The impact of sludge return liquors on South African wastewater treatment plants

There have been three considerable shifts, in the past 20 years, in the conventional design and modelling of wastewater treatment plants (WWTPs): (i) single unit process to plant-wide modelling, (ii) consideration of WWTPs as water and resource recovery facilities (WRRFs), and (iii) the need to simplify WWTP models to allow their intake by new stakeholders (i.e. plant operators, designers and decision-makers) who use these models for evaluation of WWTP optimisation strategies. The latter shift has prompted the debate about model complexity versus the required modelling purpose among modellers. In addition to the aforementioned shifts, there has been limited research on the impact of sludge recycling dewatering liquor on the overall plant performance, especially in the context of South African WWTPs. A simplified full-scale steady-state WWTP simulation tool was developed, based on principles of sound mass-balance stoichiometry and rate-limiting kinetics. This tool enables the user to analyse the impact of recycling the DWL on the plant performance through different scenarios. The strategic scenarios evaluated included the implementation of two side-stream treatment processes (STPs), namely BABE and struvite precipitation. The evaluation of various strategies was done using the benchmark simulation model (BSM) task group plant performance indices (i.e. effluent quality and operational cost indices, EQI and OCI, respectively) incorporated into the simplified steady-state full-scale models. The integration of STP in the WWTP layout results in better EQI and OCI. The composition of the DWL affects the choice of the STP to be used, i.e., for DWL from an AD treating WAS that is not P-rich the recommended side-stream treatment operation would be the BABE process rather than struvite precipitation.

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Evaluation and design of full-scale wastewater treatment plants using biological process models

Water Science & Technology ◽

10.2166/wst.1995.0112 ◽

1995 ◽

Vol 31 (2) ◽

pp. 245-255 ◽

Cited By ~ 4

Author(s):

Glen T. Daigger ◽

Daniel Nolasco

Keyword(s):

Wastewater Treatment ◽

Steady State ◽

Phosphorus Removal ◽

Wastewater Treatment Plants ◽

Full Scale ◽

Process Models ◽

Plant Performance ◽

Biological Phosphorus Removal ◽

Biological Phosphorus ◽

Steady State Performance

Results from application of the IAWQ Activated Sludge Model No. 1, either with or without the excess biological phosphorus removal model of Dold, to thirteen full-scale wastewater treatment plants are presented. For nitrogen removal applications the model is capable of accurately predicting full-scale plant performance and trends in performance, even using model default parameters. Additional work is needed to allow accurate predictions of the effect of reactor configuration and oxygen transfer systems on plant performance. The model of Dold accurately characterized the steady-state performance of biological nitrogen and phosphorus removal systems, but not their dynamic behavior. Detailed wastewater characterization is necessary to allow accurate prediction of the steady-state performance of biological phosphorus removal systems. Further work is necessary to demonstrate its applicability to dynamic applications.

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The impact of the art-ICA control technology on the performance, energy consumption and greenhouse gas emissions of full-scale wastewater treatment plants

Journal of Cleaner Production ◽

10.1016/j.jclepro.2018.12.229 ◽

2019 ◽

Vol 213 ◽

pp. 680-687 ◽

Cited By ~ 1

Author(s):

Anabela Vieira ◽

Ricardo Marques ◽

Ricardo Raposo ◽

Margarida Martins ◽

Rita Alves ◽

...

Keyword(s):

Wastewater Treatment ◽

Energy Consumption ◽

Greenhouse Gas Emissions ◽

Greenhouse Gas ◽

Wastewater Treatment Plants ◽

Full Scale ◽

Control Technology ◽

Gas Emissions ◽

The Impact

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Evaluation of IAWQ Activated Sludge Model No. 2 using steady-state data from four full-scale wastewater treatment plants

Water Environment Research ◽

10.2175/106143098x123552 ◽

1998 ◽

Vol 70 (6) ◽

pp. 1216-1224 ◽

Cited By ~ 15

Author(s):

Özer Çinar ◽

Glen T. Daigger ◽

Stephen P. Graef

Keyword(s):

Wastewater Treatment ◽

Steady State ◽

Activated Sludge ◽

Wastewater Treatment Plants ◽

Full Scale ◽

State Data ◽

Activated Sludge Model

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Analysis of Techniques for Evaluating and Optimizing Existing Full-Scale Wastewater Treatment Plants

