Science topic

Nitrification - Science topic

A process facilitated by specialized bacteria involving the oxidation of ammonium to nitrite and nitrate.
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I have recently been studying a book entitled "EXPERIMENTAL METHODS IN WASTEWATER TREATMENT", published by Prof. Gürkan Sin and Prof. Krist V. Gernaey, in which Chapter 5 (DATA HANDLING AND PARAMETER ESTIMATION) is an introduction to methods for parameter estimation and uncertainty analysis of water treatment models. However, in the process of learning, it was difficult for me to understand the operation of the specific methods from the book. I would like to have the complete MATLAB code for Example 5.3 (parameter estimation for nitrification process) (this is a TU DELFT web course). Finally, I attach the content URL:https://experimentalmethods.org/courses/data-handling-and-parameter-estimation/
I would be very grateful if you could provide information about this or the complete MATLAB code.
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Did you sign up for the course? It looks as if you have to do that to get the data for the exercise, and then you demonstrate that you use the code pointers to solve the problem, and finally discuss how you did with the tutors, and get a better code set if necessary.
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Biodenitrification was performed using Thiobacillus denitrificans in the presence of nanostructures.
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Continuous denitrification is definitely the better way than the discontinuous system. The following article might help you on this aspect:
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Basal Salt Medium culture medium was used to study the denitrification process of Thiobacillus denitrificans ATCC 23644. In this medium, potassium nitrate was added to the medium as the only source of nitrate. To create anaerobic conditions, 4 ml of bacterial suspension was added to 40 ml vials containing 36 ml of BSM medium. The flasks were heated in an incubator (30 ° C) for 24-48 hours. To investigate the nitrification process, microorganisms were inoculated in BSM medium with a concentration of 300 mg / L nitrate. Sampling was performed with an interval of 6 hours and the vials containing microorganisms were centrifuged for 20 minutes at 5000 rpm. After centrifuge, the samples were passed through filter paper and the optical absorption of soluble nitrate at 410 nm was read using a spectrophotometer and the concentration of soluble nitrate would be obtained.
Now I want to measure the growth of microorganisms by spectrophotometer at the same time as measuring nitrate, in other words, I want to conclude that as the growth of microorganisms increases, nitrate in the culture medium decreases. How should I measure the growth of a microorganism? What wavelength should I use? Is a half McFarland concentration of microorganisms necessary?
If you can help me to complete this method, I am very grateful.
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you can measure Optical density
at 600nm.
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I am culturing N. europaea ATCC25978 in minimal media with phenol red pH indicator, wrapped in foil at 30degC. I supplement the media with more sodium carbonate when the media turns yellow/acidifies. I usually sub culture once every two weeks (or when the culture stops turning yellow within 2 days after adding more carbonate), or start a new culture from a frozen stock (stored at -80degC in 5% DMSO). This was working just fine for about a year, and then suddenly, the cultures became non-viable. Even the frozen stocks would not grow again. I waited 9 weeks for a sign of viability - nada.
I had re-ordered the strain from the culture collection, and it looks like I may have lost viability after only two sub-cultures. I assess viability by the media acidifying, and confirm by measuring nitrite production. Are these cultures dead? Inactive? What could I do to revive/reactivate these cultures? And what could have happened that suddenly killed them off?
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Many thanks, V.J Rejish Kumar and Yaw Akosah, for your replies. I tried your suggestions, but my cultures were still nonviable. However, I was able to solve the problem eventually, and I just thought I'd update in case anyone else comes across this problem: the glassware.
Heterotrophic bacteria had been growing fine throughout this ordeal, but I noticed a footnote on ATCC website stated that Nitrosomonas was sensitive to impurities on glassware. There must have been some impurities (from other users? the washing process?), as I was able to culture Nitrosomonas within a week in sterile, virgin plastic. Now, I rinse each piece of glassware for media and culturing with distilled water several times before use, and I haven't had issues since.
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the soils I am experimenting with is highly sodic (high Na) with a pH of 8.3 to 8.6. When I checked the NH4+ and NO3- concentrations in the soil compared to a reference soil from an unaffected area, NH4+ of the test soil was similar to reference soils at all times; however, NO3- is gradually decreasing. I have two assumptions,
1) Sodicity/alkalinity induce denitrification
2) Sodicity/Alkalinity inhibit nitrification
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Dear Dr Samadhi Gunathunga, see the following useful links:
•Krishnamurthy, S.L., Sharma, P.C., Sharma, D.K. et al. Identification of mega-environments and rice genotypes for general and specific adaptation to saline and alkaline stresses in India. Sci Rep 7, 7968 (2017). https://doi.org/10.1038/s41598-017-08532-7
•Hammerl, V., Kastl, EM., Schloter, M. et al. Influence of rewetting on microbial communities involved in nitrification and denitrification in a grassland soil after a prolonged drought period. Sci Rep 9, 2280 (2019). https://doi.org/10.1038/s41598-018-38147-5
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I have completed an experiment based on the reduction of ammonia in biofloc. There are three treatments and a control. Treatment 1 = 4mg/L of ammonia, Treatment 2 = 8mg/L, Treatment 3 = 12mg/L.
I measured the ammonia content in beakers containing two bioflocs (Seed and Commercial), and monitored the decline of ammonia, as the nitrifying bacteria within turned it to nitrate. I took a water sample on Tuesday when the experiment began, and one every 24 hours (Excluding the weekend) until the following Monday as shown in the image attached.
I want to compare the decrease in ammonia of all treatments for each biofloc in order to see which biofloc is the most efficient when it comes to nitrification. What statistical test could I do to measure the statistical differences?
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Also check on this paper
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Hi all,
I am looking for models like Vollenweider Loading Plots and want to calculate and predict eutrophication in some reservoirs. I have some data about their incoming monthly flows, incoming flows quality, their capacity, and so on.
Could you please introduce me to other models?
Thanks a lot.
Alireza Shahmirnoori
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Personally, I strongly recommend this article which will certainly be useful to you.
Regards
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Hi! I am trying to measure the potential nitrification rate (PNR) using the "shaken soil slurry method", following one from Drury et al. 2008. Because of sample limitation, I scaled down the sample and working solution amount to 6g and 40mL. In the past I tried it without shaking the samples during incubation but of course I got useless results with negative PNR. So I tried using a rotary shaker this time. Here is what I did:
1. After putting the soil sample and working solution (made according to the protocol above) in a 50mL tube, I shook the mixture vigorously.
2. Immediately I took the initial 15mL of the aliquot for t=0.
3. I put the rest of the tube on rotary shaker at 200 rpm for 24 hr incubation (I also transferred couple of samples in 125 mL Erlenmeyer flasks, also shaken, for comparison)
4. I added few drops of flocculent solution (CaCl2 and MaCl2) into the aliquot and it was centrifuged at 3000 rpm for 5 minutes and the supernatant was filtered using filter paper
5. The filtered solution was analyzed in SmartChem for NH4 and NO2+NO3
6. After incubation, 15mL of the incubated sample was processed as 4 and 5.
I know that I should have taken multiple samples along the incubation to do linear regression but I am short on materials. After all this, I compared the results among control (no rotary shaker), 50 mL tube incubation, and 125mL erlenmeyer flask incubation. I was expecting some notable decrease in NH4 and increase in NO3 with the later two, or at least the flask samples. However, I see that NH4 did not decrease consistently (some even increase with incubation) and NO3 content even decreased for one of the flask samples. I am really confused why the results would come out like this. Here are my thoughts:
1. SmartChem measurements are being inaccurate? I do see that the NO3 levels are quite low compared to the standards used in SmartChem. Maybe this is creating some inaccurate measurements?
