Method for treating highly concentrated resin-desorption liquid generated from wastewater deep purification

Abstract

A method for treating highly concentrated resin-desorption liquid generated from wastewater deep purification, including channeling the highly concentrated desorption liquid generated from anion exchange resin treatment through a nanofiltration membrane, the liquid being separated into nanofiltration permeate that can be reused as the desorption agent and highly concentrated nanofiltration retentate; adding a coagulating agent to the highly concentrated nanofiltration retentate to generate coagulation-precipitation; subjecting the supernatant formed after the coagulation-precipitation process to Fenton oxidation or ozone oxidation; after the reaction, adding to the liquid an alkali solution for further coagulation-precipitation; then channeling the liquid so treated back to the biochemical system of biochemical effluent treatment for further biodegradation is provided. The recycled treatment of the highly concentrated desorption liquid consequently reduces the treatment cost and prevents secondary pollution by realizing innocuous treatment and reclamation of resin-desorption liquid as well as reduction of its total volume.

Claims

1. A method for treating a highly concentrated resin-desorption liquid generated from a wastewater deep purification biochemical system, comprising: a) channeling the highly concentrated resin-desorption liquid generated from an anion exchange resin treatment of wastewater through a nanofiltration membrane and separating the highly concentrated resin-desorption liquid into a highly concentrated nanofiltration retentate and a nanofiltration permeate, wherein the nanofiltration permeate is reused as an desorption agent after oxidation; b) inducing a first coagulation-precipitation process by adding a coagulating agent to the highly concentrated nanofiltration retentate obtained in step a); c) subjecting a supernatant formed after the first coagulation-precipitation process to 1-5 hours of Fenton oxidation or ozone oxidation to obtain a solution; d) inducing a second coagulation-precipitation process by adding an alkali solution to the solution obtained in step c) for adjusting its pH value at 8.5-10.5; e) channeling a liquid obtained after the second coagulation-precipitation process of step d) to an activated sludge for further biodegradation; and f) channeling a liquid resulting from further biodegradation of the liquid obtained after the second coagulation-precipitation process of step d) with the activated sludge back to the wastewater deep purification biochemical system for further use in biodegradation, wherein the wastewater deep purification biochemical system uses an anion exchange resin.

2. A method for treating highly concentrated resin-desorption liquid generated from wastewater deep purification as defined in claim 1, wherein the coagulating agent used in step b) is FeCl.sub.3.6H.sub.2O, FeSO.sub.4.7H.sub.2O, Al.sub.2(SO4).sub.3.18H.sub.2O or polyaluminum chloride (PAC).

3. A method for treating highly concentrated resin-desorption liquid generated from wastewater deep purification as defined in claim 2, wherein in step b) a mass percentage of the coagulating agent in the highly concentrated nanofiltration retentate is 1%-5%.

4. A method for treating highly concentrated resin-desorption liquid generated from wastewater deep purification as defined in claim 3, wherein in step b) the pH value of the solution obtained after the first coagulation-precipitation process is 2-5.

5. A method for treating highly concentrated resin-desorption liquid generated from wastewater deep purification as defined in claim 1, wherein in step c) is performed by Fenton oxidation, FeSO4-7H20 is used as an oxidant for Fenton oxidation, and a mass percentage of the FeSO4-7H20 in the solution is 0.1%-2%.

6. A method for treating highly concentrated resin-desorption liquid generated from wastewater deep purification as defined in claim 1, wherein as to the Fenton reagent mentioned in step c), a mass percentage of 30% (by weight) H.sub.2O.sub.2 solution in the solution is 1%-4%.

7. A method for treating highly concentrated resin-desorption liquid generated from wastewater deep purification as defined in claim 1, wherein a concentration of the ozone used in step c) is 3 mg/L-10 mg/L.

8. A method for treating highly concentrated resin-desorption liquid generated from wastewater deep purification as defined in claim 1, wherein the alkali solution used in step d) is NaOH or Ca(OH).sub.2 solution.

9. A method for treating highly concentrated resin-desorption liquid generated from wastewater deep purification as defined in claim 1, wherein in step e), retention time in the activated sludge system is 12-18 h.

10. The method of treating highly concentrated resin-desorption liquid generated from wastewater deep purification as defined in claim 9, further wherein, after 12 hours of treatment, the removal percentage of outflow chemical oxygen demand is 40%.

11. The method of treating highly concentrated resin-desorption liquid generated from wastewater deep purification as defined in claim 9, further wherein, after 18 hours of treatment, the removal percentage of outflow chemical oxygen demand is 65%.

