65    TREATMENT OF HIGH NITROGEN (NaN02) WASTEWATER
BY BIOLOGICAL NITRIFICATION/DENITRIFICATION
Satish Kamath, Associate Engineer
James M. Montgomery, Consulting Engineers Inc.
Pasadena, California 91101
David A. Sabalini, Assistant Professor
School of Civil Engineering and Environmental Science
The University of Oklahoma
Norman, Oklahoma 73019
Larry W. Canter, Director
Environmental and Ground Water Institute
The University of Oklahoma
Norman, Oklahoma 73019-0470
INTRODUCTION
Nitrogen in its various forms can be of concern relative to water quality. If excess ammonia is
present in a water body it can deplete the dissolved oxygen in the process of being oxidized to nitrite or
nitrate. Nitrite in acidic solution can react with secondary amines to form nitrosamines which are
carcinogens. Nitrate is of concern because it is the agent causing methemoglobinemia, a disease
affecting infants. Thus, there is a need to develop economical treatment methods to treat wastewaters
contaminated with various forms of nitrogen. This paper presents the findings of the bench scale
studies conducted to evaluate the feasibility of using a suspended growth biological system to treat a
wastestream containing high sodium nitrite (1,200 mg/L as N02). The wastewater also contained
heavy metals, which are of concern because of the detrimental effects they have on the aquatic and
terrestrial life.
BACKGROUND
Sodium nitrite (NaN02) is typically added to boiler tube water in many U.S. Navy ships, because of
its excellent corrosion inhibition properties. Routine cleaning of the ship boiler tubes by hydroblasting
(injection of water into the tubes at very high pressures) results in the production of a wastestream
with a high concentration of sodium nitrite (as high as 1200 mg/L as N02) and low concentrations of
heavy metals. The U.S. Navy has been transporting the wastewater offsite for treatment and disposal,
resulting in relatively high expenditures. Hence, a need existed to evaluate various on-site treatment
methods for this wastewater. This research evaluated the use of several suspended growth biological
systems for treating the high sodium nitrite wastewater. The general objective was to evaluate the
feasibility of using biological denitrification in treating U.S. Navy boiler tube wastewater. The specific research objectives were:
1. To   compare   two   biological   processes   (direct   denitrification   and   nitrification/
denitrification) in their ability to treat the high nitrite wastewater.
2. To evaluate the impact of metals on the biological process and to determine the removal
of metals across the process.
3. To assess the nitrite removal efficiencies with increasing sludge ages and comparison of
the nitrite removal efficiencies with actual and synthetic wastewater.
A review of the pertinent literature was conducted to determine the main factors influencing
nitrification/denitrification and to establish typical values of these factors. The factors are pH, solid
retention time(SRT), hydraulic retention time(HRT), temperature, type and quantity of carbon
source and nutrients. Typical pH values used for denitrification vary between 7 and 7.5.' The solid
retention time used in denitrification varies between 1 to 5 days,2-3 and hydraulic retention time varies
46th Purdue Industrial Waste Conference Proceedings, 1992 Lewis Publishers, Inc., Chelsea, Michigan 48118.
Printed in U.S.A.
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