scholarly journals Design and assessment of species-level qPCR primers targeting comammox

2018 ◽  
Author(s):  
Natalie Keene-Beach ◽  
Daniel R. Noguera
Keyword(s):  
Activated Sludge ◽  
Pcr Primers ◽  
Species Level ◽  
Minor Role ◽  
Ammonium Oxidation ◽  
Candidate Species ◽  
Solids Retention ◽  
A Minor ◽  
Activated Sludge Systems ◽  
Low Do

AbstractPublished PCR primers targeting the ammonia monooxygenase gene (amoA) were applied to samples from activated sludge systems operated with low dissolved oxygen (DO) to quantify total and clade-levelNitrospirathat perform complete ammonium oxidation (comammox); however, we found these existing primers resulted in significant artifact-associated non-target amplification. This not only overestimated comammoxamoAcopies but also resulted in numerous false positive detections in the environmental samples tested, as confirmed by gel electrophoresis. Therefore, to more accurately quantify known comammox, we designed specific and sensitive primers targeting three candidate species:Candidatus(Ca.) Nitrospira nitrosa,Ca.N. inopinata, andCa.N. nitrificans. The primers were tested withamoAtemplates of these candidate species, and used to quantify comammox at the species level in low DO activated sludge systems. We found that comammox related toCa.N. nitrosa were present and abundant in the majority of samples from low DO bioreactors and were not detected in samples from a high DO system. In addition, the greatest abundance ofCa.N. nitrosa was found in bioreactors operated with a long solids retention time.Ca.N. inopinata andCa.N. nitrificans were only detected sporadically in these samples, indicating a minor role of these comammox in nitrification under low DO conditions.Abstract art

Nitrogen removal in activated sludge systems including denitrification in secondary clarifiers

1994 ◽  
Vol 30 (6) ◽  
pp. 101-111 ◽  
Author(s):  
H. Siegrist ◽  
W. Gujer
Keyword(s):  
Activated Sludge ◽  
Nitrogen Removal ◽  
Retention Time ◽  
Secondary Clarifier ◽  
Solids Retention Time ◽  
Solids Retention ◽  
Activated Sludge Systems

Denitrification in the secondary clarifier can contribute substantially to the nitrogen removal of activated sludge systems. This is illustrated on two treatment plants with different secondary clarifier systems. A model to estimate denitrification capacity and to design activated sludge systems for nitrogen removal is developed and verified with data from two treatment plants. The model includes denitrification in the secondary clarifier, wastewater composition (soluble readily biodegradable COD, particulate degradable COD), oxygen input into the anoxic volume, temperature, and solids retention time (SRT). The influence of aerated grit chambers and primary sedimentation on denitrification is discussed.

Effects of different hydraulic models on predicting longitudinal profiles of reactive pollutants in activated sludge reactors

2008 ◽  
Vol 58 (3) ◽  
pp. 555-561 ◽  
Author(s):  
P. Zima ◽  
J. Makinia ◽  
M. Swinarski ◽  
K. Czerwionka
Keyword(s):  
Activated Sludge ◽  
Ammonia Concentration ◽  
Minor Role ◽  
Nitrification Rate ◽  
Concentration Profiles ◽  
One Dimensional ◽  
Advection Dispersion ◽  
In Series ◽  
The One ◽  
A Minor

This paper presents effects of dispersion on predicting longitudinal ammonia concentration profiles in activated sludge bioreactor located at “Wschod” WWTP in Gdansk. The aim of this study was to use the one-dimensional advection-dispersion Equation (ADE) to simulate the flow conditions (based on the inert tracer concentrations in selected points) and longitudinal profile of reactive pollutant (based on the ammonia concentration profiles in selected points). The simulation results were compared with the predictions obtained using a traditional “tanks-in-series” (TIS) approach, commonly used in designing biological reactors. The use of dispersion coefficient calculated from an empirical formula resulted in substantial differences in the tracer concentration distributions in two sampling points in the bioreactor. Simulations using the one-dimensional ADE and TIS model, with the nitrification rate incorporated as the source term, revealed that the hydraulic model plays a minor role compared to the biochemical transformations in predicting the longitudinal ammonia concentration profiles.