2. Perhaps rotary shaking falcon tubes is not enough to create aerobic conditions throughout the sample, thus leading to denitrification. However, this does not explain why I saw decreased NO3 with one of the flask samples which should have thoroughly aerobic condition.
And here are my main questions:
1. Why would NH4 levels increase with incubation? My understanding is that the conditions of PNR assay should only decrease NH4 via nitrification and immobilization.
2. Is there a way to salvage PNR results riddled with negative PNR? I think negative PNR occurs due to either insensitive measurements or denitrification and NO3 immobilization during incubation. Is there a way to account for the latter possibility in my data?
Can anyone offer to explain???
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Hi,
First, you should use a bigger bottle, if you incubate 6g in 40ml a 50 ml Bottle is to small and you can´t expect aerobic conditions. I would suggest to use 100 ml Duranbottles.
Second, don´t shake the nitrifiers so much. It is better just to use 100 rpm
Third, the initial NH4 concentration should not be higher than 1mM.
Forth, your incubations should be longer, up to one week. Depending on soil type and temperature.
For you Ammonium, Nitrite and Nitrate measurements: I don´t know the SmartChem method. Maybe you should use the classical photometric ones.
To distinguish between net und gross nitrification, labelling with 15N nitrate is a possible method.
Best,
Tina
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Why the transformation of NH4+ to NO3- by nitrification produces 2 H+, whereas transformation of urea to NO3- by hydrolysis and nitrification produces 1 H+?
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In case of nitrification (oxidative reactions demanding oxygen and aerobic conditions) of ammonium ions, first nitrite will form by nitrosomonas and nitrosococcus aerobes and then to the nitrate by nitrobactor...this nitrate is used by the crop for its metabolic need and assimilations...while in case of nitrification of urea, first urea should be hydrolyzed by adding water molecules yielding ammonium carbonate and then to the ammonium ions..for this urease enzyme play a role..after that, the same process will occur to convert ammonium ions finally to nitrate...This process is just like mineralisation where unavailable form of a fertilizer get changed into available form for plant uptake...
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whether nitrification inhibitor completely restrict the conversion from NH4-N to NO3-N or delay the conversion? if yes, to what extent be it will inhibit?
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The process of conversion of ammonium into nitrates is a two step microbial process , could take time from few hours to few weeks , depending upon soil and associated environmental conditions..
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I am about to start experiments on nitrogen removal by MBBR. I started some trial tests in batch mode to see if biofilms form before the main ones, and I have some questions regarding the operation.
1) First and foremost, water keeps evaporating from the reactor, and I do not know how to prevent this.
2) What is the best inoculum (seed sludge) to substrate ratio to start the experiments?
3) What is the best way to measure the filling ratio?
4) What is the optimum range for DO? I have seen several ranges, and I do not know which is the best.
Any other suggestions and references are welcomed.
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Kasra Pourrostami Niavol , Your first question about the evaporation from the reactor. I am very familiar with this problem. A long time ago I learned to use a air humidifier on the airflow that is used for the reactor.
It is essentially a bottle of water which the airflow is passed through. I have the air entering the bottle from a pipe that goes through the lid and end in the bottom of the bottle. The air make bubbles which take up water vapor and this air i take from the headspace in the top of the bottle with a tube into the reactor I work with. I'll look for a picture of a setup.
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Can somebody advise of a publication that determines the nitrification and denitrification rates of mixed toilet waste (aka feces and urine only) or at least of pure urine in an MBR or CAS?
I am interested in knowing how much ammonium (nitrification) and nitrate (denitrification) nitrogen is removed per unit of time and unit mass of VSS.
Thank you!
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Dear Pompilia,
Please attached find some recent published papers may help you for determination of nitrification-denitrification rates in wastes.
Good luck.
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Hello colleagues,
We are trying to induce a liner consequences reaction of nitrification follows de nitrification processes. The main challenge is the redox potential. we need to reduce it from 250 mv by the nitrification chamber into -50 mv by the anoxic denitrification chamber. We are using a potassium carbonate to reduce the redox potential. Any new ideas how to reduce the redox potential?
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Thank you Dr. Murphy!
I just sent you an e-mail for a discussion.
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Is it a good idea to add a nitrification inhibitor (e.g. dicyandiamide) to a forest soil for a short-term experiment on nitrogen uptake by young trees? The duration of experiment is 3 days. I am wondering if the added N in dicyandiamide will transform and cause an undesirable fertilization effect?
If so, how to determine what quantity of the inhibitor to apply in order not to cause this effect.
Thank you, KM
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Hi Klara Mrak , adding nitrification inhibitors also can reduce the potential of climate change. You also need to consider the type of nitrification inhibitors due to there are some specific inhibitors such as PTIO (specific inhibit AOA) or 1-octyne (specific inhibit AOB) that can inhibit specific ammonia oxidizers. On the other hand, DMPP can also be considered in your experiment since the half-life of DMPP is more than DCD.
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I was reading about hydraulic performances and Nitrogen removal processes in bioretention cells as LID, or BMP practices, and just wondered if there would be advantages (or significant negative impacts) if a gravel layer is put on top of the media layer.
There are some aspects that I think of. Any discussions are welcome.
When putting gravel storage layer on top:
(a) we have similar water storage capacity. If we install drainage pipes or orifices in storage layers, we can better prevent overflow (runoff peak goes: gravel layer--discharge vs media layer--gravel layer--discharge)
(b) worry less about groundwater mounds, groundwater intrusion or draining too much groundwater, because the media layers have wetting-drying curves more similar to the original soil
(c) probably can be easier maintained. Consider: sedimentation happen primarily in gravel layer, and the next rain event can flush the large pores
(d) DO drops before water enters soil layer, thus soil media can be more efficient for denitrification per depth
(e) In addition, do denitrification bacteria has higher activity, because the soil layer is adjacent to original soil? Can ammonification and nitrification happen in gravel layer or the interface, and provide higher nitrate concentration to enhance denitrification?
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Our team studied the use of engineered media used in a bioretention tree system to treat stormwater runoff from roof catchments. In this study, there was gravel on top and below the filter media. the key purpose of these gravels was for different functions. The top layer was to disburse the water flow (which was flowing from a higher elevation, the adjacent classroom blocks). Whereas the gravel below is to prevent the soil particles/ smaller grains of particles from coming out of the retention tree system. The key novelty of the system is the self-containment and the relatively small footprint. Hence the control of the soil/ small particulates being washed out is crucial.
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I have been working with melon TSS% level in Bangaldesh for four years. Here melon become very low in brix in soil plantation. I ahve tried many ways to improve ssc%. We do not have nitrate fertilizers available here. We have to use urea or DAP as a source of nitrogen. I believe, if I can use nitrates, it might change the result! This is why i am interested in making organic liquid fertilizers rich in nitrates. I am making mustard cake liquid fertilizer as well as fish fertilizer.Can I add nitrifying bacteria culture to the drums of those fertilizers to increase N?
