scholarly journals Tailing propensity in the ultraviolet disinfection of trickling filter and activated sludge wastewater treatment processes

2017 ◽  
Vol 76 (3) ◽  
pp. 623-632 ◽  
Author(s):  
Thiam C. Tan ◽  
Yaldah Azimi ◽  
Ramin R. Farnood
Keyword(s):  
Activated Sludge ◽  
Suspended Particle ◽  
Uv Disinfection ◽  
Distribution Data ◽  
Trickling Filter ◽  
Floc Size ◽  
Sludge Flocs ◽  
Filter System ◽  
Secondary Effluents ◽  
Wastewater Samples

In this paper, the effect of suspended flocs on the tailing of ultraviolet (UV) disinfection kinetics of secondary effluents was examined. To achieve this goal, final effluents produced in two processes for treating wastewater; namely, a trickling filter system and an activated sludge system, were collected and their UV disinfection were compared. Tailing of the UV dose response curve was controlled by the fraction of flocs that are both culturable and UV-resistant, referred to as the ‘tailing propensity’. Using this parameter, the contribution of various floc size fractions in reducing the UV disinfection efficiency of wastewater samples was quantified. Activated sludge flocs larger than 125 μm exhibited as much as 35 times greater tailing propensity than smaller flocs in the range of 20–25 μm. Within a fixed size range, the tailing propensity of flocs generated in the trickling filter system was 3 to 8 times higher than that of activated sludge flocs, and this difference increased with the floc size. A mathematical model was developed to predict the UV disinfection of secondary effluents from suspended particle size distribution data. The model showed good agreement with experimental results.

Study of factors affecting simultaneous nitrification and denitrification (SND)

1999 ◽  
Vol 39 (6) ◽  
pp. 61-68 ◽  
Author(s):  
Klangduen Pochana ◽  
Jürg Keller
Keyword(s):  
Carbon Source ◽  
Activated Sludge ◽  
Physical Phenomenon ◽  
Treatment Plant ◽  
Batch Reactors ◽  
Sequencing Batch Reactors ◽  
Factors Affecting ◽  
Floc Size ◽  
Sludge Flocs ◽  
Activated Sludge Systems

Experiments have been performed to gain an understanding of the conditions and processes governing the occurrence of SND in activated sludge systems. Sequencing batch reactors (SBRs) have been operated under controlled conditions using the wastewater from the first anaerobic pond in an abattoir wastewater treatment plant. Under specific circumstances, up to 95% of total nitrogen removal through SND has been found in the system. Carbon source and oxygen concentrations were found to be important process parameters. The addition of acetate as an external carbon source resulted in a significant increase of SND activity in the system. Stepwise change of DO concentration has also been observed in this study. Experiments to determine the effect of the floc size on SND have been performed in order to test the hypothesis that SND is a physical phenomenon, governed by the diffusion of oxygen into the activated sludge flocs. Initial results support this hypothesis but further experimental confirmation is still required.

Activated sludge flocculation: direct determination of the effect of calcium ions

2001 ◽  
Vol 43 (11) ◽  
pp. 75-82 ◽  
Author(s):  
C. A. Biggs ◽  
A. M. Ford ◽  
P. A. Lant
Keyword(s):  
Activated Sludge ◽  
Direct Determination ◽  
Rate Of Change ◽  
Valuable Insight ◽  
Floc Size ◽  
Sludge Flocs ◽  
On Line ◽  
Flocculation Process ◽  
Insight Into

The effect of calcium on activated sludge flocculation dynamics is investigated using a unique experimental technique. The technique allows on-line analysis of the size of activated sludge flocs during flocculation and provides valuable insight into the mechanisms of flocculation. Activated sludge samples were firstly sonicated for 3 minutes at 50W and then stirred at 100 rpm. The floc size was subsequently measured on-line using a Malvern Mastersizer/E. For concentrations of calcium less than 4 meq/L no significant increase in final floc size was observed even though an increase in the initial rate of change of floc size could be seen. Addition of calcium greater than 4 meq/L resulted in a dramatic increase in floc size. Results from this investigation support the theory that cations are involved in flocculation through cationic bridging, and will be used in ongoing investigations to model the flocculation process.

