A method for oil-containing wastewater resource utilization

Abstract

The present disclosure relates to the technical field of oily wastewater treatment, and particularly relates to a method for oily wastewater resource utilization, a method for oily wastewater resource utilization, which comprises the following steps: S1: adding oily wastewater into a reaction kettle and stirring for 1-2 hours, and meanwhile, CO2 is introduced into the reaction kettle to keep the reaction kettle in positive pressure; S2: releasing the pressure in the reaction kettle to normal pressure, adding sodium carbonate powder into the reaction kettle and stirring; S3: adding an oleophilic adsorbent into the reaction kettle, and stirring the reaction kettle at room temperature and negative pressure for 1-2 hours; S4: filtering the mixed liquid after stirring in the reaction kettle through a water phase filter, and the purified water phase flows out from the bottom of the filter; S5: transferring the filter residue to a centrifuge for centrifugal treatment; S6: transferring the centrifuged oil phase to an oil storage tank, and recycling the solid material after centrifugation to S3 for continuously adsorbing oily substances.

Description

TECHNICAL FIELD

[0001] The present disclosure relates to the technical field of oily wastewater treatment, and particularly relates to a method for resource utilization of oily wastewater. BACKGROUND

[0002] Industrial wastewater is widely sourced, mainly including: oilfield wastewater, petrochemical wastewater, food processing wastewater, metal cutting fluid wastewater, and tannery wastewater, etc. These industries are water-consuming and pollution-discharging big-hitters in China. Industrial wastewater refers to wastewater and waste liquid generated in industrial production, which contains industrial production materials, intermediate products, by-products, and pollutants generated in the production process.

[0003] The oil substances contained in oily wastewater include natural oil, petroleum products, tar and its fractions, as well as edible animal and vegetable oil and fat. In terms of water pollution, the main ones are oil and tar. The concentration of oil substances contained in wastewater discharged by different industrial departments varies greatly, and industrial oily wastewater often contains various toxic substances. In recent years, the continuous discharge of industrial oily wastewater and the frequent occurrence of oil spill accidents have led to increasingly serious oil-water pollution problems, which not only cause catastrophic damage to the ecological environment, but also pose a serious threat to human health. Therefore, the deep purification of oily wastewater has become a problem that must be solved in industry. The treatment methods of industrial wastewater are different for different industries and different sources of industrial wastewater. The appropriate treatment method should be selected according to the actual source, yield, content, etc. of the industrial wastewater, and at the same time, the treatment and utilization of sludge and residues generated in the wastewater treatment process, the possible secondary pollution problems, and the recycling of flocculants should also be considered. Common industrial wastewater treatment methods include chemical treatment, biological treatment, physical treatment, and physical-chemical comprehensive treatment.

[0004] A multi-stage interception type filtration method is disclosed in Chinese patent with the authorization announcement No. CN106430674A, which includes three-stage filtration of oily wastewater in sequence through a corrugated inclined plate filtration unit, a coarse granulation filtration unit, and an ultrafiltration membrane filtration unit. The oily wastewater flows through the corrugated inclined plate filtration unit to remove most of the floating oil, suspended particulate matter, and part of the dispersed oil. The effluent enters the coarse granulation filtration unit, and the fine dispersed oil and part of the emulsified oil are removed by the coarse granulation process, while the fine particles are further settled and treated. Finally, the emulsified oil and dispersed oil are removed by the ultrafiltration membrane filtration unit, which is discharged or recycled. The present invention is stable and reliable, with oil content in the effluent not exceeding 5 ppm, COD removal rate of more than 85%, and SS removal rate of more than 97%. No chemical agents are used, and there is no secondary pollution. However, the process flow of this method is complex, and the water pressure difference is difficult to control. SUMMARY

[0005] In view of the deficiencies of the prior art, the present disclosure provides a method for oil-containing wastewater resource utilization, which is simple, green and economical, can separate oil and water in the oil-containing wastewater, and can also recycle the oil phase, having good environmental and economic benefits.