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Yesterday, I attented in a seminer on the use of vermicompost and cowdung. The results showed that vermicompost was better both in rice field and vegetable crops.
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What is the hydraulic retention time HRT and Sludge retention time?
can you give example in nitrification process
thank u
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Biofloc culture is recent promising and sustainable technology for shrimp/fish production. Using nitrification process converting waste as productive nutrients with zero water exchange.
Is it possible, biofloc culture in earthen ponds?
Is it possible, without using HDPE sheets or cement tanks?
Vertical aeration (without disturbing soil) in earthen ponds and what is the sludge impact on earthen ponds?
Is it possible to zero water exchange in earthen ponds?
Diseases?
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Hi
Thank you very much for this nice question. Obviously, BFT system can be conducted in earthen pond and concrete pond based system. I had found some papers on BFT, which were conducted in earten pond or concrete pond.There were some species such as tilapia, filter feeder carps and giant river prawn cultured in Bangladesh, China and Brazil or Mexico. Please find this paper from e-resources sources. The pond based BFT having enormous prospects in tropical and subtropical regions, but management will be be different than indoor system.
Best regards and thank you.
Md Eilious Hosain
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I have a heterogeneous culture of nitrifying bacteria that was originally isolated from the field.
It has been kept alive for several months in a bioreactor.
I want to pull some of this bacteria out of the bioreactor and put it in a fridge for several months to examine later and possibly use it to re-seed a different bioreactor.
What would be the best way to preserve a heterogeneous culture of nitrifying bacteria?
(As a note, this culture contains ammonia oxidizing, nitrite oxidizing, AND heterotrophic bacteria)
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Lin Jyh-Yan Thankyou
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Hello everyone,
In my experiment, I find that N2O emission rates from long-term warmed soils (+2.5 °C; 10 years) do not change during a four-week drought compared to pre-drought level. In control soils (no warming) emission rates decline almost 100%. I am thinking that the long-term warmed soils are better aerated due to intesified dryout dynamics after each wetting and thus soil disaggregation. I get that this may pronounce waterlogging in rewetted soils after drought and influence denitrification. But how does this look like at drought conditions? Which shift on organismal or functional level (within nitrification?) can serve as an explanation for mny observations?
I appreciate any suggestions,
best regards!
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The effects of simulated climate change on N2O emissions and the related functional genes were much more significant in phase II than in phase I in the urea treatments, mainly because of the adaption and growth of the microbial communities following urea application under the simulated conditions. The simulated warmer and drier conditions under the greenhouse gases following urea application significantly increased N2O emissions due to reduced N losses by leaching and enhanced microbial growth. Both AOB and AOA were shown to be able to grow following urea application in phase II following some exposure to urea-N in this strongly acidic soil. The simulated climate change conditions in phase II also changed the composition of AOAwith the species affiliated to marine group 1.1a-associated lineage increasing significantly. The simulated climate change decreased the abundance of all the functional denitrifier genes and the legacy effect stimulated the abundance of nirK and nosZ gene in urea-treated soil. In general, the effect of the simulated climate change was shortlived, with the denitrifier communities being able to recover once exposed to ambient conditions. As plants, which were excluded in our study, can also have significant effects on N2O emissions and related microorganisms, it would be interesting to conduct further studies where there is the presence of plants.
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Diazotrophs 'fix' atmospheric nitrogen into biologically available forms. In very general, non-technical terms, an over-abundance of these organic nitrogen forms within a soil beyond what biota in the soil metabolically require has been suggested to result in the increase of nitric acid in the soil. What I would be very interested in is if anyone has done work to help establish a rate of nitric acid production in response to this over abundance of organic nitrogen.
Cheers!
Eron
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I think yes...please do experiment
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I am going to add carbon source as sodium acetate and Nitrogen source as ammonium sulfate in basal media for nitrification experiments.
I would like to estimate carbon/nitrogen ratio in basal media.
I need a method to estimate carbon nitrogen ratio in basal media.
I am finding most of references towards soil carbon nitrogen ratio estimation.
Kindly please provide any reference with reference to carbon nitrogen ratio estimation in liquid media.
Thank you
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Tuning of the Carbon-to-Nitrogen Ratio for the ... - MDPI
www.mdpi.com › pdf
PDFNov 10, 2017 - C/N ratio in E. coli fermentations has further been demonstrated for heterologous gene expression [30] ... Batch fermentations in minimal medium were performed in ... Figure 3. The fermentation profiles with different C/N ratios during growth in bioreactors with. Figure 3 ... Licensee MDPI, Basel, Switzerland.by M Ginésy - ‎2017
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I want to identify ammonia and nitrite-oxidizing gene or enzyme by phototrophs
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Nitrite-oxidizing bacteria are a small group of primarily organo and/or chemoautotrophs that are difficult to grow and work with. For many years they drew very little attention, although it was realized that they provide a key link in the global nitrogen cycle between the ammonia-oxidizing bacteria, which generate nitrite, and the various denitrifying microorganisms that remove nitrate by reducing it to ammonia or molecular nitrogen, thus completing the global nitrogen cycle
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Hello every one,
My master's thesis focuses on the development of a decentralized wastewater treatment method with the purpose of irrigation reuse in a town in India. Based on my research, there is no guideline for irrigation reuse in India. I tried to use international guidelines like USEPA, WHO or EU. All of these guidelines have a focus on human leath risk and the requirments for pathogen removal and BOD are mentioned in them. But they did not mention the required amount of nitrification and denitrification in treatment process. O could not find any limitation for nitrate and ammonia or TN concentration in final effluent. However, I think becuse of ground water pollution risk, there should be a limitation. Otherwise, the nitrate can infiltrate into groundwater. Is there any one who could help me. I really appreciate it.
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With this article on the links below, you will find what you are looking for.
Saudi wastewater reuse standards for agricultural irrigation: Riyadh treatment plants effluent compliance
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Rhizosphere microorganisms are the main drivers of turnover of organic C, N, and P and thus recycling of organically bound nutrients, for example by ammonification and nitrification, but may also increase N loss via denitrification.
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@ Bayu, Nitrates are the preferred nitrogen source under any situation except water logging conditions. Unlike ammonium, nitrate is non-volatile, so there is no need to incorporate it in the soil when applied by top- or side dressing, which makes it a convenient source for application.Nitrate is mobile in the soil , direct uptake by the plant and have highest efficiency. Plants can use ammonia as a nitrogen source. ... Plants absorb ammonium and nitrate during the assimilation process, after which they are converted into nitrogen-containing organic molecules, such as amino acids and DNA. When the plant takes up ammonium (NH4+), it releases a proton (H+) to the soil solution. Increase of protons concentration around the roots, decreases the pH around the roots. Accordingly, when the plant takes up nitrate (NO3-) it releases bicarbonate (HCO3-), which increases the pH around the roots.
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Respected Researcher,
I want to know about the personal experiences of those who are dealing with Anaerobic Digestion with a focus on "Biogas production".
1: How can we increase the Biogas production from the anaerobic membrane Bioreactors having "Synthetic Wastewater" as feed. The initial COD conc. of the Synthetic Wastewater is around 200 mg/L.
2: What could be a few possible factors overcoming/decreasing Biogas production from those AnMBRs?