Early warning-system for operation-failures in biological stages of WWTPs by on-line image analysis

2002 ◽  
Vol 46 (4-5) ◽  
pp. 117-124 ◽  
Author(s):  
W. Heine ◽  
I. Sekoulov ◽  
H. Burkhardt ◽  
L. Bergen ◽  
J. Behrendt
Keyword(s):  
Wastewater Treatment ◽  
Activated Sludge ◽  
Wastewater Treatment Plants ◽  
Biological Parameter ◽  
Chemical Parameters ◽  
Floc Size ◽  
Sludge Flocs ◽  
Operation Conditions ◽  
Physico Chemical ◽  
Microscopic Picture

By the observation and evaluation of the microscopic picture of activated sludge samples it is possible to introduce another biological parameter additional to conventional physico-chemical parameters for the control of biological stages of waste water treatment plants. Considering the fact that parameters like floc size and floc size distribution, structure of the flocs (compact/open), shape of the flocs (round/irregular) allow perceptions of the adjusted operation conditions of the biological stages, evidence for changing operation conditions or threatening operation disturbances can be recognised. This recognition takes place at a very early phase, because the morphology of activated sludge flocs reacts very fast to changing conditions. An automatic image analysis of activated sludge floc pictures would enable the introduction of a new sum parameter to enhance operation control of aeration tanks. By a statistical evaluation of the processed sludge images several parameters can be used to describe the alteration of activated sludge flocs characteristics. With these biological parameters it is possible to detect altered operation conditions or threatening or existing operation problems at an early phase. Thus it is possible to plan suitable countermeasures. Furthermore, the microscopic picture is the only parameter, that gives important information about the structure of the activated sludge flocs and the biozenosis. In comparison with the mainly used physico-chemical parameters, that just give information about the inlet and outlet of the wastewater treatment plants, the microscopic picture is the only parameter that gives information about the biology of the wastewater treatment process. By means of this biological parameter an improved control and regulation of the biological stages of wastewater treatment plants can be obtained.

Spatial arrangement of the components of activated sludge flocs

1994 ◽  
Vol 30 (11) ◽  
pp. 243-250 ◽  
Author(s):  
F. Zartarian ◽  
C. Mustin ◽  
J. Y. Bottero ◽  
G. Villemin ◽  
F. Thomas ◽  
...  
Keyword(s):  
Activated Sludge ◽  
Laser Scanning ◽  
Sewage Treatment ◽  
Sewage Treatment Plant ◽  
Treatment Plant ◽  
Spatial Arrangement ◽  
Municipal Sewage ◽  
Cellular Division ◽  
Floc Size ◽  
Sludge Flocs

The purpose of this work was to observe the internal structure of activated sludge flocs and the relationship between the different components. Activated sludge flocs from the municipal sewage treatment plant at Nancy (France) were physically stabilized and solidified in an epoxy resin. The flocs were sliced into 0.1 μm thick sections and stained for characterisation of components and exopolymers by transmission electron microscopy. One small floc (10 μm × 20 μm), embedded in resin, was chosen and studied using a laser scanning confocal microscope. The focal plane was incremented in steps of 2 μm along the z axis of the microaggregate. In order to extract quantitative data (number of cells, floc size) a numerical treatment of the images was applied. A typical floc exhibits an unhomogeneous distribution of the mass of the exocellular polymer matrix (mainly polysaccharides). This matrix maintains the integrity of the floc and connects most of the components. These components are isolated bacteria, waste and debris inherited from the effluent and microcolonies. The structure of the microflocs is fractal with a fractal dimension Df ≈ 3. This large value implies that the growth of the small aggregates is possibly generated by cellular division and polymer production.

