Nitrate and Nitrite

INTRODUCTION

 Nitrate and nitrite are naturally occurring ions that are part of the nitrogen cycle. c ycle. The nitrate ion (NO3−) is the stable form of combined nitrogen for oxygenated systems. Although chemically unreactive it can be reduced by microbial action. The nitrite ion (NO!−) contains nitrogen in a relatively unstable oxidation state. "hemical and biological processes can further reduce nitrite to various compounds or oxidi#e it to nitrate ($"A$% &ife 'ystems $nc. *+ ).  Nitrate is used mainly in inorganic fertili#ers. $t is also used as an oxidi#ing agent and in the  production of explosives and purified potassium nitrate is used for glass ma,ing. 'odium nitrite is used as a food preservative especially in cured meats. Nitrate is sometimes also added to food to serve as a reservoir for nitrite. Nitrates occur naturally in plants for -hich it is a ,ey nutrient.  Nitrate and nitrite are also formed endogenously in mammals including humans. Nitrate is secreted in saliva and then converted to nitrite by oral micro flora.  Nitrate can reach both surface -ater and ground-ater as a conseuence of agricultural activity (including excess application of inorganic nitrogenous fertili#ers and manures) from -aste-ater  treatment and from oxidation of nitrogenous -aste products in human and animal excreta incl includi uding ng sept septic ic tan, tan,s. s. Nitr Nitrit itee can can also also be form formed ed chem chemic ical ally ly in dist distri ribu buti tion on pipes pipes by  Nitrosomonas bacteria  Nitrosomonas bacteria during stagnation of nitrate/containing and oxygen/poor drin,ing/-ater in galvani#ed steel pipes or if chloramination is used to provide a residual disinfectant and the  process is not sufficiently sufficiently -ell controlled.

OBJECTIVES

. To determine determine the concentra concentration tion of nitrate nitrate and and nitrite nitrite in the samples samples given. given. !. To understand understand the effect effectss of nitrate nitrate and nitrit nitritee in -aste-ater -aste-ater analysi analysis. s.

APPARATUS

0ea,ers sample cells ( inch1 2m&) rodblender spectrophotometer Nitri4er 3 reagent po-der   pillo- Nitri4er 5 reagent po-der pillo-.

PROCEDURES

6rocedure for nitrite . '-itch ON the spectrophotometer and select method of stored program (3+N Nitrite &% 66). !. $nsert the 7ulti/cell adapter -ith the /inch suare cell holder facing user. 3. 8ill a suare sample cell -ith 2m& of sample. 9. Add the contents of  Nitri4er 3 reagent po-der pillo-. '-irl to dissolve. 6in, colour -ill slo-ly develop if nitrite is present. :. 'et :/minute reaction time by press T$7;%
6rocedure for nitrate . '-itch ON the spectrophotometer and select method of stored program (3:N Nitrite &% 66). !. $nsert the 7ulti/cell adapter -ith the /inch suare cell holder facing user. 3. 8ill a !:/m& graduated mixing cylinder -ith :m& of sample. 9. Add the contents of  Nitri4er 5 reagent po-der pillo- to the cylinder stopper. :. 'et 3/minute reaction time by press T$7;%hen the time expires press T$7;%hen the timer expires carefully pour 2m& of the sample into a clean suare sample cell. ?o not transfer any cadmium particle to the sample. . 8or sample preparation add the content of one Nitri4er 3 reagent po-der pillo- to the sample. 2. 6ress T$7;%
'A76&; 0;8O%;(mg&) A8T;%(mg&)

A 2.222 2.25!

0 2.222 2.2+5

" 2.222 2.259

A 2.222 2.2+2

0 2.222 2.252

" 2.222 2.252

RESULTS

'A76&; 0;8O%;(mg&) A8T;%(mg&)  N$T%$T;

 N$T%AT;

