Nitrification preservation in activated sludge during curative bulking chlorination

2003 ◽  
Vol 47 (11) ◽  
pp. 85-92 ◽  
Author(s):  
E. Cotteux ◽  
P. Duchene
Keyword(s):  
Activated Sludge ◽  
Pilot Plant ◽  
Wastewater Treatment Plants ◽  
Oxygen Uptake Rate ◽  
Ammonia Concentration ◽  
Synthetic Wastewater ◽  
Biological Wastewater Treatment ◽  
Simple Method ◽  
Method Of Measurement ◽  
The Impact

The bulking that occurs in biological wastewater treatment plants using activated sludge is very often controlled by the injection of sodium hypochlorite into the return activated sludge (RAS) stream. In the present study undertaken at two pilot plants fed with synthetic wastewater, the impact of the pass frequency of the sludge at the chlorine dosing point on the nitrifying flora is analysed. The pass frequency is one for the pilot plant 1 and two for the pilot plant 2. A dose of chlorine of 4.85 ± 0.05 g/kg/MLVSS per day was applied at both pilots. The preservative effect on nitrifying activity of the lowest concentration of chlorine at the dosing point and therefore of the highest pass frequency was evidenced. Among other tools, a simple method of measurement of the oxygen uptake rate enabled us to monitor the effect of chlorination on nitrification before recording an increase in the ammonia concentration in the bulking.

Estimation of Kinetic Parameters of Heterotrophic Biomass under Aerobic Conditions and Characterization of Wastewater for Activated Sludge Modelling

1992 ◽  
Vol 25 (6) ◽  
pp. 125-139 ◽  
Author(s):  
J. Kappeler ◽  
W. Gujer
Keyword(s):  
Wastewater Treatment ◽  
Activated Sludge ◽  
Kinetic Parameters ◽  
Specific Growth ◽  
Wastewater Treatment Plants ◽  
Simple Method ◽  
Batch Tests ◽  
Different Types ◽  
Heterotrophic Biomass

To predict the behaviour of biological wastewater treatment plants, the Activated Sludge Model No. 1 is often used. For the application of this model kinetic parameters and wastewater composition must be known. A simple method to estimate kinetic parameters of heterotrophic biomass and COD wastewater fractions is presented. With three different types of batch-tests these parameters and fractions can be determined by measuring oxygen respiration. Our measurements showed that the maximum specific growth rate µmax of heterotrophic biomass depends on temperature, reactor configuration and SRT. In typical wastewater treatment plants of Switzerland the amount of readily biodegradable substrate was generally small (about 9 % of the COD in primary effluent). The same method can also be used to determine kinetic parameters of nitrifying biomass.

Inhibition of sulfide generation by dosing formaldehyde and its derivatives in sewage under anaerobic conditions

2008 ◽  
Vol 57 (6) ◽  
pp. 915-919 ◽  
Author(s):  
L. Zhang ◽  
L. Mendoza ◽  
M. Marzorati ◽  
W. Verstraete
Keyword(s):  
Hydrogen Sulfide ◽  
Oxygen Uptake ◽  
Activated Sludge ◽  
Oxygen Uptake Rate ◽  
Urea Formaldehyde ◽  
Nitrification Rate ◽  
Economic Aspects ◽  
Anaerobic Conditions ◽  
Activated Sludge System ◽  
The Impact

Hydrogen sulfide emission in sewers is associated with toxicity, corrosion, odor nuisance and a lot of costs. The possibility to inhibit sulfide generation by formaldehyde and its derivatives (paraformaldehyde and urea formaldehyde) has been evaluated under anaerobic conditions. The impact of formaldehyde on an activated sludge system and an appraisal of the economic aspects are also presented. The optimum dosage to inhibit sulfide generation in sewage was 12–19 mg L−1 formaldehyde. The dosages of 32 mg L−1 paraformaldehyde or 100 mg L−1 urea formaldehyde were not capable of inhibiting sulfide generation in sewage. The impact of 19 mg L−1 formaldehyde on activated sludge system was negligible in terms of COD removal, nitrification rate and oxygen uptake rate.

scholarly journals The Impact of Selected Parameters on the Condition of Activated Sludge in a Biologic Reactor in the Treatment Plant in Nowy Targ, Poland

Water ◽  
2020 ◽  
Vol 12 (10) ◽  
pp. 2657
Author(s):  
Elwira Nowobilska-Majewska ◽  
Piotr Bugajski
Keyword(s):  
Wastewater Treatment ◽  
Statistical Analysis ◽  
Activated Sludge ◽  
Partial Correlation ◽  
Oxygen Uptake Rate ◽  
Treatment Plant ◽  
Oxygen Demand ◽  
Test Results ◽  
Partial Correlation Analysis ◽  
The Impact

