Nitrification - Science topic

Gifole Gidago Wabalo

In acidic soils, nitrification, the process where ammonia is converted to nitrite and then to nitrate, is significantly slowed down due to several factors, primarily the low pH and the resulting impact on nitrifying bacteria. Key factors include soil pH, temperature, moisture, oxygen supply, and the population of nitrifying organisms.

Thanks!

In special cases ammonia/organic matter is higher and BOD is used to oxidize the natural organic matter and organic waste in the water. these bacteria use oxygen to convert ammonia into nitrate. If the wastewater contains high levels of ammonia, the nitrifying bacteria consume a significant amount of oxygen, which can lead to an increase in BOD relative to COD

Not directly related to nitrification potential but similar issues also present for enzyme activities. I think most important thing is to make sure every sample is treated in the same way for all. You can take them out of freezer one by one and keep them on ice while weighing them. It's important you try to follow the same procedure for each sample.

Some further reading might help you figure out also some other things for yourself;

Considerations in the storage of soil samples for enzyme activity analysis - ScienceDirect

On a root there is a principle of electrical neutrality so when a cation is taken in a cation need be released.

So, when ammonium is up taken hydrogen ions are released resulting in acidification of the rhizosphere.

In a root when an anion is up taken it must release an anion for the uptake of nitrate the balance is releasing hydroxyl which means the rhizosphere is limed from the rhizosphere release.

In a controlled situation the use of mono and dibasic phosphate can result in a 7.4 buffering and many natural substances also. A carbonate bicarbonate buffer would also be effective.

Hope some of this is useful for your purposes.

Low concentration of nitrifiers bacteria leads to less efficient sedimentation and escaping the suspended solids in the settling tank Samsul Islam

Bacillus mesentericus (now known as Bacillus subtilis) is not known to directly affect, limit, or inhibit the nitrification process. Nitrification is the biological process by which ammonia is converted to nitrate and then to nitrite by specific groups of microorganisms.

Bacillus subtilis is a Gram-positive, aerobic bacterium that is commonly found in soil and has various beneficial roles in agriculture and biotechnology. However, it is not typically associated with nitrification processes.

Hello! I am also starting to do PNR according to the methodology

developed by Smolders et al. (2001), however I have not found I comprehensive protocol ad struggling, I have some concerns:

1. After weighting the soil samples do we directly incubate for 3 days followed by ammonium sulfate addition or add water to reach 60% WHC and then incubate?

2. What is the standard I can use, rates, and standards also should be incubated?

3. What are the control samples, and how do I proceed with them?

Many analysts do not pay sufficient attention to the predictive quality of their calibration data, especially as Sal suggested, at the low concentration end. Regression fits the bigger values more closely than the smaller values and if the range is large, R2 values can be 0.99 yet therre can be appreciable bias at low concentrations. This shows up in plots of residuals. In addition, some calibration programs 'force' the fits through zero.

In addition, the efficiency of conversion (reduction) of nitrate to nitrate can vary during a 'run' i.e., the sensitivity can change, added to which the instrument can 'drift' over time. To accommodate this a mixed standard of nitrate and nitrite should be measured every few samples, the frequency being based on the actual performance.

My advice is to get the raw instrument data and analyse it yourself. You may hen need to chat with the analyst and arrange to have the instrument operated to meet your requirements.

However, ultimately as the concentration approaches zero there will be small positive and neg values.

Usually wastewater is closer to neutral pH so we will find reduced nitrogen as ammonium, in which case the process appears to consume alkalinity and reduce pH:

Nitritation: NH4+ + 1.5 O2 -> NO2- + 2H2O + 2H+

Anammox: NH4+ + NO2- -> N2 + 2H2O

Sum 2NH4+ + 1.5 O2 -> 3H2O + 2H+

Not my field but engineers who work on wastewater treatment would know what excess of the Fe is typically added

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.

Continuous denitrification is definitely the better way than the discontinuous system. The following article might help you on this aspect:

:

you can measure Optical density

at 600nm.

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.

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

•

Also check on this paper

Personally, I strongly recommend this article which will certainly be useful to you.

Regards

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...

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..

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.

Dear Pompilia,

Please attached find some recent published papers may help you for determination of nitrification-denitrification rates in wastes.

Good luck.

Thank you Dr. Murphy!

I just sent you an e-mail for a discussion.

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.

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.

please look at these links:

wish all the best

Pablo Ribeiro J. C. Tarafdar Thank you. I have now found this study and similars, see Figure 1:

It seems like the shortest duration of similar experiments that makes use of NIs is ca 7 days.

Best, Klara

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

Lin Jyh-Yan Thankyou

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.

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

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

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

@ 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.

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).

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.

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...

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

thank you

You can refer to this document

Please check the following RG link and PDF attachment.

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

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

Following

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.

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

Do you have a lot amount of organic nitrogen ?. If yes, the ammonification process (First step of nitrogen degradation) raise the pH.

Yann

This link might be little bit helpful for your query!

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.

I didn’t work in nymph oil, but nitrification inhibitors based on pyridines and pyrimidines had a positive effect on wheat yield.

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

@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.

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

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!

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 .

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.

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 (P_b) and particle density (P_p) of the substance.

E = 1- (P_b/P_p)

P_b = mass of substance/volume filled

P_p = mass of substance/volume of water

Think this answer may helpful for the analysis.

I think to get true condition you should use intact soil cores and then sieve the soil before the 15N extraction.

If you wish i can be co author of the chapter.

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

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.

Respected Dr. J. C. Tarafdar and Dr. Kulvir Singh, thank you so much for your valuable answers. It has served my purpose. Blessings.

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.

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.

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.

Hi Maria,

I have upload the Poster of the EGU Conference from 2015 to my profile.

Cheers,

Tina

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.

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.

Please have a look at these attachments...

First, NH₄  can not be reduced, but only oxidised ( to NO₂ or NO₃ for example).

Second, this is a biological oxidation : then it requires, besides CO_2, autotrophic bacteria, which can utilize CO_2, by deriving the necessary energy through the oxidation of N forms.

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. 

Yes, we collect 24 samples from all seasons. we analyzed all other parameter like salinity, DO, BOD and all nutrients.

Regards,

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. 

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

Thank you all for your reply

CO₂ retention 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.

 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.

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