DISCUSSION

8rom the results that -e have obtain the largest nitrite and nitrate values that -e have determine  by using the spectrophotometer are from sample 0. the reading sho-s the value of 2.2+5mg& for  nitrite and 2.25mg& for nitrate. ;ven though this value are still can be considered under the safety margin for the nitrate and nitrite value for the drin,ing -ater -hich is 2mg& (van ?uivenboden B 7atthisen *). Csually this value is cause by the agriculture plant or lea,ing in the sea-age system. Therefore this indicate that sample 0 is come from the area -here there are population and plantation exists. 8or sample A and sample " the amount of nitrate and nitrite reading is less than sample 0. -e can assume that this samples are ta,en from the upstream and do-nstream of the river. This is  because the -ater are not contaminated by the chemical. 0esides that -ater that being release by the -ater treatment plant also contributes to the value obtain by the sample. The proved is that the -ater that being released to the river have to be treated until it can be consumed by the environment. There are fe- factors that contributes to the increasing in the values of nitrate and nitrite in the -ater. The common source are from the agricultural runoff refuse dump runoff or contamination -ith human or animal -astes. The concentration often fluctuates -ith the season and may increase -hen the river is fed by nitrate/rich auifers. Nitrate concentrations have gradually increased in many ;uropean countries in the last fe- decades and have sometimes doubled over  the past !2 years. $n the Cnited =ingdom for example an average annual increase of 2.+ mgl has been observed in some rivers (Doung B 7organ/Eones *2). Fo-ever if the concentration of the nitrate and nitrite in the -ater exceeded the reuirement the -ater are dangerous to be consumed by the human body. 7ean-hile excess nitrate and nitrite in -ater also cause depletion of oxygen in the -ater. This -ill cause the auatic habitats to die and at the mean time effects the ecosystem.

 Nitrate can be removed from drin,ing -ater by three methodsG distillation reverse osmosis and ion exchange. Fome treatment euipment using these processes are available from several manufacturers. "arbon adsorption filters mechanical filters of various types and standard -ater  softeners do not remove nitrate/nitrogen. The distillation process involves heating the -ater to boiling and collecting and condensing the steam by means of a metal coil. Nearly 22 percent of the nitrate/nitrogen can be removed by this  process. 7erely boiling -ater -ill increase rather than decrease the nitrate concentration. >ater  -ithout nitrate is obtained by collecting and condensing the steam generated as the -ater boils.

$n the reverse osmosis process pressure is applied to -ater to force it through a semi/permeable membrane. As the -ater passes through the membrane filters out most of the impurities. According to manufacturersH literature from *: to : percent of the nitrate can be removed -ith reverse osmosis. Actual removal rates may vary depending on the initial uality of the -ater the system pressure and -ater temperature.

$on exchange for nitrate/nitrogen removal operates on the same principle as a household -ater  softener. $n a standard -ater softener calcium and magnesium ions are exchanged for sodium ions. Fo-ever for the nitrate removal process special anion exchange resins are used that exchange chloride ions for nitrate and sulfate ions in the -ater as it passes through the resin. 'ince most anion exchange resins have a higher selectivity for sulfate than nitrate the level of  sulfate in the -ater is an important factor in the efficiency of an ion exchange system for  removing nitrates.

CONCLUSION

$n conclusion -e have determined that the values of nitrate and nitrite of samples A 0 and " are less than the maximum amount of nitrate and nitrite that can be allo-ed -hich is 2mg&. from the experiment also -e assume that sample A and " coming from upstream and do-nstream of  the rivers mean-hile sample 0 is from main land.  Nitrate in drin,ing -ater can be a problem especially for infants. A -ater test is the only -ay to determine -hether the nitrate/nitrogen concentration is under the acceptable standard of 2 mg&. 6roper -ell location and construction are ,ey practices to avoiding nitrate contamination of  drin,ing -ater. 7anagement practices to reduce the ris, of contamination from applied fertili#ers help ,eep the -ater supply safe. $f drin,ing -ater exceeds the acceptable nitrate/nitrogen standard the choices are to use an alternate -ater supply or treat the -ater. An alternate supply may be bottled -ater for drin,ing especially for infant formula or a ne- -ell in a different location or auifer. >ater treatment options are distillation reverse osmosis or ion exchange.

REFERENCES

van ?uivenboden > 7atthisen AE"7 (*) Integrated criteria document nitrate. 0ilthoven  National $nstitute for 6ublic Fealth and the ;nvironment (%$47 %eport No. +:*9+32!). Doung "6 7organ/Eones 7 (*2) A hydrogeochemical survey of the chal, ground-ater of the 0anstead area 'urrey -ith particular reference to nitrate. Journal of the Institute of Water  Engineers and Scientists 39G!3I!35.