The aim of this study was to determine the condition of activated sludge in the biologic reactor located in the collective wastewater treatment plant in Nowy Targ (Poland) based on OUR tests in the aspect of the impact of sludge’s concentration in the biologic reactor and dependence of BOD5/TN and BOD5/TP in wastewater flowing into the biologic reactor. The analysis was conducted based on test results from 61 samples of activated sludge taken from the biologic reactor and 61 samples of wastewater flowing into the biologic reactor. The analysis included the concentration of sludge in the biologic reactor. The following indicators were analyzed in wastewater flowing into the reactor: biochemical oxygen demand (BOD5), total nitrogen (TN) and total phosphorus (TP). The statistical analysis concerning the impact of the analyzed factors on oxygen uptake rate (OUR) tests was developed based on the Pearson’s correlation coefficient and partial correlation of many variables. Based on the results of the partial correlation analysis, nomograms were developed to determine the condition of activated sludge microorganisms (OUR) based on the BOD5/TN and BOD5/TP connection and knowledge of the sludge concentration in the bioreactor of the treatment plant. The presented nomograms can be formulated for each bioreactor based on activated sludge technology related the load of organic and biogenic pollutants in the wastewater flowing into the bioreactor and the concentration of the sludge in the bioreactor.

OPTIMISATION OF W ASTEW A TER TREATMENT PLANTS BY MEANS OF COMPUTER MODELS

1994 ◽  
Vol 30 (4) ◽  
pp. 181-190 ◽  
Author(s):  
René Dupont ◽  
Ole Sinkjær
Keyword(s):  
Wastewater Treatment ◽  
Activated Sludge ◽  
Pilot Plant ◽  
Wastewater Treatment Plants ◽  
Treatment Plant ◽  
Operational Strategies ◽  
Nitrification Process ◽  
Computer Based ◽  
Calibration Tool ◽  
Denitrification Process

The objective of the work presented is to demonstrate how computer based models can be used to improve the effluent quality from wastewater treatment plants by optimisation of the operation. The investigation was carried out in connection with pilot plant investigations at Damhusllen Wastewater Treatment Plant in order to establish the design basis for upgrading the treatment plants in the city of Copenhagen. Calibration of the model was done with thorough characterisation of the wastewater and the activated sludge as the primary calibration tool. Special attention was paid to the nitrification process, which by previous investigations was shown to be occasionally inhibited. Model constants for the nitrification process were detennined from experiments. Default constants were used for nearly all other constants. The pilot plant was optimized with the calibrated model. Different operational strategies for improvement of the denitrification process were tested. The denitrification process was operated relatively poorly at the time for the optimisation. The calibration showed that it was possible to calibrate the model using the characterization of the wastewater and the activated sludge as the primary calibration tool. Further it was shown that the calihrated model could be used as a tool for optimising the operation of the pilot plant. The suggested operation correlated well with the practical realisable operation.

Batch test procedures as tools for calibration of the activated sludge model - a pilot scale demonstration

1998 ◽  
Vol 37 (4-5) ◽  
pp. 235-242 ◽  
Author(s):  
Gert Holm Kristensen ◽  
Jes la Cour Jansen ◽  
Per Elberg Jørgensen
Keyword(s):  
Activated Sludge ◽  
Pilot Plant ◽  
Model Calibration ◽  
Pilot Scale ◽  
Biological Nutrient Removal ◽  
Test Procedures ◽  
Process Dynamics ◽  
Analysis System ◽  
Nitrate And Nitrite ◽  
The Impact

Various mathematical models have been developed to facilitate the design and operation of biological nutrient removal plants. Proper calibration of such models can be a difficult task due to the large number of variable process coefficients. The paper describes a strategy for model calibration based on batch characterizations of wastewater and activated sludge biomass and demonstrates its applicability through modelling of the process dynamics in a highly dynamic activated sludge pilot plant. A comprehensive experimental programme was undertaken comprising batch characterizations of readily degradable and easily hydrolysable COD in influent wastewater, maximum and endogenous process rates for functional microorganism groups in the activated sludge, and half-saturation process constants to describe the impact of oxygen on nitrification and denitrification. An on-line measurement of ammonia and nitrate and nitrite using a Flow Injection Analysis System was conducted for two consecutive days to study the process dynamics in a BioDenitro pilot plant for two parallel activated sludge process tanks. It was possible to closely mimic the dynamics of the nitrogen removal processes in the two tanks based on the model calibration strategy using wastewater and biomass characteristics determined in batch experiments.