Any examples, personal experiences, detailed descriptions/opinions are mostly welcome.
Best,
S.S.A. Shah
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Hi Prem - please reach out to me at jcleary@geosyntec.com and I can advise you from my experience doing projects with organics and food waste. Joe
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Kindly provide detailed reactions involved in heterotrophic nitrification and aerobic denitrification and how to calculate the gibbs energy of these process
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This software will calculate the GFE for you. It comes with a gas and aqueous database. http://dudleybenton.altervista.org/software/CREST614.zip The software is described in this book https://www.amazon.com/dp/B07SLBZJK3, which is free tomorrow (1/4/2020).
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Hi all,
I'm trying to run an incubation experiment to verify the nitrification rate in the water column using Tedlar bags. The problem is that I need to take all the air bubbles out from each bag. The method that I'm using introduces some air (hose or peristaltic pump). Two problems arose from this: too many handling (some bags leaked); time-consuming processing.
It would be great to know if someone has another approach to avoid these major problems.
Experiment design:
a) Take water samples from 3 depths and put them into the bags (triplicate).
b) injection of NH4 isotope
c) take the first sample (nutrients, 15NO2, 15NO3) immediately after the injection
d) take the second sample after 3 hours of incubation.
Thank you in advance
Regards
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The method will certainly add air, even if the tedlar bags are evacuated flat before use. Please advise what volume you will need for each sample and allow for duplicates and QC samples. I would think maybe purge the fill line before sampling and be careful about bubbles entering the sample cell or container. You may want to try enclosed samples of PVC or other pipe with valves on each end so you can purge the air out of the sampler with the fill line purging water and then close both valves to capture the sample. Consider making the ends removable for cleaning. Good luck with your project.
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Low soil pH is thought to inhibit or reduce nitrification, however, in some instances, nitrification still occurs after lowering soil pH. Why? Could be due to the inherent nitrifier population which is already present in the whole soil systme and continues to survive even after soil acidification.
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Neither high pH nor low pH is required for rapid multiplication of nitrifying bacteria...optimum pH for efficient proliferation of these autotrophic bacteria comes in between neutral range 6.5 to 7.5 or upto 8 also...however certain spp have been identify which shows tolerance against salt also...
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Current, I am simulating the OPR for irreversible biochemical reactions. The reactions mainly include the processes of nitrification, denitrification, carbon oxidized by oxygen and so on. I noticed that lots of reference use Nernst Equation to solve the ORP, but I tired this method for about half a month and still do not get the results that are well matched with the experimental data.
It is also said that Nernst Equation is only suitable for equilibrium reactions. Does someone who familiar with the ORP calculation can provide some advices and recommend a method for irreversible kinetic reactions. If Butler-Volmer equation is suitable for my situation?
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Yes you can use“Butler-Volmer equation”. Here we argue that the Butler-Volmer equation is unsuited to PEMFC kinetics and offers no advantages over simpler empirical approaches
Redox potential is measured in volts (V), or millivolts (mV). Each species has its own intrinsic redox potential; for example, the more positive the reduction potential (reduction potential is more often used due to general formalism in electrochemistry), the greater the species' affinity for electrons and tendency to be reduced. ORP can reflect the antimicrobial potential of the water.
Empirical models, linear reversible kinetics for irreversible kinetics for the oxygen reduction reaction (ORR), avoiding superfluous parameterization in the Butler-Volmer equation. Reduction of empiricism requires more mechanistically detailed models than the Butler-Volmer equation. You can emphasize that incorrectly formulated kinetic equations risk generating incorrect data or misleading conclusions.
Mathematically, by “Butler-Volmer equation” we mean:
i=i0(exp(βfη)−exp(−αfη))
η=E−Eeq
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Hi, everyone, now I have a question about the efficiency of denitrification and nitrification in N2O production. do you know is there paper or data that talk about this question?
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thank you
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I have tried to isolate ammonifying and nitrifying bacteria from soil sample in an ammonia broth. Qualitative test to show the presence of both types of bacteria can be done by using Nessler and Trommsdrof reagent. But I just couldn't find the formula and preparation step for the reagents.
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You can refer to this document
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Hi everyone
It is well-know that most of soil N2O emissions come from N-fertilization. Leguminose perennial crops such as Medicago sativa can reduce N2O emissions, but how?
I understand that such crops do not require any N-fertilizaion (Thus, we have an indirect reduction of emission) and consuidering a life-span of 3-5 years with no soil tillage we reduce the soil areation.
Moreover leguminose are N-Fixing crops since they perfom a symbiotic fixation of atmospheric N2.
But, the things that is still not clear to are:
1) Such N2 wich is fixed by Medicago sativa is it also an intermediate of denitrifcation/nitrification and other soil process? Or is it just the one which is present in the atmosphere?
2) If the answear to the prvious one is positive, can I say that Medicago sativa reduces N2O emission by the fixation of N2 (the intermediate of denitrification/nitrification etc.)?
3) Apart from the atmospheric N2 fixed by Medicago sativa, does this plant catchs some other N from the soil via roots?
Thank you
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Please check the following RG link and PDF attachment.
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Hello,
I wish to measure the nitrification in soils, to do so I put 10g of dry soil in a plastic jar. I need to add (NH4)2SO4 solution at 100mg NH4-N Kg-1 and set the soil moisture to 60% WHC. How could I have the desired concentration ?
Thanks in advance
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You will have to prepare a solution by dissolving 1.556 g of ammonum sulfate (dried because its higroscopicity) in 1 liter of deionised water. And than when you add 3 mL of this solution you will add both water for setting moisture to 60% WHC and N at level of 100 mg/kg
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oxitop deals with vacuum produced due to CO2 absorption, through nitrification there is no CO2 production, hence no vacuum
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oxitop measures all the oxygen consumed, either by degradation of organic matter or by nitrification. With two samples, one with inhibitor and one without it, you can know the oxygen used in nitrification. Maybe it will be possible perform a kinetic study with other additional tests
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During nitrification process, protons are released, which reduce the soil pH and results in soil acidification. I am interested in knowing at how much depth these protons can travel down the soil profile.
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Following
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Has anyone had any success using DAF FM diacetate, for Nitric Oxide detection, on bacterial or archaeal cells? I am seeing very little literature using this.
If so, are there any specific techniques I should know about for getting it through the cell membrane of various bacterial groups?
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Hello everybody!
For the last 6 months, I run a COD and BOD test once a month for effluent wastewater sample and the result for BOD is always much greater than COD (about 3-4 times higher). Initial D.O value is always accepted, about 9 mg/L. Could this be due to nitrification? I have never added nitrification inhibitor, because total nitrogen isn't much high. What should I do? Thank you!
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Joshua O. Ighalo Thank you, I haven't heard about endogenic respiration before. I will search some info about it. What do you mean when you say to carry a blank with biomass? I always carry a BOD blank with distilled water and the value is less than 0.8 mg/L.
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Should I estimate the oxygen requirement in wastewater treatment (both biological and industrial effluents) based on BOD or COD and what would be the ratio? Also how should I deal with oxygen requirement to nitrification (would it be included in the oxygen requirement based on COD)?
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Well,
COD, is a chemical oxygen requirement and measures the amount of oxygen needed to oxidize organic substances in wastewater and is expressed in mg / l. The test includes all the organic materials that can be oxidized, so the BOD value is smaller than the COD value.
