CHARACTERISATION OF THE NITRIFICATION PROCESS FOR DESIGN PURPOSES

1994 ◽  
Vol 30 (4) ◽  
pp. 47-56 ◽  
Author(s):  
O. Sinkjær ◽  
L. Yndgaard ◽  
P. Harremoës ◽  
J. L. Hansen
Keyword(s):  
Kinetic Theory ◽  
Nitrification Rate ◽  
Experimental Basis ◽  
Batch Tests ◽  
Mode Of Operation ◽  
Nitrification Process ◽  
Aerobic Reactor ◽  
The City ◽  
Specific Evaluation ◽  
Aerobic Sludge

Pilot plant experiments have been performed over a period of four years in order to establish an experimental basis for the upgrading of the treatment plants of the city of Copenhagen to nitrogen removal. The design chosen is based on the alternating mode of operation. Nitrification rates have been determined in batch tests on activated sludge extracted from the pilot plants and through the measuring of transient concentrations during the alternating mode of operation in the aerobic reactor. The data have been nonnalised to standard conditions by correcting them according to the kinetic theory. By monitoring the normalised nitrification rate it could be established that the nitrification process was occasionally inhibited. The aerobic sludge age required to maintain nitrification has been estimated. A specific evaluation has been made of the sensitivity of the required sludge age to the oxygen concentration and temperature.

Potential of hybrid processes for nitrogen removal from swine wastewater

2009 ◽  
Vol 4 (3) ◽  
Author(s):  
T. López de Armentia ◽  
L. Larrea
Keyword(s):  
Suspended Solids ◽  
Swine Wastewater ◽  
Hybrid Reactor ◽  
Nitrification Rate ◽  
Hybrid Processes ◽  
Batch Tests ◽  
Inhibition Of Nitrification ◽  
Aerobic Reactor ◽  
High Level ◽  
Two Hybrid

A comprehensive investigation was carried out using a bench-scale plant (70l) with the aim of evaluatingthe potential of two hybrid processes that use plastic moving carriers for nitrification and denitrification, given the restriction that low and stable values of ammonium and nitrate had to be met. In one process, the nitrification aerobic reactor operated with the biomass in biofilm exclusively and achieved a nitrification rate of 0,8 gN/m2·d. In the other process, nitrification operated as a hybrid process and a similar nitrification rate in the biofilm was found. Batch tests revealed that suspended solids in the hybrid reactor provided an additional 20% nitrification rate. This resulted in a potential volumetric nitrification rate of 380 gN/m3·d at 20°C, which is 2.5 times the expected rate in activated sludge plants under the same conditions. A high anoxic fraction (55%) was used in both processes with hybrid denitrification, since it minimized inhibition of nitrification in the biofilm due to the biodegradable COD applied load. Batch tests undertaken with high suspended solids (4 g/l) revealed that 60% of the denitrification took place in the biomass in suspension, and 40% in biofilm, providing a high level and robust performance. The dosage of methanol was crucial in regulating effluent nitrate. It is concluded that both processes offer great potential regarding the design of more compact new plants and the upgrading of existing facilities.

Designing Experiments for Model Identification of the Nitrification Process

1991 ◽  
Vol 24 (6) ◽  
pp. 9-16 ◽  
Author(s):  
P. J. Ossenbruggen ◽  
H. Spanjers ◽  
H. Aspegren ◽  
A. Klapwijk
Keyword(s):  
Mechanistic Model ◽  
Nonlinear Differential Equations ◽  
Model Identification ◽  
Reaction Rates ◽  
Variable Coefficients ◽  
Model Specification ◽  
First Order ◽  
Interactive Behavior ◽  
Batch Tests ◽  
Nitrification Process

A series of batch tests were performed to study the competition for oxygen by Nitrosomonas and Nitrobacter in the nitrification of ammonia in activated sludge. Oxygen uptake rate (OUR) and dynamic (compartment) models describing the process are proposed and tested. The OUR model is described by a Monod relationship and the biogradation process by a set of first order nonlinear differential equations with variable coefficients. The results show a mechanistic model and ten reaction rates are sufficient to capture the interactive behavior of the nitrification process. Methods for model specification, calibrating, and testing the model and the design of additional experiments are described.

