85    PILOT AND FULL SCALE TREATABILITY STUDIES ON
WASTEWATERS FROM AN EDIBLE OIL REFINING
INDUSTRY
Izzet Ozturk, Associate Professor
Hasan Ali San, Associate Professor
Veysel Eroglu, Associate Professor
Environmental Engineering Division
Department of Civil Engineering
Istanbul Technical University
80626, Maslak
Istanbul, TURKEY
INTRODUCTION
Increased concern over a clean environment by public and authorities, is forcing the implementation of stringent regulations in improving the quality of environment not only in industrialized but in
also developing countries. The role of industry has the major impact both in deterioration and
preservation of the quality of natural sources. Any country is also affected by the results of these
adverse effects on environment since pollution is international. The scope of this chapter is to evaluate
the characteristics and treatability of process wastewaters from an edible oil refining industry, which
was installed in a nonresidential area in 1950s but now has become surrounded by a metropolitan
city.
The process of edible oil refining includes neutralization of free fatty acids, removal of gummy
materials, deodorization and color removal stages. First three stages of refining is carried out in the
same reactor as a batch process that produce a soapstock from which fatty acids are recovered by
means of acids splitting. Acids splitting is carried out by addition of sulfuric acid to the soapstock
which causes the free fatty acids to be separated from the medium. The resulting effluent is highly
acidic, with an average pH of 1.7, and S042" content of 4,000 mg/L constitutes the main source of
process wastewaters.
The main object was to design a treatment plant that would produce an effluent having a five day
biochemical oxygen demand (BOD5) below 250 mg/L prior to discharge to municipal sewer system.
Because of the lack of satisfactory design criteria, we decided that a multilateral treatability study,
including physicochemical and biochemical phases, would be useful; consequently, investigations
were continued about one and half years.
WASTE CHARACTERIZATION
Waste characterization includes flow rate measurements and determination of effluent parameters.
Hourly flow rate fluctuations were monitored for two weeks by means of a triangular weir installed
on the main discharge channel. Results of these measurements are shown in Figures 1 and 2. Investigation of flow rate variations for different days in Figure 1 shows that maximum and minimum values
do not differ too much from the average. Daily averages are illustrated in Figure 2. It is observed from
this figure that average flows for a ten day period are almost around 7.1 cubic meter per hour.
Maximum deviation is observed once in ten days and is equal to 10 m3/h. Minimum value is about 5
m3/h and is observed twice.1
Acidic discharge contains materials such as fatty acids, neutral oil, protein, glycerol, and glyceride.
This waste is considered to be harmful to concrete even after neutralization. The volume of acidic
wastewater is approximately 0.5 to 0.6 mVton edible oil. Wastewater samples from related industry
were collected and analyzed for the parameters considered to be necessary for waste characterization,
and summarized in Table I. As indicated in Table I, wastewaters from edible oil industry are high in
organic loading (0.85-1.42 Kg BOD5/ton edible oil). Investigations showed that there are strong
44th Purdue Industrial Waste Conference Proceedings, © 1990 Lewis Publishers, Inc., Chelsea, Michigan 48118.
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