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

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.

scholarly journals Air concentrations and particle–gas partitioning of polyfluoroalkyl compounds at a wastewater treatment plant

2011 ◽  
Vol 8 (4) ◽  
pp. 363 ◽  
Author(s):  
Lena Vierke ◽  
Lutz Ahrens ◽  
Mahiba Shoeib ◽  
Eric J. Reiner ◽  
Rui Guo ◽  
...  
Keyword(s):  
Wastewater Treatment ◽  
Wastewater Treatment Plant ◽  
Treatment Plant ◽  
Air Sampling ◽  
Passive Samplers ◽  
Aeration Tank ◽  
Sampling Campaign ◽  
Secondary Clarifier ◽  
Polyfluoroalkyl Compounds ◽  
Air Concentrations

Environmental contextPolyfluoroalkyl compounds, widely used chemicals in consumer and industrial products, are global pollutants in the environment. Transport mechanisms and environmental pathways of these compounds, however, are not yet fully understood. We show that a wastewater treatment plant can be an important source for polyfluoroalkyl compounds to the atmosphere where they have the potential to be transported long distances. AbstractAn air sampling campaign was conducted at a wastewater treatment plant (WWTP) to investigate air concentrations and particle–gas partitioning of polyfluoroalkyl compounds (PFCs). Samples were collected at an aeration tank and a secondary clarifier using both active high volume samplers and passive samplers comprising sorbent-impregnated polyurethane foam (SIP) disks. Water to air transport of PFCs was believed to be enhanced at the aeration tank owing to aerosol-mediated transport caused by surface turbulence induced by aeration. Mean air concentrations of target PFCs at the aeration tank were enriched relative to the secondary clarifier by factors of ~19, ~4 and ~3 for ∑fluorotelomer alcohols (FTOHs) (11 000 v. 590 pg m–3), ∑perfluorooctane sulfonamides & perfluorooctane sulfonamidoethanols (FOSAs & FOSEs) (120 v. 30 pg m–3) and ∑perfluoroalkyl carboxylates & perfluoroalkyl sulfonates (PFCAs & PFSAs) (4000 v. 1300 pg m–3) respectively. The particle associated fraction in the atmosphere increased with increasing chain length for PFCAs (from 60 to 100%) and PFSAs were predominantly bound to particles (~98%). Lower fractions on particles were found for FTOHs (~3%), FOSAs (~30%) and FOSEs (~40%). The comparison of the active and passive air sampling showed good agreement.

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.

scholarly journals Upgrading of Kish Island Markazi wastewater treatment plant by MBBR

2011 ◽  
Vol 1 (4) ◽  
pp. 243-249 ◽  
Author(s):  
Mehdi Ahmadi ◽  
Hassan Izanloo ◽  
Aliakbar Mehr alian ◽  
Hoda Amiri ◽  
Mohammad Noori Sepehr
Keyword(s):  
Wastewater Treatment ◽  
Retention Time ◽  
Wastewater Treatment Plant ◽  
Loading Rate ◽  
Treatment Plant ◽  
Biofilm Reactor ◽  
Volume Index ◽  
Organic Loading Rate ◽  
Aeration Tank ◽  
Operation Condition

The potential of a moving bed biofilm reactor (MBBR) in full scale has been investigated as an alternative for upgrading of the Kish Island Markazi wastewater treatment plant. In this regard, the activated sludge process (ASP) upgraded to an MBBR process and different operating parameters results in this change compared with ASP. Results show that with increasing the average flow influent from 1,049 ± 88 to 1,944 ± 275 m3 d−1 and reducing the aeration tank volume from 300 to 150 m3, organic loading rate (OLR), mixed liquor suspended solids (MLSS), sludge retention time (SRT), sludge volume index (SVI), hydraulic loading rate (HLR) and hydraulic retention time (HRT) were changed to 0.32 ± 0.04–1.8 ± 0.36 kg COD/m3d, 2,641.19 ± 284.99–7,354.2 ± 778.35 mg L−1, 5.28 ± 0.64–22.1 ± 1.53 d, 135 ± 37.3–29.2 ± 3.81, 23.14 ± 1.94–43.37 ± 5.04 m d−1 and 2.76 ± 0.22–1.48 ± 0.18 h, respectively. Effluent concentrations under this operation condition were well below the discharge limits for irrigation water. Therefore, the MBBR process is a good alternative for upgrading wastewater plants especially when there is inadequate space or modifications are needed that will require large investment.

scholarly journals Probabilistic modelling and evaluation of wastewater treatment plant upgrades in a water quality based evaluation context

