Section 7.   TEXTILE WASTES
TREATMENT OF WOOL SCOUR WASTEWATER:
RECENT TRENDS IN NEW ZEALAND
Francis Wilson, Professor
Department of Civil Engineering
University of Canterbury
Christchurch, New Zealand
Paul H. King, Professor
Department of Civil Engineering
and Engineering Mechanics
University of Arizona
Tucson, Arizona 85721
INTRODUCTION
The land mass of New Zealand is comprised of two major and a number of minor islands close to
175° longitude and in the mid latitudes. The land is geologically active, the collision of two tectonic
plates creating mountainous regions, especially in the South island. In addition, volcanic eruptions in
recent geologic time has led to rolling hilly landscapes, particularly in the North island. The relative
scarcity of high quality, low level farmland, coupled with the even distribution of rain throughout the
year, encouraged the early European settlers to raise sheep, in many instances burning the existing
ground cover to establish pastures. The introduction of Merinos in the 1840s was followed by
Southdowns, Leicesters, Lincolns and Romneys from Britain in the 1860s. The success of refrigerated
shipments of mutton and lamb in 1882 led to moves away from the Merino and Merino crosses, which
were suitable for wool (and tallow), and toward the introduction of Romneys, Corriedales and
crossbreeds. New Zealand currently has a sheep population of approximately 66 million sheep and
lambs, with the major breeds being predominantly Romneys in the North island, Merino crosses in the
dryer part of the South island mountains, Corriedales in the better hill country, and long wooled
British breeds and crossbreeds at lower levels [1].
New Zealand is ranked third in the world as a wool producer and second as a wool exporter of
mainly cross-bred wool. Total exports vary, but average 334,000 tonnes per year (1977-81) with a net
worth of $NZ 0.94 billion per year (1981). Table I shows the value to the New Zealand economy of
greasy and scoured wool compared with other major exports [1], and Table II shows the growth in the
quantity of wool scoured [1].
The dispersed nature of wool production in New Zealand coupled with the very small human
population (3.2 million in 1981) leads to the wool scour industry being scattered through six major
provinces and producing grossly polluting localized discharges of scour liquors which often outweigh
the BOD contribution from the local population. Depending on the method used to scour the wool,
the 136,000 tonnes scoured in 1981 is estimated to produce 8 x 10* kg BOD5 and 3 x 107 kg COD.
The human population would contribute perhaps 8 x 107 kg BOD5, but this would be spread evenly
throughout the year.
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