Oil-contaminated waste water treatment
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Satbayev University, Almaty, Kazakhstan
Association «KAZENERGY», Nur-Sultan, Kazakhstan
JSC OC «KazMunaiGas», Nur-Sultan, Kazakhstan
Publication date: 2021-09-27
Public Health Toxicol 2021;1(Supplement 1):A40

Wastewater from industrial production, as well as from enterprises for the extraction and processing of oil, containing organic substances, polluting groundwater and rivers through the soil is one of the main environmental problems.
Effective technologies of wastewater treatment from these enterprises and bringing them to production standards for further use is one of the most important tasks of environmental protection.
In this work, to solve the noted problem, a purification method has been developed, including the addition of a coagulant based on an aluminum-containing component, followed by thickening and filtration of the precipitate. Rau-85 aluminum alloy was used as the aluminum-containing component. The aluminum alloy is used in the form of a powder that is stable in air. Alloy composition (wt%): 85 aluminum, 5 indium, 5 gallium and 5 tin. The method takes place in one stage, it is environmentally friendly, since it does not require large amounts of coagulant (10-50 g/t). When the alloy is added to oily waste water, it actively interacts with water with the formation of a precipitate of metal hydroxides that sorb polluting oil molecules. The formation of hydroxides of aluminum and other metals included in the alloy occurs with the release of hydrogen and heat. The release of hydrogen creates an additional effect of gas flotation. Higher efficiency of separation of oil impurities is achieved by increasing the efficiency of collision and adhesion of oil droplets, which are smaller in size of gas bubbles. The presence of coagulants promotes coalescence of the droplets, which increases the probability of collision and adhesion with gas bubbles. Hydrogen evolution turbulence results in better collision and trapping of bubbles and oil droplets. Treatment of oily wastewater is carried out within 30 minutes; the formed precipitate is filtered. The oily wastewater treatment process is carried out on standard equipment at room temperature.
Studies on oily, low-mineralized wastewater from enterprises producing bitumen (oil content from 4.01-17.79 mg/l, salt content 500 mg/l) showed that for wastewater with a high oil content - 110 mg/l with the use of a coagulant in a wide in the pH range from 5.5 to 10, the oil removal efficiency was 98.6% (residual oil content 1.6 - 3 mg/l). For wastewater with an oil content of 4.0-17.8mg/l, the oil removal efficiency was 92.7%. The reagent effectively coagulates oil at pH 7, temperature 25˚C and flow rate 10g/t. Apparently, with an increase in the concentration of oil in water, the probability of collision of colloids increases, which possibly leads to a greater removal of oil.