Wastewater treatment and nutrient removal in the combined reactor

1998 ◽  
Vol 38 (1) ◽  
pp. 87-95 ◽  
Author(s):  
M. Roš ◽  
J. Vrtovšek
Keyword(s):  
Organic Compounds ◽  
Industrial Wastewater ◽  
Design Procedure ◽  
Order Reaction ◽  
Treated Wastewater ◽  
Nitrification Rate ◽  
Zero Order Reaction ◽  
Aerobic Reactor ◽  
Complex Organic

A combined anaerobic anoxic aerobic reactor for the treatment of the industrial wastewater that contains nitrogen and complex organic compounds as well as its design procedure is presented. The purpose of our experiments was to find a simple methodology that would provide combined reactor design. The reactor is based on the combination of anaerobic, anoxic and aerobic process in one unit only. It was found that the HRT even under 1 hour in the anaerobic zone is long enough for the efficient transformation of complex organic compounds into readily biodegradable COD which is then used in dentrification process. In the N-NO3 concentration range 1.5-50 mg/l the denitrification rate could be expressed as half-order reaction when the CODrb was in excess. N-NO3 removal efficiency is controlled by the recycle flow from the aerobic to the anoxic zone. Nitrification rate can be expressed as first, half or zero-order reaction with respect to effluent N-NH4 concentration. Nitrification rate depends on the dissolved oxygen concentration and hydrodynamic conditions in the reactor. Case study for design of a pilot plant of the combined reactor for treatment of pre-treated pharmaceutical wastewater is shown. Characteristics of pre-treated wastewater were: COD=200 mg/l, BOD5=20 mg/l, N-Kjeldahl=80 mg/l, N-NH4=70 mg/l, N-NOx<1 mg/l, P-PO4=5 mg/l. Legal requirements for treated wastewater were: COD=<100 mg/l, BOD5<5 mg/l, N-NH4=<1 mg/l, N-NOx=<10 mg/l.

Temporal variation in maximum cell-specific nitrification rate

2010 ◽  
Vol 61 (8) ◽  
pp. 2069-2073 ◽  
Author(s):  
M. Fujita ◽  
K. Tsuji ◽  
A. Akashi
Keyword(s):  
Ammonia Oxidation ◽  
Thermal Power ◽  
Nitrification Rate ◽  
Nitrite Oxidation ◽  
Cell Numbers ◽  
Oxidation Rates ◽  
Batch Tests ◽  
Nitrogen Loads ◽  
Clone Analysis ◽  
Maximum Cell

The cell numbers of ammonia-oxidising bacteria (AOBs), Nitrospira and Nitrobacter in activated sludge used to treat wastewater from a thermal power plant in Japan were examined for nine months using a real-time PCR quantification technique. AOB cell numbers ranged 2.8 × 1010–2.3 × 1011 cell/L. The amoA clone analysis showed that the only Nitrosomonas halophila was responsible for ammonia oxidation over the period. Nitrospira were in the range of 2.6 × 109–2.4 × 1010 cell/L and Nitrobacter were less than 1% as common as Nitrospira. Meanwhile, maximum nitrification rates, maximum ammonia- and nitrite-oxidation rates obtained from aerobic batch tests, ranged 0.5–1.3 mmol-N/L h and 1.0–2.5 mmol-N/L h, respectively. No clear correlations were observed between the cell numbers of AOBs or Nitrospira and their maximum rates, because the maximum cell-specific ammonia- and nitrite-oxidation rates varied remarkably over the ranges of 1.1–11.9 and 2.4–21.6 fmol-N/cell h, respectively. To explore the factors controlling maximum cell-specific nitrification rates, the relationship to influent nitrogen loads per AOB or Nitrospira cell numbers was investigated. Fairly good correlations were obtained. Considering the effluent ammonia and nitrite concentrations were zero and only Nitrosomonas halophila had a role in ammonia oxidation over the period, we conclude that the amount of nitrogen oxidised per AOB or Nitrospira cell numbers likely controls maximum cell-specific ammonia- or nitrite-oxidation rates, respectively.

