Simultaneous autotrophic denitrification and nitrification in a low-oxygen reaction environment

2014 ◽  
Vol 70 (4) ◽  
pp. 729-735 ◽  
Author(s):  
Ganapathy Ramanathan ◽  
Christopher M. Sales ◽  
Wen K. Shieh
Keyword(s):  
Residence Time ◽  
Oxygen Demand ◽  
Autotrophic Denitrification ◽  
Low Oxygen ◽  
Total N ◽  
N Removal ◽  
Bioreactor System ◽  
The Mean ◽  
The Stability ◽  
Ammonia Oxidising Bacteria

The occurrence of autotrophic denitrification and nitrification activities by ammonia-oxidising bacteria and nitrite-oxidising bacteria is studied in a bioreactor system operable at low-dissolved oxygen (DO) and at variable oxygen influx rates. At a loading of 3.6 mg NH4+–N/h into the bioreactor, simultaneous autotrophic denitrification and nitrification contributed to NH4+–N removal over oxygen influxes of 2–14 mg O2/h and DO <0.5 mg/L. The maximum autotrophic denitrification (or total-N removal) rates were achieved in a narrow oxygen influx band of 3–5 mg O2/h, where it accounted for up to 36% of NH4+–N removal. At oxygen influx >16 mg O2/h and DO >2 mg/L, autotrophic denitrification ceases and roughly 90% of feed NH4+–N is oxidised to NOX−–N. The stability of total effluent chemical oxygen demand (COD) over the range of oxygen influxes tested confirms the absence of heterotrophic denitrification in the bioreactor. The long solids residence time of the stable biomass zone (21 days) led to production of effluent COD as a result of cell decay, and thus effluent COD was used to calculate more accurately the mean cell residence time.

Simultaneous Nitrification-Denitrification Processes in Activated Sludge Plants: Performance and Applicability

1999 ◽  
Vol 40 (4-5) ◽  
pp. 187-194 ◽  
Author(s):  
C. Collivignarelli ◽  
G. Bertanza
Keyword(s):  
Activated Sludge ◽  
Waste Water Treatment ◽  
Electric Energy ◽  
Low Oxygen ◽  
Total N ◽  
Electric Energy Consumption ◽  
N Removal ◽  
Aeration System ◽  
Anoxic Basin ◽  
Removal Efficiencies

This paper deals with the development of technologies aimed to upgrade existing waste water treatment plants, paying attention to high process efficiencies and low costs. We established conditions for good N removal efficiencies in extended aeration activated sludge plants which are not equipped with specific denitrification steps. The experimental process is based on establishing conditions in the biological reactor which allow simultaneous nitrification and denitrification without alternating (in time or in space) anoxic and aerobic phases; the aeration system is controlled by means of dissolved oxygen and/or redox potential measurements. The research was carried out on two real plants (design size: 2,500 p.e. and 440,000 p.e. respectively). The main advantages of this process (even if some aspects are still under investigation) are: total N removal efficiencies similar to a pre-denitrification process, without the need for an anoxic basin and decrease of operating costs (savings in electric energy consumption in particular) due to the low oxygen concentration required in the biological reactor.

The Treatment of Concentrated Landfill Leachate from Membrane-Based Processes by Supercritical Water Oxidation

2014 ◽  
Vol 522-524 ◽  
pp. 560-564 ◽  
Author(s):  
Yan Meng Gong ◽  
Shu Zhong Wang ◽  
Yan Hui Li
Keyword(s):  
Residence Time ◽  
Supercritical Water ◽  
Landfill Leachate ◽  
Water Oxidation ◽  
Batch Reactor ◽  
Oxygen Demand ◽  
Ammonia Nitrogen ◽  
Supercritical Water Oxidation ◽  
N Removal ◽  
Varied Temperature

Supercritical water oxidation (SCWO) of concentrated landfill leachate has been carried out in a batch reactor in fluidized bed sand bath, operated under varied temperature (450-600 °C), pressure (23-29 MPa), residence time (5-20 min) and oxidation coefficient (1.5-3.0). The experimental results indicated that temperature and oxidation coefficient had significant influences on the oxidation reaction, whereas the pressure and residence time were not crucial factors. The chemical oxygen demand (COD) and ammonia nitrogen (NH4-N) removal efficiencies could reach up to 99.23% and 98.64% at 600 °C, 25 MPa and 5 min with a oxidation coefficient of 2, respectively, and the effluents could be discharged harmlessly.