[0006] The technical solution adopted by the present disclosure to solve the above technical problems is: a method for oil-containing wastewater resource utilization, comprising the following steps:

[0007] S1: adding oil-containing wastewater into a reaction kettle and stirring for 1-2 hours, while introducing CO2 into the reaction kettle to maintain positive pressure in the reaction kettle;

[0008] S2: releasing the pressure in the reaction kettle to normal pressure, adding sodium carbonate into the reaction kettle and stirring;

[0009] S3: adding an oleophilic adsorbent into the reaction kettle, and stirring the reaction kettle at room temperature and negative pressure for 1-2 hours;

[0010] S4: filtering the mixed liquid after stirring in the reaction kettle through a water phase filter, and letting the purified water phase flow out from the bottom of the filter;

[0011] S5: transferring the filter residue to a centrifuge for centrifugal treatment;

[0012] S6: transferring the centrifuged oil phase to an oil storage tank, and recycling the solid material after centrifugation to S3 for continuous adsorption of oily substances.

[0013] In S1, the stirring temperature is 70-90℃, too low temperature will not improve the aggregation efficiency of oily substances in the liquid phase, and too high temperature will reduce the solubility of CO2, which is not conducive to the aggregation of oily substances; the stirring speed is 100-400r / min, a stirring speed lower than this range will increase the aggregation time of oily substances in the liquid phase, thereby increasing the operating cost; a stirring speed higher than this range will easily disperse the aggregated oily substances again. The positive pressure in the reaction kettle is 0.2-0.4MPa, a certain positive pressure in the reaction kettle is to accelerate the aggregation rate, when the positive pressure is lower than 0.2MPa, the aggregation phenomenon is not obvious, and when the positive pressure is higher than 0.4MPa, the operating cost increases with the increase of the pressure, but the aggregation efficiency is almost not improved.

[0014] Introducing CO2 in S1 has two effects, one is that CO2 can cause the aggregation of oily substances in the oil-water mixture, and the other is that it provides positive pressure, which is conducive to accelerating the generation of aggregation phenomenon, since the oily substances are mainly carbon-oxygen bonds, the composition of the oily substances will not be damaged, if other gases such as NO2, SO2 and O2 are introduced, secondary pollutants such as nitrate and sulfate will be produced. If inorganic inert gas such as N2 is added, it will not have the effect of aggregating oily substances, therefore, introducing CO2 to maintain positive pressure is a key step.

[0015] In S2, sodium carbonate is added into the reactor for adjusting the pH of the liquid phase in the reactor, the amount of sodium carbonate added depends on the required pH, the pH range is 7.5-9.5, oily substances are easily adsorbed by the adsorbent in the alkaline environment (i.e. pH > 7.0), but when pH > 9.5, the oily substances will undergo saponification reaction, therefore, the pH range is preferably 7.5-9.5.

[0016] In S3, the oleophilic adsorbent is bio-activated carbon impregnated with oxalic acid, the amount of the oleophilic adsorbent added is 2-5 kg / m 3 (by volume of the liquid phase in the reactor), when the content of oily substances is low, 2 kg / m 3 is enough to completely adsorb and remove the oily substances, when the content of oily substances is high, 5 kg / m 3 is able to adsorb and remove the oily substances, therefore, too low amount of the adsorbent cannot completely adsorb and remove the oily substances, and too high amount of the adsorbent will cause waste of the adsorbent and increase the operation cost. The negative pressure in the reactor is -10 to -30 kPa, under the negative pressure condition, the dissolved CO2 remaining in S1 can be deeply removed, which is beneficial to improving the adsorption efficiency of the adsorbent to the oily substances, when the negative pressure is less than -30 kPa, the dissolved CO2 cannot be completely removed, and when the negative pressure is higher than -10 kPa, the light oily substances are also easily volatilized, therefore, maintaining the negative pressure is a key step.

[0017] In S4, the bio-activated carbon is coconut shell or walnut shell or straw.

[0018] In S5, the rotating speed of the centrifuge is 15000-18000 r / min, because the adsorption strength of the oily substances on the adsorbent is high, and the rotating speed is too low, the oily substances cannot be separated from the adsorbent, and the centrifuging time is 60-150 s.

