Disposal of Titanium Dioxide Waste in a
Stratified Estuary
TERJE SIMENSEN, Chief Sanitary Engineer
PAUL LISETH, Sanitary Engineer
The Norwegian Institute for Water Research
Oslo, Norway
INTRODUCTION
The Norwegian Institute for Water Research was consulted by the Titan Company A/S, Fredrikstad, Norway, a producer of titanium dioxide, to help find a
solution to its waste disposal problems in the estuary of the Glomma River.
Based on observations of the waste properties and the exchange mechanism of
water in the estuary, a proposal for the functional design of a disposal arrangement was presented by the Institute in 1965.
The plans were agreed upon by the Central River Authorities, a detailed design carried out by a private consulting firm, and the construction completed by
the summer of 1966. The Institute then carried out an efficiency study of the
disposal system.   This outfall system is the subject of this paper.
THE GLOMMA RIVER
The Glomma River is the largest river in Norway, with a catchment area of
41,425 sq km (16, 000 sq mi) and an average flow in its lower part just below 700
cu m/sec (25, 000 cfs).
Near the river mouth at the City of Fredrikstad, in south eastern Norway, the
river runs through a rather heavy industrialized area for Norwegian conditions.
The estuarial part of the river has a maximum length of about 13 km (Figure
1). With an average tidal amplitude in the area of 13 cm, the ratio of freshwater
volume to the tidal prism is 17:1. According to Ippen (1) such a large ratio corresponds to a high degree of stratification. This situation gives rise to a considerable inflow of salt-water through the salt-water wedge along the river bottom, and
continuous transport of salt through the water interface (Figure 2).
Through a series of observations of temperature, salinity and velocity distribution with depth along the estuary, under varying flow conditions, there were
established relations between seaward transport of salt-water, level of water interface and freshwater flow. Near the river mouth, at the point of waste disposal
from Titan A/S, such relations are given (Figures 3 and 4).
It can be seen in Figure 3 that additional dilution water due to salt-water intrusion is 43 per cent at a fresh water flow of 400 cu m/sec and about 30 per cent
at 900 cu m/sec. In the region of 1,000 to 1,100 cu m/sec the fresh water causes
a complete flushing of the estuary. The form of the transition zone on the flow-
line in Figure 3 is, however, unknown due to lack of observations under periods
with this critical fresh water flow.
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