Improvement of ammonia removal in activated sludge process with feedforward-feedback aeration controllers

In the paper three linear aeration controllers that can be easily implemented are presented and evaluated on the activated sludge process pilot plant. Controllers differ according to the information that is used about the process, which can be oxygen in the last aerobic reactor, ammonia in the last aerobic reactor and ammonia in the influent. The aeration controllers that are addressed are: oxygen cascade PI controller, ammonia cascade PI controller and ammonia feedforward-cascade PI controller. Experiments show that, in comparison with the oxygen cascade PI controller, the ammonia cascade PI controller allows better control of effluent ammonia and airflow savings of around 23%, while the ammonia feedforward-cascade PI controller gives the best reduction of ammonia peaks and can save up to 45% of the airflow.

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The application of model predictive control of ammonia nitrogen in an activated sludge process

Water Science & Technology ◽

10.2166/wst.2011.477 ◽

2011 ◽

Vol 64 (5) ◽

pp. 1115-1121 ◽

Cited By ~ 26

Author(s):

D. Vrečko ◽

N. Hvala ◽

M. Stražar

Keyword(s):

Activated Sludge ◽

Prediction Interval ◽

Ammonia Nitrogen ◽

Pi Controller ◽

Ammonia Removal ◽

Activated Sludge Process ◽

Pi Controllers ◽

Predictive Controller ◽

Control Criteria ◽

Improved Accuracy

In this paper a model predictive controller (MPC) for ammonia nitrogen is presented and evaluated in a real activated sludge process. A reduced nonlinear mathematical model based on mass balances is used to model the ammonia nitrogen in the activated sludge plant. An MPC algorithm that minimises only the control error at the end of the prediction interval is applied. The results of the ammonia MPC were compared with the results of the ammonia feedforward-PI and ammonia PI controllers from our previous study. The ammonia MPC and ammonia feedforward-PI controller give better results in terms of ammonia removal and aeration energy consumption than the ammonia PI controller because of the measurable disturbances used. On the other hand, with the ammonia MPC, comparable or even slightly poorer results than with the ammonia feedforward-PI controller are obtained. Further improvements to the MPC could be possible with an improved accuracy of the nonlinear reduced model of the ammonia nitrogen, more sophisticated control criteria used inside the controller and the extension of the problem from univariable ammonia to multivariable total nitrogen control.

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Automatic control for DO and pH in the activated sludge process in a coke wastewater treatment plant

Water Science & Technology ◽

10.2166/wst.1998.0524 ◽

1998 ◽

Vol 37 (12) ◽

pp. 141-148 ◽

Cited By ~ 2

Author(s):

B. K. Lee ◽

S. W. Sung ◽

H. D. Chun ◽

J. K. Koo

Keyword(s):

Wastewater Treatment ◽

Control System ◽

Activated Sludge ◽

Automatic Control ◽

Wastewater Treatment Plant ◽

Treatment Plant ◽

Pi Controller ◽

Activated Sludge Process ◽

Set Point ◽

Coke Wastewater

The objective of this study is to develop an automatic control system for dissolved oxygen (DO) and pH of the activated sludge process in a coke wastewater treatment plant. A discrete type autotuned proportional-integral (PI) controller using an auto-regressive exogenous (ARX) model as a process model was developed to maintain the DO concentration in aerators by controlling the speed of surface aerators. Also a nonlinear pH controller using the titration curve was used to control the pH of influent wastewater. This control system was tested in a pilot scale plant. During this pilot plant experiment, there was small deviation of pH and the electric power consumption of surface aerators was reduced up to 70% with respect to the full operation when the DO set point was 2 mg/l. For real plant operation with this system, the discrete PI controller showed good tracking for set point change. The electricity saving was more than 40% of the electricity consumption when considering surface aerators. As a result of maintaining the DO constantly at the set point by the automatic control system, the fluctuation of effluent quality was decreased and overall improvement of the effluent water quality was achieved.

