Application of mathematical tools to improve the design and operation of activated sludge plants. Case study: the new WWTP of Galindo-Bilbao Part II: Operational strategies and automatic controllers

2001 ◽  
Vol 43 (7) ◽  
pp. 167-174 ◽  
Author(s):  
A. Galarza ◽  
E. Ayesa ◽  
M. T. Linaza ◽  
A. Rivas ◽  
A. Salterain
Keyword(s):  
Activated Sludge ◽  
Operational Strategies ◽  
Effluent Quality ◽  
Analysis Methodology ◽  
State Behaviour ◽  
Operating Space ◽  
Input Variables ◽  
Automatic Controllers ◽  
Operating Constraints

This paper presents a new sensitivity analysis methodology for Activated Sludge WWTPs. It is based on both (a) the calculation of the range of “manipulated input variables” that satisfy the restrictions imposed on the “output variables” and (b) on the computation of isolines of the output variables inside the feasible operating space. This analysis allows a more precise description of the operating constraints, facilitates the understanding of the steady-state behaviour of the process and detects possible areas where the process is very sensitive to small disturbances. The feasible operating space for two Activated Sludge WWTP processes for CN removal (RDN, DRDN), using SRT and DO level as “input variables” as well as effluent quality and exploitation costs as the main “output variables” is studied. The proposed methodology facilitates the selection of the appropriate operational strategy and the design of automatic controllers. Some examples of the application of this methodology for the design of automatic controllers in a real WWTP are briefly presented.

Design and Operational Analyses of Activated Sludge Processes Using Respirometrically Calibrated Models

1992 ◽  
Vol 26 (3-4) ◽  
pp. 753-762 ◽  
Author(s):  
A. F. Rozich
Keyword(s):  
Activated Sludge ◽  
Model Calibration ◽  
Process Model ◽  
Process Analysis ◽  
Case Histories ◽  
Model Case ◽  
Operational Strategies ◽  
Analysis Methodology ◽  
Technical Basis ◽  
Activated Sludge Processes

The purpose of this paper is to present the background and examples of methodology which enable environmental engineers and scientists to analyze activated sludge processes much more effectively than is otherwise possible with conventional approaches. Good process analyses are key for devising optimal design and operational strategies. The key features to the technique presented herein are the field-proven predictability of the model and the methodology for collecting data needed for calibrating the process model. Case histories prove the predictability of the model that is associated with the process analysis approach. The advantage of the approach advocated herein is the use of respirometric techniques to calibrate the model. These methods enable the process analyst to collect the requisite data for model calibration in twenty-four hours or less. This feature enables one to use this process analysis methodology for both design and operational applications. The paper will present the technical basis for the process model and how respirometric methods are utilized to compute biokinetic constants in a manner which is consistent with kinetic theory. Case histories will be discussed that demonstrate the predictability of the modeling approach and demonstrate the utility of this tool for process analysis.

scholarly journals Aboriginal Tourism as Sustainable Social-Environmental Enterprise (SSEE): A Tlingit Case Study from Southeast Alaska

2015 ◽  
Vol 6 (4) ◽  
Author(s):  
Paphaphit Wanasuk ◽  
Thomas F Thornton
Keyword(s):  
Cultural Economic ◽  
Southeast Alaska ◽  
Operational Strategies ◽  
Cultural Sustainability ◽  
Operating Space ◽  
Social Environmental ◽  
Short Time ◽  
Safe Operating ◽  
Dominant Influence

The Tlingit Aboriginal tourism enterprise named Icy Strait Point in Hoonah, Southeast Alaska is used as a case study to develop the new concept of Sustainable Social-Environmental Enterprise (SSEE). SSEE is defined as an innovative enterprise that has dynamic operational strategies while still maintaining its corporate core values and integrating social, environmental, cultural, economic and political (SECEP) sustainabilities in its operations. The SSEE framework assesses enterprises according to five domains of sustainability: social, environmental, cultural, economic, and political. Applying this framework, we find that while social, economic, and cultural sustainability goals have been achieved in a relatively short time by the Aboriginal tourism enterprise in Hoonah, the political and environmental spheres of sustainability are constrained by the dominant influence of the multinational cruise ship industry over tourism development. Thus, for an emerging tourism enterprise to be sustainable, we suggest each of these livelihood dimensions needs to achieve "a safe operating space" that is adaptable over time and to changing social and environmental circumstances.

