Biomass yield reduction: is biochemical manipulation possible without affecting activated sludge process efficiency?

The emphasis for operation of the activated sludge process has switched from the volume of wastewater turnover and effluent quality to minimisation of biomass produced. Attempts including extended aeration, promotion of bacterial predation by higher organisms and increasing process temperature have been successful in lowering yield. These all involve increased operating costs and capital works, whereas the process of chemical uncoupling may be cheaper. After initial chemical screening 2,4 dinitrophenol (2,4 DNP) was continuously dosed in an activated sludge simulation (31 working volume, 5.55h HRT). Effect on process efficiency was monitored by measuring BOD removal and biomass production by MLSS. After 7 weeks of chemical treatment the mean yield coefficient of the treated simulation (Y=0.30) was significantly lower than that of the control (Y=0.42). BOD removal from treated and control samples was comparable and not significantly different.

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Biomass yield reduction: Is biochemical manipulation possible without affecting activated sludge process efficiency?

Water Science & Technology ◽

10.1016/s0273-1223(98)00687-8 ◽

1998 ◽

Vol 38 (8-9) ◽

Cited By ~ 19

Keyword(s):

Activated Sludge ◽

Biomass Yield ◽

Process Efficiency ◽

Yield Reduction ◽

Activated Sludge Process

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System Identification and Control of the Activated Sludge Process by Use of a Statistical Model

Water Science & Technology ◽

10.2166/wst.1989.0316 ◽

1989 ◽

Vol 21 (10-11) ◽

pp. 1161-1172 ◽

Cited By ~ 8

Author(s):

M. Hiraoka ◽

K. Tsumura

Keyword(s):

Control System ◽

System Identification ◽

Statistical Model ◽

Activated Sludge ◽

Sewage Treatment Plant ◽

Treatment Plant ◽

Ar Model ◽

Diurnal Changes ◽

Activated Sludge Process ◽

And Control

The authors have been developing a hierarchical control system for the activated sludge process which consists of an upper level system controlling long-term seasonal variations, a control system of intermediate level aiming at optimization of the process and a control system of lower level controlling diurnal changes or hourly fluctuations. The control system using the multi-variable statistical model is one of the most appropriate control systems based on the modern control theory, for applying the lower level control of the activated sludge process. This paper introduces our efforts for developing the reliable data acquisition system, the control experiments applying the AR-model, one of the statistical models which were conducted at a pilot plant and present studies on the system identification and control at a field sewage treatment plant.

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Modelling of activated sludge for textile wastewaters

Water Science & Technology ◽

10.2166/wst.1998.0570 ◽

1998 ◽

Vol 38 (4-5) ◽

pp. 9-17 ◽

Cited By ~ 16

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.

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Multivariable modeling and control of an activated sludge process

Water Science & Technology ◽

10.2166/wst.1998.0527 ◽

1998 ◽

Vol 37 (12) ◽

pp. 149-156 ◽

Cited By ~ 4

Author(s):

Carl-Fredrik Lindberg

Keyword(s):

Activated Sludge ◽

Nitrate Concentration ◽

State Space Model ◽

Activated Sludge Process ◽

Invariant State ◽

Linear Quadratic ◽

Modeling And Control ◽

Space Model ◽

And Control ◽

Time Invariant

This paper contains two contributions. First it is shown, in a simulation study using the IAWQ model, that a linear multivariable time-invariant state-space model can be used to predict the ammonium and nitrate concentration in the last aerated zone in a pre-denitrifying activated sludge process. Secondly, using the estimated linear model, a multivariable linear quadratic (LQ) controller is designed and used to control the ammonium and nitrate concentration.

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

Water Science & Technology ◽

10.2166/wst.2002.0246 ◽

2002 ◽

Vol 46 (9) ◽

pp. 229-236 ◽

Cited By ~ 19

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.

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