Comparison of imidazolium ionic liquids and traditional organic solvents: effect on activated sludge processes

2013 ◽  
Vol 68 (12) ◽  
pp. 2654-2660 ◽  
Author(s):  
Dorota Gendaszewska ◽  
Ewa Liwarska-Bizukojc
Keyword(s):  
Ionic Liquids ◽  
Activated Sludge ◽  
Organic Solvents ◽  
Biomass Concentration ◽  
Alkyl Substituent ◽  
Imidazolium Ionic Liquids ◽  
Floc Size ◽  
Sludge Flocs ◽  
Pollutants Removal ◽  
Activated Sludge Processes

Data concerning the biodegradability and ecotoxicity of ionic liquids (ILs) obtained so far are insufficient in the context of IL removal from wastewater in activated sludge systems. Thus, in this work the selected imidazolium ionic liquids and two organic solvents (methanol and acetone) were tested with respect to their influence on activated sludge processes, particularly on the morphology of sludge flocs. The presence of ionic liquids with the chemical structure of 1-alkyl-3-methyl imidazolium bromide in wastewater did not deteriorate biological wastewater treatment processes if their concentration was not higher than 5 mg l−1. Regarding the structure of the ILs studied, the longer the alkyl substituent was, the stronger the effect on sludge flocs. The highest decrease in activated sludge floc area and biomass concentration was exerted by the ionic liquid with the longest alkyl chain, i.e. 1-decyl-3-methylimidazolium bromide. The action of both methanol and acetone on floc size, activated sludge concentration and efficiency of organic pollutants removal was weaker compared to all tested 1-alkyl-3-methyl imidazolium bromides.

Effect of floc size and structure on biosolids capillary suction time

2003 ◽  
Vol 47 (12) ◽  
pp. 255-260 ◽  
Author(s):  
J. Guan ◽  
R. Amal ◽  
T.D. Waite
Keyword(s):  
Activated Sludge ◽  
Fractal Dimensions ◽  
Scattering Method ◽  
Capillary Suction ◽  
Floc Size ◽  
Sludge Flocs ◽  
Floc Structure ◽  
Small Angle Light Scattering ◽  
Size And Structure

Both size and structure of wastewater solids (biosolids) have been hypothesised to have an impact on the dewaterability of these solids yet very little data exists to validate this hypothesis or to elucidate the relative effects of size and structure. We have recently undertaken studies in which the size and structure of activated sludge flocs were altered in a controlled manner and the dewaterability of resultant flocs examined using the well established capillary suction time (CST) test. A small angle light scattering method was applied for the determination of activated sludge floc size and structure. The results obtained in this work show that floc structure is a major determinant of capillary suction time. In some instances, flocs have almost double the median (D(4,3)) size but possess similar fractal dimensions and similar CST values.

Application of Image Analysis System for Study of Activated Sludge Flocs

1986 ◽  
Vol 21 (1) ◽  
pp. 130-140 ◽  
Author(s):  
Da-hong Li ◽  
J. J. Ganczarczyk
Keyword(s):  
Image Analysis ◽  
Activated Sludge ◽  
Statistical Processing ◽  
Equivalent Diameter ◽  
Image Analysis System ◽  
Sectional Area ◽  
Cross Sectional ◽  
Computerized Image Analysis ◽  
Sludge Flocs ◽  
Analysis System

Abstract The computerized image analysis system has been successfully used for determination and statistical processing of the following geometric characteristics of activated sludge flocs: longest dimension, breadth, equivalent diameter, cross-sectional area, perimeter, elongation, and circularity. These parameters could be effectively and precisely determined by the system applied. In addition, the studied method, as compared to direct microscope observation and photography floc-sizing methods, was found to be more accurate, less time-consuming, and less dependent on the investigators.

Rehabilitation and Upgrading of the Beni Suef City Wastewater Treatment Plant

1990 ◽  
Vol 22 (7-8) ◽  
pp. 131-138
Author(s):  
Ahmed Fadel
Keyword(s):  
Wastewater Treatment ◽  
Activated Sludge ◽  
Wastewater Treatment Plant ◽  
Treatment Plant ◽  
Primary Treatment ◽  
High Rate ◽  
Shock Load ◽  
Economic Evaluations ◽  
Activated Sludge Process ◽  
Trickling Filter