COD testing is used to measure organic matter in industrial waste water containing toxic compounds for biological life. Oxidizing compounds in wastewater are oxidized by reacting with a mixture of sulfuric and chromic acid at high temperature.
COD can only be set within 3 hours when compared to a 5-day BOD. The COD value of wastewater is higher than the BOD value because the compounds can be oxidized chemically and only some can be oxidized biologically. Often, the ratio of chemical oxygen consumed to bio-oxygen consumed is 2: 1.5 in industrial waste water containing biologically degradable substances (such as food industry). For COD / BOD wastewater above 3, the oxidizing substances present in the sample are not biological degradation. Biologically non-degradable substances are called thermal materials, which are found in wastewater from chemical and paper industries.
Sincerely
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I'm exploring leachate treatment and I see pH during aerobic digestion increase.
There is a lot of ammonium in the solution and nitrification should decrease pH, but it goes the other way. My only guess is that this happens because of aerobic digestion of organic matter (is that true?), but I would like it described with a sum equation (so I could see how much H+ is spent / or how much OH- is created).
If it isn't possible to describe it with a equation, is there any other description of pH change?
Thank you
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Stjepan Džalto , in your conditions, ammonification is mainly a biological process aerobic bacteria, fungi, anaerobic bacteria can do ammonification during a normal biodegradation process.
Yann
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I'm going to do an experiment in lab in which I examine the effect of nitrapyrin ( it is a nitrification inhibitor ) on more ammonia-oxidizers bacteria. There are several experiments proved that nitrapyrin inhibits Nitrosomonas nitrification bacteria which are responsible for convert the ammonium to nitrite. Howewer, according to the heterogenity of soils, I guess there is a huge heterogenity of population bacteria. If there are other similar function bacteria in soil which are also responsible this mechanism (converting ammonia to nitrite), the impact of nitrapyrin will be not effective. If Nitrosomonas are inhibited, other bacteria may can multiply.
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This link might be little bit helpful for your query!
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Dear All,
I am now running a continuous aerobic MBBR system treating synthetic wastewater of TKN ~40 ppm and NH3-N ~30 ppm. Now I can acheive effluent NH3-N of <5 ppm at an HRT of ~1.5 days. However, to my surprise, NO2-N accumulates in the system (>23 ppm) with only low levels of NO3-N (~6 ppm). The pH is 7.5-8.0 and the DO is always >7 ppm. Can anyone help me to suggest some reasons behinds and some solutions to enhance the NOB activity?
Thank you very much!
Dennis Tang
Hong Kong, China
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Due to a bit outdated classical view nitrification is performed in 2 steps by 2 microorganisms. Modern data proved that some nitrifiers may perform both steps within 1 microorganisms. However, in this case both steps sometimes are not tightly coupled and sometimes significant part of nitrite is released into the medium and then later is oxidised to nitrate . That is my personal observation during cultivation the COMAMOX culture.
Thus, in your case 2 processes are incoupled. That could be that you lack nitrite-oxidising organisms.
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In 2015, the Government of India ordered that all urea produced in the country or imported will be sold will be coated with neem oil at the rate of 0.5 kg per tonne. Neem oil is a nitrification inhibitor. Is there any observation that due to treatment of urea with neem oil there is any reduction in the use of urea or increase in agricultural production?
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I didn’t work in nymph oil, but nitrification inhibitors based on pyridines and pyrimidines had a positive effect on wheat yield.
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I have to design the biological system that can reduce very high amount of BOD from food waste industry. I am always confused with BOD consumption path in Biological process. By definition, BOD is the amount of oxygen required to degrade the organic material but the weird part is when I read the nitrification and denitrification, I came to know that, denitrification bacteria are actually consuming organic substances as their carbon source. The nitrification bacteria uses inorganic form of carbon source, So, when we are providing air, it helps nitrification bacteria to consume only inorganic carbon which is not BOD. Actually BOD is consumed by denitrification bacteria which do not need oxygen So, why in definition of BOD, it is stated that amount of oxygen required to degrade organic substances???
In real life, anoxic bacteria (denitrfiers) are consuming BOD. Can any biological expert help me to clarify that? I have to design biological system for BOD removal but I do not have nitrogen source (NH3) in my feed. Do I have to provide nitrogen source like urea for bacteria to work or there are certain bacteria which do not need any nitrogen source. It is a crucial design and I am struggling still with biology after reading tons of literature. Any specific explanation would be highly helpful to me.
Is is worth it to go for biological treatment with high soluble BOD upto 6000 ppm? Is there any other way to reduce soluble BOD?
Thank you.
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Dear. Bhavik
1.- Bod is consumed in nitrification or denitrification?
The nitrification is a microbiological process in which the ammonium is oxidized by autotrophic bacteria in presence of oxygen and carbon inoganic, in this process does not eliminate BOD. on the other hand DENITRIFICATION uses the nitrate generated in nitrification to generate nitrogen molecular, in this process (denitrification) takes place in the absence of oxygen and at this stage the bacteria remove organic matter quantified as BOD or COD.
2.- why in definition of BOD, it is stated that amount of oxygen required to degrade organic substances???
Biochemical Oxygen Demand (BOD) is the amount of dissolved oxygen needed (i.e. demanded) by aerobic biological organisms to break down organic material present in a given water sample at certain temperature over 5 days.
Your confusion is that you are taking a textual definition, and BOD is an indirect parameter that allows you to measure the amount of biodegradable organic matter present in the wastewater based on the amount of oxygen required to oxidize it. That is, it is the amount of oxygen that you need biologically speaking to oxidize the organic matter present, a concept very similar to the COD. The difference is that here all the organic matter is oxidized by chemical reactions (degradable and non-biodegradable).
3.- In real life, anoxic bacteria (denitrfiers) are consuming BOD
Yes, in real life, these bacteria consume the organic matter measured as BOD or COD as a carbon source to transform nitrate into molecular nitrogen.
4. I have to design biological system for BOD removal but I do not have nitrogen source (NH3) in my feed. Do I have to provide nitrogen source like urea for bacteria to work or there are certain bacteria which do not need any nitrogen source.
If you do not have a source nitrogen, because you want to use a nitrification / denitrification process, this biological process is used when your wastewater is rich in nitrogen, based on your coments, I recommend you use another type of treatment, for example using a anaerobic bioreactor such as a uasb, egsb or anaerobic filter. If you give me more information related to your water type, not only your dbo could help you decide which bioreactor to use to eliminate that BOD.
dbo, dqo, nitrogen, sulfates and ph.
All the bacteria used in wastewater treatments need nitrogen since without this they can not synthesize new cells or their genetic information, so there is a C / N relationship as a rule of thumb which must be met depending on the biological process.
If my wastewater does not have the minimum requirements of nitrogen, it is necessary to add it
5. is worth it to go for biological treatment with high soluble BOD upto 6000 ppm? Is there any other way to reduce soluble BOD?
yes, but I need more information to suggest you what process yuo need use.
Best regards
Abumalé
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In a set of nitrification of black wastewater experiments, nitrate formation took place despite low levels of alkalinity (lower than 7.14 mg alkainity per mg of NH4-N oxidised. what could be the reason? whether heterotrophic nitrification can take place or autotrophic nitrifiers can work at low levels of alkalinity? Is there any literature available for this kind of case?
