Hydrophobicity of activated sludge flocs and laboratory-grown bacteria

1994 ◽  
Vol 30 (11) ◽  
pp. 211-218 ◽  
Author(s):  
F. Jorand ◽  
P. Guicherd ◽  
V. Urbain ◽  
J. Manem ◽  
J. C. Block
Keyword(s):  
Activated Sludge ◽  
Environmental Conditions ◽  
Hydrophobic Interactions ◽  
Volume Index ◽  
Sludge Volume Index ◽  
Hydrophobic Property ◽  
Sludge Flocs ◽  
Highly Hydrophobic ◽  
Different Strains

The cohesion of activated sludge biological flocs is controlled by the ratio between hydrophilic exopolymers in which bacteria are embedded and hydrophobic interactions. As shown in this study highly hydrophobic bacteria coexist in the flocs with highly hydrophilic bacteria which seem to release large quantities of exopolymers (polysaccharides, DNA, proteins…). Addition to the activated sludge of easily assimilable nutrients such as glucose does not change the hydrophobicity of bacteria but increases both exopolymer production and the sludge volume index. The environmental conditions and the bioavailability of nutrients may considerably shift the hydrophilic/hydrophobic balance. Moreover experiments carried out with four different strains to fourteen isolated from activated sludges have shown that a few strains (variable types) have quite considerable possibilities of hydrophobic property variations in the course of growth.

PRELIMINARY STUDIES ON THE INFLUENCE OF NEGATIVE PRESSURE ON ACTIVATED SLUDGE FLOCS

2018 ◽  
Vol 170 (50) ◽  
pp. 51-60 ◽  
Author(s):  
Anna Gnida ◽  
Dagmara Witecy
Keyword(s):  
Activated Sludge ◽  
Negative Pressure ◽  
Municipal Wastewater ◽  
Volume Index ◽  
Contaminant Removal ◽  
Sludge Volume Index ◽  
Sludge Flocs ◽  
Shear Sensitivity ◽  
Before And After ◽  
Negative Pressures

A sludge from municipal wastewater plant operated for biological contaminant removal was exposed to three different negative pressures (-200, -500 and -800 hPa) for three different duration times (30 second, 1 and 2 minutes). Sludge volume index, shear sensitivity of the sludge and activated sludge floc characteristic was the object of the study before and after negative pressure treatment. After the treatment the sludge settled better independently on the pressure value and duration time. The shear sensitivity changed the most when the pressure exposure of -800 hPa was 1 minute and longer. The flocs structure was more open after negative pressur and larger part of activated sludge was comprised by large flocs.

On-line measurements of settling characteristics in activated sludge

1997 ◽  
Vol 36 (4) ◽  
pp. 307-312
Author(s):  
Michael R. Rasmussen ◽  
Torben Larsen
Keyword(s):  
Activated Sludge ◽  
Settling Velocity ◽  
Continuous Measurement ◽  
Batch Reactor ◽  
Volume Index ◽  
Sludge Volume Index ◽  
Dynamic Variations ◽  
On Line ◽  
Settling Column ◽  
Settling Characteristics

An on-line settling column for measuring the dynamic variations of settling velocity of activated sludge has been developed. The settling column is automatic and self-cleansing insuring continuous and reliable measurements. The settling column was tested on sludge from a batch reactor where sucrose was added as an impulse to activated sludge. The continuous measurement of settling velocity revealed a highly dynamic response after the sucrose was added. The results were verified with simultaneous measurement of the initial settling rate. A 200 hour experiment showed variations in settling velocity, which was not apparent in the DSVI (Diluted Sludge Volume Index).

