ex 3 ammonia nitrogen and nitrate

8/3/2019 Ex 3 Ammonia Nitrogen and Nitrate

1/4

5.0 RESULTS

Sample (different sources) NH3-N, mg/L NO3--N, mg/L

INDUSTRIAL WATER 0.42 0.40

RIVER WATER 0.00 1.60

DOMESTIC WATER 0.01 0.40

6.0 DISCUSSIONS


2/4

1. Results Discussion

Ammonia-Nitrogen(NH3-N)

Ammonia (NH3+) is a colorless gas with a strong pungent odor. It is easily liquefied and

solidified and is very soluble in water. One volume of water will dissolve 1,300 volumes of

NH 3. Ammonia will react with water to form a weak base. Usually industrial wastewater

contains high amount of ammonia due to usage in chemical processes. This supports the data

that we gain that the industrial water contains 0.42 mg/L, whereas the river water and

domestic water contain 0.00 mg/L and 0.01 mg/L respectively. The amount of ammonia in

later sample is negligible due to the very low concentration of it. For the traceable amount of

ammonia in domestic water can be reasoned out that the household uses ammonia based

products such as detergents, plastic, food wrappings.

Nitrate Ion Nitrogen(NO3N)

Nitrogen is the nutrient applied in the largest quantities for lawn and garden care and crop

production. In addition to fertilizer, nitrogen occurs naturally in the soil in organic forms

from decaying plant and animal residues. In the soil, bacteria convert various forms of

nitrogen to nitrate, a nitrogen/oxygen ion (NO3-). This is desirable as the majority of the

nitrogen used by plants is absorbed in the nitrate form. However, nitrate is highly leachable

and readily moves with water through the soil profile. If there is excessive rainfall or over-

irrigation, nitrate will be leached below the plant's root zone and may eventually reach

groundwater and all goes back into river. This clearly explains the high content of nitrate

amount in river water that is 1.60 mg/L. Nitrates stimulate the growth of aquatic plants that

can lead to reduced oxygen levels.

High nitrate levels occur in areas of extensive agriculture, animal feedlots and septic waste

systems. Thus, the nitrate concentration of domestic water and industrial water are the same

of the reading 0.40 mg/L. Nitrate in irrigation water has much the same effect as soil-applied

fertilizer nitrogen can be considered useable nitrogen, and, along with a conversion factor can

be incorporated into growers fertilizer program.


3/4

2. Sources of Ammonia in Water and Wastewater

Wastewater

About three quarters of the ammonia produced in the world is used in fertilizers either as the

compound itself or as ammonium salts such as sulfate and nitrate. Large quantities of

ammonia are used in the production of nitric acid, urea and nitrogen compounds. It is used in

the production of ice and in refrigerating plants. Household ammonia is an aqueous solution

of ammonia. It is used to remove carbonate from hard water. Since ammonia is a

decomposition product from urea and protein, it is found in domestic wastewater. Cement

mortar used for coating the insides of water pipes may release considerable amounts of

ammonia into drinking-water and compromise disinfection with chlorine.

Water

Aquatic life and fish also contribute to ammonia levels in a stream.NH3 is the principal form

of toxic ammonia. It has been reported toxic to fresh water organisms at concentrations

ranging from 0.53 to 22.8 mg/L. Toxic levels are both pH and temperature dependent.

Toxicity increases as pH decreases and as temperature decreases. Plants are more tolerant of

ammonia than animals, and invertebrates are more tolerant than fish. Natural levels in

groundwaters are usually below 0.2 mg of ammonia per liter. Higher natural contents are

found in humid substances or iron or in forests. Surface waters may contain up to 12 mg/liter.

Ammonia may be present in drinking-water as a result of disinfection with chloramines. The

presence of ammonia at higher than geogenic levels is an important indicator of fecal

pollution. Taste and odour problems as well as decreased disinfection efficiency are to be

expected if drinking-water containing more than 0.2 mg of ammonia per liter is chlorinated.


4/4

3. Biochemical reactions that can remove nitrate from water

2 NO2- + O2 -> 2 NO3

- - by nitrobacter bacteria

During the denitrification bacteria decompose nitrates to nitrogen. This does not require aeration,

as it is an anaerobic process. Nitrogen is eventually released into air. A carbon source is often

added to speed up the decomposition process. One example of a possible reaction mechanism is:

6 NO3- + 5 CH3OH -> 3 N2 + 5 CO2 + 7 H2O + 6 OH

-

These processes exclude one another, because one requires oxygen and one does not. Wastewater

treatment requires both aeration, and the presence of oxygen-pour spaces. When these processes

are applied as a third water purification step, approximately 90% of nitrogen may be removed. In

countries such as Brazil, water hyacinths are applied as a third water purification step. These

remove both nitrogen and phosphorus from water.

Bio-chemical Denitrification;

By using denitrifying bacteria and microbes, the nitrate ion can be reduced into its elemental state

of N2. These organisms are able to carry out this process through a reaction such as:

6H+ + 6NO3- + 5CH3OH -> 3N2 + 5CO2 + 13H2O

By using a chemical such as ethanol, the removal of nitrate is possible. Sometimes it is necessary

to convert the nitrogen from the ammonium ion into nitrite with the use of nitrosomas

(specialized bacteria) to facilitate the removal of all nitrogen from the solution. The nitrite

compound is then oxidized to nitrate, which can then be eliminated by the reaction shown above.
http://www.lenntech.com/water-purification-steps-FAQ.htmhttp://www.lenntech.com/water-purification-steps-FAQ.htm

ex 3 ammonia nitrogen and nitrate

Documents