2010 ◽  
Vol 12 (4) ◽  
pp. 380-395 ◽  
Author(s):  
Lorenzo Benedetti ◽  
Webbey De Keyser ◽  
Ingmar Nopens ◽  
Peter A. Vanrolleghem
Keyword(s):  
Water Quality ◽  
Wastewater Treatment ◽  
Wastewater Treatment Plants ◽  
Treatment Plant ◽  
Dynamic Modelling ◽  
Effluent Quality ◽  
Wwtp Effluent ◽  
Regulatory Standards ◽  
The Eu

Process choice and dimensioning of wastewater treatment plants (WWTPs) is difficult while ensuring regulatory standards are met and cost-efficiency is maintained. This step only accounts for a small fraction of the upfront costs, but can lead to substantial savings. This paper illustrates the results of a systematic methodology to evaluate system upgrade options by means of dynamic modelling. In contrast to conventional practice, the presented approach allows the most appropriate trade-off between cost of measures and effluent quality to be chosen and the reliability of a process layout to be assessed by means of uncertainty analysis. In a hypothetical case study, thirteen WWTP upgrade options are compared in terms of their effluent quality and economic performance. A further comparison of two options with regard to the resulting receiving water quality reveals the paramount importance of this aspect, and highlights the inadequacy of evaluation frameworks limited to the performance relative to a sub-system (WWTP effluent) when a wider perspective (as induced by the EU Water Framework Directive) has to be adopted.

High salinity wastewater treatment

2013 ◽  
Vol 68 (6) ◽  
pp. 1400-1405 ◽  
Author(s):  
M. Linarić ◽  
M. Markić ◽  
L. Sipos
Keyword(s):  
Wastewater Treatment ◽  
Activated Sludge ◽  
Suspended Solids ◽  
High Salinity ◽  
Electrokinetic Potential ◽  
Treatment Plant ◽  
Volume Index ◽  
Aeration Tank ◽  
Surge Flooding ◽  
Salinity Wastewater

The shock effect, survival and ability of activated sludge to acclimatize to wastewater containing different concentrations of NaCl and Na2SO4 were investigated under laboratory conditions. To accomplish this, the potential penetration of a sewage system by seawater as a consequence of storm surge flooding was simulated. The experiments were conducted using activated sludge taken from the aeration tank of a communal wastewater treatment plant and adding different concentrations up to 40 g/L of NaCl and 4.33 g/L of Na2SO4. The effects of salinity on the activated sludge were monitored for 5 weeks based on the values of pH, dissolved oxygen, total suspended solids, volatile suspended solids, sludge volume, sludge volume index, electrokinetic potential, respirometric measurements and enzymatic activity. The addition of salt sharply reduced or completely inhibited the microbial activity in activated sludge. When salt concentrations were below 10 g/L NaCl, microorganisms were able to acclimatize in several weeks and achieve the same initial activity as in raw sludge samples. When the salt concentration was above 30 g/L NaCl, the acclimatization process was very slow or impossible.

Co-Treatment of Septage and Domestic Sewage for the Greater Athens Area

1992 ◽  
Vol 25 (4-5) ◽  
pp. 119-126
Author(s):  
A. D. Andreadakis
Keyword(s):  
Treatment Plant ◽  
Primary Treatment ◽  
Domestic Sewage ◽  
Systematic Research ◽  
Effluent Quality ◽  
Design Load ◽  
Future Performance ◽  
Sludge Thickening ◽  
Athens Area ◽  
Final Effluent

The paper evaluates the performance of the Metamorphosis treatment plant, designed to treat 20,000 m3.d−1 domestic sewage and 24,000 m3. d−1 septage from the Greater Athens region. During the period 1987-1989 the plant received about one third of the design load. Sewage and septage were subjected to separate preliminary and primary treatment and subsequently to joint activated sludge treatment. The performance of the treatment plant was satisfactory, resulting in an overall mean effluent BOD5 concentration of 24 mg.l−1 and an adequately stabilised sludge. However, persistent sludge bulking, which prevailed for most of the studied period, casts doubts on the effectiveness of future performance at full load, not only with respect to final effluent quality but also in relation to the degree of sludge stabilisation, due to possible short retention times in the digestors. Identification of the causes of bulking through systematic research and improvement of the sludge thickening processes are two priority aspects which should be presently addressed, in order to ensure efficient future performance of the plant.