[0019] Compared with the prior art, the process is simple and the whole process is free of secondary pollution, in S5, the oily substances and the adsorbent are separated by centrifuging, the separated oily substances can be stored and used, and the separated adsorbent can be reused in S3 for adsorbing the oily substances again, thereby realizing reuse of the adsorbent, which is green and economical. BRIEF DESCRIPTION OF DRAWINGS

[0020] The application will be further described in detail below in combination with the drawings and preferred embodiments, but those skilled in the art will appreciate that the drawings are only drawn for the purpose of explaining the preferred embodiments and therefore should not be regarded as a limitation on the scope of the application. In addition, unless specifically indicated, the drawings only schematically show the composition or structure of the described objects and can contain exaggerated display, and the drawings are not necessarily drawn to scale.

[0021] Figure 1 is a process flow diagram of the present disclosure. DETAILED DESCRIPTION

[0022] In order for those skilled in the art to better understand the technical solutions of the present disclosure, the present disclosure is described in detail, clearly and completely in combination with the drawings and examples. It should be understood that the specific examples described herein are only used to explain the present disclosure and do not limit the present disclosure.

[0023] In the description of the present application, if the first, second, only for the purpose of distinguishing technical features, and can not be understood as indicating or implying relative importance or implicitly indicating the number of indicated technical features or implicitly indicating the order of the indicated technical features.

[0024] Those skilled in the art should understand that in the disclosure of the present application, the orientation or positional relationship indicated by the terms "longitudinal", "transverse", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer" and the like is based on the orientation or positional relationship shown in the drawings. It is only for the convenience of describing the present application and simplifying the description, and does not indicate or imply that the devices or elements referred to must have a particular orientation, be constructed and operated in a particular orientation, so the above terms cannot be understood as limiting the present application.

[0025] Example 1

[0026] The method for oil-containing wastewater resource utilization described in this embodiment specifically includes the following steps:

[0027] S1: add oil-containing wastewater into a reaction kettle, stir at 70℃ and a rotation speed of 400r / min for 1h, while introducing CO2 into the reaction kettle and maintaining the positive pressure in the reaction kettle at 0.2MPa;

[0028] S2: release the pressure in the reaction kettle to normal pressure, reduce the temperature to room temperature, then add sodium carbonate powder into the reaction kettle and stir, and adjust the pH of the liquid phase in the reaction kettle to 8.5;

[0029] S3: add lipophilic adsorbent (i.e. coconut shell activated carbon impregnated with oxalic acid) into the reaction kettle at a concentration of 5kg / m 3 (by volume of the liquid phase in the reaction kettle) and set the negative pressure in the reaction kettle to-15kPa, and stir at room temperature for 2h;

[0030] S4: filter the mixed liquid after stirring in the reaction kettle through a water phase filter, and the purified water phase flows out from the bottom of the filter;

[0031] S5: The filter residue is transferred to a centrifuge for centrifugal treatment, the centrifuge rotation speed is 17000r / min, and the centrifugal time is 80s;

[0032] S6: The centrifuged oil phase material is transferred to an oil storage tank, and the centrifuged solid material is reused to S3 to continue to adsorb oily substances.

[0033] After the process, the oil-water separation efficiency of the oily wastewater reaches 100%, which shows that the process has obvious effect on the separation of oil-water mixture.

[0034] Example 2

[0035] The method for resource utilization of oily wastewater described in this embodiment specifically comprises the following steps:

[0036] S1: The oily wastewater is added to a reaction kettle and stirred at 75℃ and a rotation speed of 350r / min for 2h, and CO2 is introduced into the reaction kettle and the positive pressure in the reaction kettle is kept at 0.4MPa;

[0037] S2: The pressure in the reaction kettle is released to normal pressure, and the temperature is lowered to room temperature, then sodium carbonate powder is added to the reaction kettle and stirred, and the pH of the liquid phase in the reaction kettle is adjusted to 8;

[0038] S3: The lipophilic adsorbent (i.e. walnut shell activated carbon impregnated with oxalic acid) is added to the reaction kettle at a concentration of 2kg / m 3 (the volume of the liquid phase in the reaction kettle) and the negative pressure in the reaction kettle is set to-10kPa, and stirred at room temperature for 2h;

[0039] S4: The mixed liquid in the reaction kettle after stirring is filtered through a water phase filter, and the purified water phase flows out from the bottom of the filter;

[0040] S5: The filter residue is transferred to a centrifuge for centrifugal treatment, the centrifuge rotation speed is 15000r / min, and the centrifugal time is 90s;

[0041] S6: The centrifuged oil phase material is transferred to an oil storage tank, and the centrifuged solid material is reused to S3 to continue to adsorb oily substances.