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@Henrik rasmus Andersen:
1.Sir, initially pH raised from 7.5 to above 8.2 because of air stripping of ammonia and bicarbonate alkalinity. Then, pH started to drop to near 6.5 as nitrification occurs.(black water from toilets)
2. Mass balance from different sets, 35 -40% N nitrified, 4-8% N remained as ammonium and rest of ammonium lost due to volatilisation plus porous media adsorption. Increase in alkalinity was not observed.
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I wan to set up an anaerobic/oxic/anoxic (AOA) SBR for simultaneous nitrification, denitrification and phosphorus removal with aerobic granular sludge. But I'm confused how to maintain the anaerobic and anoxic phase in AOA system.
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Dear Pankaj Kumar Saha: I rocommened you learn the basics of the process and only then to start designing A/O/A SBR for SNDPR system.
Without basic knowledge of the process it is not possible perform quality designing at all.
Best regards
Vit
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Even in nitrogen fixation, both candidates (bugs) can participate but in the case of nitrification, only bacteria? Expecting a good explanation.
Regards!
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Dear Paudel,
Both archaea and bacteria can participate in nitrification. Although, the issue regarding the niche differentiation between ammonium-oxidizing bacteria (AOB) and ammonium-oxidizing archaea (AOA) is still not well settled.
I give you some suggestions to read:
I hope I have helped.
Best regards!
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Hi everyone,
I am working on bacteria which are capable of ammonia oxidation. Presently i have some isolates (heterotrophs) capable of utilizing ammonia but such isolates are showing negative for amoA gene (true marker for autotrophic nitrifiers) amplification. Can any one recommend some molecular genes which are ideal for heterotrophic bacteria showing nitrification. Is there any true marker or gene for heterotphic nitifiers or ammonia oxidizers.
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Hi,
Does anyone know how to experimentally estimate ammonia uptake rate (AUR), nitrite uptake rate (NUR), nitrate production rate (NPR), and nitrite accumulation rate (NO2AR)
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Biological nitrification and denitrification are key processes to remove nitrogen from wastewater and have become more important due to stringent discharge regulations.Nitrifier’s population (ammonia oxidizing bacteria (AOB) + nitrite oxidizing bacteria (NOB)) should be more than 5–8% of the biomass for good nitrification. However, nitrifiers have slow growth rates and they are also believed to be sensitive to environmental changes such as toxic shocks, pH, and temperature changes. Due to these characteristics, it is difficult to obtain and maintain sufficient nitrifies in wastewater treatment plants (WWTPs), if solids retention time (SRT) gets shorter. And as a consequence, it is difficult to maintain nitrification in municipal and industrial wastewater treatment plants (WWTPs). Organic material in wastewater is removed in order to reduce oxygen consuming substances in the recipient and it is performed by bacteria at wastewater treatment plants (WWTP). In activated sludge the biomass consists of different types of bacteria. The aerobic degradation process of organic material can be determined by measuring the oxygen uptake rate (OUR) for the microorganisms. Oxygen uptake rate measurements can provide much information concerning treatment plant performance, wastewater characteristics, degradability of special concentrated streams as well as parameters needed for mathematical models, in order to predict possible optimizations of a treatment plant. In addition it is useful for daily operation control.
Nitrification is of great importance for nitrogen removal from municipal wastewater in the biological nutrient removal process (BNR) employed in waste water treatment plants (WWTPs). In nitrification, ammonium is firstly oxidized to nitrite via ammonia-oxidizing bacteria (AOB), and then to nitrate by nitrite-oxidizing bacteria (NOB).
Nitrifier's population (ammonia oxidizing bacteria (AOB) + nitrite oxidizing bacteria (NOB)) should be more than 5–8% of the biomass for good nitrification [. However, nitrifiers have slow growth rates and they are also believed to be sensitive to environmental changes such as toxic shocks, pH, and temperature changes. Due to these characteristics, it is difficult to obtain and maintain sufficient nitrifiers in wastewater treatment plants (WWTPs), if solids retention time (SRT) gets shorter . And as a consequence, it is difficult to maintain nitrification in municipal and industrial wastewater treatment plants (WWTPs).In conventional activated sludge processes, a long SRT is necessary to maintain sufficient nitrifiers for nitrification. The long SRT increases the concentration of mixed liquor suspended solids (MLSS) which requires large tanks and clarifiers to accommodate the accumulation of solids inventory .
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We have used dicyandiamide (a well known nitrification inhibitor) in soil and I want to determine the degradation of dicyandiamide with time. An HPLC method is available for its determination, however at present don't have the facility to use HPLC. Could someone please give any other suitable method using equipments like atomic absorption spectrophotometer or UV-visible spectrophotometer.
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The method to determine DCD in soil samples using a UV-VIS spectrophotometer has been adopted by many researchers. Some examples are as follows.
Jacinthe, P.A. and Pichtel, 1991. Interaction of nitrapyrin and dicyaniamide with soil humic compounds. Soil Science Society of America Journal, 56(2): 465-470.
Rajbanshi, S.S., Benckiser, G., Ottow, J.C.G., 1992. Effects of concentration, incubation temperature and repeated applications on degradation kinetics of dicyandiamide (DCD) in soils. Biology and Fertility of Soils, 13: 61-64.
Vilsmeier, K., 1979. Kolorimetrische Bestimmung von Dicyandiamid in Boden. Z Pflanenernaehr Bodenkd, 142: 792-798.
Weiske, A., Benckiser, G., Herbert, T., Ottow, J.C.G., 2001. Influence of nitrification inhibitor 3, 4-dimethylpyrazole phosphate (DMPP) in comparison to dicyandiamide (DCD) on nitrous oxide emissions, carbon dioxide fluxes and methane oxidation during 3 years of repeated application in field experiments. Biology and Fertility Soils, 34: 109-117.
I recommend you check out the sensitivity and correlation between the adsorption (A) and DCD concentration in your samples at 540 nm first. However, sometimes pretreatment (e.g., pH adjustment) is required for the soil extracts depending on the specific samples. Let me know if you need any references and would like to expand the discussion.
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I need to know the porosity of coarser brick pieces, so that i can determine the working volume of wastewater reactor with media?
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Refer the manual of soil sampling and analysis, soil sciences society of Sri Lanka.
According to this, porosity (E) can be calculated by determining bulk density (Pb) and particle density (Pp) of the substance.
E = 1- (Pb/Pp)
Pb = mass of substance/volume filled
Pp = mass of substance/volume of water
Think this answer may helpful for the analysis.
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I’m designing an experiment to analyze gross N mineralization and nitrification rates in tropical pastures using 15N dilution technique. These fields have all very high root density and strong aggregation, it is Vertisol. Under such conditions, is it advisable to use intact soil cores or would it be better to use disturbed soil, remove the roots and then apply the 15N label? Also, is it better to use disturbed soil and sieve the samples prior the 15N application or use intact soil cores and then sieve the soil before the 15N extraction? Thank you very much in advance
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I think to get true condition you should use intact soil cores and then sieve the soil before the 15N extraction.
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I deeply want to write a review on N2O emissions from agriculture soil under aerobic conditions. My focus is nitrification and N2O-derived nitrification. I would like to invite you to be co-authors to do this work if you are interested in.