Performance of plastic- and sponge-based trickling filters treating effluents from an UASB reactor

2013 ◽  
Vol 67 (5) ◽  
pp. 1034-1042 ◽  
Author(s):  
P. G. S. Almeida ◽  
A. K. Marcus ◽  
B. E. Rittmann ◽  
C. A. L. Chernicharo
Keyword(s):  
Organic Matter ◽  
Oxygen Demand ◽  
Upflow Anaerobic Sludge Blanket ◽  
Uasb Reactor ◽  
Organic Loading Rate ◽  
Anaerobic Sludge ◽  
Total N ◽  
Trickling Filters ◽  
N Removal ◽  
Anaerobic Sludge Blanket

The paper compares the performance of two trickling filters (TFs) filled with plastic- or sponge-based packing media treating the effluent from an upflow anaerobic sludge blanket (UASB) reactor. The UASB reactor was operated with an organic loading rate (OLR) of 1.2 kgCOD m−3 d−1, and the OLR applied to the TFs was 0.30–0.65 kgCOD m−3 d−1 (COD: chemical oxygen demand). The sponge-based packing medium (Rotosponge) gave substantially better performance for ammonia, total-N, and organic matter removal. The superior TF-Rotosponge performance for NH4+-N removal (80–95%) can be attributed to its longer biomass and hydraulic retention times (SRT and HRT), as well as enhancements in oxygen mass transfer by dispersion and advection inside the sponges. Nitrogen removals were significant (15 mgN L−1) in TF-Rotosponge when the OLRs were close to 0.75 kgCOD m−3 d−1, due to denitrification that was related to solids hydrolysis in the sponge interstices. For biochemical oxygen demand removal, higher HRT and SRT were especially important because the UASB removed most of the readily biodegradable organic matter. The new configuration of the sponge-based packing medium called Rotosponge can enhance the feasibility of scaling-up the UASB/TF treatment, including when retrofitting is necessary.

Combined photosynthesis and mechanical aeration for nitrification in dairy waste stabilisation ponds

2003 ◽  
Vol 48 (2) ◽  
pp. 137-144 ◽  
Author(s):  
J.P.S. Sukias ◽  
R.J. Craggs ◽  
C.C. Tanner ◽  
R.J. Davies-Colley ◽  
J.W. Nagels
Keyword(s):  
Electrical Power ◽  
Oxygen Demand ◽  
Aquatic Organisms ◽  
Ammonia Toxicity ◽  
Nitrifying Bacteria ◽  
Matched Pair ◽  
Total N ◽  
N Removal ◽  
Algal Photosynthesis ◽  
Mechanical Aeration

New Zealand has 16,500 dairy farms (avg. 220 cows), with cows kept on pasture throughout the year. During the 9-month dairy season, the cows are milked twice a day (averaging 2.5-3 h per day in the dairy parlour). Urine and faecal wastes deposited in the dairy parlour are washed away with high pressure hoses, using large volumes of water. A common method of treatment is in simple two-pond (anaerobic/facultative) lagoon systems, which remove about 95% of suspended solids and BOD5, but only 75% of total-N prior to discharge. High concentrations of ammoniacal-N in the effluent can cause toxicity to aquatic organisms in receiving waters. Mechanical aeration of the second (facultative) lagoon to promote nitrification improves effluent quality by reducing oxygen demand and potential ammonia toxicity to streamlife. Mechanical aeration however is associated with considerable mixing, which may prevent algae from optimising photosynthesis in the facultative lagoon. A series of experiments was undertaken which tested the efficiency of mechanical aeration and then attempted to combine it with daytime algal oxygen production in order to maximise ammonia conversion to nitrate, while minimising costs to the farmer. An experimental facility was developed by dividing a large facultative lagoon into two, producing a matched pair of lagoons, operated in parallel with influent flow split equally. Over successive dairy seasons, various aeration regimes were compared. Continuous aeration promoted nearly complete nitrification of the ammoniacal-N (99% removal), and effluent BOD was approximately halved. However the continuous mixing reduced algal biomass, and thus daytime algal photosynthesis. Night-only aeration permitted greater algal photosynthesis to occur, as well as halving electrical power consumption. Ammoniacal-N removal reduced to 90% (10 g m-3 remaining in the effluent), while BOD removal was also lower than in the continuously aerated lagoon (59 and 69% respectively). Providing a series of biofilm attachment surfaces for nitrifying bacteria by suspending geotextile material close to the surface in the pond in consistently aerobic water resulted in improved ammoniacal-N removal efficiency (93%) with night aeration, but still lower removal than continuous aeration.

