NaCl for OMBR-RO to be cost effective, depending on the FO membrane price.

Variation in Sludge Settleability with Temperature

1980 ◽  
Vol 15 (1) ◽  
pp. 73-82 ◽  
Author(s):  
J.G. Henry ◽  
E.E. Salenieks
Keyword(s):  
Activated Sludge ◽  
Effect Of Temperature ◽  
Organic Load ◽  
Limiting Factor ◽  
Appreciable Effect ◽  
Loading Rates ◽  
Bench Scale ◽  
Filamentous Bulking ◽  
Filamentous Microorganisms ◽  
Sludge Settleability

Abstract This study examined the effect of temperature on the settleabi1ity of activated sludge at various organic loading rates. Five completely mixed, bench-scale, activated sludge plants, operating under similar conditions at 5, 10 and 19°C, were continuously fed diluted, settled sewage supplemented with carbohydrate (sucrose). Hydraulic loading rates, MLSS and pH were maintained at constant levels during the experiments to eliminate these factors are variables. Dissolved oxygen was kept in excess of 3 mg/1 so that it would not be a limiting factor. Sludge Volume Indices (SVI ) and zone settling velocities were used to indicate changes in sludge settleability. Microscopic examination of the activated sludge indicated significant differences in the morphological features of filamentous microorganisms present at the two temperature extremes. At 19°C, the predominant forms were characterized by long curving trichomes, occasionally falsely branching, containing short cylindrical cells. At 5 °C, much smaller straight filaments, composed of long, narrow, rod-shaped cells appeared to be the principal microorganisms responsible for bulking. Various other filamentous forms were always present at each of the temperatures studied. Stirred sludge settling tests of moderately bulking sludges generally exhibited much higher settling velocities and lower SVI's than unstirred bulking samples. However, extremely filamentous bulking sludge exhibited comparable stirred and unstirred settling velocity and SVI values. The standard SVI test was found to be an inadequate indicator of the extent of bulking when trying to correlate the SVI failures from bench-scale performance with the results from continuous units. Lower temperature had no appreciable effect on COD removal efficiency as long as bulking did not cause a loss of solids in the effluent. However, results suggested that less than half the organic load could be accepted at 5°C, that could be handled at 19°C, before filamentous bulking occurred. A plot of loading versus temperature for various SVI's provided a visual indication of the safe loading limit below which bulking was unlikely to occur. The study clearly demonstrated that temperature can have a significant effect on sludge settleability.

A Batch Activated Sludge Study of Pineapple Wastewater Using a Bioaugmentation Process

1991 ◽  
Vol 24 (5) ◽  
pp. 233-240 ◽  
Author(s):  
Nik Fuaad Nik Abllah ◽  
Aik Heng Lee
Keyword(s):  
Activated Sludge ◽  
Removal Efficiency ◽  
Treatment Plant ◽  
Domestic Wastewater ◽  
Ammonia Nitrogen ◽  
Batch Reactors ◽  
Organic Loading ◽  
Suitable Alternative ◽  
Organic Removal ◽  
Sludge Production

A laboratory study was conducted to determine the feasibility of batch activated sludge reactor for treating pineapple wastewater and to examine the effects of bioaugmentation on treatment performance. The experimental set-up consists of eleven batch reactors. Activated sludge obtained from a wastewater treatment plant treating domestic wastewater was used as seed for the reactors. Synthetic pineapple wastewater was used as feed for the reactors. The eleven reactors were arranged to evaluate the total organic removal, nitrification, and sludge production by bioaugmentation process. Three major factors considered were influent organic loading, ammonia-nitrogen, and dosage of bacterial-culture-product addition. Removal of TOG (total organic carbon), sludge production in terms of SS(suspended solids), and ammonia-nitrogen removal variation are used as evaluation parameters. The TOC removal efficiency after the end of a 48 hour reactor run, for influent TOC of 350.14 to 363.30 mg/l, and 145.92 to 169.66 mg/l, was 94.41 to 95.89%, and 93.72 to 94.73% respectively. Higher organic removal was observed in the bioaugmented reactors with higher organic loading. The better organic removal efficiency in the bioaugmented reactors was probably due to activities of bacteria added. The test results also indicated that sludge yield was enhanced by the bacteria additive and high bacteria dosage produced less sludge. Bioaugmentation was observed to be a suitable alternative for enhancing the biological treatment of pineapple wastewater.

Minimization of activated sludge production by chemically stimulated energy spilling

2000 ◽  
Vol 42 (12) ◽  
pp. 189-200 ◽  
Author(s):  
G.-H. Chen ◽  
H.-K. Mo ◽  
S. Saby ◽  
W.-k. Yip ◽  
Y. Liu
Keyword(s):  
Activated Sludge ◽  
Growth Yield ◽  
Dry Weight ◽  
Staining Technique ◽  
Microbial Culture ◽  
Dapi Staining ◽  
E Coli ◽  
Energy Spilling ◽  
Activated Sludge Processes ◽  
Sludge Production

Minimization of excess sludge production in activated sludge processes has been pursued around the world in order to meet stringent environmental regulations on sludge treatment and disposal. To achieve this goal, physical, chemical, and biological approaches have been proposed. In this paper, a chemical compound, 3,3′,4′,5-tetrachlorosalicylanilide (TCS) was tested for enhancing microbial energy spilling of the sludgeso as to minimize its growth. In order to examine this, an exploratory study was conducted using both batch and continuous activated sludge cultures. Batch experiments with these two cultures were carried out at different initial concentrations of TCS. It has been confirmed that an addition of TCS is effective in reducing the production of both the sludge cultures, particularly the continuous culture where the observed growth yield was reduced by around 70%, when the initial TCS concentration was 0.8 ppm. Meanwhile, the substrate removal activity of this culture was found not to be affected at this TCS concentration. To further evaluate the TCS effect, a pure microbial culture of E. coli was employed. Batch experiment results with this culture implied that TCS might be able to reduce the cell density of E. coli drastically when an initial TCS concentration was greater than 0.12 ppm. It was also found that TCS was not toxic to this type of bacteria. Microscopic examinations with a 4′, 6-diamidino-2-phenylindole (DAPI) staining technique revealed that TCS neither affected the cell division nor altered the cell size of E. coli. However, both the cell ATP content and the cell dry weight were reduced significantly with the addition of TCS.

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