Design of aeration systems in activated sludge plants at different wastewater temperatures

2012 ◽  
Vol 7 (1) ◽  
Author(s):  
T. Guenkel ◽  
M. Wagner
Keyword(s):  
Oxygen Uptake ◽  
Activated Sludge ◽  
Uptake Rate ◽  
Oxygen Transfer ◽  
Transfer Rate ◽  
Oxygen Uptake Rate ◽  
Oxygen Transfer Rate ◽  
Decisive Factor ◽  
Volume Increase ◽  
The Impact

The standard oxygen transfer rate (SOTR) is the decisive factor in the dimensioning of activated sludge plants. It depends on the required oxygen uptake rate (OUR) by microorganisms. The dependencies of the SOTR and OUR on the wastewater temperature (range 5–30 °C) are discussed. It is shown that the absolute values of the SOTR depend only slightly on the wastewater temperature, while the specific values, in relation to the aerated tank volume, increase considerably as a function of the wastewater temperature. Within this context, the decisive dimensioning temperature is discussed. In addition, two design approaches for determining the SOTR, temperature-dependant and temperature-independent, are presented and compared, showing the impact of the water dependency. Finally, the sensitivity of the decisive factors for determining the SOTR is discussed, particularly addressing the influence of the α-value.

scholarly journals Impact of hydraulic retention time on phosphorus removal from wastewater using reactive media

2020 ◽  
Vol 82 (12) ◽  
pp. 2920-2928
Author(s):  
S. Benzing ◽  
F. Couceiro ◽  
S. Barnett ◽  
J. B. Williams ◽  
P. Pearce ◽  
...  
Keyword(s):  
Retention Time ◽  
Hydraulic Retention Time ◽  
Wastewater Treatment Plants ◽  
Appropriate Technology ◽  
Synthetic Wastewater ◽  
Depth Analysis ◽  
The Impact ◽  
Over Time ◽  
P Removal ◽  
Reactive Media

Abstract Phosphorus (P) discharge from wastewater treatment plants into the environment contributes to eutrophication issues. Reactive media filters represent an effective, simple and cost-effective solution to decrease the P content. Previous research used various experimental designs and often synthetic wastewater, making assessment of real-world performance difficult. This study assesses the impact of the hydraulic retention time (HRT) on P removal using real wastewater to refine design criteria for full-scale installations. Four media were compared in column experiments for >200 days. Different HRTs were applied and initially the media achieved low P effluent concentrations of >0.1 mg/L PO4–P, increasing over time. Best P removal was observed for the highest HRT with on average >99%. HRT was seen to be the driving factor for P removal rather than media capacity. Three of the four materials showed pH levels above 12 initially, decreasing over time. Water quality parameters, including organics, solids and metals, were monitored. In-depth analysis confirmed formation of calcium phosphate precipitation on the media's surface. The results suggest the importance of an optimal HRT to achieve high P removal and show that the reactive media application is an appropriate technology for P removal on small sites if the elevated pH is addressed.

Selector Volume in Pulp and Paper Activated Sludge Wastewater Treatment Plants – Bench Scale and Pilot Plant Studies

1994 ◽  
Vol 29 (5-6) ◽  
pp. 303-311
Author(s):  
J. Wessberg ◽  
T. Welander ◽  
M. Jönsson
Keyword(s):  
Activated Sludge ◽  
Pilot Plant ◽  
Wastewater Treatment Plants ◽  
Pulp And Paper ◽  
Volume Index ◽  
Sludge Volume Index ◽  
Bench Scale ◽  
Reference Process ◽  
Kraft Mill

Laboratory activated sludge reactors were operated on effluent wastewater from a kraft mill. Two of the three reactors were initially preceded with a “normal” size aerated selector, 2% of the total aerated volume, with unsatisfactory sludge volume index development. When the selectors were replaced by larger ones, 13% of the aerated volume, the sludge volume index could be kept below 50 ml/g for the selector processes while continuing to be higher and more unstable in the reference process. A pilot plant, operated in situ on the same wastewater, showed a comparable improvement in sludge volume index when its selector, 7% of the total volume, was replaced by one that constituted 13% of the total volume, corresponding to a selector load of 3 g BOD / g VSS * d. According to studies of the COD balance around one bench scale selector, the COD removal mechanism in the selector was respiration/assimilation rather than uptake/storage.

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