Method for ecologic configuration of oil production high-salt wastewater artificial wetland to realize up-to-standard operation in winter

Abstract

A method for ecologic configuration of an oil production wastewater artificial wetland to realize up-to-standard operation in winter. When artificial wetland is utilized to treat oil production high-salt wastewater, ecologic configuration of subsurface and surface flow artificial wetland is modified to realize up-to-standard operation in winter. Subsurface flow artificial wetland is composed of soil matrix, water distribution pipe disposed on bottom of soil matrix, wrapped with water-permeable nonwoven cloth and configured to deliver wastewater, and reeds with root systems growing on an inner side of wall of water distribution pipe, stems growing on outer side of wall of water distribution pipe and length being greater than thickness of soil matrix; and surface flow artificial wetland is composed of soil matrix, reeds growing on matrix, water, winter aquatic salt-resistant cold-liking plants, block-stocked fishes, shrimps, crabs, mussels, Mytilus edulis, oysters or clams and artificial sand dam.

Claims

1. A method for ecologically configuring an artificial wetland for treating a high-salt wastewater from oil production to realize an up-to-standard operation in winter, the method comprising: (1) performing pretreatment reaction on wastewater from oil production with at least one selected from the group consisting of NaOH, Na.sub.2CO.sub.3, CaO, Ca(OH).sub.2, NH.sub.3.H.sub.2O, polyaluminium chloride (PAC) and polyacrylamide (PAM) at a weight ratio of (5 to 10):1 for 2 to 4 hours, then introducing the wastewater into a sedimentation tank or an air floatation tank for treatment for 1 to 10 hours, removing sludge from the wastewater, and regulating a pH value of outlet water to be in a range of 6 to 8 to prepare pretreated outlet water with a water quality of chemical oxygen demand (COD) being in a range from 150 to 300 mg/L, a suspended matter content being in a range from 30 to 50 mg/L, and a petroleum content being in a range from 10 to 20 mg/L; (2) introducing the pretreated outlet water into an oxidation pond for a hydraulic retention time of from 3 to 21 days to prepare oxidation pond outlet water with a water quality of COD being in a range from 100 to 150 mg/L, a suspended matter content being in a range from 20 to 30 mg/L and a petroleum content being in a range from 1 to 10 mg/L; wherein a reflux pump station is disposed at an oxidation pond water outlet, and partial oxidation pond outlet water can be refluxed to an oxidation pond water inlet at a reflux ratio of from 20% to 50%; (3) introducing the oxidation pond outlet water prepared in the step (2) into a subsurface flow artificial wetland for a hydraulic retention time of from 0.5 to 2 days to prepare subsurface flow artificial wetland outlet water with thea water quality of COD being in a range from 60 to 100 mg/L, a suspended matter content being in a range from 10 to 20 mg/L, and a petroleum content being in a range from 1 to 5 mg/L; and (4) introducing the subsurface flow artificial wetland outlet water prepared in the step (3) into a surface flow artificial wetland for a hydraulic retention time of from 20 to 30 days at a hydraulic load of at most 0.5 m.sup.3/d/m.sup.2 to prepare surface flow artificial wetland outlet water with a water quality of COD being in a range from 40 to 50 mg/L, a suspended matter content being from 10 to 20 mg/L, a petroleum content being in a range from 0.01 to 3 mg/L, and a mineralization degree being in a range from 15000 to 24000 mg/L; wherein in the step (3), the subsurface flow artificial wetland is composed of a soil matrix, a water distribution pipe disposed on a bottom of the soil matrix, which is wrapped with water-permeable nonwoven cloth and configured to deliver the wastewater, reeds with root systems growing on an inner side of a wall of the water distribution pipe, and stems growing on an outer side of the wall of the water distribution pipe and the water distribution pipe has a length greater than a thickness of the soil matrix, wherein the oxidation pond outlet water prepared in the step (2) only flows through the water distribution pipe, a wastewater purification unit is defined in the water distribution pipe, and a distance from the water distribution pipe to a ground surface is in a range from 50 to 100 cm; and in the step (4), the surface flow artificial wetland is composed of a soil matrix, reeds growing on the soil matrix, water, winter aquatic salt-resistant cold-liking plants, block-stocked fishes, shrimps, crabs, mussels, mytilus edulis, oysters or clams and an artificial sand dam, wherein the block-stocked fishes, the shrimps and the crabs are cultured in a mixed-stocked way, and the mussels, the mytilus edulis, the oysters or the clams are cultured in a floating body seedling rope hanging or artificial sand dam stocked way.

