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.

A Dynamic Secondary Clarifier Model including Processes of Sludge Thickening

1992 ◽  
Vol 25 (6) ◽  
pp. 267-284 ◽  
Author(s):  
L. Härtel ◽  
H. J. Pöpel
Keyword(s):  
Treatment Plant ◽  
Dynamic Modelling ◽  
Simulation Models ◽  
Reaction Model ◽  
Volume Index ◽  
Aeration Tank ◽  
Hindered Settling ◽  
Effluent Quality ◽  
Secondary Clarifier ◽  
Sludge Thickening

Dynamic simulation models of the activated sludge process are a planning and designing tool solving and answering problems that cannot be dealt with by static design models or procedures. In dynamic modelling, however, the settling and thickening processes have to be taken into account which have been neglected until now. Therefore, a dynamic model simulating the processes of settling and of thickening in the secondary clarifier is developed and finally integrated into a dynamic biochemical reaction model. The validity of the model approach is evaluated by simulation runs showing the velocities of hindered settling, the concentration profiles of MLSS over the tank depth, and the effluent concentrations of MLSS. Basic variables for the validation are the influent MLSS concentrations and the sludge volume index quantifying the settling characteristics of the sludge. The consequences for the MLSS content in the aeration tank, as well as for the plant effluent quality, of neglecting and of including the clarifier model into the integrated model are shown at variable conditions of wastewater inflow, especially for periods of higher storm water flows to the treatment plant

A Combination of the Activated Sludge Process with Fixed Film Biomass to Increase the Capacity of Waste Water Treatment Plants

1984 ◽  
Vol 16 (10-11) ◽  
pp. 119-130 ◽  
Author(s):  
W Hegemann
Keyword(s):  
Waste Water ◽  
Activated Sludge ◽  
Waste Water Treatment ◽  
Biomass Concentration ◽  
Volume Index ◽  
Aeration Tank ◽  
Sludge Flocs ◽  
Fixed Film ◽  
Different Types ◽  
Porous Plastic

The volume of the activated sludge aeration tank is influenced by f/m ratio and attainable biomass concentration. Increase of biomass results in smaller tank volume. In case of overloaded plants restoration may be achieved by increase of biomass instead of construction of further tank volume. Pieces of porous plastic media filled into ordinary compressed air aeration tanks may serve as fixed film biomass support. By this method biomass concentration in the tank may be increased to two or three times normal values. At the same time the sludge volume index of the activated sludge flocs still present in the aeration tank is improved. Better sedimentation and thickening of the activated sludge occurs because smaller quantities of flocs are passed to the final clarifiers. Results of tests with different types of waste water in semi-technical scale pilot plants as well as in existing plants of different sizes are presented.

Effect of important operational parameters on performance of coarse pore filtration activated sludge process

2002 ◽  
Vol 46 (9) ◽  
pp. 229-236 ◽  
Author(s):  
M.R. Alavi Moghaddam ◽  
H. Satoh ◽  
T. Mino
Keyword(s):  
Activated Sludge ◽  
Aeration Tank ◽  
Activated Sludge Process ◽  
Operational Parameters ◽  
Solid Retention Time ◽  
Effluent Quality ◽  
Membrane Pores ◽  
Filtration Membrane ◽  
Operation Pressure ◽  
Filter Clogging

A coarse pore filter can be applied inside the aeration tank instead of sedimentation tank for liquid separation from the sludge. It has pores, which are irregular in shape, and much bigger than micro-filtration membrane pores in size. The objective of the study was to investigate the effect of important operational parameters such as flux, aeration intensity, and solid retention time (SRT) on the performance of the coarse pore filtration activated sludge process. The effect of these parameters was studied in laboratory scale experiments. It was found that the flux had a significant role in the effluent quality of this system. The effluent SS and turbidity were not changed significantly at different aeration intensities. Three SRTs, 10, 30 and longer days (without excess sludge) were used for three reactors to check the effect of this parameter on the system performance. The results of the reactors with SRTs about 10 and 30 days have shown very good effluent quality without any filter clogging for more than 4 months operation. For the reactor with long SRT, the filter clogging was observed after about 80 days of operation, which caused the increase of the operation pressure and deterioration in the effluent quality for a few days.