Water Science & Technology ◽

10.2166/wst.1992.0485 ◽

1992 ◽

Vol 25 (4-5) ◽

pp. 103-118 ◽

Cited By ~ 2

Author(s):

G. T. Daigger ◽

J. A. Buttz ◽

J. P. Stephenson

Keyword(s):

Hydrogen Peroxide ◽

Wastewater Treatment ◽

Oxygen Transfer ◽

Stress Testing ◽

Wastewater Treatment Plants ◽

Full Scale ◽

Hydraulic Analysis ◽

Tracer Testing ◽

On Line ◽

The Impact

This paper presents an analysis of techniques applied to the evaluation and optimization of nearly 40 full-scale wastewater treatment plants. The techniques evaluated included oxygen transfer analysis by off-gas and hydrogen peroxide techniques, clarifier analysis by stress testing and hydraulic analysis, on-line monitoring, and reactor tracer testing. The results indicate that the process performance of full-scale wastewater treatment units can be measured using these techniques. Advantages exist for off-gas testing when applied to the analysis of low to moderate turbulence diffused air systems. Hydrogen peroxide analysis can be applied to essentially all oxygen transfer systems. Stress testing can be used to quantify the treatment capability of clarifier units; hydraulic analysis can then be used to identify clarifier upgrade opportunities and to quantify the impact of any modifications implemented. On-line monitoring is the most powerful technique tested. It has been used successfully to optimize and improve full-scale treatment plants. Reactor tracer testing can be used to identify upgrade opportunities for full-scale units.

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Benefits and drawbacks of thermal pre-hydrolysis for operational performance of wastewater treatment plants

Water Science & Technology ◽

10.2166/wst.2008.500 ◽

2008 ◽

Vol 58 (8) ◽

pp. 1547-1553 ◽

Cited By ~ 17

Author(s):

P. Phothilangka ◽

M. A. Schoen ◽

B. Wett

Keyword(s):

Wastewater Treatment ◽

Activated Sludge ◽

Wastewater Treatment Plants ◽

Biogas Production ◽

Treatment Plant ◽

Full Scale ◽

Plant Performance ◽

Ammonia Release ◽

Hydrolysis Process ◽

Solids Content

This paper presents benefits and potential drawbacks of thermal pre-hydrolysis of sewage sludge from an operator's prospective. The innovative continuous Thermo-Pressure-Hydrolysis Process (TDH) has been tested in full-scale at Zirl wastewater treatment plant (WWTP), Austria, and its influence on sludge digestion and dewatering has been evaluated. A mathematical plant-wide model with application of the IWA Activated Sludge Model No.1 (ASM1) and the Anaerobic Digestion Model No.1 (ADM1) has been used for a systematic comparison of both scenarios—operational plant performance with and without thermal pre-hydrolysis. The impacts of TDH pre-hydrolysis on biogas potential, dewatering performance and return load in terms of ammonia and inert organic compounds (Si) have been simulated by the calibrated model and are displayed by Sankey mass flow figures. Implementation of full scale TDH process provided higher anaerobic degradation efficiency with subsequent increased biogas production (+75–80%) from waste activated sludge (WAS). Both effects—enhanced degradation of organic matter and improved cake's solids content from 25.2 to 32.7% TSS—promise a reduction in sludge disposal costs of about 25%. However, increased ammonia release and generation of soluble inerts Si was observed when TDH process was introduced.

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Automatic buffer capacity based sensor for effluent quality monitoring

Water Science & Technology ◽

10.2166/wst.1996.0008 ◽

1996 ◽

Vol 33 (1) ◽

pp. 81-87

Author(s):

L. Van Vooren ◽

P. Willems ◽

J. P. Ottoy ◽

G. C. Vansteenkiste ◽

W. Verstraete

Keyword(s):

Wastewater Treatment ◽

Buffer Capacity ◽

Wastewater Treatment Plants ◽

Data Interpretation ◽

Full Scale ◽

Quality Monitoring ◽

Effluent Quality ◽

Capacity Curves ◽

On Line

The use of an automatic on-line titration unit for monitoring the effluent quality of wastewater plants is presented. Buffer capacity curves of different effluent types were studied and validation results are presented for both domestic and industrial full-scale wastewater treatment plants. Ammonium and ortho-phosphate monitoring of the effluent were established by using a simple titration device, connected to a data-interpretation unit. The use of this sensor as the activator of an effluent quality proportional sampler is discussed.

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