2. The method according to claim 1, wherein in the step (3), the water distribution pipes have a diameter in a range of 10 to 30 cm, and are laid at intervals in a range of 20 to 60 cm in a reticular shape.

3. The method according to claim 2, wherein in the step (3), the water distribution pipes have a diameter in a range of 20 to 30 cm, and are laid at intervals in a range of 30 to 50 cm in a reticular shape.

4. The method according to claim 1, wherein in the step (4), the winter aquatic salt-resistant cold-liking plants are ulva pertusa at a planting density in a range of 10 to 40 plants/m.sup.2.

5. The method according to claim 1, wherein in the step (4), the block-stocked fishes are trout at a stocking density in a range of 1 to 5 kg/m.sup.2.

6. The method according to claim 1, wherein in the step (4), the shrimps are exopalaemon carinicauda holthuis or penaeus vannamei at a stocking density in a range of 0.1 to 2 kg/m.sup.2.

7. The method according to claim 1, wherein in the step (4), the crabs are eriocheir sinensis at a stocking density in a range of 0.5 to 1 kg/m.sup.2.

8. The method winter according to claim 1, wherein in the step (4), a laying area of the floating body seedling rope hanging or artificial sand dam for stocking the mussels, the mytilus edulis, the oysters or the clams is 10% of the area per mu.

9. The method according to claim 1, wherein in the step (4), the artificial sand dam is laid such that a width along a waterflow direction is in a range from 1 to 5 m, a length is identical to a length of the surface flow artificial wetland, a sand surface is laid obliquely, a top end of sand is in a range from 5 to 20 cm lower than a water level, a height is in a range from 20 to 40 cm, and a particle size of the sand is in a range from 20 to 40 meshes.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) FIG. 1 is a schematic structure diagram of a subsurface flow artificial wetland according to the present invention, in which

(2) 1, reed; 2, soil matrix; 3, soil-retaining water-permeable nonwoven cloth; and 4, water distribution pipe.

(3) FIG. 2 is a schematic structure diagram and winter operation state demonstration of a surface flow artificial wetland according to the present invention, in which

(4) 5, Ulva pertusa; 6, hollow reed stalk; 7, trout; 8, shrimp; 9, Eriocheir sinensis; 10, floating body; 11, Mytilus edulis and oyster; 12, clam; and 13, artificial sand dam.

DETAILED DESCRIPTION

(5) The contents of the present invention will now be illustrated in detail with reference to concrete embodiments. The following examples are merely preferred implementations of the present invention and are not intended to limit the present invention in any form, and all simple modifications, equivalent variations and modifications made according to the technical spirit of the present invention are within the scope of the technical solution of the present invention.

Embodiment 1

(6) The oil production wastewater utilized in the present embodiment was oil production wastewater obtained after oil-water separation in a combined station of an oil production plant in Shengli Oilfield, Dongying City and had following main indexes: COD=300 mg/L, a suspended matter content=100 mg/L, a petroleum content=50 mg/L, a polymer content=40 mg/L, and mineralization degree=12000 mg/L. The daily sewage treatment capacity is 3000 m.sup.3/d.