Settling Characteristics of Activated Sludge in Danish Treatment Plants with Biological Nutrient Removal

1994 ◽  
Vol 29 (7) ◽  
pp. 157-165 ◽  
Author(s):  
Gert Holm Kristensen ◽  
Per Elberg Jørgensen ◽  
Per Halkjær Nielsen
Keyword(s):  
Activated Sludge ◽  
Nutrient Removal ◽  
Volume Index ◽  
Biological Nutrient Removal ◽  
Sludge Volume Index ◽  
Filamentous Microorganisms ◽  
Best Parameter ◽  
One Year ◽  
Sludge Settling ◽  
Settling Characteristics

In 1989-91, a study was performed to investigate the settling characteristics of activated sludge in Danish treatment plants with biological nutrient removal. The study included three screening series on 38 treatment plants. Furthermore, the study included investigations during one year on seasonal variations in sludge settling characteristics at three treatment plants. The screening investigations were performed in November 1989 and May and September, 1990. Results showed that in the May-screening, 35-45% of the plants had a filament index of 2-2.5 or above, corresponding to a sludge volume index above 150 ml/g. When comparing data for diluted and non-diluted sludge volume indices, a SVI value of 150 ml/g seemed parallel to a DSVI of 110 ml/g. In the November- and September-screenings, some 30% of the plants had activated sludge showing a filament index in or above the critical area. Dominating filamentous microorganisms were found to be (in decreasing order): Microthrix parvicella, Type 0041, Type 021N, Type 0092, Type 0914, and Type 1851. A distinct variation over the year in sludge settling characteristics was found for the three plants. Sludge settling characteristics improved during summer, and deteriorated during winter. For activated sludge with a high content of filamentous microorganisms, the best parameter to follow the variations in sludge settling properties was the filament number. If the activated sludge concentration, the MLSS, varied significantly, the specific filament number was to be applied.

Effects of Temperature and pH on the Settleability of Activated Sludge Flocs

1990 ◽  
Vol 22 (9) ◽  
pp. 249-254 ◽  
Author(s):  
F. Dilek Çetin ◽  
Gülerman Sürücü
Keyword(s):  
Activated Sludge ◽  
Volume Index ◽  
Aeration Tank ◽  
Effluent Quality ◽  
Sludge Flocs ◽  
Secondary Clarifier ◽  
Different Temperatures ◽  
Effects Of Temperature ◽  
Two Parameters ◽  
Physiological And Biochemical

In efficient and economical treatment of wastewaters,the settleability of activated sludge is of prime importance. Efficient settlement in the secondary sedimentation tank is required, both to keep the desired effluent quality and to sustain the necessary amount of microorganisms in the aeration tank. On the other hand, the settleability of microorganisms in the secondary clarifier is very dependent on the physiological and biochemical nature of activated sludge flocs, which are determined by the conditions of the aeration tank. In this research, effects of temperature and pH of aeration basin on settleability of activated sludge were studied. Settleability was measured by zone settling velocity and sludge volume index (SVI). Five different temperatures and four different pH values were operated in the aeration basin. It was found that the settleability of activated sludge is greatly affected by these two parameters.

Impact of septic compounds and operational conditions on the microbiology of an activated sludge system

2007 ◽  
Vol 55 (6) ◽  
pp. 135-142 ◽  
Author(s):  
Carl Pelletier ◽  
Mary Ann Fitzsimmons ◽  
Sophie Deschênes ◽  
Michael Paice
Keyword(s):  
Activated Sludge ◽  
Digital Imaging ◽  
Volume Index ◽  
Operating Parameters ◽  
Sludge Volume Index ◽  
Sulphur Compounds ◽  
Operational Conditions ◽  
Volatile Organic ◽  
Volatile Organic Acids ◽  
Reduced Sulphur Compounds

In activated sludge (AS) biotreatment, septic compounds such as volatile organic acids and reduced sulphur compounds have been frequently cited as a major cause of Thiothrix and Type 021N filamentous bulking. These filaments are common in Canadian pulp and paper biotreatment systems, where they cause settling problems in secondary clarifiers. We conducted a 14-week study of a TMP/newsprint mill effluent to characterize the septic compounds entering the biotreatment, and to determine correlations with AS biomass characteristics and biotreatment operating parameters. A significant correlation was found between the sludge volume index, the abundance of Type 021N, and the propionic acid (PA) concentration in the primary clarified effluent. PA also induced a significant change in the flocculating bacteria size distribution determined by digital imaging. Consequently, the correlation observed between PA and Type 021N bulking is an indirect effect of inhibition of floc-forming microorganisms, giving a competitive advantage to filaments.