A pilot-scale evaluation of aerobic–anoxic sludge digestion

1990 ◽  
Vol 17 (1) ◽  
pp. 68-78 ◽  
Author(s):  
C. C. Peddie ◽  
D. S. Mavinic
Keyword(s):  
Pilot Scale ◽  
Intermittent Aeration ◽  
Scale Evaluation ◽  
Digestion Process ◽  
Batch Tests ◽  
Sludge Digestion ◽  
Volatile Solids ◽  
Mode Of Operation ◽  
Experimental Runs

A pilot-scale (300 L) evaluation of waste-activated sludge digestion by a cyclical aerobic–anoxic mode of operation was undertaken at ambient liquid temperatures (14–17 °C). Three experimental runs were conducted over a 2-year period. The first run compared the aerobic–anoxic process to a conventional, continuously aerated, digestion process. During the second run, the aerobic–anoxic digester was compared to a lime-supplemented conventional aerobic process. The third run compared two aerobic–anoxic digester units, operating at reduced (50 and 25% of normal) aeration rates during the aerobic period. In addition, basic data from batch tests are outlined and discussed. Results from the various experimental runs indicated numerous potential advantages for the aerobic–anoxic mode of digester operation. The main advantage was that turning the air on and off resulted in volatile solids reduction efficiencies similar to that in the continuously aerated systems. In addition to the potential for significant savings in aeration costs, another benefit of the intermittent aeration mode of operation involved improved supernatant quality of the final, settled effluent. Key words: aerobic digestion, anoxic, intermittent aeration, lime, pilot-scale, Redox potential, sludge, solids reduction.

scholarly journals Nitrification and its oxygen consumption along the turbid Chang Jiang River plume

2014 ◽  
Vol 11 (7) ◽  
pp. 2083-2098 ◽  
Author(s):  
S. S.-Y. Hsiao ◽  
T.-C. Hsu ◽  
J.-w. Liu ◽  
X. Xie ◽  
Y. Zhang ◽  
...  
Keyword(s):  
Ammonia Oxidation ◽  
River Mouth ◽  
Amoa Gene ◽  
Free Water ◽  
River Plume ◽  
Community Respiration ◽  
Ammonium Concentration ◽  
Nitrification Rate ◽  
Nitrification Process ◽  
Iron And Manganese

Abstract. Nitrification is a series of processes that oxidizes ammonia to nitrate, which contributes to hypoxia development in coastal oceans, especially in eutrophicated regions. The nitrification rate of bulk water (NRb) and particle free water (NRpf, particle > 3 μm eliminated) were determined along the Chang Jiang River plume in August 2011 by nitrogen isotope tracer technique. Measurements of dissolved oxygen (DO), community respiration rate (CR), nutrients, dissolved organic nitrogen (DON), total suspended matter (TSM), particulate organic carbon/nitrogen (POC / PON), acid-leachable iron and manganese on suspended particles and both archaeal and β-proteobacterial ammonia monooxygenase subunit A gene (amoA) abundance on size-fractioned particles (> 3 μm and 0.22–3 μm) were conducted. The NRb ranged from undetectable up to 4.6 μmol L−1 day−1, peaking at a salinity of ~ 29. NRb values were positively correlated with ammonium concentration, suggesting the importance of substrate in nitrification. In the river mouth and the inner plume, NRb was much higher than NRpf, indicating that the nitrifying microorganism is mainly particle associated, which was supported by its significant correlation with amoA gene abundance and TSM concentration. The estimated oxygen demands of nitrification accounted for 0.32 to 318% of CR, in which 50% samples demanded more oxygen than that predicted by by the Redfield model (23%), indicating that oxygen might not be the sole oxidant though DO was sufficient (> 58 μmol kg−1) throughout the observation period. The excess nitrification-associated oxygen demand (NOD) showed a tendency to occur at lower DO samples accompanied by higher acid-leachable Fe / Mn, which implied reactive Fe3+ / Mn4+ may play a role as oxidant in the nitrification process. Stoichiometric calculation suggested that reactive Fe on particles was 10 times the oxidant demand required to complete ammonia oxidation in the entire plume. The potential involvement of reactive iron and manganese in the nitrification process in oxygenated water further complicated nitrogen cycling in the turbid river plume.

