Automatic monitoring of denitrification rates and capacities in activated sludge processes using fluorescence or redox potential

1998 ◽  
Vol 37 (12) ◽  
pp. 121-129 ◽  
Author(s):  
S. Isaacs ◽  
Terry Mah ◽  
S. K. Maneshin
Keyword(s):  
Biological Activity ◽  
Activated Sludge ◽  
Redox Potential ◽  
Treatment Plant ◽  
Automatic Monitoring ◽  
Organic Substrate ◽  
Anoxic Zone ◽  
Optimal Dosing ◽  
Denitrifying Microorganisms ◽  
Activated Sludge Processes

A novel method is described to automatically estimate several key parameters affecting denitrification in activated sludge processes: the nitrate concentration, the denitrification capacity, and the maximum (substrate unlimited) and actual denitrification rates. From these, the concentration of active denitrifying microorganisms and the quality of available organic substrate pool can be estimated. Additionally, a modification of the method allows the determination of the efficacy of various carbon substrates to enhance denitrification, and this can be used to determine optimal dosing rates of an external carbon source. The method is based on measurements of either fluorescence or redox potential (ORP) in an isolated mini-reactor, the Biological Activity Meter (BAM), situated in the anoxic zone of the wastewater treatment plant. Advantages of the method are that it is in situ, operating at the same temperature as in the measured anoxic zone, requires no pumps or pipes for mixed liquor sampling, consumes little or no reagents, and uses measurement signals which are instantaneous and low maintenance, one of which provides a direct measure of biological activity.

Use of contact tank to enhance denitrification in oxidation ditches

1996 ◽  
Vol 34 (1-2) ◽  
pp. 195-202 ◽  
Author(s):  
X Hao ◽  
H. J. Doddema ◽  
J. W. van Groenestijn
Keyword(s):  
Carbon Sources ◽  
Organic Substrate ◽  
Adsorptive Capacity ◽  
Oxidation Ditch ◽  
Anoxic Zone ◽  
Time Zone ◽  
Floc Structure ◽  
N Removal ◽  
Denitrifying Microorganisms ◽  
Set Up

Poor denitrification in a Pasveeer oxidation ditch is attributed to a lack of carbon sources available in the anoxic zone as it is essential to maintain a high C/N ratio for denitrification. Influent of sewage directly into the anoxic zone is not useful to maintain a high C/N ratio. The adsorptive capacity of activated sludge can rapidly increase the C/N ratio. Similar to a contact-stabilization process, a contact tank can be combined with the Pasveer ditch; it provides contact time (zone) between raw sewage and return sludge before entering the ditch. In principle, insoluble organic substrate can be easily adsorbed onto the floc surfaces and enmeshed in the floc structure at a short retention time. After the contact, mixed influent is introduced into the anoxic zone. As a result, a high C/N ratio is obtained which enhances denitrification. Using this set up, the Pasveer ditch was operated. The experimental results show that the efficiency of denitrification has been enhanced from 45 to 83% for NO−3-N removal. The corresponding denitrification capacity of the sludge is increased by 240%. The contact tank has also the same principle as a ‘selector’ to control bulking sludge caused by filamentous bacteria. The SVI data and microscopic examination indicated improved settleability of the sludge. Further enhancement of denitrification needs an exact control of the dissolved oxygen level in the ditch and/or a concentration increase of denitrifying microorganisms.

A comparison of NH4/NO3 control strategies for alternating activated sludge processes

1999 ◽  
Vol 39 (4) ◽  
pp. 93-102 ◽  
Author(s):  
L. J. S. Lukasse ◽  
K. J. Keesman ◽  
A. Klapwijk ◽  
G. van Straten
Keyword(s):  
Activated Sludge ◽  
Time Delays ◽  
Control Strategies ◽  
Treatment Plant ◽  
Biological Processes ◽  
Effluent Quality ◽  
N Removal ◽  
Activated Sludge Reactor ◽  
The Difference ◽  
Activated Sludge Processes

