Control of an activated sludge process with nitrogen removal – a benchmark study

2002 ◽  
Vol 45 (4-5) ◽  
pp. 135-142 ◽  
Author(s):  
B. Carlsson ◽  
A. Rehnström
Keyword(s):  
Activated Sludge ◽  
Flow Rate ◽  
Control Strategies ◽  
Ammonia Level ◽  
Physical Models ◽  
Activated Sludge Process ◽  
Nitrate Level ◽  
Recirculation Flow ◽  
Set Up ◽  
Aeration Capacity

In this paper, a simulation benchmark of a predenitrifying activated sludge process is used to evaluate a number of control strategies. A main procedure has been to use feedforward terms that are based on simplified physical models. Important mass balance relations may then be incorporated in the control law. The nitrate level in the last anoxic zone is controlled by the dosage of an external carbon source and the nitrate level in the last aerobic zone is controlled by the internal recirculation flow rate. The ammonia level is controlled by a DO set-point controller. In order to be able to have as high a sludge level as possible without sludge escape, the sludge blanket height in the settler is controlled by the excess sludge flow rate. Compared to the default set up of the benchmark, the controllers could reduce the effluent nitrate significantly whereas the effluent ammonia was only marginally decreased. The main problem is that the aeration capacity defined in the benchmark is too low.

Effect of biosorption on the damping of influent fluctuation in activated sludge aeration tanks

1997 ◽  
Vol 35 (7) ◽  
pp. 79-87 ◽  
Author(s):  
Koichi Fujie ◽  
Hong-Ying Hu ◽  
Byung-Ran Lim ◽  
Huang Xia
Keyword(s):  
Activated Sludge ◽  
Organic Pollutants ◽  
Control Strategies ◽  
Domestic Wastewater ◽  
Activated Sludge Process ◽  
Organic Substances ◽  
Effluent Water ◽  
Organic Removal ◽  
Set Up ◽  
The Mathematical Model

To describe the organic removal performance in an activated sludge process, the effect of biological adsorption (biosorption, hereinafter) of both soluble and particulate organic substances (SOS and POS, respectively, hereinafter) on the rate of organic removal must be taken into account. This study quantitatively investigated the biosorption of organic pollutants in the domestic wastewater by the activated sludge. The capability of biosorption and the rate of bio-oxidation of organic pollutants were formulated based on the experimental results as functions of both COD concentration and temperature. The biosorption capacity of activated sludge was proportional to COD concentration in the mixed liquor originated from the influent. The kinetic expressions were combined with the equation of longitudinal liquid mixing to set up the mathematical model to predict the effluent COD, and thus to clarify the effect of biosorption on the damping of influent fluctuations of both COD concentration and the inflow rate. The model was also successfully applied to assessing the effectiveness of MLSS control strategies in equalizing the effluent water quality.

Respirometry for determination of the influents SS-concentration

1996 ◽  
Vol 33 (1) ◽  
pp. 311-323 ◽  
Author(s):  
A. Witteborg ◽  
A. van der Last ◽  
R. Hamming ◽  
I. Hemmers
Keyword(s):  
Experimental Design ◽  
Activated Sludge ◽  
Substrate Concentration ◽  
Full Scale ◽  
Activated Sludge Process ◽  
Respiration Rates ◽  
On Line ◽  
Large Measurement ◽  
Set Up

A method is presented for determining influent readily biodegradable substrate concentration (SS). The method is based on three different respiration rates, which can be measured with a continuous respiration meter which is operated in a cyclic way. Within the respiration meter nitrification is inhibited through the addition of ATU. Simulations were used to develop the respirometry set-up and decide upon the experimental design. The method was tested as part of a large measurement programme executed at a full-scale plant. The proposed respirometry set-up has been shown to be suitable for a semi-on-line determination of an influent SS which is fully based on the IAWQ #1 vision of the activated sludge process. The YH and the KS play a major role in the principle, and should be measured directly from the process.