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If you wish i can be co author of the chapter.
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Not getting 100% conversion of NO3 to N2.
feed:
CBOD5 -150mg/L
TSS -200mg/L
Ammonia N -60mg/L
TP -10mg/L
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Dear Bhavik,
Of course there are potentially many factors that I am unfamiliar with for your system. However, just on a big picture level, it would seem that there is not enough BOD for the amount of denitrification required (based on the initial BOD/ammonium-N ratio), if this is a classic nitrification/denitrification system. Could that be the problem? Good luck in any case!
- Peter
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What changes does evaporation losses cause in organic and inorganic concentrations of aerobic reactor?
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I suggest it is well known that ammonia strip from water and it is in pH dependant equilibrium with ammonium. Therefor some loss can be expected depending on the pH.
Biarbonate and nitrate are ionic so they don't evaporate.
Any loss of COD depends on the organic matter that constitute the COD. If it is large and/or ionic molecules it will not evaporate. If some of the COD comes from small molecules such as volatile organic acids(VFA), ethanol some evaporation can be expected.
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Loess soils are assumed to be light textured with higher nitrification activity, which makes them susceptible to excessive nitrogen losses. I am not sure whether the statement is true, needs clarity and justifications.
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Respected Dr. J. C. Tarafdar and Dr. Kulvir Singh, thank you so much for your valuable answers. It has served my purpose. Blessings.
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Hi friends...
I found in the literature that Tannin acts as inhibitor for ammonia oxidizing bacteria in wastewater treatment. In other words, nitrification process in wastewater treatment would be slower if Tannin is present in this wastewater. Any one can help me to to understand why or how?
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Thank you so much Dr. Huub for your help.
I would highly appreciate your help if you share me any paper related to this topic.
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According table 8-19 metcalf (fifth editin) , f/m ratio in coplete mix is about 0.2-0.4, but in the example 8-3 in part B ( BOD removal and nitrification) f/m ratio is less than 0.2-0.4?
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A good F:M is where you get the best effluent results - low suspended solids, COD and the nitrogen balance you need to achieve. In a typical CMAS system you want to extend the sludge age for better nitrification. There is a limit and would suggest you stay within the 20-30 day SRT as you will begin affecting solids settling. This should push the F:M below 0.2.
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Present water supply treatment uses chlorine as primary disinfectant followed by the addition of ammonia to form chloramine as a secondary disinfection. When water temperature is above 23 -24 degrees centigrade nitrification is severe in downstream storage tanks. Decay of 1 -1.5 mg/L total chlorine is also observed in the bulk water mains before reaching the storage tanks. Treated water leaves the water treatment plant at pH 7.5 -7.8. Although not widely reported some water authorities had demonstrated that chloramine is much more stable at pH 8.5 - 9.0.
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If your chloramine turns into nitrate it indicates you have a lot of biofilm in the storage tanks. They should be be drained and cleaned regularly.
If you have biofilm in pipes and other places that cannot be cleaned you can periodically dose chlorine dioxide which penetrated biofilm better than chlorine and chloramine.
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Our research is focused on the impact of glyphosate on soil microbiota. Just now, we want to evaluate the biological inhibition of nitrification in the rhizosphere of Avena sativa (used as cover crop in Argentina) treated with glyphosate as dessicant . We would like to perform the colourimetric microplate assay developed by O' Sullivan et al (2017).
We need to test BNI against a control of Nitrosomonas europea and/or Nitrosospira multiformis, which are sold by ATCC but are quite expensive in terms of our funding resources.
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Hi Maria,
I have upload the Poster of the EGU Conference from 2015 to my profile.
Cheers,
Tina
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I need to analyse Monod kinetics for nitrogen removal from wastewater. Can anyone provide me with alternative biomass estimation methods( instead of VSS)?
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Dear Nitish,
as already mentioned above only a small fraction of (ML)VSS will be nitrifiers/denitrifiers. Anyway, if you are just searching for an alternative method to estimate your biomass in activated sludge (since MLVSS measurement requires some time and sample volume), the following rough rules of thumb (!) so far seemed pretty reliable to me:
1) Carbon content in bacterial cells: 50% (dry weight)
2) MLVSS = 0.8 x MLSS
Therefore, if you measure the TOC (for example Hach Cuvette Test):
3) TOC x 2 = MLVSS
4) TOC x 2.5 = MLSS
Only applicable, if your DOC (dissolved organic carbon) is neglectable in comparison to biomass, otherwise you would have to subtract the DOC.
Be careful to shred your sludge flocks, and don't use pipette tips with narrow openings to avoid sludge separation by pipetting.
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Is nitrification directly affected by major minerals (Ca, Mg, K, Na) concentration in water? Does the nitrifying bacteria need these minerals significantly?
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As with all biochemical transformation processes, both macro- and micro-nutrients are required.  Macronutrients usually considered are N and P, which are needed in substantial quantity when compared with micronutrients (i.e., elements that are not used by microorganisms as the electron acceptor or donor).  Micronutrient (relative mass) requirements are difficult to define and may vary by reaction/bacteria type, but principal inorganic nutrients needed by microorganisms include S, K, Mg, Ca, Fe, Na, Cl.  Consideration should also be given to Zn, Mn, Mo, Se, Co, Cu, and Ni.
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How much ammonium to nitrate conversion has observed and how much nitrification percentage inhbited in response to application of nitrification inhibitors?
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A current modern trickling filter (TF) system with plastic filters has an input of BOD = 200 mg/L, COD = 350 mg/L and TN = 45 mg/L (effluent volume being 15,000 m3/d) has an output (in mg/L) of BOD = 50, TKN = 15, NO3-N = 3, NH4 = 10, TP = 5 and DRP = 3.
Given the high NH4-N in the TF effluent, aeration (by diffusers) appears to be the next obvious step to nitrify. Should such an aeration being performed can good nitrification be achieved without introducing RAS given there is already 50 BOD being present? Given nitrification requires CO2 as a C source, why would it need RAS (organic-C)? Please ignore the next steps involved in denitrification after full nitrification. If you could share any existing cases rather than laboratory studies that will be great.
Kind regards
Selva
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First, NH can not be reduced, but only oxidised ( to NOor NO3 for example).
Second, this is a biological oxidation : then it requires, besides CO2, autotrophic bacteria, which can utilize CO2, by deriving the necessary energy through the oxidation of N forms.
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Fish excrete ammonia, a much smaller molecule than urea, which is the end product of protein degradation, excreted by mammals. There is good explanation for this evolutionary design. The fish can excrete ammonia through the gills (in exchange of sodium ions) into the ambient medium (water), whereas mammals live in land (aquatic mammals are part of secondary evolution).      
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It appears the excretion of nitrogen is more efficient in fish than in mammals. This could be related to the body component of these animals as well as the medium of nitrogen excretion employed by these animals. it is more easier for fish to dissipate its waste either nitrogen or other forms of waste without stress. 
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during the my investigation of physico-chemical study of seawater i found that during low tide and high tide pH shows strongly negatively correlated with Nitrate-Nitrogen. If there is any chemical proceed or other  possible factor ??
Persons  correlation of pH and Nitrate-Nitrogen; low tide (r = -0.631, p<0.01) , and high tide NO3--N (r = -0.633, p<0.01).