Estimation of suspended solids concentrations in activated sludge settling tanks

1997 ◽  
Vol 35 (8) ◽  
pp. 127-135 ◽  
Author(s):  
Youngchul Kim ◽  
Wesley O. Pipes ◽  
Paul-Gene Chung
Keyword(s):  
Activated Sludge ◽  
Suspended Solids ◽  
Marked Effect ◽  
Treatment Plant ◽  
Accurate Method ◽  
Volume Index ◽  
Sludge Volume Index ◽  
Solids Concentration ◽  
Exponential Decrease ◽  
Sludge Settling

This is a report of a field study based on data from an activated sludge process in a wastewater treatment plant in Chester, Pennsylvania, USA. The objective was to develop an accurate method for estimation of the average suspended solids concentration (SSB) of the layer of sludge in the settling tanks (the “sludge blanket”). Plant operators estimated SSB by averaging the mixed liquor suspended solids (Sm) and the return sludge suspended solids (Su) concentrations. Measurement of SSB showed that averaging Sm and Su frequently overestimated SSB by a large amount. A different relationship between SSB and parameters which are normally measured for operational purposes was developed. The parameters are Su, the overflow rates and data from the sludge volume index (SVI) measurement. It was found that an increasing overflow rate will result in an exponential decrease in the ratio of SSB to Su. Also, the SVI has a marked effect on the ratio of SSB to Su and thus on the amount of suspended solids which can be stored in the settling tanks. The proposed estimation equation was found to be statistically superior to estimation by averaging the Sm and Su.

Prediction of sludge volume index bulking using image analysis and neural network at a full-scale activated sludge plant

2015 ◽  
Vol 57 (37) ◽  
pp. 17195-17205 ◽  
Author(s):  
Halime Boztoprak ◽  
Yüksel Özbay ◽  
Dünyamin Güçlü ◽  
Murat Küçükhemek
Keyword(s):  
Neural Network ◽  
Image Analysis ◽  
Activated Sludge ◽  
Full Scale ◽  
Volume Index ◽  
Sludge Volume Index

scholarly journals Effects of Salinity on Physical Characteristics of Activated Sludge Flocs

1998 ◽  
Vol 33 (4) ◽  
pp. 565-588 ◽  
Author(s):  
Christopher P. Cousin ◽  
Jerzy J. Ganczarczyk
Keyword(s):  
Activated Sludge ◽  
Pore Size ◽  
Shape Factor ◽  
Hydrophobic Interactions ◽  
Physical Characteristics ◽  
Time Response ◽  
Equivalent Diameter ◽  
Sludge Flocs ◽  
Nacl Concentration ◽  
Size Population

Abstract The effect of increased wastewater salinity on the physical characteristics of activated sludge flocs was studied. Samples of activated sludge were exposed to increments of NaCl and the physical structure of the individual flocs, was then investigated. A time response of the flocs to these changes was also measured. Two separate series of tests were run and for both series, it was determined that as the NaCl concentration increased, the mean floc area, equivalent diameter, perimeter and longest dimension all increased, with the flocs becoming more elongated with decreasing shape factor. The mechanism involved in the increase of the floc sizes is considered to be a combination of electrostatic and hydrophobic interactions. Examination of the size distributions revealed that the data were best fitted by a log normal distribution and that, as the NaCl concentration was increased, the distribution of the characteristic tended to shift towards a higher proportion of larger values, or smaller values for the shape factor results. Both the porosity and boundary fractal dimension were found to provide different values in the two series of tests. The flocs were found to exhibit two distinct Sierpinski fractal dimensions, thus indicating the presence of two pore size populations. The increasing salinity had little effect on the smaller pore size population, but a significant effect on the larger pore size population. The time response test indicated that the flocs achieved the new characteristics in about 15 minutes.