scholarly journals Product Concentration, Yield and Productivity in Anaerobic Digestion to Produce Short Chain Organic Acids: A Critical Analysis of Literature Data

Processes ◽  
2020 ◽  
Vol 8 (12) ◽  
pp. 1538
Author(s):  
Serena Simonetti ◽  
Agus Saptoro ◽  
Claudia Fernández Martín ◽  
Davide Dionisi
Keyword(s):  
Anaerobic Digestion ◽  
Residence Time ◽  
Oxygen Demand ◽  
Short Chain ◽  
Feed Concentration ◽  
Product Concentration ◽  
Hydraulic Residence Time ◽  
Mean Values ◽  
Performance Variables ◽  
The Mean

In order to make anaerobic digestion-based processes for short chain organic acid (SCOA) production attractive, the key performance variables, i.e., concentration, yield, and productivity of the produced SCOAs need to be maximised. This study analysed recent literature, looking for the effect of process operating parameters (feed concentration, pH, temperature, and residence time) on the performance variables. Data from 551 experiments were analysed. Mean values of the SCOA concentration, yield, and productivity were 10 g l−1, 32% (chemical oxygen demand (COD) COD−1), and 1.9 g l−1 day−1, respectively. Feed concentration and residence time had the most important effect. Higher feed concentration corresponded to higher product concentration and productivity, but to lower yield. The mean feed concentration was 109 gCOD l−1 and 19 gCOD l−1 in the experiments with the highest product concentrations and in the experiments with the highest yields, respectively. Shorter residence times corresponded to higher productivity. The mean HRT (hydraulic residence time) in the experiments with the highest productivities was 2.5 days. Sequencing batch reactors gave higher values of the performance variables (mean values 29 g l−1, 41% COD COD−1, and 12 g l−1 day−1 for product concentration, yield, and productivity, respectively) than processes without phase separation.

scholarly journals Nitrogen removal by denitrification and annamox processes in freshwater rivers of high nitrogen loading region of China

2017 ◽  
Vol 19 (4) ◽  
pp. 650-657 ◽  
Keyword(s):  
River System ◽  
Nitrogen Loading ◽  
Ammonium Oxidation ◽  
Total N ◽  
Membrane Inlet Mass Spectrometry ◽  
Relative Contribution ◽  
N Removal ◽  
The Mean ◽  
High Nitrogen Loading

The importance of anaerobic ammonium oxidation (anammox) – a metabolic pathway that can generate dinitrogen – remains poorly understood in freshwater river system. Using the 15N-isotope pairing technique (15N IPT) combined with membrane inlet mass spectrometry (MIMS), the potential rates of denitrification, anammox and total N removal, and their respective contributions to total N2 production were evaluated in 11 rivers in the Taihu Lake region of China. The measured potential rates of denitrification, total N removal and anammox varied from 18.9±0.3 to 70.0±11.4, 26.3±0.4 to 71.3±11.1 and 1.3±0.3 to 11.0±2.5 μmol N m-2 h-1, respectively. The relative contribution of anammox to total N2 production (ra%) ranged from 2.0±0.8% to 29.9±0.7%. The mean potential denitrification and the total N removal rates varied spatially in these 11 rivers, with the highest rates occurring in the western rivers of the region, while the mean potential anammox rates and ra% displayed the opposite trend with the highest values occurring in the southern rivers of the region. The contents of nitrate and dissolved organic carbon in sediments appeared to be the primary controlling factors for denitrification and anammox in these studied rivers. Our results indicated that the potential rates of N removal varied spatially, and denitrification is the dominant activity for removing fixed N but the role of anammox is not negligible in freshwater rivers.

Simultaneous nitrification-denitrification process in extended aeration plants: pilot and real scale experiences

1997 ◽  
Vol 35 (6) ◽  
pp. 53-61 ◽  
Author(s):  
G. Bertanza
Keyword(s):  
Waste Water ◽  
Waste Water Treatment ◽  
Electric Energy ◽  
Pilot Scale ◽  
Low Oxygen ◽  
Total N ◽  
Electric Energy Consumption ◽  
N Removal ◽  
Removal Efficiencies ◽  
Denitrification Process