scholarly journals Colloids, flocculation and carbon capture – a comprehensive plant-wide model

2018 ◽  
Vol 79 (1) ◽  
pp. 15-25 ◽  
Author(s):  
Hélène Hauduc ◽  
Ahmed Al-Omari ◽  
Bernhard Wett ◽  
Jose Jimenez ◽  
Haydee De Clippeleir ◽  
...  
Keyword(s):  
Activated Sludge ◽  
Carbon Capture ◽  
Oxygen Demand ◽  
High Rate ◽  
Reactor Performance ◽  
Whole Plant ◽  
Solids Retention ◽  
Methane Potential ◽  
Intracellular Storage ◽  
Activated Sludge Systems

Abstract The implementation of carbon capture technologies such as high-rate activated sludge (HRAS) systems are gaining interests in water resource and recovery facilities (WRRFs) to minimize carbon oxidation and maximize organic carbon recovery and methane potential through biosorption of biodegradable organics into the biomass. Existing activated sludge models were developed to describe chemical oxygen demand (COD) removal in activated sludge systems operating at long solids retention times (SRT) (i.e. 3 days or longer) and fail to simulate the biological reactions at low SRT systems. A new model is developed to describe colloidal material removal and extracellular polymeric substance (EPS) generation, flocculation, and intracellular storage with the objective of extending the range of whole plant models to very short SRT systems. In this study, the model is tested against A-stage (adsorption) pilot reactor performance data and proved to match the COD and colloids removal at low SRT. The model was also tested on longer SRT systems where effluents do not contain much residual colloids, and digestion where colloids from decay processes are present.

Validating the Colloid model to optimise the design and operation of both moving-bed biofilm reactor and integrated fixed-film activated sludge systems

2014 ◽  
Vol 69 (7) ◽  
pp. 1552-1557 ◽  
Author(s):  
J. Albizuri ◽  
P. Grau ◽  
M. Christensson ◽  
L. Larrea
Keyword(s):  
Activated Sludge ◽  
Oxygen Demand ◽  
Biofilm Reactor ◽  
Nitrification Rate ◽  
Moving Bed Biofilm Reactor ◽  
Moving Bed ◽  
Fixed Film ◽  
Solids Retention ◽  
Lower Effect ◽  
Activated Sludge Systems

The paper presents a systematic study of simulations, using a previously calibrated Colloid model, from which it was found that: (i) for pure moving-bed biofilm reactor (MBBR) processes with tertiary nitrification conditions (no influent chemical oxygen demand (COD)), dissolved oxygen = 5 mg/L and residual NH4-N > 4 mgN/L, a nitrification rate of 1.2 gN/(m2d) was obtained at 10 °C. This rate decreases sharply when residual NH4-N is lower than 2 mgN/L, (ii) for MBBR systems with predenitrification–nitrification zones and COD in the influent (soluble and particulate), the nitrification rate (0.6 gN/(m2d)) is half of that in tertiary nitrification due to the effect of influent colloidal XS (particulate slowly biodegradable COD) and (iii) for integrated fixed-film activated sludge (IFAS) processes the nitrification rate in the biofilm (0.72 gN/(m2d)) is 20% higher than for the pure MBBR due to the lower effect of influent XS since it is adsorbed onto flocs. However, it is still 40% lower than the tertiary nitrification rate. In the IFAS, the fraction of the nitrification rate in suspension ranges from 10 to 70% when the aerobic solids retention time varies from 1.4 to 6 days.