Four control strategies for N-removal in alternating activated sludge plants (ASP's) are compared: 1. timer-based, 2. switching the aeration on/off when depletion of nitrate/ammonium is detected, 3. switching the aeration on/off when ammonium crosses an upper/lower-bound, 4. the newly developed adaptive receding horizon optimal controller (ARHOC) as presented in Lukasse et al. (1997). The comparison is made by simulating the controllers' application to an alternating continuously-mixed activated sludge reactor preceded by a small anoxic reactor for predenitrification. The biological processes in the reactors are modelled by the activated sludge model no. 1. Realistic influent patterns, measured at a full-scale wastewater treatment plant, are used. The results show that three totally different controllers (timer-based, NH4-bounds based and ARHOC) can achieve a more or less equal effluent quality, if tuned optimally. The difference mainly occurs in the sensitivity to suboptimal tunings. The timer-based strategy has a higher aeration demand. The sensitivity of the ARHOC controller to sub-optimal tuning, known measurement time delays and changing plant loads is significantly less than that of the other controllers. Also its tuning is more natural and explicit.

Improving the Performance of the Activated Sludge Process: A Time Controlled Flow Equalisation Basin

1978 ◽  
Vol 13 (1) ◽  
pp. 183-201
Author(s):  
N. Thérien ◽  
B. Marcos ◽  
G. Muratet
Keyword(s):  
Activated Sludge ◽  
Treatment Plant ◽  
Control Policy ◽  
Organic Content ◽  
Organic Substrate ◽  
Activated Sludge Process ◽  
Water Stream ◽  
Actual Case ◽  
Differential Model ◽  
Controlled Flow

Abstract The performance of a time controlled flow equalisation basin in minimizing the mean daily concentration of organic substrate flowing out the clarifier unit has been investigated. This was done considering fluctuations in both the flowrate and organic content of the entering raw water stream to an activated sludge process. A differential model apt at describing the dynamic behaviour of the activated sludge process of an existing wastewater treatment plant for periods of one to several days has been used. The control strategy, consisting in finding how much wastewater to pump in time from the basin to the aeration unit has been designed using iteration in control vector space with a second order minimization algorithm based on the concept of dynamic programming. Situations for which this procedure would lead to an optimal control policy are discussed and an actual case of this occuring is shown for the data gathered at the plant. The results obtained are also compared to more conservative and known control policies for the operation of an equalisation basin.

Proof of concept for a new energy-positive wastewater treatment scheme

2014 ◽  
Vol 70 (10) ◽  
pp. 1709-1716 ◽  
Author(s):  
C. Remy ◽  
M. Boulestreau ◽  
B. Lesjean
Keyword(s):  
Organic Matter ◽  
Energy Balance ◽  
Activated Sludge ◽  
Municipal Wastewater ◽  
Treatment Plant ◽  
Anaerobic Sludge ◽  
Stable Operation ◽  
Conventional Activated Sludge ◽  
Pilot Trials ◽  
Activated Sludge Processes

For improved exploitation of the energy content present in the organic matter of raw sewage, an innovative concept for treatment of municipal wastewater is tested in pilot trials and assessed in energy balance and operational costs. The concept is based on a maximum extraction of organic matter into the sludge via coagulation, flocculation and microsieving (100 μm mesh size) to increase the energy recovery in anaerobic sludge digestion and decrease aeration demand for carbon mineralisation. Pilot trials with real wastewater yield an extraction of 70–80% of total chemical oxygen demand into the sludge while dosing 15–20 mg/L Al and 5–7 mg/L polymer with stable operation of the microsieve and effluent limits below 2–3 mg/L total phosphorus. Anaerobic digestion of the microsieve sludge results in high biogas yields of 600 NL/kg organic dry matter input (oDMin) compared to 430 NL/kg oDMin for mixed sludge from a conventional activated sludge process. The overall energy balance for a 100,000 population equivalent (PE) treatment plant (including biofilter for post-treatment with full nitrification and denitrification with external carbon source) shows that the new concept is an energy-positive treatment process with comparable effluent quality than conventional processes, even when including energy demand for chemicals production. Estimated operating costs for electricity and chemicals are in the same range for conventional activated sludge processes and the new concept.

