81    A WAY FOR WATER POLLUTION CONTROL IN DYE
MANUFACTURING INDUSTRY
An Huren
China-Japan Friendship Environmental Protection Centre
Peoples Republic of China
Qian Yi, Professor
Gu Xiasheng, Professor
Tsinghua University, Beijing, Peoples Republic of China
INTRODUCTION
With development of industry and improvement of human life, more and more dyes are used and
needed. Nowadays most of the dyes used are synthetic, which inevitably cause serious environmental
pollution in many ways. Water pollution is one of the most serious problems. Dye wastewater, with
strong color, contains a large quantity of chemicals, some of them are even toxic or refractory.
Without suitable treatment, it will seriously influence the water body and endanger human life. This
problem brings to researchers and industrial workers much attention, and many treatment methods
including chemical, biological methods etc. have been researched or already used.1'2 Because of its
high cost, chemical process is acceptable only for treating a small amount of highly polluted water.
The biological treatment method is promising due to its comparatively low cost and is widely used.
But it is still not satisfactory for removal of color and refractory chemicals, especially under aerobic
condition. In many factories aerobic processes are used the most. The efficiency is limited because
some organic chemicals are refractory in aerobic condition.
Tests on anaerobic treatment of some industrial wastewater have shown that anaerobic biological
process can attack the structure of some refractory organic compounds,3,4 and therefore the biode-
gradability of these compounds could be improved. A few studies on anaerobic treatment of dye
industrial wastewater obtain similar result.
The purpose of this study is to investigate the biodegradability of dyes both in aerobic and anaerobic conditions and then to explore a proper system for the treatment of dye industrial wastewater.
MATERIAL AND METHODS
Twenty-six water soluble dyes were tested in the study, including five direct, six reactive, four acid,
two mordant, and nine basic dyes. Their chemical structure includes triarylmethane, azo, heterocycle
and the others. A dye wastewater from C.I. Acid Blue 7, C.I. Basic Green 4 etc. producing workshops
and an artificial domestic sewage containing glucose and other gradients (COD:N:P = 200:5:1) were
treated. The composition of the dye wastewater is shown in Table I. The dye wastewater from the
workshops had been neutralized in the factory.
Biodegradability of those dyes was tested aerobically by static flask screening test, Warburg respi-
rometer and semicontinuous flow activated sludge system; and anaerobically by batch and continuous
flow anaerobic digesters.
The dye wastewater was treated in an anaerobic-aerobic system with UASB reactor as anaerobic
reactor and aeration tank as aerobic reactor. The whole system is shown in Figure 1.
Table I.    Composition of the Dye Wastewater
SS (mg/L)
pH              COD (mg/L)          Color          NH4-N (mg/L)
BOD5 (mg/L)
55
7.0-7.2                   2500                  5000                       0
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49th Purdue Industrial Waste Conference Proceedings, 1994 Lewis Publishers, Chelsea, Michigan 48118. Printed in
U.S.A.
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