(7) A method for ecologic configuration of an oil production high-salt wastewater artificial wetland to realize up-to-standard operation in winter according to the present invention was performed according to following steps:

(8) (1) NaOH and Ca(OH).sub.2 mixed according to an equal weight ratio were added into the above oil production wastewater according to a weight ratio of 5:1; reaction was performed for 2.5 h; then, the oil production wastewater was introduced into a sedimentation tank for sedimentation for 15 h; and after a pH value of outlet water of the sedimentation tank was regulated to 6 to 8, pretreated outlet water with the water quality of COD being 150 mg/L, a suspended matter content being 50 mg/L and a petroleum content being 10 mg/L was prepared.

(9) (2) The pretreated outlet water prepared in the step (1) was introduced into an oxidation pond for a hydraulic retention time of 20 days to prepare oxidation pond outlet water with the water quality of COD being 100 mg/L, a suspended matter content being 30 mg/L and a petroleum content being 1 mg/L, and the area of the oxidation pond was 67500 m.sup.2 according to a pollutant load of 40 kg COD/(10.sup.4 m.sup.2.Math.d).

(10) A reflux pump station is disposed at an oxidation pond water outlet. The oil production wastewater generally had a high temperature (40 to 60° C.) and poor biodegradability, and was difficult for microorganisms to survive. Partial oxidation pond outlet water was refluxed to an oxidation pond water inlet at a reflux ratio of 50%; the temperature of the oxidation pond inlet water was regulated, the water quality of inlet water was improved, the quantity of degradation microorganisms was increased, and an oxygen gas concentration of the inlet water was improved. Meanwhile, plant humus (such as reeds, Suaeda glauca bunge and Tamarix chinensis branches) carried or artificially added in the reflux water could be used as a carbon source available to the microorganisms. An inlet water BOD.sub.5/COD.sub.C.sub.r ratio was improved, nutrition conditions of biological treatment were optimized, and an addition range was 0.3 kg/m.sup.2.

(11) (3) The oxidation pond outlet water prepared in the step (2) was introduced into a subsurface flow artificial wetland for a hydraulic retention time of 2 days to prepare subsurface flow artificial wetland outlet water with the water quality of COD being 60 mg/L, a suspended matter content being 20 mg/L and a petroleum content being 5 mg/L;

(12) the subsurface flow artificial wetland was composed of a soil matrix, a water distribution pipe disposed on a bottom of the soil matrix, wrapped with water-permeable nonwoven cloth and configured to deliver the wastewater, and reeds with root systems growing on an inner side of a wall of the water distribution pipe, stems growing on an outer sides of the wall of the water distribution pipe and a length being greater than a thickness of the soil matrix, and a structure of the subsurface flow artificial wetland is as shown in FIG. 1; the oxidation pond outlet water prepared in the step (2) only flowed through the water distribution pipe, wastewater purification unit is defined in the water distribution pipe, and a distance from the water distribution pipe to a ground surface was 60 to 80 cm; the water distribution pipes had a diameter of 25 cm, and were laid at intervals of 30 to 40 cm in a reticular shape.

(13) (4) The subsurface flow artificial wetland outlet water prepared in the step (3) was introduced into a surface flow artificial wetland, the surface flow artificial wetland was composed of a soil matrix, reeds growing on the matrix, water, winter aquatic salt-resistant cold-liking plants, block-stocked fishes, shrimps, crabs, Mytilus edulis, oysters or clams and an artificial sand dam, and a structure of the surface flow artificial wetland is as shown in FIG. 2; a planting intensity of Ulva pertusa in the surface flow artificial wetland was 25 plants/m.sup.2, stocking was performed at a stocking intensity of trout of 1 kg/m.sup.2, a stocking intensity of exopalaemon carinicauda holthuis of 0.5 kg/m.sup.2, a stocking intensity of Eriocheir sinensis of 0.5 kg/m.sup.2, and the mussels and the Mytilus edulis were hung on seedling ropes according to a 10% area stocking rate of per mu water surface. The artificial sand dam was disposed at 50 m from a water outlet of the surface flow artificial wetland, was laid by 30-mesh sand, and had a width being 4 m and a length being 150 m, a sand surface was laid obliquely, the top end of the sand was 15 cm lower than the water level, and the height was 30 cm. A hydraulic retention time was 20 days, and a hydraulic load is 0.3 m.sup.3/d/m.sup.2, the surface flow artificial wetland outlet water with the water quality of COD being 40 mg/L, a suspended matter content being 10 mg/L, a petroleum content being 0.5 mg/L and a mineralization degree being 20000 mg/L was prepared, and an environment protection standard for operation of the oil production high-salt wastewater artificial wetland in winter was reached.