Activated sludge optimization using ATP in pulp and paper industry

2015 ◽  
Vol 71 (8) ◽  
pp. 1173-1179 ◽  
Author(s):  
Göran Bäckman ◽  
Ulla Gytel
Keyword(s):  
Biological Activity ◽  
Activated Sludge ◽  
Operating Cost ◽  
Pulp And Paper ◽  
Effluent Treatment ◽  
Stress Index ◽  
Activated Sludge Process ◽  
Living Biomass ◽  
Test Kit ◽  
Activated Sludge Processes

The activated sludge process is an old technology, but still the most commonly used one for treatment of wastewater. Despite the wide spread usage the technology still suffers from instability (Tandoi et al. 2006) and high operating cost. Activated sludge processes often carry a large solids inventory. Managing the total inventory without interference is the key component of the optimization process described in this paper. Use of nutrients is common in pulp and paper effluent treatment. Feeding enough nutrients to support the biomass growth is a delicate balance. Overfeeding or underfeeding of nutrients can result in higher costs. Detrimental substances and toxic components in effluents entering a biological treatment system can cause severe, long lasting disturbances (Hynninen & Ingman 1998; Bergeron & Pelletier 2004). A LumiKem test kit is used to measure biological activity with adenosine triphosphate (ATP) in a pulp and paper mill. ATP data are integrated with other standardized mill parameters. Measurements of active volatile suspended solids based on ATP can be used to quantify the living biomass in the activated sludge process and to ensure that sufficient biomass is present in order to degrade the wastewater constituents entering the process. Information about active biomass will assist in optimizing sludge inventories and feeding of nutrients allowing the living biomass to re-populate to create optimal efficiency. ATP measurements can also be used to alert operators if any components toxic to bacteria are present in wastewater. The bio stress index represents the stress level experienced by the microbiological population. This parameter is very useful in monitoring toxicity in and around bioreactors. Results from the wastewater process optimization and ATP measurements showed that treatment cost could be reduced by approximately 20–30% with fewer disturbances and sustained biological activity compared to the reference period. This was mainly achieved by the removal of detrimental substances and optimized nutrient dosage.

Comparison of denitrification-nitrification and step-feed activated sludge processes with dynamic simulation

2012 ◽  
Vol 7 (3) ◽  
Author(s):  
K. Sahlstedt ◽  
H. Haimi ◽  
J. Yli-Kuivila
Keyword(s):  
Wastewater Treatment ◽  
Activated Sludge ◽  
Dynamic Simulation ◽  
Dynamic Process ◽  
Wastewater Treatment Plant ◽  
Process Simulation ◽  
Treatment Process ◽  
Treatment Plant ◽  
Dynamic Process Simulation ◽  
Activated Sludge Processes

In conjunction with choosing the treatment process for the new wastewater treatment plant of Espoo, Finland (400,000 P.E.), Denitrification-Nitrification (DN) and Step-Feed activated sludge processes were compared in terms of required basin volume and consumption of aeration air and methanol. The comparison was made using dynamic process simulation. The advantages of the step-feed process reported in literature – smaller volume required to treat an equal load or ability to treat a higher load in an equal volume – were questioned. In terms of consumables, the two processes were found practically equal. This is, to the best of our knowledge, the first comparison of these process configurations with dynamic simulation.

Modelling Simulation and Control of an Existing Activated Sludge Wastewater Treatment Process

1976 ◽  
Vol 11 (1) ◽  
pp. 108-121
Author(s):  
N. Thérien ◽  
P. Harrington
Keyword(s):  
Wastewater Treatment ◽  
Activated Sludge ◽  
Flow Rate ◽  
Treatment Plant ◽  
Organic Substrate ◽  
Activated Sludge Process ◽  
Two Phase ◽  
Wastewater Treatment Process ◽  
Wastewater Stream ◽  
And Control

