sewage collection and treatment systems or, if discharged directly to surface waters,
on the receiving water use classification.
There are some precautions for the prevention of process wastewater which are
listed below:
• Emulsion breaking techniques (e.g., dissolved air flotation (DAF)) should be used
to remove high BOD and COD oils from wastewater.
• Condensates should be recycled.
• Grids are needed to be used to protect drains in the production area and to prevent
solid wastes and concentrated liquids from entering the wastewater stream.
• The dose and application of cleaning chemicals should be carefully determined
and applied.
• Cleaning-in-place procedures should be carefully prepared and applied to help
reduce chemical, water, and energy consumption in cleaning operations.
• Cleaning solutions (e.g., through a soap-splitting process) should be properly
treated and discharged to separate oil and fatty acids from the water phase and
then through a fat trap.
• Phosphoric acid may be replaced with citric acid in degumming operations if
feasible; thus, the phosphorus load in the wastewater is reduced and a small
reduction in sludge quantities occurs.
3.3 Wastewater Treatment
Treatment of industrial wastewaters is difficult and generally requires chemical or
physicochemical treatment prior to biological treatment or discharge to a sewer
system. Wastewaters from the vegetable oil refining processes fall in this category.
The operating conditions and processes carried out influence the amount and characteristics of the by-products and wastes produced. The wastewater varies both in
quantity and characteristics from one oil industry to another. The composition of
wastewater from the same industry also varies widely from day to day [17]. These
fluctuations may also be attributed to different types of oils processed. Because of
quantity and characteristic variations and complexity, wastewater treatment to meet
the desired effluent standards is complicated, and the selection of wastewater
treatment method depends on various local conditions and, therefore, cannot be
standardized. Treatability studies become very important at this point and must be
performed to describe wastewater characteristics before selecting any pretreatment
process to treat wastewater containing emulsified oil and grease wastewater. Thus,
an oil-grease removal process can be designed efficiently and effectively [18].
Oily wastewater treatment in many respects is similar to the treatment domestic of
wastewater. Firstly, settleable solids are removed in domestic wastewater treatment
plant. Similarly, for the treatment of vegetable oil refining wastewaters, the separation of free-floating oil from disperse emulsified and soluble fractions is performed at
the first stage of wastewater treatment. At the second stage of treatment, oil-water
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D. Kaya and Y.-T. Hung
on the receiving water use classification.
There are some precautions for the prevention of process wastewater which are
listed below:
• Emulsion breaking techniques (e.g., dissolved air flotation (DAF)) should be used
to remove high BOD and COD oils from wastewater.
• Condensates should be recycled.
• Grids are needed to be used to protect drains in the production area and to prevent
solid wastes and concentrated liquids from entering the wastewater stream.
• The dose and application of cleaning chemicals should be carefully determined
and applied.
• Cleaning-in-place procedures should be carefully prepared and applied to help
reduce chemical, water, and energy consumption in cleaning operations.
• Cleaning solutions (e.g., through a soap-splitting process) should be properly
treated and discharged to separate oil and fatty acids from the water phase and
then through a fat trap.
• Phosphoric acid may be replaced with citric acid in degumming operations if
feasible; thus, the phosphorus load in the wastewater is reduced and a small
reduction in sludge quantities occurs.
3.3 Wastewater Treatment
Treatment of industrial wastewaters is difficult and generally requires chemical or
physicochemical treatment prior to biological treatment or discharge to a sewer
system. Wastewaters from the vegetable oil refining processes fall in this category.
The operating conditions and processes carried out influence the amount and characteristics of the by-products and wastes produced. The wastewater varies both in
quantity and characteristics from one oil industry to another. The composition of
wastewater from the same industry also varies widely from day to day [17]. These
fluctuations may also be attributed to different types of oils processed. Because of
quantity and characteristic variations and complexity, wastewater treatment to meet
the desired effluent standards is complicated, and the selection of wastewater
treatment method depends on various local conditions and, therefore, cannot be
standardized. Treatability studies become very important at this point and must be
performed to describe wastewater characteristics before selecting any pretreatment
process to treat wastewater containing emulsified oil and grease wastewater. Thus,
an oil-grease removal process can be designed efficiently and effectively [18].
Oily wastewater treatment in many respects is similar to the treatment domestic of
wastewater. Firstly, settleable solids are removed in domestic wastewater treatment
plant. Similarly, for the treatment of vegetable oil refining wastewaters, the separation of free-floating oil from disperse emulsified and soluble fractions is performed at
the first stage of wastewater treatment. At the second stage of treatment, oil-water
338
D. Kaya and Y.-T. Hung