(14) The trout and exopalaemon carinicauda holthuis stocked in the surface flow artificial wetland might be utilized to feed minks, mink meat was utilized to feed foxes, fox meat was utilized to feed alligators, alligator meat might be utilized to feed fishes, minks and foxes, and economical benefits were obtained through preparing mink fur, alligator skin and fox fur.

(15) A circulation chain is that artificial

(16) ##STR00001##
wastewater-artificial wetland.

(17) It should be stated that the fishes stocked in the wetland had risk of threatening human health, and for the sake of safety, did not enter the market as aquatic products and only served as feed for animals; and economic benefits could be obtained by preparing fur of the minks, the foxes, the alligators and the like. The water after animals were stocked might be used for water supplementation to composite wetlands, excrement of the animals was utilized for methane tank fermentation, thus providing green fuel for daily life of field workers, and waste residues after fermentation might be utilized as organic fertilizers of wetland plants such as reeds.

Embodiment 2

(18) A method for ecologic configuration of an oil production high-salt wastewater artificial wetland to realize up-to-standard operation in winter was performed according to following steps:

(19) (1) oil production wastewater was subjected to pretreatment reaction for 4 hours by NaOH according to a weight of 10:1, then, the oil production wastewater was introduced into a sedimentation tank or an air floatation tank for treatment for 10 hours, sludge was removed, a pH value of outlet water of the sedimentation tank was regulated to 6 to 8, and pretreated outlet water with the water quality of COD being 200 mg/L, a suspended matter content being 35 mg/L and a petroleum content being 15 mg/L was prepared;

(20) (2) the pretreated outlet water prepared in the step (1) was introduced into an oxidation pond for a hydraulic retention time of 11 days to prepare oxidation pond outlet water with the water quality of COD being 120 mg/L, a suspended matter content being 25 mg/L and a petroleum content being 6 mg/L; a reflux pump station was disposed at an oxidation pond water outlet, and partial oxidation pond outlet water could be refluxed to an oxidation pond water inlet at a reflux ratio of 30%;

(21) (3) the oxidation pond outlet water prepared in the step (2) was introduced into a subsurface flow artificial wetland for a hydraulic retention time of 1.5 days to prepare subsurface flow artificial wetland outlet water with the water quality of COD being 80 mg/L, a suspended matter content being 15 mg/L and a petroleum content being 3 mg/L; and

(22) (4) the subsurface flow artificial wetland outlet water prepared in the step (3) was introduced into a surface flow artificial wetland for a hydraulic retention time of 26 days at a hydraulic load of at most 0.5 m.sup.3/d/m.sup.2 to prepare surface flow artificial wetland outlet water with the water quality of COD being 40 mg/L, a suspended matter content being 10 mg/L, a petroleum content being 1.5 mg/L and a mineralization degree being 17000 mg/L;

(23) where

(24) in the step (3), the subsurface flow artificial wetland was composed of a soil matrix, a water distribution pipe disposed on a bottom of the soil matrix, wrapped with water-permeable nonwoven cloth and configured to deliver the wastewater, and reeds with root systems growing on an inner side of a wall of the water distribution pipe, stems growing on outer side of the wall of the water distribution pipe and a length being greater than a thickness of the soil matrix, and a structure of the subsurface flow artificial wetland is as shown in FIG. 1; the oxidation pond outlet water prepared in the step (2) only flowed through the water distribution pipe, wastewater purification unit is defined in the water distribution pipe, and a distance from the water distribution pipe to a ground surface was 70 cm; and