Impact of the volume of rain water on the operating constraints for a treatment plant

1999 ◽  
Vol 39 (2) ◽  
pp. 145-150
Author(s):  
T. Dormoy ◽  
B. Tisserand ◽  
L. Herremans
Keyword(s):  
Wastewater Treatment ◽  
Activated Sludge ◽  
Wastewater Treatment Plant ◽  
Wastewater Treatment Plants ◽  
Treatment Plant ◽  
Simulation Software ◽  
Quality Requirements ◽  
Effluent Quality ◽  
Operating Constraints ◽  
Pollution Loads

The new regulations require an increased amount of treatment of stormwater and a reduction of pollution loads discharged into the natural surroundings to be considered. Drainage systems therefore and particularly wastewater treatment plants should be sized correctly to cope with these peaks. Using a simulation software of wastewater treatment plant with activated sludge, such as SIMBAD, enables us to check that planned structures are appropriate in relation to the effluent quality requirements laid down, and to fix the most appropriate operating procedures. Operating constraints on a plant for treating stormwater are not negligible. It is advisable to allow for increased sludge production, O2 requirements and also sludge quality (fermentability).

Operating space diagrams: a tool for designers of wastewater treatment plants

2001 ◽  
Vol 44 (2-3) ◽  
pp. 69-76 ◽  
Author(s):  
L. N. Hopkins ◽  
P. A. Lant ◽  
R. B. Newell
Keyword(s):  
Wastewater Treatment ◽  
Activated Sludge ◽  
Wastewater Treatment Plants ◽  
Control Strategies ◽  
Design Stage ◽  
Operating Space

Recent years have seen the introduction of new and varied designs of activated sludge plants. With increasing needs for higher efficiencies and lower costs, the possibility of a plant that operates more effectively has created the need for tools that can be used to evaluate and compare designs at the design stage. One such tool is the operating space diagram. It is the aim of this paper to present this tool and demonstrate its application and relevance to design using a simple case study. In the case study, use of the operating space diagram suggested changes in design that would improve the flexibility of the process. It also was useful for designing suitable control strategies.

Modelling of activated sludge for textile wastewaters

1998 ◽  
Vol 38 (4-5) ◽  
pp. 9-17 ◽  
Author(s):  
F. Germirli Babuna ◽  
D. Orhon ◽  
E. Ubay Çokgör ◽  
G. Insel ◽  
B. Yaprakli
Keyword(s):  
Activated Sludge ◽  
Comprehensive Evaluation ◽  
Component Model ◽  
Activated Sludge Process ◽  
Experimental Basis ◽  
Model Simulations ◽  
Effluent Quality ◽  
Model Based ◽  
Major Process ◽  
Textile Wastewaters

A comprehensive evaluation of four different textile wastewaters was carried out to set the experimental basis for the modelling of activated sludge process. Experiments involved beside conventional characterization, detailed COD fractionation and assessment of major kinetic and stoichiometric coefficients by means of respirometric measurements. A multi-component model based on the endogenous decay concept was used for the kinetic interpretation and design of activated sludge. The fate and variation of major process components affecting effluent quality with the sludge age were evaluated by means of model simulations.

Maximum Heat Recovery And Utilization System In A Municipal Activated Sludge Fluidized Bed Incineration (FBI) Plant : A Case Study For Bursa, Turkey

2016 ◽  
Vol 2016 (9) ◽  
pp. 174-184
Author(s):  
Ercument Aktuz ◽  
John Yu ◽  
Bilge Alpaslan Kocamemi ◽  
Talat Ozen ◽  
Devrim İzgi ◽  
...  
Keyword(s):  
Activated Sludge ◽  
Fluidized Bed ◽  
Heat Recovery ◽  
Maximum Heat ◽  
Fluidized Bed Incineration

Controlling the Settling of Activated Sludge in Pulp and Paper Wastewater Treatment Plants

1999 ◽  
Vol 40 (11-12) ◽  
pp. 223-229 ◽  
Author(s):  
Frédéric Clauss ◽  
Christel Balavoine ◽  
Delphine Hélaine ◽  
Gaëtan Martin
Keyword(s):  
Wastewater Treatment ◽  
Activated Sludge ◽  
Wastewater Treatment Plants ◽  
Pulp And Paper ◽  
Organic Load ◽  
Forest Industry ◽  
Filamentous Bulking ◽  
Mineral Particles ◽  
Mineral Powder