Sensitivity of Effluent Variables in Activated Sludge Process

2017 ◽  
Vol 13 (2) ◽  
Author(s):  
B Vivekanandan ◽  
K Jeyannathann ◽  
A. Seshagiri Rao
Keyword(s):  
Activated Sludge ◽  
Flow Rate ◽  
Oxygen Transfer Rate ◽  
Treatment Plant ◽  
Oxygen Demand ◽  
Maximum Flow ◽  
Activated Sludge Process ◽  
Flow Conditions ◽  
Treated Effluent ◽  
Influent Flow

Abstract The quality of a treated effluent changes when there is a sudden variation in the influent flow to the wastewater treatment plant during dry, rain, and storm weather conditions. In this study, various influent flow conditions in an activated sludge process are considered that affect the sensitivity of effluent variables such as chemical oxygen demand (COD), biological oxygen demand (BOD), nitrate nitrogen (SNO), ammonical nitrogen (SNH), and total nitrogen (TN) with respect to varying internal recycle flow rate (Qa), sludge recycle flow rate (Qr), sludge wastage flow rate (Qw) and oxygen transfer rate co-efficient of aerobic tanks (KLa(3,4,5)). The analysis has been carried out based on benchmark simulation model no.1 (BSM 1) plant layout which comprises of two models namely activated sludge model no.1 (ASM 1) and simple one dimensional (Simple 1-D) Takacs model. Based on the present analysis, it is observed that the changes in influent flow rate have larger impact on the effluent variables. This variation can be subdued by introducing additional tanks to smoothen the perturbations or using internal recycle rate from the fifth tank in order to maintain the flow around the optimal influent flow rate. The sludge wastage rate has a greater impact on all effluent variables except nitrogenous variables during maximum flow conditions.

Fuzzy Control of a Dynamic Activated Sludge Process for the Forecast and Control of Effluent Suspended Solid Concentration

1993 ◽  
Vol 28 (11-12) ◽  
pp. 355-367 ◽  
Author(s):  
Y. P. Tsai ◽  
C. F. Ouyang ◽  
M. Y. Wu ◽  
W. L. Chiang
Keyword(s):  
Fuzzy Control ◽  
Activated Sludge ◽  
Flow Rate ◽  
Suspended Solid ◽  
Aeration Tank ◽  
Activated Sludge Process ◽  
Solid Concentration ◽  
Suspended Solid Concentration ◽  
And Control ◽  
Influent Flow

The effluent total BOD (or COD) concentration of the activated sludge process (A.S.P.) usually increases with suspended solid concentration. How to reduce effluent S.S. concentration, therefore, is the key issue of treatment efficiency for A.S.P. The varied return sludge and influent flow rate are two major operational factors of those affecting effluent S.S. concentration. However, the wastewater flow rate and substrate concentration in municipal wastewater treatment plant, due to the differences of city scale and life style, are significantly time-varied every day. Based on the above, the purpose of this study is to control in timely fashion return sludge flow rate with the variation of influent flow rate to minimize effluent S.S. concentration and meanwhile decrease the effluent total BOD (or COD) concentration. The fuzzy control theory is utilized in this study to forecast and control effluent S.S. concentration and further predict the MLSS concentration in aeration tank. It reveals that the inferred control strategies not only enable one to decrease effluent S.S.

Feedforward-feedback control of an activated sludge process: a simulation study

2003 ◽  
Vol 47 (12) ◽  
pp. 19-26 ◽  
Author(s):  
D. Vrečko ◽  
N. Hvala ◽  
B. Carlsson
Keyword(s):  
Feedback Control ◽  
Activated Sludge ◽  
Simulation Study ◽  
Physical Models ◽  
Pi Control ◽  
Activated Sludge Process ◽  
Feedback Controllers ◽  
Control Laws ◽  
Operational Costs ◽  
Feedforward Controller

In this paper a simulated plant based on a wastewater treatment benchmark is used to evaluate a number of controllers. Feedforward-feedback controllers for dissolved oxygen set-point and external carbon flow, and feedforward controller for internal recycle flow are evaluated separately and altogether. In the feedforward parts of the controllers, static physical models are incorporated in the control laws. The feedback parts of the controllers are used to compensate for model approximations. A simulation study shows that feedforward-feedback control of the activated sludge plant is more successful than standard PI control in meeting the effluent standards and reducing operational costs.

Sign in / Sign up

Export Citation Format

Share Document