Abstract The dynamic response of the activated sludge process in the wastewater treatment plant of the Centre Hospitalier Universitaire de Sherbrooke was analysed with respect to large disturbances in both the flow rate and the quality of wastewater entering the plant. A mass balance conducted for the organic substrate and biomass entering and leaving the process led to a model consisting of two separate differential equations in terms of BOD and VSS with a two-phase bio-kinetic relationship for the reaction term. Predictions of the model for BOD and VSS variations in time were compared to experimental observations at the plant. A model using mean daily values for VSS and expressed in terms of BOD for the stream flowing out the clarifier unit in response to flow rate and BOD cyclic fluctuations of the entering wastewater stream to the process was found apt at describing the time at which BOD peaks in the process effluent occurred as well as predicting the magnitude of these peaks. The dynamic behaviour of the activated sludge process has been simulated for periods of one to several days using this model. Its use in predicting appropriate control action in time in order to improve the treatment efficiency is also indicated.

Upgrading of the wastewater treatment plant of the city of Oldenburg

1994 ◽  
Vol 29 (12) ◽  
pp. 89-95 ◽  
Author(s):  
Rolf Kayser
Keyword(s):  
Wastewater Treatment ◽  
Activated Sludge ◽  
Wastewater Treatment Plant ◽  
Treatment Plant ◽  
Phosphate Removal ◽  
Single Stage ◽  
Anoxic Zone ◽  
Two Stage ◽  
Flexible Operation ◽  
The City

Instead of a planned two stage activated sludge plant the design was changed to a single stage activated sludge plant with enhanced biological phosphate removal and pre-anoxic zone denitrification. For flexible operation it is possible to vary the rato of VD/V from 0.3 to 0.5. Problems with the aeration equipment in the nitrification/denitrification cells occurred and were solved. The circular clarifiers are equipped with scrapers. Instead of a sludge hopper a collector in the centre of the tank was constructed.

Full-scale application of the BABE® technology

2004 ◽  
Vol 50 (7) ◽  
pp. 87-96 ◽  
Author(s):  
S. Salem ◽  
D.H.J.G. Berends ◽  
H.F. van der Roest ◽  
R.J. van der Kuij ◽  
M.C.M. van Loosdrecht
Keyword(s):  
Activated Sludge ◽  
Treatment Plant ◽  
Full Scale ◽  
Nitrification Rate ◽  
Stable Operation ◽  
Water Line ◽  
Ambient Temperatures ◽  
N Removal ◽  
Set Up ◽  
Activated Sludge Processes

Bio-augmentation can be used to obtain nitrification in activated sludge processes that operate at ub-optimal solid retention times. A side-stream process, the so-called BABE® process that incorporates Nremoval and augmentation of nitrifiers has been developed. The principle is to implement a nitrification reactor in the sludge return line, the so-called BABE reactor. This reactor can be fed with an internal N-rich flow (e.g. effluent from the sludge treatment). Hence the nitrification capacity of an activated sludge process can be augmented by the addition of nitrifiers cultivated in the BABE reactor. A full-scale test of the BABE technology has been at the treatment plant Garmerwolde in Groningen, the Netherlands. The set-up allowed comparing between three different lines: with the BABE reactor, without rejectwater and with untreated rejectwater. Based on this, the two important tasks (N-removal and inoculation) performed by the BABE reactor could be quantified. The results of the practical work in Garmerwolde showed a higher nitrification rate in the water line where the BABE reactor was implemented and also lower effluent ammonia. The experiments on a practical scale have demonstrated univocally the effective and stable operation of the BABE technology. In addition, sludge samples in different streams as well as from the BABE reactor were analysed with FISH technique. The FISH results illustrated the augmentation effect of the BABE reactor on the stream with the BABE reactor. A mathematical model, based on ASM1 model and implemented in AQUASIM was developed and used for simulating the treatment plant of Garmerwolde. The simulation results indicated that better effect of the BABE technology is expected at lower ambient temperatures and smaller volume of the BABE reactor. The BABE reactor could also allow for providing more space for de-nitrification in the main water line when nitrification is efficient enough.

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