Many of Egypt's cities have existing treatment plants under operation that have been constructed before 1970. Almost all of these treatment plants now need rehabilitation and upgrading to extend their services for a longer period. One of these plants is the Beni Suef City Wastewater Treatment Plant. The Beni Suef WWTP was constructed in 1956. It has primary treatment followed by secondary treatment employing intermediate rate trickling filters. The BOD, COD, and SS concentration levels are relatively high. They are approximately 800, 1100, and 600 mg/litre, respectively. The Beni Suef city required the determination of the level of work needed for the rehabilitation and upgrading of the existing 200 l/s plant and to extend its capacity to 440 l/s at year 2000 A description of the existing units, their deficiencies and operation problems, and the required rehabilitation are presented and discussed in this paper. Major problems facing the upgrading were the lack of space for expansion and the shortage of funds. It was, therefore, necessary to study several alternative solutions and methods of treatment. The choice of alternatives was from one of the following schemes: a) changing the filter medium, its mode of operation and increasing the number of units, b) changing the trickling filter to high rate and combining it with the activated sludge process, for operation by one of several possible combinations such as: trickling filter-solids contact, roughing filter-activated sludge, and trickling filter-activated sludge process, c) dividing the flow into two parts, the first part to be treated using the existing system and the second part to be treated by activated sludge process, and d) expanding the existing system by increasing the numbers of the different process units. The selection of the alternative was based on technical, operational and economic evaluations. The different alternatives were compared on the basis of system costs, shock load handling, treatment plant operation and predicted effluent quality. The flow schemes for the alternatives are presented. The methodology of selecting the best alternative is discussed. From the study it was concluded that the first alternative is the most reliable from the point of view of costs, handling shock load, and operation.

Floc size distribution and bacterial activities in membrane separation activated sludge processes for small-scale wastewater treatment/reclamation

1997 ◽  
Vol 35 (6) ◽  
pp. 37-44 ◽  
Author(s):  
Boran Zhang ◽  
Kazuo Yamamoto ◽  
Shinichiro Ohgaki ◽  
Naoyuki Kamiko
Keyword(s):  
Wastewater Treatment ◽  
Activated Sludge ◽  
Municipal Wastewater ◽  
Membrane Separation ◽  
Small Scale ◽  
Nitrification Rate ◽  
Floc Size ◽  
Denitrification Activity ◽  
Concentration Changes ◽  
Activated Sludge Processes

Activated sludges taken from full-scale membrane separation processes, building wastewater reuse system (400m3/d), and two nightsoil treatment plants (50m3/d) as well as laboratory scale membrane separation bioreactor (0.062m3/d) were analyzed to characterize membrane separation activated sludge processes (MSAS). They were also compared with conventional activated sludges(CAS) taken from municipal wastewater treatment plants. Specific nitrification activity in MSAS processes averaged at 2.28gNH4-N/kgMLSS.h were higher than that in CAS processes averaged at 0.96gNH4-N/kgMLSS.h. The denitrification activity in both processes were in the range of 0.62-3.2gNO3-N/kgMLSS.h without organic addition and in the range of 4.25-6.4gNO3-N/kgMLSS.h with organic addition. The organic removal activity in nightsoil treatment process averaged at 123gCOD/kgMLSS.h which was significantly higher than others. Floc size distributions were measured by particle sedimentation technique and image analysis technique. Flocs in MSAS processes changed their sizes with MLSS concentration changes and were concentrated at small sizes at low MLSS concentration, mostly less than 60 μm. On the contrary, floc sizes in CAS processes have not much changed with MLSS concentration changes and they were distributed in large range. In addition, the effects of floc size on specific nitrification rate, denitrification rate with and without organic carbon addition were investigated. Specific nitrification rate was decreased as floc size increased. However, little effect of floc size on denitrification activity was observed.

scholarly journals Deep learning-based morphology classification of activated sludge flocs in wastewater treatment plants

2021 ◽  
Author(s):  
Hisashi Satoh ◽  
Yukari Kashimoto ◽  
Naoki Takahashi ◽  
Takashi Tsujimura
Keyword(s):  
Wastewater Treatment ◽  
Deep Learning ◽  
Activated Sludge ◽  
Morphological Change ◽  
Wastewater Treatment Plants ◽  
Filamentous Bacteria ◽  
Sludge Flocs

A deep learning-based two-label classifier 1 recognized a 20% morphological change in the activated flocs. Classifier-2 quantitatively recognized an abundance of filamentous bacteria in activated flocs.

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