Reliability Evaluation in Modern Urban Distribution Considering Islands Impacts

2011 ◽  
Vol 48-49 ◽  
pp. 886-890
Author(s):  
Qian Chen ◽  
Xiao Li Li ◽  
Jian Hua Zhang
Keyword(s):  
Operation Mode ◽  
Distribution Networks ◽  
Reliability Evaluation ◽  
Distributed Generators ◽  
Mode Of Operation ◽  
Workload Capacity ◽  
Importance Factor ◽  
Urban Distribution ◽  
The City ◽  
Distribution Grids

A growing number of distributed generators have been connected to urban distribution networks in recent years, which brings great challenges to the traditional reliability evaluation of the distribution grids. Island is a new kind of operation mode of the city grid. In consideration of the importance factor of system load, establish the model of island taking the maximum equivalent workload capacity as objective function and heuristic search technology is proposed to solve the problem. According to the island mode of operation, assess the reliability of the network with islands based on equivalent resistance and minimal path, which have certain instructive significance to the improvement of reliability of the modern urban distribution nets.

scholarly journals Combined Anaerobic-Aerobic Bacterial Degradation of Dyes

2010 ◽  
Vol 7 (3) ◽  
pp. 739-744 ◽  
Author(s):  
R. Wilfred Sugumar ◽  
Sandhya Sadanandan
Keyword(s):  
Mixed Culture ◽  
Bacterial Degradation ◽  
Acid Orange 7 ◽  
Anaerobic Reactor ◽  
Anaerobic Microorganisms ◽  
Degradation Of Dyes ◽  
Textile Dyeing ◽  
Nitrification Process ◽  
Aerobic Reactor ◽  
Reactive Red 2

Wastewaters from the dye baths of a non-formal textile-dyeing unit containing C.I. Acid Orange 7 and C.I. Reactive Red 2 were subjected to degradation in a sequential anaerobic-aerobic treatment process based on mixed culture of bacteria. The technical samples of the dyestuffs and the dye bath wastes were treated in an anaerobic reactor, using an adapted mixed culture of anaerobic microorganisms. The dyestuffs were biotransformed into colourless substituted amine metabolites in the reactor. The biotransformation was assisted by co-metabolic process. The amine metabolites did not undergo further degradation in the anaerobic reactor. The effluent from the anaerobic reactor was treated in an aerobic rotating biological contactor and the amine metabolites were found to undergo complete mineralization. This two stage treatment resulted in 94% elimination of dissolved organic carbon. In addition, 85% of organic nitrogen was converted into nitrate in the aerobic reactor during nitrification process.

scholarly journals The effect of temperature on the efficiency of industrial wastewater nitrification and its (geno)toxicity

2016 ◽  
Vol 42 (1) ◽  
pp. 27-34 ◽  
Author(s):  
Anna Gnida ◽  
Jarosław Wiszniowski ◽  
Ewa Felis ◽  
Jan Sikora ◽  
Joanna Surmacz-Górska ◽  
...  
Keyword(s):  
Activated Sludge ◽  
Industrial Wastewater ◽  
Treatment Plant ◽  
Oxygen Demand ◽  
Nitrogen Fertilizers ◽  
Effect Of Temperature ◽  
Winter Period ◽  
Batch Tests ◽  
Nitrification Process ◽  
Test Organisms

AbstractThe paper deals with the problem of the determination of the effects of temperature on the efficiency of the nitrification process of industrial wastewater, as well as its toxicity to the test organisms. The study on nitrification efficiency was performed using wastewater from one of Polish chemical factories. The chemical factory produces nitrogen fertilizers and various chemicals. The investigated wastewater was taken from the influent to the industrial mechanical-biological wastewater treatment plant (WWTP). The WWTP guaranteed high removal efficiency of organic compounds defined as chemical oxygen demand (COD) but periodical failure of nitrification performance was noted in last years of the WWTP operation. The research aim was to establish the cause of recurring failures of nitrification process in the above mentioned WWTP. The tested wastewater was not acutely toxic to activated sludge microorganisms. However, the wastewater was genotoxic to activated sludge microorganisms and the genotoxicity was greater in winter than in spring time. Analysis of almost 3 years’ period of the WWTP operation data and laboratory batch tests showed that activated sludge from the WWTP under study is very sensitive to temperature changes and the nitrification efficiency collapses rapidly under 16°C. Additionally, it was calculated that in order to provide the stable nitrification, in winter period the sludge age (SRT) in the WWTP should be higher than 35 days.

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