This work deals with the study of technologies aimed to upgrade the existing waste water treatment plants, paying attention to high process efficiencies and low costs. We verified the possibility to reach high N removal efficiencies in extended aeration activated sludge plants which are not equipped with specific denitrification steps. The experimented process is based on particular conditions, kept in the biological reactor, which allow simultaneous nitrification and denitrification, even without alternating (in time or in space) of anoxic and aerobic phases: aeration system is controlled by means of dissolved oxygen and redox potential measurements. Our research was carried out, for about three years, on a laboratory plant (V = 40 L) fed with synthetic waste water, a pilot scale plant (V = 1,400 L) fed with waste water coming from a real plant, and two full-scale plants (1,500-2,000 p.e.). The main advantages of the studied process are the following: high total N removal efficiencies (up to 90%) without the realization of new specific basins for the denitrification process; decreasing of operating costs (savings in Electric Energy consumption) due to the low oxygen concentration required in the biological reactor.

scholarly journals Nitrogen Removal by Sulfur-Based Carriers in a Membrane Bioreactor (MBR)

Membranes ◽  
2018 ◽  
Vol 8 (4) ◽  
pp. 115 ◽  
Author(s):  
Thi-Kim-Quyen Vo ◽  
Jeong-Jun Lee ◽  
Joon-Seok Kang ◽  
Seogyeong Park ◽  
Han-Seung Kim
Keyword(s):  
Removal Efficiency ◽  
Total Phosphorus ◽  
Nitrogen Removal ◽  
Membrane Bioreactor ◽  
Oxygen Demand ◽  
Autotrophic Denitrification ◽  
Nitrogen Gas ◽  
Sulfate Ions ◽  
Major Disadvantage ◽  
Bioreactor System

Sulfur-based carriers were examined to enhance the nitrogen removal efficiency in a mixed anoxic–anaerobic-membrane bioreactor system, in which sulfur from the carrier acts as an electron donor for the conversion of nitrate to nitrogen gas through the autotrophic denitrification process. A total nitrogen removal efficiency of 63% was observed in the system with carriers, which showed an increase in the removal efficiency of around 20%, compared to the system without carriers. The results also indicated that the carriers had no adverse effect on biological treatment for the organic matter and total phosphorus. The removal efficiencies for chemical oxygen demand (COD) and total phosphorus (TP) were 98% and 37% in both systems, respectively. The generation of sulfate ions was a major disadvantage of using sulfur-based carriers, and resulted in pH drop. The ratio of sulfate in the effluent to nitrate removed in the system ranged from 0.86 to 1.97 mgSO42−/mgNO3−-N, which was lower than the theoretical value and could be regarded as due to the occurrence of simultaneous heterotrophic and autotrophic denitrification.

Injuries to the Coronoid Process of the Ulna with Involvement of the Lesser Sigmoid Notch

2020 ◽  
Author(s):  
Valentin Rausch ◽  
Sina Neugebauer ◽  
Tim Leschinger ◽  
Lars Müller ◽  
Kilian Wegmann ◽  
...  
Keyword(s):  
Fragment Size ◽  
Coronoid Process ◽  
Annular Ligament ◽  
Concomitant Injuries ◽  
Proximal Ulna ◽  
Sigmoid Notch ◽  
Coronoid Fractures ◽  
The Mean ◽  
The Stability ◽  
Arthritic Changes

Abstract Introduction This study aimed to describe the involvement of the lesser sigmoid notch in fractures to the coronoid process. We hypothesized that injuries to the lateral aspect of the coronoid process regularly involve the annular ligament insertion at the anterior lesser sigmoid notch. Material and Methods Patients treated for a coronoid process fracture at our institution between 06/2011 and 07/2018 were included. We excluded patients < 18 years, patients with arthritic changes or previous operative treatment to the elbow, and patients with concomitant injuries to the proximal ulna. In patients with involvement of the lesser sigmoid notch, the coronoid height and fragment size (anteroposterior, mediolateral, and craniocaudal) were measured. Results Seventy-two patients (mean age: 47 years ± 17.6) could be included in the study. Twenty-one patients (29.2%) had a fracture involving the lateral sigmoid notch. The mean anteroposterior fragment length was 7 ± 1.6 mm. The fragment affected a mean of 43 ± 10.8% of the coronoid height. The mean mediolateral size of the fragment was 10 ± 5.0 mm, and the mean cranio-caudal size was 7 ± 2.7 mm. Conclusion Coronoid fractures regularly include the lesser sigmoid notch. These injuries possibly affect the anterior annular ligament insertion which is important for the stability of the proximal radioulnar joint and varus stability of the elbow.

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