Electro-kinetic dewatering of oily sludges

Yang, Lin; Nakhla, George; Bassi, Amarjeet

doi:10.1016/j.jhazmat.2005.05.040

Cited by 91 publications

(64 citation statements)

References 14 publications

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“…However, the use of this method has only been reported for separating "oil" phase of sludge, in which the weight fraction of oil is 22.9 (wt%), and is not suitable for the release of water in oily sludge produced from flotation. Most other dewatering approaches for treating sludge have poor applicability and effectiveness; for example ultrasonication [11] is very difficult to perform and electro-kinetic treatment [12,13] consumes relatively high amounts of energy. It can be seen, therefore, that existing methods for the release of water are currently quite inefficient with regard to their application in oilfields at the industrial scale.…”

Section: Introductionmentioning

confidence: 99%

Improvement of acidification on dewaterability of oily sludge from flotation

Guo

et al. 2011

Chemical Engineering Journal

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a b s t r a c tThis paper presents the improvement of acidification on the dewaterability of oily sludge from a flotation process. Various parameters, including the volume of supernatant water, capillary suction time (CST), and specific resistance to filtration (SRF) were used to evaluate the dewaterability of oily sludge. In addition, floc size distribution and release rates of Al(III) were used to explain skeleton breakage as a result of the acidification treatment. Results show that dewaterability increased obviously as the sludge pH decreased. After 120 min of settling, the volume of supernatant water reached 77% at pH 4.0. Maximum reductions in CST and SRF were 93.1% and 89.2%, respectively. Following acidification, the flocs in the oily sludge achieved a broader particle size distribution and a smaller median diameter [d (0.5)] of 36.0 m (cf. 74.4 m for the raw sample). In addition, lower pH led to a greater rate of release of Al(III). This study verifies that the floc skeleton of oily sludge can be broken through the dissolution of aluminum hydroxide; i.e., acidification enhances the dewaterability of oily sludge by changing the floc structure. All results indicate that acidification is advisable as a pretreatment of oily sludge.

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Section: Introductionmentioning

confidence: 99%

Improvement of acidification on dewaterability of oily sludge from flotation

Guo

et al. 2011

Chemical Engineering Journal

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“…It has been proven that the energy saving by EOD is about 75% compared with vaporization of water [4]. The technique has been used for concentration of food materials [5][6][7][8], activated sludge [9][10][11], contaminated sediment [12] and organic soil [13].…”

Section: Introductionmentioning

confidence: 99%

Treatment of Olive-Mills effluent using Electro-osmosis Dewatering

Al‐Asheh¹,

Juma²,

Banat³

et al. 2011

Hydrol Current Res

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Direct current is applied to olive mill wastewater effluent which is held between two electrodes in a vertical mode. Wastewater with a total dissolved solid and COD of about 39,300 and 120,000 mg/l, respectively, is used. The effect of pH, voltage, current, and bed height on the dewatering process is investigated. The results, under certain conditions, showed that EOD is an energy saving process for water removal and can be used for treatment of olive mill wastewater. The process revealed high efficiency in reducing COD and total dissolved solid (TDS). Water medium converted from acidic to basic upon application of direct current. Increasing the voltage or the current enhanced the EOD process. Use of additives at certain level also enhanced the dewatering process; addition of alum or electrolyte at certain concentration enhanced the removal rate. Sodium chloride is the most effective electrolyte in EOD process. The on/off test, although saves energy, but did not perform better in the term of percentage water removal compared to that of the continuous process, without on/off test.

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“…Electrokinetic process utilizes a low-intensity direct current across an electrode pair on each side of a porous medium, causing the electro osmosis of liquid phase, migration of ions and electrophoresis of charged particles in a colloidal system to the respective electrode (Virkutyte et al, 2002;Yang et al , 2005). The separation of different phases (water, oil, and solids) from oily sludge using electrokinetic process can be based on three main mechanisms.…”