scholarly journals Evaluation of the accuracy of two simple methods for microscopic activated sludge analysis

2018 ◽  
Vol 78 (10) ◽  
pp. 2104-2112
Author(s):  
Mateusz Sobczyk ◽  
Agnieszka Pajdak-Stós ◽  
Edyta Fiałkowska ◽  
Wioleta Kocerba-Soroka ◽  
Joanna Starzycka-Giża ◽  
...  
Keyword(s):  
Activated Sludge ◽  
Wastewater Treatment Plants ◽  
Oxygen Demand ◽  
Microscopic Analysis ◽  
Volume Index ◽  
Sign Test ◽  
Nitrogen And Phosphorus ◽  
Nitrogen And Phosphorus Removal ◽  
Effluent Quality ◽  
Significant Difference

Abstract Biological microscopic analysis is a popular method employed in wastewater treatment plants worldwide for evaluating activated sludge condition. However, many operators still have reservations regarding its reliability. In this study, we evaluated and compared two methods of microscopic sludge investigation: the sludge index (SI) and the Eikelboom–van Buijsen method (EB). We investigated 79 activated sludge samples from nine treatment plants located in southern Poland over a 1-year period. For each sample, sludge volume index values were calculated and compared with the results of evaluation made on the basis of microscopic analysis. Additionally, the effluent quality was analysed in 45 of 79 cases, including investigation of suspended solids, biochemical oxygen demand, chemical oxygen demand, total nitrogen and total phosphorous. The sign test and Wilcoxon matched pairs test showed that a significant difference existed between the two investigated methods. General conclusions from both methods do not provide reliable information concerning nitrogen and phosphorus removal. The EB method had a tendency to be more conservative in its general conclusions than the SI method. Both are highly reliable for estimating activated sludge quality and solid separation properties.

Modelling of the Secondary Clarifier Combined with the Activated Sludge Model No. 1

1992 ◽  
Vol 25 (6) ◽  
pp. 285-300 ◽  
Author(s):  
René Dupont ◽  
Mogens Henze
Keyword(s):  
Wastewater Treatment ◽  
Simple Model ◽  
Activated Sludge ◽  
Wastewater Treatment Plants ◽  
Treatment Plant ◽  
Activated Sludge Model ◽  
Effluent Quality ◽  
Secondary Clarifier ◽  
Hydraulic Load ◽  
Flux Model

Modelling of activated sludge wastewater treatment plants is today generally based on the Activated Sludge Model No. 1 combined with a very simple model for the secondary settler. This paper describes the development of a model for the secondary clarifier based on the general flux theory for zone settling, which can be used in combination with the Activated Sludge Model to form a dynamic computer model/program for a wastewater treatment plant. In addition to the flux model, the developed model includes a simple model for predicting the contents of paniculate components in the effluent This latter model is a purely empirical model, which connects the effluent quality with the hydraulic load, suspended solids load and the nitrate load. The paper describes the model and gives some basic examples on computer simulations and verification of the model.

Batch Operated Activated Sludge Plant for Production of High Effluent Quality at Small Works

1993 ◽  
Vol 28 (10) ◽  
pp. 251-258 ◽  
Author(s):  
B. Chambers
Keyword(s):  
Activated Sludge ◽  
Sewage Treatment ◽  
Batch Process ◽  
Ammonia Nitrogen ◽  
Aeration Tank ◽  
Coated Steel ◽  
Effluent Quality ◽  
Water Companies ◽  
The Uk ◽  
Activated Sludge Systems

In the UK there are about 7500 sewage treatment works of which 85% serve populations of less than 5000. Many of the smaller works do not comply with effluent quality standards and options for improving treatment are being pursued by many water companies. WRc have developed designs for packaged activated sludge systems to serve populations in the range 100 - 1000 persons. A detailed design has been completed for a population equivalent of about 600. Target effluent quality is 15:20:5 mg/l of BOD, SS and ammonia nitrogen respectively on a 95 percentile basis. The activated sludge system is designed to operate as a batch process with aeration and sludge settlement both occurring in the same tank. Batch operated activated sludge plants are known to produce sludges with good settling properties providing the influent wastewater is admitted into the aeration tank in controlled manner. Therefore a specially designed holding tank has been included as the first stage in the treatment sequence. All process tanks are specified as glass-coated steel installed on a flat concrete base. Target construction cost for 600 population is ₤350 per capita.