[0042] After the process, the oil-water separation efficiency of the oily wastewater reaches 100%, which shows that the process has obvious effect on the separation of oil-water mixture.

[0043] Example 3

[0044] The method for resource utilization of oily wastewater described in this embodiment specifically comprises the following steps:

[0045] S1: the oily wastewater is added into a reaction kettle and stirred at 80℃ and a rotating speed of 200r / min for 2h, and CO2 is introduced into the reaction kettle and the positive pressure in the reaction kettle is kept at 0.3MPa;

[0046] S2: the pressure in the reaction kettle is released to normal pressure, and the temperature is reduced to room temperature, then sodium carbonate powder is added into the reaction kettle and stirred, and the pH of the liquid phase in the reaction kettle is adjusted to 7.5;

[0047] S3: the lipophilic adsorbent (i.e. the straw activated carbon impregnated with oxalic acid) is added into the reaction kettle at a concentration of 3kg / m 3 (the volume of the liquid phase in the reaction kettle) and the negative pressure in the reaction kettle is set to -25kPa, and the mixture is stirred at room temperature for 1h;

[0048] S4: the mixture after stirring in the reaction kettle is filtered through a water phase filter, and the purified water phase flows out from the bottom of the filter;

[0049] S5: the filter residue is transferred to a centrifuge for centrifugal treatment, and the rotating speed of the centrifuge is 16000r / min and the centrifugal time is 60s;

[0050] S6: the oil phase material after centrifugation is transferred to an oil storage tank, and the solid material after centrifugation is reused to S3 for continuing to adsorb oily substances.

[0051] After the process, the oil-water separation efficiency of the oily wastewater reaches 100%, which shows that the process has obvious effect on the separation of oil-water mixture.

[0052] Example 4

[0053] The method for resource utilization of oily wastewater described in the embodiment specifically comprises the following steps:

[0054] S1: the oily wastewater is added into a reaction kettle and stirred at 70℃ and a rotating speed of 250r / min for 1.5h, and CO2 is introduced into the reaction kettle and the positive pressure in the reaction kettle is kept at 0.2MPa;

[0055] S2: the pressure in the reaction kettle is released to normal pressure, and the temperature is reduced to room temperature, then sodium carbonate powder is added into the reaction kettle and stirred, and the pH of the liquid phase in the reaction kettle is adjusted to 8.3;

[0056] S3: the lipophilic adsorbent (i.e. the coconut shell activated carbon impregnated with oxalic acid) is added into the reaction kettle at a concentration of 3.5kg / m 3 (the volume of the liquid phase in the reaction kettle) and the negative pressure in the reaction kettle is set to -20kPa, and the mixture is stirred at room temperature for 1.5h;

[0057] S4: the mixed liquid after stirring in the reaction kettle is filtered through an aqueous phase filter, and the purified aqueous phase flows out from the bottom of the filter;

[0058] S5: the filter residue is transferred to a centrifuge for centrifugal treatment, the centrifuge speed is 17000r / min, and the centrifugal time is 150s;

[0059] S6: the oil phase material centrifuged out is transferred to an oil storage tank, and the solid material after centrifugation is reused to S3 to continue to adsorb oily substances.

[0060] After the process, the oil-water separation efficiency in the oily wastewater reaches 100%, which shows that the process has obvious effect on the separation of oil-water mixture.

