scholarly journals The Sensitivity of a Specific Denitrification Rate under the Dissolved Oxygen Pressure

2020 ◽  
Vol 17 (24) ◽  
pp. 9366
Author(s):  
Massimo Raboni ◽  
Paolo Viotti ◽  
Elena Cristina Rada ◽  
Fabio Conti ◽  
Maria Rosaria Boni
Keyword(s):  
Sensitivity Analysis ◽  
Dissolved Oxygen ◽  
Scientific Literature ◽  
Full Scale ◽  
Denitrification Rate ◽  
The Third ◽  
Small Influence ◽  
Denitrification Reactor ◽  
Activated Sludge Processes ◽  
Denitrification Process

The biological denitrification process is extensively discussed in scientific literature. The process requires anoxic conditions, but the influence of residual dissolved oxygen (DO) on the efficiency is not yet adequately documented. The present research aims to fill this gap by highlighting the effects of DO on the specific denitrification rate (SDNR) and consequently on the efficiency of the process. SDNR at a temperature of 20 °C (SDNR20°C) is the parameter normally used for the sizing of the denitrification reactor in biological-activated sludge processes. A sensitivity analysis of SNDR20°C to DO variations is developed. For this purpose, two of the main empirical models illustrated in the scientific literature are taken into consideration, with the addition of a deterministic third model proposed by the authors and validated by recent experimentations on several full-scale plants. In the first two models, SDNR20°C is expressed as a function of the only variable food:microrganism ratio in denitrification (F:MDEN), while in the third one, the dependence on DO is made explicit. The sensitivity analysis highlights all the significant dependence of SDNR20°C on DO characterized by a logarithmic decrease with a very pronounced gradient in correspondence with low DO concentrations. Moreover, the analysis demonstrates the relatively small influence of F:MDEN on the SDNR20°C and on the correlation between SDNR20°C and DO. The results confirm the great importance of minimizing DO and limiting, as much as possible, the transport of oxygen in the denitrification reactor through the incoming flows and mainly the mixed liquor recycle. Solutions to achieve this result in full-scale plants are reported.

scholarly journals The role of food/microorganism ratio in denitrification reactors: how it affects the sizing and operation of the denitrification process

2021 ◽  
Vol 16 (1) ◽  
pp. 1
Author(s):  
Renato Gavasci ◽  
Francesco Lombardi ◽  
Massimo Raboni
Keyword(s):  
Dissolved Oxygen ◽  
Linear Dependence ◽  
Narrow Range ◽  
Sewage Treatment ◽  
Denitrification Rate ◽  
Sewage Treatment Plants ◽  
First Approximation ◽  
Denitrification Reactor ◽  
Denitrification Process

Two calculation models of the Specific Denitrification Rate (SDNR) are analyzed to highlight the sensitivity of this parameter to the Food:Microorganisms ratio in the denitrification reactor (F:MDEN). One of these models is empirical while the second was elaborated on a deterministic basis. Both models reveal a linear dependence of SDNR20°C on F:MDEN and in a first approximation they are comparable only in a narrow range of concentration of dissolved oxygen (DO) in denitrification, specifically DO=0.25-0.35 mg L-1. These values frequently occur in well designed and well operated sewage treatment plants. Outside this range, the role of F:MDEN must necessarily be examined in combination with DO because of the relevant influence of the latter on the efficiency of the denitrification process.

Samuel the Third in the Midst of the Hebrew Creative Activity towards the End of the First Millennium in Eretz Israel

Ginzei Qedem ◽  
2020 ◽  
Author(s):  
Joseph Yahalom
Keyword(s):  
General Public ◽  
Critical Edition ◽  
Full Scale ◽  
Creative Activity ◽  
The Third ◽  
First Millennium

The article serves as a supplement to a recent critical edition: The Yotserot of R. Samuel the Third: A Leading Figure in Jerusalem of the 10th Century (Joseph Yahalom and Naoya Katsumata eds., Yad Izhak Ben-Zvi, Jerusalem 2014, 1139 pp.). The article includes some new texts in the genre of the author's well-known activity in the field of Yotserot as well as a fragment in the genre of the Azharot. The article deals by way of introduction to the full scale of activity in establishing the newly full-fledged Yotserot genre which was introduced mainly in the middle of the century by Sa‛adia Gaon. In so doing he was able to produce two entirely new sets of Yotserot according to his well-known habits of creating parallel literary oeuvre, one for the general public and one for the elite. In a totally different capacity the article deals with a special liturgical technique established by Samuel to be used in his Ahavot and for his Meʼorot. He basically described his wretched nation as a special two-part construct state embodying a plethora of information and a whole world of sympathy.