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Experience with Two-Stage Activated Sludge Plants for Industrial Wastewaters in Korea

Water Science & Technology ◽

10.2166/wst.1992.0528 ◽

1992 ◽

Vol 25 (4-5) ◽

pp. 427-428 ◽

Cited By ~ 1

Author(s):

R. Schulze-Rettmer ◽

S. S. Kim ◽

S. S. Son

Keyword(s):

Wastewater Treatment ◽

Activated Sludge ◽

Wastewater Treatment Plant ◽

Pilot Plant ◽

Treatment Plant ◽

Activated Sludge Process ◽

Two Stage ◽

Industrial Wastewaters ◽

Textile Dyeing ◽

One Year

The two-stage activated sludge process (AB-process, i.e. adsorption activated sludge process) invented by Boehnke was successfully applied to several municipal and industrial wastewaters in Korea. The first large wastewater treatment plant for the combined effluents of 22 textile dyeing companies was constructed in Taegu and started operation in 1989. Two years earlier pilot plant runs were performed. The AB-process proved to be superior to any other activated sludge process. BOD was reduced from 1200 mg/l down to 24 mg/l. In the meantime in Korea several further AB-process treatment plants were constructed, the overall planning and constructing period being not longer than one year.

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Application of adaptive decentralized PI controller for activated sludge process

2013 IEEE 8th Conference on Industrial Electronics and Applications (ICIEA) ◽

10.1109/iciea.2013.6566659 ◽

2013 ◽

Cited By ~ 3

Author(s):

S. I. Samsudin ◽

F. Rahmat ◽

N. A. Wahab ◽

Muhammad Sani Gaya ◽

M. C. Razali

Keyword(s):

Activated Sludge ◽

Pi Controller ◽

Activated Sludge Process

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The use of the kaldnes suspended carrier process in treatment of wastewaters from the forest industry

Water Science & Technology ◽

10.2166/wst.1997.0498 ◽

1997 ◽

Vol 35 (2-3) ◽

pp. 123-130 ◽

Cited By ~ 7

Author(s):

Eva Dalentoft ◽

Peter Thulin

Keyword(s):

Activated Sludge ◽

Pilot Plant ◽

Operating Costs ◽

Forest Industry ◽

Activated Sludge Process ◽

Combination Process ◽

In Series ◽

Suspended Carrier ◽

Highly Loaded ◽

Pilot Plant Study

One pilot plant study and two full scale studies have been carried out seeking for the optimal use of the Kaldnes suspended carrier process in treatment of wastewaters from the forest industry. The wastewater used in all three cases came from secondary fiber mills. The studies show that the Kaldnes process as a highly loaded stage (typically 15-25 kg COD/m3·d) in series with an activated sludge stage forms an efficient, stable and competitive combination process both regarding investment and operating costs. This is especially true when treating wastewaters with a composition that makes them unsuited for treatment in an activated sludge process. The flexibility and compactness of the Kaldnes suspended carrier process also makes it an ideal choice for upgrading of existing treatment plants.

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Effect of Supplemental Carbon Source on Phosphate Removal in an Alternating Activated Sludge Process

Water Science & Technology ◽

10.2166/wst.1993.0690 ◽

1993 ◽

Vol 28 (11-12) ◽

pp. 499-512 ◽

Cited By ~ 1

Author(s):

S. H. Isaacs ◽

M. Henze ◽

H. Søeberg ◽

M. Kümmel

Keyword(s):

Carbon Source ◽

Activated Sludge ◽

Nutrient Removal ◽

Pilot Plant ◽

Phosphate Uptake ◽

Phosphate Removal ◽

Activated Sludge Process ◽

Significant Release

Pilot plant studies indicate that the addition of COD in the form of acetate to an alternating nutrient removal activated sludge process as a means to improve denitrification rates is not detrimental to biological phosphate removal. This is in spite of the fact that the added acetate can cause a significant release of phosphate during the anoxic phases in the aeration tanks. The added COD also appears to result in increased rates of aerobic phosphate uptake, thus improving the phosphate removal ability of the process. These observations are presented and discussed in the paper.

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