scholarly journals PENGARUH CO-PRECIPITATION BESI KLORIDA TERHADAP KINERJA LUMPUR AKTIF PADA PROSES PENGOLAHAN AIR LIMBAH DOMESTIK SINTETIK

REAKTOR ◽  
2015 ◽  
Vol 15 (3) ◽  
pp. 182
Author(s):  
Dian Fatikha Aristiami ◽  
I Nyoman Widiasa
Keyword(s):  
Activated Sludge ◽  
Oxygen Demand ◽  
Domestic Wastewater ◽  
Suspended Solid ◽  
Volume Index ◽  
Sludge Volume Index ◽  
Mixed Liquor Suspended Solid ◽  
Effluent Quality ◽  
Co Precipitation ◽  
Settling Characteristics

The increase of population leads to an increase of the quantity of domestic wastewater. Activated sludge system is the most cost-efective to treat the domestic wastewater treatment. This study is aimed to evaluate the co-precipitation coagulant effect of FeCl3 on the growth of activated sludge, settling characteristics of the activated sludge, and effluent quality. sludge sedimentation characteristics (settling) as well as on the effluent quality. The activated sludge systems were operated in batch mode and synthetic domestic wastewaters with C:N:P ratio of 100:5:1 were used as feed wastewater. The growth of activated sludge was based on concentration of Mixed Liquor Suspended Solid (MLSS), settling characteristics of activated sludge was based on value of Sludge Volume Index (SVI), and effluent quality was based on turbidity, colour, N-ammonia concentration, and Chemical Oxygen Demand content. Results indicate that inhibition effect of FeCl3 to activated sludge activity was not significant at dosage ≤ 30 mg/L. Good settling characterisic (SVI 70-150 mg/L) was achieved at dosage of 20-30 mg/L. Finally, the best effluent quality, i.e. turbidity (9.4), colour (96), amonia removal (83.6%), and COD removal (72.97%), at dosage of 30 mg/L. Keywords: activated sludge; co-precipitation; domestic wastewater; wastewater treatment Abstrak Peningkatan jumlah penduduk mengakibatkan kenaikan jumlah air limbah domestik. Sistem lumpur aktif merupakan proses yang paling efektif untuk mengolah air limbah domestik. Penelitian ini bertujuan untuk mengevaluasi pengaruh co-precipitation koagulan FeCl3 terhadap pertumbuhan lumpur aktif, karakteristik pengendapan lumpur aktif, dan kualitas efluen. Sistem lumpur aktif dioperasikan secara curah dan umpan air limbah yang digunakan adalah air limbah domestik sintesis dengan rasio C:N:P = 100:5:1. Pertumbuhan lumpur aktif  berdasarkan konsentrasi Mixed Liquor Suspended Solid (MLSS), karakteristik pengendapan lumpur berdasarkan  nilai Sludge Volume Index (SVI), dan kualitas efluen berdasarkan tingkat kekeruhan, warna, kadar N-amonia dan kadar Chemical Oxygen Demand (COD). Hasil penelitian menunjukkan bahwa inhibisi FeCl3 terhadap aktivitas lumpur aktif tidak signifikan pada dosis ≤ 30 mg/L. Karakteristik pengendapan yang baik (SVI 70-150 mg/L) tercapai pada dosis 20-30 mg/L. Kualitas efluen terbaik, yaitu  kekeruhan (9,4),  warna (96), penyisihan amonia (83,6%) dan penyisihan COD (72,97%), pada dosis 30 mg/L. Kata kunci: lumpur aktif; co-precipitation; air limbah domestik; pengolahan air limbah  

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