Upgrading Wastewater Treatment Plants with Anaerobic Selectors

1990 ◽  
Vol 22 (7-8) ◽  
pp. 35-43
Author(s):  
K. D. Tracy ◽  
S. N. Hong
Keyword(s):  
Phosphorus Removal ◽  
Wastewater Treatment Plants ◽  
Full Scale ◽  
High Rate ◽  
Nitrogen Control ◽  
Biological Phosphorus Removal ◽  
Conventional Activated Sludge ◽  
And Performance ◽  
Activated Sludge Processes ◽  
Biological Phosphorus

The anaerobic selector of the A/0™ process offers many advantages over conventional activated sludge processes with respect to process performance and operational stability. This high-rate, single-sludge process has been successfully demonstrated in full-scale operations for biological phosphorus removal and total nitrogen control in addition to BOD and TSS removal. This process can be easily utilized in upgrading existing treatment plants to meet stringent discharge limitations and to provide capacity expansion. Upgrades of two full-scale installations are described and performance data from the two facilities are presented.

Experiment of Polyester Wastewater Treatment by Aerobic Membrane Bioreactor and an Engineering Application

2012 ◽  
Vol 518-523 ◽  
pp. 2130-2137
Author(s):  
Si Hao Lv ◽  
Hui Chang ◽  
Zhi Hui Liang ◽  
Yan Yan Zeng ◽  
Hong Bo Fan
Keyword(s):  
Water Quality ◽  
Pilot Study ◽  
Membrane Bioreactor ◽  
Suspended Solids ◽  
Loading Rate ◽  
Engineering Application ◽  
Full Scale ◽  
Effluent Water ◽  
Small Influence ◽  
Volumetric Loading

A pilot study was carried out to evaluate the application of aerobic submerged MBR in treating polyester wastewater and a full scale system in which MBR was adopted as the key aspect was put forward to treat the polyester wastewater of Zhuhai Yuhua Polyester co., Ltd., China. The pilot study revealed that HRT could be affected by the influent COD, and a HRT larger than 36h was proposed for treating polyester wastewater by MBR. Volumetric loading rate and sludge loading rate ranged in 0.7-2.0 kgCOD/m3•d and 0.09~0.24 kgCOD/ kgMLSS•d respectively were of small influence on the COD removal. DO in the range of 2.5-4.0 mg/L seemed to be optimal for avoiding limitations due to oxygen concentration and creating an effective turbulence. The modified full scale system which includes anaerobic digesting tank and MBR followed by a stabilization pond was verified to be effective to treat the polyester wastewater in the latest two years. The results illustrated that the effluent water quality could meet the discharge limits of water pollutants (DB 44/26-2001) which was established in Guangdong, China. Observed sludge yield of the system fluctuated between 0.10-0.18 gMLSS/gCOD and averaged at 0.137 gMLSS/gCOD. The membrane permeate at around 10 L/m2h, TMP of less than 0.7bar, and total mixed liquor suspended solids (MLSS) between 6-7g/L were suitable to operate the MBR.

Screening and Characterization of a Bacterium Capable of Simultaneous Heterotrophic Nitrification and Aerobic Denitrification at High Concentrations of Ammonia-Nitrogen

2014 ◽  
Vol 665 ◽  
pp. 487-490
Author(s):  
Te Wang ◽  
Zhao Xia Liu ◽  
Mei Juan Wu ◽  
Fu Hui Kang ◽  
Qing Chen ◽  
...  
Keyword(s):  
16S Rdna ◽  
Ammonia Nitrogen ◽  
Heterotrophic Nitrification ◽  
Denitrification Rate ◽  
Aerobic Denitrification ◽  
Optimal Conditions ◽  
Carbon And Nitrogen ◽  
Mass Ratios ◽  
High Concentrations ◽  
Denitrification Process

A bacterium capable of simultaneous heterotrophic nitrification and aerobic denitrification at high concentrations of ammonia-nitrogen was screened and identified and the denitrification property was investigated in this paper. The strain was isolated from aeration tank of wastewater disposed by activated sludge and analyzed and identified by 16S rDNA. The effects of different carbon sources and carbon and nitrogen mass ratios on denitrification rate were studied. The changes of various forms of ammonia-nitrogens during the simultaneous heterotrophic nitrification and aerobic denitrification process were characterized. A strain capable of simultaneous heterotrophic nitrification and aerobic denitrification at 600 mg/L nitrogen concentration has been isolated and screened. Comparison of its 16S rDNA sequence showed 100% similarity to Bacillus licheniformis strain Lr124/6. The strain was named as Bacillus sp. A22. The optimal conditions for degradation of ammonia-nitrogen by Bacillus sp. A22 were trisodium citrate as carbon source and carbon and nitrogen mass ratios of 10. The denitrification rate was 98.2% after 96 h of culture under the optimal conditions and there was hardly any intermediates accumulation in the denitrification process. It has practical applications that the denitrification can be performed efficiently at high concentrations of ammonia-nitrogen by method of simultaneous heterotrophic nitrification and aerobic denitrification by Bacillus sp. A22 in nitrogen purification treatment of wastewater with high concentrations of ammonia-nitrogen.

scholarly journals Review: Peluang Pengembangan Imbuhan Pakan Fitogenik Sebagai Pengganti Antibiotika dalam Ransum Ayam Pedaging di Indonesia

2019 ◽  
Vol 6 (2) ◽  
pp. 188
Author(s):  
Cecep Hidayat ◽  
Rahman Rahman
Keyword(s):  
Broiler Chicken ◽  
Scientific Literature ◽  
Feed Additives ◽  
Feed Additive ◽  
Growth Promoter ◽  
Literature Study ◽  
The Third ◽  
Feed Industry ◽  
Broiler Diet ◽  
Main Support