Forest industry wastewaters are difficult to clean: hydraulic and organic load variations, filamentous bulking or pin-point flocs negatively impact depollution processes. The addition of a fine, mineral, talc-based powder, Aquatal, into the aeration tanks of wastewater treatment plants connected to pulp and paper factories has been successfully tested since end of '97. The first case-study presents full results obtained over a period of 18 months in a 20,000 p.e. plant connected to a paper factory. The mineral powder was regularly added to control sludge volume index, thereby ensuring low suspended solids concentration in the outfluent. Plant operators could easily adapt biomass concentration to match organic load variation, thereby maintaining pollution micro-organisms ratio constant. In a second case study, a trouble-shooting strategy was implemented to counteract filamentous bulking. A one-off, large dosage enabled the plant operator to deal effectively with poor settleability sludge and rapidly control sludge blanket expansion. In both cases, the main common characteristics observed were an increase in floc aggregation and the production of heavier and well-structured flocs. The sludge settling velocity increased and an efficient solid/liquid separation was obtained. After a few days, the mineral particles of Aquatal were progressively integrated into the sludge floc structure. When the mineral powder was added to the activated sludge in the aeration basin, chemical interactions frequently encountered with other wastewater treatment additives did not pose a problem. Moreover, with this mineral additive, the biological excess sludge displayed good thickening properties and dewatering was improved. Despite the addition of the insoluble mineral particles, the amount of wet sludge expelled did not increase. Aquatal offers a rapid solution to floc settleability problems which so frequently arise when physical or biological disorders appear in forest industry wastewater treatment plants.

Problem-posing in management classrooms for collective sustainability transformation

2021 ◽  
Vol 22 (3) ◽  
pp. 477-496
Author(s):  
Janette Brunstein ◽  
Mark Edward Walvoord ◽  
Ed Cunliff
Keyword(s):  
Transformative Learning ◽  
Learning Objectives ◽  
Problem Posing ◽  
Content Type ◽  
Analysis Methodology ◽  
Unique Approach ◽  
Teaching Cases ◽  
Classroom Use

Purpose The purpose of this study is to examine the possible benefits of approaching sustainability-related teaching cases from the perspective of problem-posing (PP) instead of problem-solving (PS). Design/methodology/approach A document analysis methodology (Silverman, 2011) was used to analyze sustainability teaching case study abstracts and learning objectives from business databases. Cases were reviewed and classified as PP, PS or other. PP cases were further subclassified on one of three axes. Findings Of 117 cases reviewed, most were PS (66%) with only 9% PP. Theoretical and pedagogical implications are discussed with recommendations for writing or converting, PS to PP cases for classroom use. Theoretical contributions include identification of three distinct and complementary views of PP, described in these axes: emancipatory; problematizing metaphors and premises; and rational, process and means-focused cases, not triggering transformative learning theory. Of 10 cases classified as PP cases, 3 were subclassified as emancipatory. Research limitations/implications This research is limited to case study titles containing “sustainability” and analyses of their descriptions and learning objectives only. Next phases of the research will examine differences in student learning between PS and PP in situ. Practical implications The research identifies a unique approach to the authoring and use of case studies that hold the potential for increasing students’ critical thinking capabilities and production of solutions to sustainability issues. Originality/value There is limited research and analysis of the identification and implications of using PP pedagogy.

scholarly journals Nonhomogeneous Boosting for Predictor Selection in Ensemble Postprocessing

2016 ◽  
Vol 145 (1) ◽  
pp. 137-147 ◽  
Author(s):  
Jakob W. Messner ◽  
Georg J. Mayr ◽  
Achim Zeileis
Keyword(s):  
Regression Coefficients ◽  
Maximum Temperature ◽  
Ensemble Forecasts ◽  
Forecast Performance ◽  
Weather Forecasts ◽  
Medium Range ◽  
Important Input ◽  
Boosting Algorithm ◽  
Input Variables

Abstract Nonhomogeneous regression is often used to statistically postprocess ensemble forecasts. Usually only ensemble forecasts of the predictand variable are used as input, but other potentially useful information sources are ignored. Although it is straightforward to add further input variables, overfitting can easily deteriorate the forecast performance for increasing numbers of input variables. This paper proposes a boosting algorithm to estimate the regression coefficients, while automatically selecting the most relevant input variables by restricting the coefficients of less important variables to zero. A case study with ensemble forecasts from the European Centre for Medium-Range Weather Forecasts (ECMWF) shows that this approach effectively selects important input variables to clearly improve minimum and maximum temperature predictions at five central European stations.

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