Optimisation and Uprating of Activated Sludge Plants by Efficient Process Design

1988 ◽  
Vol 20 (4-5) ◽  
pp. 121-132 ◽  
Author(s):  
B. Chambers ◽  
G. L. Jones
Keyword(s):  
Mathematical Model ◽  
Activated Sludge ◽  
Plug Flow ◽  
Oxygen Demand ◽  
Full Scale ◽  
Aeration Tank ◽  
Effluent Quality ◽  
Integration Techniques ◽  
In Series ◽  
The Uk

Requirements to improve effluent quality and reduce operating costs at existing activated sludge plants in the UK have led to the development of an accurate mathematical model of the process which can be used for full-scale design. The WRc Activated Sludge Model has been developed over a number of years and is based on the concept of describing the kinetics of BOD removal by including a Monod term for growth and a Michaelis-Menten term for enzymatic activity. Since the first formulation of the model, further equations have been added which describe the use of oxygen and nitrate as electron acceptors for the conversion of BOD. The model equations can be used to predict the performance of most configurations of the activated sludge process by using the ‘tanks in series' concept to describe aeration tank mixing characteristics. Solutions to the equations are easily obtained by standard numerical integration techniques using a computer. The software has been written in such a way that the model can be used interactively by a plant designer. Results obtained using the mathematical model have been used to redesign several full-scale activated sludge plants in the UK. In some cases, it has been possible to reduce the energy costs for aeration by 40% whilst maintaining effluent quality by accurately matching the supply of oxygen to the spatially-varying oxygen demand in plug-flow aeration tanks. Bulking sludge problems have also been solved by the conversion of completely-mixed aeration tanks to plug-flow aeration tanks with complementary redesign of the aeration system.

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.

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  

Effect of salinity on the activity, settling and microbial community of activated sludge in sequencing batch reactors treating synthetic saline wastewater

2008 ◽  
Vol 58 (2) ◽  
pp. 351-358 ◽  
Author(s):  
G. Wu ◽  
Y. Guan ◽  
X. Zhan
Keyword(s):  
Microbial Community ◽  
Activated Sludge ◽  
Volume Index ◽  
Synthetic Wastewater ◽  
Utilization Rate ◽  
Yield Coefficient ◽  
Batch Reactors ◽  
Sequencing Batch Reactors ◽  
Saline Wastewater ◽  
Sludge Flocs

The effects of salinity on the activity in nutrient removal, settling and microbial community of activated sludge in sequencing batch reactors (SBRs) treating synthetic saline wastewater were investigated. Two SBRs, one treating synthetic saline wastewater (the N-Reactor, with NaCl addition) and the other treating fresh synthetic wastewater (the C-Reactor, without NaCl addition), were operated for 68 days. Three salinities (in terms of concentrations of NaCl)—10, 20 and 40 g NaCl/l—were examined. The microbial activity described with the specific glucose utilization rate, specific nitritation and nitratation rates, and specific phosphorus release and uptake rates, was inhibited in the N-Reactor, in comparison with that in the C-Reactor, except that the specific nitritation and nitratation rates were improved at the salinity of 10 g NaCl/l. The sludge yield coefficient decreased at salinities of 10 and 20 g NaCl/l but it rose at the salinity of 40 g NaCl/l. The settling of activated sludge flocs, in terms of the sludge volume index (SVI), was improved by adding NaCl. Particularly in the first 5 minutes during the SVI measurement, activated sludge flocs in the N-Reactor settled much faster than those in the C-Reactor. However, the effluent from the N-Reactor contained higher suspended solids than the effluent from the C-Reactor. The microbial diversity decreased with increasing the salinity, and the microbial community structure was greatly influenced by the salinity. Bacteriodetes and Actinobacteria were the dominant phylums detected with molecular fingerprinting techniques.

Sign in / Sign up

Export Citation Format

Share Document