ABSTRAK                                                            Seiring dengan telah dilarangnya penggunaan antibiotic growth promotor (AGP) dalam pakan oleh pemerintah Indonesia, maka pencarian pengganti AGP mejadi penting saat ini. Imbuhan pakan fitogenik menjadi salah satu pengganti AGP potensial. Makalah ini ditulis untuk mengungkap peluang pengembangan imbuhan pakan fitogenik sebagai pengganti AGP dalam ransum ayam pedaging di Indonesia. Metode penulisan makalah dilakukan dengan beberapa tahapan. Tahapan pertama, tahap persiapan, dilakukan dengan mengumpulkan dan membaca jurnal, makalah prosiding, buku yang diperoleh dari hasil dari pencarian  pada internet. Dilanjutkan dengan memilih dan menentukan jurnal hasil penelitian, makalah ilmiah pada prosiding, buku terkait dengan topik yang sudah ditentukan. Tahapan ke dua, penyusunan outline makalah yang akan ditulis, dimana pada tahapan ini untuk menentukan skema berfikir penulis terkait dengan topik yang akan di bahas. Tahapan ke tiga, mengembangkan kerangka makalah dengan menggunakan literatur ilmiah, teori, hasil penelitian yang sudah diperoleh. Tahapan ke empat, pemeriksaan terhadap isi makalah yang sudah ditulis, baik secara substansi maupun redaksional. Berdasarkan studi pustaka yang dilakukan disimpulkan bahwa imbuhan pakan fitogenik dari berbagai jenis tanaman potensial digunakan sebagai pengganti AGP dalam pakan ayam pedaging. Kebutuhan akan daging ayam nasional yang semakin tinggi setiap tahunnya, menjadi peluang betapa besarnya pasar akan kebutuhan pengganti AGP di Indonesia. Sinergisme antara lembaga penelitian-perguruan tinggi dengan pelaku industri pakan dan imbuhan pakan menjadi penopang utama dalam pengembangan imbuhan pakan fitogenik di Indonesia.Kata Kunci: imbuhan pakan fitogenik, ayam pedagingABSTRACTKeywords: pytogenic feed additive, broiler chicken The use of antibiotic growth promoter (AGP) in feed has been banned by the Indonesian government. Therefore, the search for alternative AGP continues to be carried out. The addition of phytogenic is one of the potential alternatives because it has the same ability as AGP. This paper was written to reveal the opportunities for developing phytogenic feed additives as a substitute for antibiotics in broiler diet in Indonesia. The method of writing this paper was done in several stages. The first stage, the preparation, is done by searching and reading journals, proceedings, books obtained from the internet. The second method is the preparation of the outline of the paper to be written, to determine the author's thinking scheme related to the topic to be discussed. The third method is developing a framework of thought by using scientific literature obtained and read before. Fourth method is examination of the contents of papers that have been written, both substantially and editorially. Based on the literature study, it was concluded that the phytogenic feed additives from various types of plants should be considered as a substitute for AGP in broiler diet.  The need for national chicken meat which is getting higher every year becomes an opportunity for how big the market will be for AGP's replacement in Indonesia. Synergism between university-research institutions and feed industry is the main support in developing phytogenic feed additives in Indonesia.Keywords: pytogenic feed additive, broiler chicken

scholarly journals Study on Sludge and Dissolved Oxygen Distribution in a Full-Scale A2/O Oxidation Ditch

Water ◽  
2021 ◽  
Vol 13 (19) ◽  
pp. 2776
Author(s):  
Chengyi Li ◽  
Zhao Han ◽  
Yuquan Zhang ◽  
Yuan Zheng ◽  
Hepeng Zhang ◽  
...  
Keyword(s):  
Dissolved Oxygen ◽  
Flow Model ◽  
Rotation Speed ◽  
Full Scale ◽  
Oxidation Ditch ◽  
Bed Height ◽  
Consumption Rates ◽  
The Relationship ◽  
Oxygenation Rate ◽  
Biological Selection

The distribution of velocity, sludge, and dissolved oxygen in a full-scale anaerobic-anoxic-oxic (A2/O) oxidation ditch was numerically simulated under three rotation speed scenarios. The viscosity and settling rate of activated sludge were defined through a user-defined function (UDF), and the sludge phase was calculated using the mixture multiphase flow model. Dissolved oxygen (DO) was set as a user-defined source (UDS) and its generation and consumption rates were defined with UDFs. The relationship between velocity and sludge concentration was found to be contradictory, with dead zones leading to large sludge concentrations at the bottom of the oxidation ditch (OD), but not at the middle-curved wall of the anoxic pool. The flow rate of the reflux slot and aerator oxygenation rate were checked and correlated with DO concentrations in the anaerobic pool. The majority of the large sludge concentrations were concentrated in the biological selection pool and these remained constant with bed height. With reduced propeller and agitator rotation speed, the sludge concentrations reduced in the biological selection pool, but increased in the anaerobic and anoxic pools.

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