[0061] Example 5

[0062] The method for resource utilization of oily wastewater described in the embodiment specifically comprises the following steps:

[0063] S1: the oily wastewater is added to a reaction kettle and stirred at 90℃ and a speed of 350r / min for 1h, and CO2 is introduced into the reaction kettle and the positive pressure in the reaction kettle is kept at 0.4MPa;

[0064] S2: the pressure in the reaction kettle is released to normal pressure, and the temperature is lowered to room temperature, then sodium carbonate powder is added to the reaction kettle and stirred, and the pH of the liquid phase in the reaction kettle is adjusted to 9.5;

[0065] S3: the lipophilic adsorbent (i.e. coconut shell activated carbon impregnated with oxalic acid) is added to the reaction kettle at a concentration of 2.5kg / m 3 (the volume of the liquid phase in the reaction kettle) and the negative pressure in the reaction kettle is set to-30kPa, and stirred at room temperature for 2h;

[0066] S4: the mixed liquid after stirring in the reaction kettle is filtered through an aqueous phase filter, and the purified aqueous phase flows out from the bottom of the filter;

[0067] S5: the filter residue is transferred to a centrifuge for centrifugal treatment, the centrifuge speed is 18000r / min, and the centrifugal time is 130s;

[0068] S6: the oil phase material centrifuged out is transferred to an oil storage tank, and the solid material after centrifugation is reused to S3 to continue to adsorb oily substances.

[0069] After the process, the oil-water separation efficiency in the oily wastewater reaches 100%, which shows that the process has obvious effect on the separation of oil-water mixture.

[0070] Example 6

[0071] The method for oil-containing wastewater resource utilization comprises the following steps:

[0072] S1: the oil-containing wastewater is added into the reaction kettle and stirred at 88 DEG C and 100 r / min for 1.5 h, and CO2 is introduced into the reaction kettle and the positive pressure in the reaction kettle is kept at 0.2 MPa;

[0073] S2: the pressure in the reaction kettle is released to normal pressure, the temperature is reduced to room temperature, then sodium carbonate powder is added into the reaction kettle and stirred, and the pH of the liquid phase in the reaction kettle is adjusted to 9;

[0074] S3: the lipophilic adsorbent (i.e. walnut shell activated carbon impregnated with oxalic acid) is added into the reaction kettle at a concentration of 4.5 kg / m 3 (the volume of the liquid phase in the reaction kettle) and the negative pressure in the reaction kettle is set to -25 kPa, and the mixture is stirred at room temperature for 1 h;

[0075] S4: the mixture after stirring in the reaction kettle is filtered through a water phase filter, and the purified water phase flows out from the bottom of the filter;

[0076] S5: the filter residue is transferred to a centrifuge for centrifugal treatment, the centrifuge rotates at 17000 r / min, and the centrifugal time is 100 s;

[0077] S6: the oil phase material centrifuged out is transferred to an oil storage tank, and the solid material after centrifugation is reused to S3 for continuing to adsorb oily substances.

[0078] After the process, the oil-water separation efficiency of the oil-containing wastewater reaches 100%, which shows that the process has obvious effect on the separation of oil-water mixture.

[0079] Example 7

[0080] The method for oil-containing wastewater resource utilization comprises the following steps:

[0081] S1: the oil-containing wastewater is added into the reaction kettle and stirred at 85 DEG C and 150 r / min for 2 h, and CO2 is introduced into the reaction kettle and the positive pressure in the reaction kettle is kept at 0.3 MPa;

[0082] S2: the pressure in the reaction kettle is released to normal pressure, the temperature is reduced to room temperature, then sodium carbonate powder is added into the reaction kettle and stirred, and the pH of the liquid phase in the reaction kettle is adjusted to 8.7;

[0083] S3: the lipophilic adsorbent (i.e. straw activated carbon impregnated with oxalic acid) is added into the reaction kettle at a concentration of 4 kg / m 3 (the volume of the liquid phase in the reaction kettle) and the negative pressure in the reaction kettle is set to -20 kPa, and the mixture is stirred at room temperature for 2 h;

[0084] S4: The mixed liquid after stirring in the reaction kettle is filtered through an aqueous phase filter, and the purified aqueous phase flows out from the bottom of the filter;

[0085] S5: The filter residue is transferred to a centrifuge for centrifugal treatment, the centrifuge speed is 16000r / min, and the centrifugal time is 90s;

[0086] S6: The oil phase material centrifuged out is transferred to an oil storage tank, and the solid material after centrifugation is reused to S3 to continue to adsorb oily substances.