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Yes, we collect 24 samples from all seasons. we analyzed all other parameter like salinity, DO, BOD and all nutrients.
Regards,
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Ammonium is neither consumed nor produced in nitrite oxidation, how does ammonium concentration suppress NOB and why?
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as far as I know, not ammonium but ammonia can poison biomass growth at high concentrations. High ammonia concentration can inhibit also AOB. A second indirect effect can be the high production of nitrous acid, which also known to inhibit at high concentrations biomass growth. 
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Any concise and clear explanation of how does high temperature affect/inhibit NOB? 
Low DO with intermittent aeration, high temperature, high salt concentration, high ammonium concentration, high nitrite/nitrous acid are all factors limiting the growth of NOB. How does high temperature inhibit NOB growth? 
Thanks in advance. 
Kulthoum 
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Dear Ismail,
it depends on what you mean with "high" temperature?
e.g. at 30-35°C, it is not the temperature that inhibits NOB, but the specific growth rate of AOB is higher that the growth rate of NOB at 30°C  (which is not the case at 15°C); so high temperature (> 30°C) is used together with low slugde age (SRT) to wash out NOB and keep AOB in the reactor. this is the principle applied in the SHARON process.
greetings, jan
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what are the favorable soil conditions (pH, CEC, EC, OM, WFPS)  for nitrification and denitrification process? 
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Thank you all for your reply
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The hypothesis is that the protons formed during the nitrification react immediately in the denitrification reaction (in a combined system). In a separated system the protons formed during nitrification will react with bicarbonate forming CO2 + H2O leading to a higher decrease in TIC compared with the combined system.
NH4+ + 1,5 O2 -> NO2- + H2O + 2 H+ (nitrification)
NO2- + 0,5 O2 -> NO3- (nitrification)
CH2O + 0,8 NO3- + 0,8 H+  -> 0,4 N2 + 1,75 H2O +1,25 CO2 (denitrification)
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COretention or release from water or wastewater is pH dependant with pH<7 promoting CO2 release, hence nitrification can be expected to reduce inorganic-C via two pathways, (a) nitrifiers use CO2 as a C source to fix C and (b) CO2 release by acidity. However, inorganic-C dynamics may not be entirely influenced by nitrification. Aeration to promote nitrification can also promote CO2 release by oxidation of organic-C. If we ignore the above, continuous nitrification without denitrification could rate limit nitrification since nitrification rates are lower below pH<7 with high build-up of H+, thereby self-limiting the release of CO2 by high acidity. It could be argued that triggering denitrification by ceasing aeration at this point in a 'combined system' could promote alkalinity and when aeration commences again, there is greater potential for nitrification and release and use of CO2.
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I know that most Anammox experiments are conducted in the dark, and someone told me that there are indications that anammox do not much like light, but I can't find a reference for that.
Thanks you for your help
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 Oh.. yes. Nicolas is absolutely right. I completely forgotten about that, however the algae could be a problem in fact, especially if you are working on synthetic medium ex. proposed by Trigo et al. in 2006. In my research I found that this medium is well suitable for algae, mainly Chlorella sp. I found both common species Ch. Elipsoidea and Ch. Vulgaris. The problem of algae on the walls of the bioreactor is depended of mixing. In my reactors there was no algae on walls, but the tubes for influent and effluent were almost always covered with it. Additionally, stepping by the oxygen generation, the algae growth changes the environmental conditions in your reactor, because they use nitrogen for their living mechanisms.
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I am looking for elaboration for measurement of nitrates and ammonium in soil through SKALAR METHODS, but the SKALAR instrument that we have in our Lab, there I have seen, mentioned only for nitrate+nitrite, ammonia and ortho phosphate, how I can calculate ammonium in this method? because I want to estimate the ammonium and nitrate to find out ammonification and nitrification? 
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Do your SKALAR equipment did have the cadmiun column? If you don´t passed through the column containing granulated copper‐cadmium you will measured only nitrite. if you pass the sample through the column you will measured nitrate+nitrite.
Amonia you do it in another channel of the equipment.
best regards
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Hi,
I am currently working on a nitrifying bioreactor project using synthetic wastewater as feed. 
Due to the extra amount of NaHCO3 added to one batch of my feed, it caused the pH of the feed went up to 8.7, which is a bit too high for nitrification. 
So I tried to lower the pH down using muriatic acid (HCl:31.5%). pH dropped initially from 8.7 to 8.0 after 2 hours mixing. However, the pH bounce back to 9.0 after 1 day mixing. 
There are probably some reactions causing the raise of pH. But I am not sure what reaction it is. I am wondering if any body would have an answer for that.
Here are the main ingredients of a 1000L feed, where I added muriatic acid.
(NH4)2SO4 (615g)
NaHCO3 (1687.5g)
FeSO4*7H2O (5g)
KH2PO4 (80g)
CaCl2*2H2O (29g)
MgSO4*7H2O (71g).
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By adding acid to hydrogencarbonate you create a large concentration of CO2 in solution causing the solution to be highly supersaturated. This keeps the pH down as CO2 is in equilibrium with carbonic acid. During the day long mixing the excess CO2 strips off and as acid leaves the solution the pH increases.
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Hi, 
I  am currently running nitrifying fixed-film bioreactors and trying to characterize the ammonia removal rates and prove the fixed-media technology I am working on. 
Last weekend, my control and experimental bioreactors encountered power outage and aeration got shut down for two days. And sadly, all the nitrifiers were not able to fight through and went to heaven and ammonia in both reactors continuously spiking up after the event. 
I reseeded the bioreactors with some fresh activated sludge from local wastewater treatment plant and resumed feeding afterwards. 
Now, the interesting thing is, the ammonia in the control reactor (no fixed-film media) went down but the ammonia in the experimental reactor (with fixed-film media)  did not go down, but went up to a higher concentration. 
I did not drain and clean up both reactors when I reseeded the two reactors as I thought the inactive biomass would provide certain nutrients to the new bugs.  
Since the the experimental reactor has fixed media to retain more nitrifying biomass than the control reactor. As the aeration got shut down, the experimental reactor therefore would ended up with more dead nitrifiers. 
My gut is telling me that the ammonia increase in the experimental reactor may have something to do with the inactive(dead) nitrifying biomass but I am entirely certain about it. 
I am wondering if anybody has ideas about what might be the cause? 
Thanks in advance, 
August
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I agree Oxygen depletion is not the major Problem.
How long it will take to get back on track depends the water temperature and how it is done. With 130 mg/l NH4-N as feed concentration it might indeed take a long time depending on you pH and temperature since you risk to have Ammonia Toxicity. To avoid this you must reduce load to approx 25% of the original loading until you see Nitrate production after that you can increase load with approx 10% per day giving approx 2 weeks to recover were I would expect 1 - 2 month if you have to restart from scratch.
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There are some literature which states a decline in the rate of Nitrification and increased rate of Denitrification in saline soil. But I am wondering if Sodium ion interact with Nitrate in positive or negative way and its effect mechanism in Non - saline soil. 
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Dear Niguss:
Saline soils are characterised by low oxygen solubility.  Under these circumstances denitrification is better induced than nitrification. 
Sodium does not affect negatively...nitrate can be assimilated or used as final electron accept (anaerobically)