AN INTEGRATED PHYSICAL-BIOLOGICAL TREATMENT PLANT
FOR NITROGENOUS FERTILIZER WASTES
R. N. Chakrabarty, Specialist and Head
B. B. Bhalerao, Supervising Engineer
S. R. Alagarsamy, Senior Engineer
Engineers India Limited
New Delhi, India
INTRODUCTION
Fertilizer production in India has steadily increased during the past decade to increase
food production in the country.   The report of Fertilizer Association of India [ 1 ] gives
an estimate that nitrogen production would increase from 1476 x 103 tonnes in 1975-76
to 3065 x 103 tonnes in 1978-79.   This means that nitrogenous fertilizer production is
expected to be more than double within a short span of three years.  While the earlier
fertilizer plants in India were mostly designed to manufacture ammonium sulfate or nitrate,
the recent and future units are primarily designed to manufacture urea.
A survey carried out on the pollution potential of the nitrogenous fertilizer wastes in
India by Chakrabarty and Arceivala [2] and Bhalerao and Alagarsamy [3] indicated that
the loss of ammonia varied between 0.5 to 1% and that of urea from 1.5 to 1.75% of the
ammonia produced per day.   Ammonia and urea losses through the wastewaters of American fertilizer industries have also been reported by the U.S. EPA [4].  A summary of the
comparative figures are shown in Table I.
Table I. Wastewater Volumes and Nitrogen Losses in Fertilizer Plants
Volume
(gpd/ton NH3)
Loss
(kg/ton NH3/day)
Wastewaters and Contaminants
Indian
U.S.
Indian
U.S.
Process Wastes in Ammonia and 456-600 100-1000
Ammonium Salts Plant
Ammonia as NH3 - -                           4.65-10                 0.4-15.0
Process Wastes in Urea Plant 1100-1500 50-2000a
UreaasCO(NH2)j - -                            15-17.5                 0.8-28.0
aExcluding cooling water and boiler blowdown.
Ammonia and urea manufacturing processes have, however, improved considerably during the past few years and the ammonia and urea losses from a modern urea plant are now
less than 20% of those from a plant using older technology.   Recent developments in the
technology of thermal hydrolysis of urea contained in a dilute solution (above 4000 mg/1
urea) and recycling the recovered ammonia back into the process have shown a promise of
further reducing the nitrogen loss from a fertilizer plant [5].
The two fertilizer factories of the National Fertilizers Ltd., which are currently under
construction at Bhatinda and Panipat in the states of Punjab and Haryana in India, and
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