(25) in the step (4), the surface flow artificial wetland was composed of a soil matrix, reeds growing on the matrix, water, winter aquatic salt-resistant cold-liking plants, block-stocked fishes, shrimps, crabs, mussels, Mytilus edulis, oysters or clams and an artificial sand dam, and a structure of the surface flow artificial wetland is as shown in FIG. 2; the fishes, the shrimps and the crabs were cultured in a mixed-stocked way, and the mussels, the Mytilus edulis, the oysters or the clams were cultured in a floating body seedling rope hanging or artificial sand dam stocked way.

(26) According to the method for ecologic configuration of the oil production high-salt wastewater artificial wetland to realize up-to-standard operation in winter, in the step (3), the water distribution pipes had a diameter of 30 cm, and were laid at intervals of 50 cm in a reticular shape.

(27) According to the method for ecologic configuration of the oil production high-salt wastewater artificial wetland to realize up-to-standard operation in winter, in the step (4), the winter aquatic salt-resistant cold-liking plants were preferably Ulva pertusa at a planting density of 40 plants/m.sup.2.

(28) According to the method for ecologic configuration of the oil production high-salt wastewater artificial wetland to realize up-to-standard operation in winter, in the step (4), the fishes were preferably trout at a stocking density of 3 kg/m.sup.2.

(29) According to the method for ecologic configuration of the oil production high-salt wastewater artificial wetland to realize up-to-standard operation in winter, in the step (4), the shrimps were preferably exopalaemon carinicauda holthuis or Penaeus vannamei at a stocking density of 1 kg/m.sup.2.

(30) According to the method for ecologic configuration of the oil production high-salt wastewater artificial wetland to realize up-to-standard operation in winter, in the step (4), the crabs were preferably Eriocheir sinensis at a stocking density of 0.7 kg/m.sup.2.

(31) According to the method for ecologic configuration of the oil production high-salt wastewater artificial wetland to realize up-to-standard operation in winter, in the step (4), a preferable density of the floating body seedling rope hanging or artificial sand dam stocking of the mussels, the Mytilus edulis, the oysters or the clams was 10% area stocking rate/mu.

(32) According to the method for ecologic configuration of the oil production high-salt wastewater artificial wetland to realize up-to-standard operation in winter, in the step (4), a method of laying the artificial sand dam was preferably that a width along a waterflow direction was 4 m, a length was identical to that of the surface flow artificial wetland, a sand surface was laid obliquely, a top end of sand was 10 cm lower than a water level, a height was 30 cm, and a particle size of the sand was 25 meshes.

Embodiment 3

(33) A method for ecologic configuration of an oil production high-salt wastewater artificial wetland to realize up-to-standard operation in winter according to the present invention was performed according to following steps:

(34) (1) NaOH, CaO and Ca(OH).sub.2 mixed according to an equal weight ratio were added into oil production wastewater according to a weight ratio of 8:1; reaction was performed for 2 hours; then, the oil production wastewater was introduced into a sedimentation tank for sedimentation for 5 hours, and after a pH value of outlet water of the sedimentation tank was regulated to 6 to 8, pretreated outlet water with the water quality of COD being 180 mg/L, a suspended matter content being 40 mg/L and a petroleum content being 20 mg/L was prepared;

(35) (2) the pretreated outlet water prepared in the step (1) was introduced into an oxidation pond for a hydraulic retention time of 7 days to prepare oxidation pond outlet water with the water quality of COD being 100 mg/L, a suspended matter content being 20 mg/L and a petroleum content being 7 mg/L, a reflux pump station was disposed at an oxidation pond water outlet, and partial oxidation pond outlet water could be refluxed to an oxidation pond water inlet at a reflux ratio of 20% to 50%;