Section: Electrokinetic Methodsmentioning

confidence: 99%

“…The separation of different phases (water, oil, and solids) from oily sludge using electrokinetic process can be based on three main mechanisms. Firstly, colloidal aggregates in oily sludge can be broken under the influence of an electrical field, leading to the movement of colloidal particles of oily sludge and solid phase towards the anode area as a result of electrophoresis, and the movement of the separated liquid phase (water and oil) towards the cathode area as a result of electroosmosis (Yang et al, 2005). As mentioned before, oily sludge is a W /0 emulsion stabilized by several kinds of emulsifiers such as asphaltenes, resins, organic acids, and finely divided solids.…”

Section: Electrokinetic Methodsmentioning

confidence: 99%

“…Elektorowicz and Habibi (2005) applied electrokinetic process to treat oily sludge, and they found that this process could reduce the amount of water by nearly 63% and light hydrocarbon content by about 43%, and the light hydrocarbon content was removed by 50% when combining electrokinetic treatment with surfactant. Yang et al (2005) conducted an oily sludge dewatering study using electrokinetic treatment, and their results showed that the water removal efficiency reached to 56.3% at a 4 cm electrode spacing and an electric potential of 30 V, while the solids content at the anode area increased from 5 to 14.1 %. A larger-scale experimental study (i.e.…”

Section: Electrokinetic Methodsmentioning

confidence: 99%

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Development of novel oil recovery methods for petroleum refinery oily sludge treatment

Hu¹

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Oily sludge is one of the most significant wastes generated in the petroleum industry.It is a complex emulsion of various petroleum hydrocarbons (PHCs), water, metals, and fine solids. Due to its hazardous nature and increased generation quantities around the world, the effective treatment of oily sludge has attracted widespread attention. The complexity of its composition and diversity of its origin sources make oily sludge management a difficult and costly undertaking. Many methods have been developed for the treatment of oily sludge through oil recovery or sludge disposal approaches, but no single specific process can be considered as a panacea since each method is associated with different advantages and limitations. Efforts should focus on the improvement of current technologies and the combination of oil recovery with sludge disposal in order to comply with both resource reuse recommendations and environmental regulations. The object of this study was to develop novel combined methods for oil recovery treatment on different refinery oily sludges. The investigation focused on the oil recovery performance of combined methods based on four individual treatment processes including ultrasonic irradiation, solvent extraction, freeze/thaw, and pyrolysis in oily sludge treatment.Firstly, the oil recovery and salt removal effects of ultrasonic irradiation on oil refinery tank bottom sludge were investigated, together with those of direct heating.Ultrasonic power, treatment duration, sludge-to-water ratio, and initial sludge-water slurry temperature were examined for their impacts on sludge treatment. It was found that the increased initial slurry temperature could enhance the ultrasonic irradiation performance, especially at lower ultrasonic power level (i.e., 21 W), but the application of higher-power ultrasonic irradiation could rapidly increase the bulk temperature of slurry. Ultrasonic 2 irradiation had a better oil recovery and salt removal performance than direct heating treatment. More than 60% of PH Cs in the sludge was recovered at an ultrasonic power of 75 W, a treatment duration of 6 min, an initial slurry temperature of 25 °C, and a sludgeto-water ratio of 1 :4, while salt content in the recovered oil was reduced to <5 mg/L, thereby satisfying the salt requirement in refinery feedstock oil. In general, ultrasonic irradiation could be an effective method in terms of oil recovery and salt removal from refinery oily sludge, but the separated wastewater still contains relatively high concentrations of PH Cs and salt which requires proper treatment.Two types of ultrasonic assisted extraction (UAE) treatment including UAE probe (UAEP) system and UAE bath (UAEB) system were investigated for oil recovery from refinery oily sludge. Their oil recovery efficiencies were compared to that of mechanical shaking extraction (MSE). Three solvents including cyclohexane (CHX), ethyl acetate (EA), and methyl ethyl ketone (MEK) were examined as the extraction solvents. The influence of experimental factors on oil an...

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Electro-kinetic dewatering of oily sludges

Cited by 91 publications

References 14 publications

Improvement of acidification on dewaterability of oily sludge from flotation

Improvement of acidification on dewaterability of oily sludge from flotation

Treatment of Olive-Mills effluent using Electro-osmosis Dewatering

Development of novel oil recovery methods for petroleum refinery oily sludge treatment

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