Low Cost Packaged Sewage Treatment Plant for Production of High Quality Effluent at Small Works

1993 ◽  
Vol 27 (5-6) ◽  
pp. 405-412 ◽  
Author(s):  
B. Chambers ◽  
J. Whitaker ◽  
A. F. Elvidge
Keyword(s):  
Suspended Solids ◽  
Low Cost ◽  
Sewage Treatment ◽  
Sewage Treatment Plant ◽  
Treatment Plant ◽  
Ammonia Nitrogen ◽  
Aeration Tank ◽  
Effluent Quality ◽  
Demonstration Plant ◽  
The Uk

In the UK there are over 7000 small works which treat the sewage from populations of less than 10,000. Many of these works are at risk of non-compliance with effluent quality consents and options for improving the standard of treatment are being pursued by many utilities. WRc and Anglian Water Services have developed designs for packaged sewage treatment plants to serve populations in the range of 1000-10,000. A demonstration plant has been constructed at the Waterbeach STW of Anglian Water to serve a population of about 6,500. Target effluent quality is 15:20:5mg/l of BOD, SS and ammonia nitrogen respectively on a 95 percentile basis. Following plant commissioning a process performance evaluation programme was commenced in February 1991. Nitrification was established after about 6 weeks of operation but suspended solids values have been affected by the presence of a stable foam on the surface of the aeration tank. Process modifications have reduced the effect of this phenomenon substantially and effluent quality has improved.

scholarly journals Radiotracer investigation of a pulp and paper mill effluent treatment plant

Nukleonika ◽  
2017 ◽  
Vol 62 (4) ◽  
pp. 289-294 ◽  
Author(s):  
Metali Sarkar ◽  
Vikas K. Sangal ◽  
Haripada Bhunia ◽  
Pramod K. Bajpai ◽  
Harish J. Pant ◽  
...  
Keyword(s):  
Paper Industry ◽  
Treatment Plant ◽  
Paper Mill ◽  
Pulp And Paper ◽  
Effluent Treatment ◽  
Aeration Tank ◽  
Pulp And Paper Mill ◽  
Dead Zones ◽  
Effluent Treatment Plant ◽  
Secondary Clarifier

Abstract The pulp and paper industry is highly dependent on water for most of its processes, producing a significant amount of wastewater that should be treated to comply with environmental standards before its discharge into surface-water reservoirs. The wastewater generated primarily consists of substantial amounts of organic, inorganic, toxic and pathogenic compounds in addition to nutrients, which are treated in an effluent treatment plant that often combines primary, secondary, tertiary and advanced treatments. However, the treatment methods vary from industry to industry according to the process utilized. The effective performance of effluent treatment plants is crucial from both environmental and economic points of view. Radiotracer techniques can be effectively used to optimize performance and detect anomalies like dead zones, bypassing, channelling, etc. in wastewater treatment plants. Experiments on the distribution of residence time were performed on the aeration tank and secondary clarifier of a full-scale pulp and paper mill to study the flow behaviour as well as locate system anomalies and hence evaluate the performance of the treatment plants using the radiotracer I-131. The convolution method was applied to model the system with an imperfect impulse radiotracer input. The aeration tank was working efficiently in the absence of any dead zones or bypassing. Various hydrodynamic models available in the literature were applied on the aeration tank and secondary clarifier to obtain the hydraulic representation of the systems.

Approach to the Reforms in Nightsoil Treatment Process Introduced Abroad

1991 ◽  
Vol 24 (5) ◽  
pp. 189-196 ◽  
Author(s):  
S. B. Guo ◽  
R. Z. Chen ◽  
G. Li ◽  
H. Y. Shoichi
Keyword(s):  
Treatment Cost ◽  
Treatment Process ◽  
Biological Process ◽  
Treatment Plant ◽  
Plant Performance ◽  
First Year ◽  
Original Design ◽  
Effluent Quality ◽  
Public Toilets

In 1987 Guangzhou Liede Nightsoil Treatment Plant started commissioning. The purpose of the plant is to dispose of 400 tons of nightsoi1 from city public toilets per day. In the first year of the commissioning a biological process was basically used according to the original design made by a Danish company. Practically it has been proved that the design is effective. The process can reduce BOD from 3800 mg/l to about 133 mg/l, or by approximately 96.5 percent. The performance of the sludge digester system is satisfactory. Because the primary investigation on characteristics of the nightsoil was insufficient there were some problems raised during the commissioning. So in the first year the effluent failed to achieve the desired quality. After the analysis of the plant performance some necessary reforms have been carried out. Now the effluent quality can stably meet the national discharge limits and the treatment cost decreases.

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