(36) (3) the oxidation pond outlet water prepared in the step (2) was introduced into a subsurface flow artificial wetland for a hydraulic retention time of 1 day to prepare subsurface flow artificial wetland outlet water with the water quality of COD being 60 mg/L, a suspended matter content being 10 mg/L, a petroleum content being 2 mg/L; and

(37) (4) the subsurface flow artificial wetland outlet water prepared in the step (3) was introduced into a surface flow artificial wetland for a hydraulic retention time of 20 days at a hydraulic load of at most 0.5 m.sup.3/d/m.sup.2 to prepare surface flow artificial wetland outlet water with the water quality of COD being 40 mg/L, a suspended matter content being 10 mg/L, a petroleum content being 0.5 mg/L and a mineralization degree being 20000 mg/L,

(38) where

(39) in the step (3), the subsurface flow artificial wetland was composed of a soil matrix, a water distribution pipe disposed a bottom of the soil matrix, wrapped with water-permeable nonwoven cloth and configured to deliver the wastewater, and reeds with root systems growing on an inner side of a wall of the water distribution pipe, stems growing on an outer side of the wall of the water distribution pipe and a length greater than a thickness of the soil matrix, and a structure of the subsurface flow artificial wetland is as shown in FIG. 1; the oxidation pond outlet water prepared in the step (2) only flowed through the water distribution pipe, wastewater purification unit is limited in the water distribution pipe, and a distance from the water distribution pipe to a ground surface was 100 cm; and in the step (4), the surface flow artificial wetland was composed of a soil matrix, reeds growing on the matrix, water, winter aquatic salt-resistant cold-liking plants, block-stocked fishes, shrimps, crabs, mussels, Mytilus edulis, oysters or clams and an artificial sand dam, and a structure of the surface flow artificial wetland is as shown in FIG. 2; the fishes, the shrimps and the crabs were cultured in a mixed-stocked way, and the mussels, the Mytilus edulis, the oysters or the clams were cultured in a floating body seedling rope hanging or artificial sand dam stocked way.

(40) According to the method for ecologic configuration of the oil production high-salt wastewater artificial wetland to realize up-to-standard operation in winter, in the step (3), the water distribution pipes had a diameter of 30 cm, and were laid at intervals of 60 cm in a reticular shape.

(41) According to the method for ecologic configuration of the oil production high-salt wastewater artificial wetland to realize up-to-standard operation in winter, in the step (4), the winter aquatic salt-resistant cold-liking plants were preferably Ulva pertusa at a planting density of 40 plants/m.sup.2.

(42) According to the method for ecologic configuration of the oil production high-salt wastewater artificial wetland to realize up-to-standard operation in winter, in the step (4), the fishes were preferably trout at a stocking density of 5 kg/m.sup.2.

(43) According to the method for ecologic configuration of the oil production high-salt wastewater artificial wetland to realize up-to-standard operation in winter, in the step (4), the shrimps were preferably exopalaemon carinicauda holthuis or Penaeus vannamei at a stocking density of 2 kg/m.sup.2.

(44) According to the method for ecologic configuration of the oil production high-salt wastewater artificial wetland to realize up-to-standard operation in winter, in the step (4), the crabs were preferably Eriocheir sinensis at a stocking density of 1 kg/m.sup.2.

(45) According to the method for ecologic configuration of the oil production high-salt wastewater artificial wetland to realize up-to-standard operation in winter, in the step (4), a preferable density of the floating body seedling rope hanging or artificial sand dam stocking of the mussels, the Mytilus edulis, the oysters or the clams was 10% area stocking rate/mu.

(46) According to the method for ecologic configuration of the oil production high-salt wastewater artificial wetland to realize up-to-standard operation in winter, in the step (4), a method of laying the artificial sand dam was preferably that a width along a waterflow direction was 3 m, a length was identical to that of the surface flow artificial wetland, a sand surface was laid obliquely, a top end of sand was 10 cm lower than a water level, a height was 20 cm, and a particle size of the sand was 20 meshes.