[0087] After the process, the oil-water separation efficiency in the oily wastewater reaches 100%, which shows that the process has obvious effect on the separation of oil-water mixture.

[0088] Example 8

[0089] The method for resource utilization of oily wastewater described in the embodiment specifically comprises the following steps:

[0090] S1: The oily wastewater is added to the reaction kettle and stirred at 72℃ and a speed of 300r / min for 2h, and CO2 is introduced into the reaction kettle and the positive pressure in the reaction kettle is kept at 0.3MPa;

[0091] S2: The pressure in the reaction kettle is released to normal pressure, and the temperature is lowered to room temperature, then sodium carbonate powder is added to the reaction kettle and stirred, and the pH of the liquid phase in the reaction kettle is adjusted to 9.2;

[0092] S3: The lipophilic adsorbent (i.e. walnut shell activated carbon impregnated with oxalic acid) is added to the reaction kettle at a concentration of 5kg / m 3 (the volume of the liquid phase in the reaction kettle) and the negative pressure in the reaction kettle is set to-20kPa, and stirred at room temperature for 1.5h;

[0093] S4: The mixed liquid after stirring in the reaction kettle is filtered through an aqueous phase filter, and the purified aqueous phase flows out from the bottom of the filter;

[0094] S5: The filter residue is transferred to a centrifuge for centrifugal treatment, the centrifuge speed is 15000r / min, and the centrifugal time is 60s;

[0095] S6: The oil phase material centrifuged out is transferred to an oil storage tank, and the solid material after centrifugation is reused to S3 to continue to adsorb oily substances.

[0096] After the process, the oil-water separation efficiency in the oily wastewater reaches 100%, which shows that the process has obvious effect on the separation of oil-water mixture.

[0097] The application is described in detail above, and the principles and implementation manners of the application are described by applying specific examples. The above description of the examples is only used to help understand the application and the core idea. It should be pointed out that, for ordinary skilled persons in the technical field, some improvements and modifications can be made to the application without departing from the principles of the application, and these improvements and modifications also fall within the protection scope of the claims of the application.

Claims

1. A method for oil-containing wastewater resource utilization, characterized in that, The method comprises the following steps: S1: adding oily wastewater into a reaction kettle and stirring for 1-2 hours, and meanwhile, CO2 is introduced into the reaction kettle to keep the reaction kettle in positive pressure; S2: releasing the pressure in the reaction kettle to normal pressure, adding sodium carbonate into the reaction kettle and stirring; S3: adding an oleophilic adsorbent into the reaction kettle, and stirring the reaction kettle at room temperature and negative pressure for 1-2 hours; S4: filtering the mixed liquid after stirring in the reaction kettle through a water phase filter, and letting the purified water phase flow out from the bottom of the filter; S5: transferring the filter residue into a centrifuge for centrifugal treatment; S6: transferring the centrifuged oil phase into an oil storage tank, and recycling the solid material after centrifugation to S3 for continuously adsorbing oily substances; The oleophilic adsorbent in S3 is bioactive carbon impregnated with oxalic acid.

2. The method for oil-containing wastewater resource utilization according to claim 1, characterized in that, The stirring temperature in S1 is 70-90℃, the stirring speed is 100-400 r / min, and the pressure of the positive pressure in the reaction kettle is 0.2-0.4 MPa.

3. The method for oil-containing wastewater resource utilization according to claim 1, characterized in that, The sodium carbonate is added in S2 for adjusting the pH of the liquid phase in the reaction kettle, the addition amount of the sodium carbonate is determined according to the required pH, and the pH ranges from 7.5 to 9.

5.

4. The method for oil-containing wastewater resource utilization according to claim 1, characterized in that, The addition amount of the lipophilic adsorbent is 2-5 kg / m 3 ; the negative pressure in the reactor is -10 to -30 kPa.

5. The method for oil-containing wastewater resourceful according to claim 1, characterized in that, The rotating speed of the centrifuge in S5 is 15000-18000 r / min, and the centrifugal time is 60-150 s.

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