New anaerobic process of nitrogen removal

2006 ◽  
Vol 54 (8) ◽  
pp. 163-170 ◽  
Author(s):  
S. Kalyuzhnyi ◽  
M. Gladchenko ◽  
A. Mulder ◽  
B. Versprille
Keyword(s):  
Activated Sludge ◽  
Electron Donor ◽  
Nitrogen Removal ◽  
Laboratory Testing ◽  
Oxidation Reaction ◽  
Loading Rate ◽  
Nitrogen Loading ◽  
Ammonium Oxidation ◽  
Conventional Activated Sludge ◽  
Activated Sludge Systems

This paper reports on successful laboratory testing of a new nitrogen removal process called DEAMOX (DEnitrifying AMmonium OXidation) for the treatment of strong nitrogenous wastewater such as baker's yeast effluent. The concept of this process combines the recently discovered ANAMMOX (ANaerobic AMMonium OXidation) reaction with autotrophic denitrifying conditions using sulfide as an electron donor for the production of nitrite within an anaerobic biofilm. The achieved results with a nitrogen loading rate of higher than 1, 000 mg/L/d and nitrogen removal of around 90% look very promising because they exceed (by 9–18 times) the corresponding nitrogen removal rates of conventional activated sludge systems. The paper describes also some characteristics of DEAMOX sludge, as well as the preliminary results of its microbiological characterization.

Control Strategies of Low DO in Step-Feed Anoxic/Oxic Process Treating Domestic Wastewater for Filamentous Bulking Inhibition

2014 ◽  
Vol 1073-1076 ◽  
pp. 738-742
Author(s):  
Wei Wang ◽  
Qiang Chen ◽  
Li Na Liu ◽  
Xin Zhang ◽  
Chun Hong Shao
Keyword(s):  
Activated Sludge ◽  
Control Strategies ◽  
Domestic Wastewater ◽  
Good Choice ◽  
Filamentous Bulking ◽  
Do Concentration ◽  
Do Control ◽  
Activated Sludge Systems ◽  
Low Do

Activated sludge systems operate at low DO concentration can save aeration energy and enhance the treatment performance. To explore the effect of DO control strategies on the settleability of activated sludge, different DO control strategies were carried out in a step-feed anoxic/oxic reactor treating domestic wastewater. The result shows that low DO concentration is not the single reason to filamentous bulking. To achieve long-term system stabilization and avoid serious filamentous bulking, feedforward-feedback DO control strategy may be a feasible and good choice.

Solids retention time, influent antibiotic concentrations, and temperature as selective pressures for antibiotic resistance in activated sludge systems

2017 ◽  
Vol 3 (5) ◽  
pp. 883-896 ◽  
Author(s):  
Majid Neyestani ◽  
Eric Dickenson ◽  
Jean McLain ◽  
Victoria Obergh ◽  
Oscar Quinones ◽  
...  
Keyword(s):  
Antibiotic Resistance ◽  
Wastewater Treatment ◽  
Activated Sludge ◽  
Retention Time ◽  
Biological Wastewater Treatment ◽  
Selective Pressures ◽  
Solids Retention Time ◽  
Solids Retention ◽  
Activated Sludge Systems

This paper evaluates changes in antibiotic resistance during biological wastewater treatment.

The Effect of Path Length and Display Size on Memory for Spatial Information

2012 ◽  
Vol 59 (3) ◽  
pp. 147-152 ◽  
Author(s):  
Katherine Guérard ◽  
Sébastien Tremblay
Keyword(s):  
Path Length ◽  
Potential Role ◽  
Spatial Information ◽  
Recall Performance ◽  
Minor Role ◽  
Length Effect ◽  
Serial Memory ◽  
Fixed Reference ◽  
A Minor

In serial memory for spatial information, some studies showed that recall performance suffers when the distance between successive locations increases relatively to the size of the display in which they are presented (the path length effect; e.g., Parmentier et al., 2005) but not when distance is increased by enlarging the size of the display (e.g., Smyth & Scholey, 1994). In the present study, we examined the effect of varying the absolute and relative distance between to-be-remembered items on memory for spatial information. We manipulated path length using small (15″) and large (64″) screens within the same design. In two experiments, we showed that distance was disruptive mainly when it is varied relatively to a fixed reference frame, though increasing the size of the display also had a small deleterious effect on recall. The insertion of a retention interval did not influence these effects, suggesting that rehearsal plays a minor role in mediating the effects of distance on serial spatial memory. We discuss the potential role of perceptual organization in light of the pattern of results.

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