53    LIME TREATMENT AND AMMONIA VOLATILIZATION
FOR INDUSTRIAL WASTEWATERS
Robert Kaszas, Project Engineer
Robert C. Harries, Manager
Earl E. Shannon, Manager
CH2M HILL Engineering Ltd.
Waterloo, Ontario, Canada
INTRODUCTION
Many industries that discharge to surface water courses are faced with stringent discharge criteria.
One of the parameters that is frequently regulated is ammonia nitrogen (NH3).
When wastewaters containing NH3 are discharged to surface waters, oxygen depletion of the
receiving water can occur as the NH3 is oxidized to nitrate and nitrite. NH3 is also toxic to some
aquatic species at relatively low concentrations and it is also a nutrient for aquatic plants such as
algae. As such it contributes to the aesthetic degradation and low dissolved oxygen concentration of
surface waters that are affected by nuisance algal blooms.
Some industries that discharge to particularly sensitive surface waters are also prohibited from
discharging their effluent during certain times of the year. These industries must therefore store their
wastewater onsite and await the onset of the discharge period. Algal blooms in the storage ponds
contribute to elevated biochemical oxygen demand (BOD5) and elevated total suspended solids (TSS)
concentrations in the impounded wastewater.
The two industries which are discussed in this paper, a rendering facility and a poultry processing
plant, discharge their treated wastewater to sensitive water courses, and must impound their wastewater for seasonal discharge. Both plants have full primary and secondary treatment facilities, but
neither plant has been able to achieve an effluent NH3 concentration suitable for discharge during the
winter months. Both have problems with toxic levels of NH3 in their effluent and algal blooms in their
ponds.
This paper describes the successful implementation of lime stripping for NH3 removal at these
facilities.
NITROGEN REMOVAL
There are three main NH3 removal processes currently in use in wastewater treatment, biological
nitrification, breakpoint chlorination, and air stripping.
BIOLOGICAL NITRIFICATION
Nitrification is the biologically mediated oxidation of NH3 to nitrite, and of nitrite to nitrate. The
process relies on the bacteria, nitrosomonas and nitrobacter to convert NH3 to nitrite, and nitrite to
nitrate, as indicated below.1
Nitrosomonas
NH4+  + 3/2 02 N02+  + 2H+  + H20 (1)
Nitrobacter
N02 +  + 1/2 02     N03+ (2)
Nitrification is achieved by maintaining the conditions in a biological reactor that would encourage
the growth of these organisms.
The process has some disadvantages:
46th Purdue Industrial Waste Conference Proceedings, 1992 Lewis Publishers, Inc., Chelsea, Michigan 48118.
Printed in U.S.A.
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