12. The method of treating highly concentrated resin-desorption liquid generated from wastewater deep purification as defined in claim 1, further wherein, after 0.5 hours of precipitation in step d), the removal percentage of total organic carbon is 60%.

13. The method of treating highly concentrated resin-desorption liquid generated from wastewater deep purification as defined in claim 1, further wherein, after 0.5 hours of precipitation in step d), the removal percentage of total organic carbon is 65%.

14. The method of treating highly concentrated resin-desorption liquid generated from wastewater deep purification as defined in claim 1, further wherein, after 0.5 hours of precipitation in step d), the removal percentage of total organic carbon is 70%.

15. The method of treating highly concentrated resin-desorption liquid generated from wastewater deep purification as defined in claim 1, further wherein, after 0.5 hours of precipitation in step d), the removal percentage of total organic carbon is 80%.

Description

DETAILED DESCRIPTION

(1) This invention is more specifically described in the following embodiments

Embodiment 1

(2) The anion exchange resin is adopted for deep treatment of effluent generated from the biochemical treatment of dyeing wastewater, which results in a large amount of resin-desorption liquid. Channeling the resin-desorption liquid through a nanofiltration membrane and the nanofiltration retentate (TOC=3000 mg/L, pH=9.0-10.5) is therefore obtained; adding in 1% (by weight) of FeCl.sub.3.6H.sub.2O solution for coagulation-precipitation, and the supernatant so obtained is subject to Fenton oxidation wherein 0.1% (by weight) of FeSO.sub.4.7H.sub.2O and 1% (by weight) of 30% H.sub.2O.sub.2 solution are added to the supernatant; after 3 hours of Fenton reaction, adding Ca(OH).sub.2 emulsion to the oxidation liquid to generate another around of coagulation-precipitation and to adjust pH value at 8.5; after 0.5 hour of precipitation, the removal percentage of TOC in the treated liquid is 60%. After the Ca(OH).sub.2 coagulation process mentioned above, channeling the treated liquid to an activated sludge system for further treatment. The concentration of inflow COD is 200 mg/L and the volume of treated liquid is 1% of that of biochemical effluent; after 12 hours of treatment, the removal percentage of outflow COD is 40%. The repeated experiments have proven that the treated liquid can be channeled back to the biochemical system of biochemical effluent treatment for further biodegradation so that the recycled treatment of the highly concentrated desorption liquid can be obtained.

Embodiment 2

(3) Channeling the resin-desorption liquid through a nanofiltration membrane and the nanofiltration retentate (TOC=3500 mg/L, pH=9.0-10.5) is therefore obtained; adding in 5% (by weight) of Al.sub.2(SO4).sub.3.18H.sub.2O solution for coagulation-precipitation, and the supernatant so obtained is subject to Fenton oxidation wherein 0.5% (by weight) of FeSO.sub.4.7H.sub.2O and 1% (by weight) of 30% H.sub.2O.sub.2 solution are added to the supernatant; after 3 hours of Fenton reaction, adding NaOH solution to the oxidation liquid to adjust pH value at 9.5; after 0.5 hour of precipitation, the removal percentage of TOC in the treated liquid is 80%. After the NaOH coagulation process mentioned above, channeling the treated liquid to an activated sludge system for further treatment. The concentration of inflow COD is 200 mg/L and the volume of treated liquid is 1% of that of biochemical effluent; after 12 hours of treatment, the removal percentage of outflow COD is 40%. The repeated experiments have proven that the treated liquid can be channeled back to the biochemical system of biochemical effluent treatment for further biodegradation so that the recycled treatment of the highly concentrated desorption liquid can be obtained.

Embodiment 3

(4) Channeling the resin-desorption liquid through a nanofiltration membrane and the nanofiltration retentate (TOC=3000 mg/L, pH=9.5-10) is therefore obtained; adding in 1% (by weight) of FeSO.sub.4.7H.sub.2O solution for coagulation-precipitation, and the supernatant so obtained is subject to ozone oxidation wherein the concentration of ozone is 3 mg/L; after 3 hours of ozone reaction, adding Ca(OH).sub.2 emulsion to the oxidation liquid to generate another around of coagulation-precipitation and to adjust pH value at 10.5; after 0.5 hour of precipitation, the removal percentage of TOC in the treated liquid is 65% and the ratio of BOD.sub.5/COD.sub.cr increases to 0.41. After the Ca(OH).sub.2 coagulation process mentioned above, channeling the treated liquid to an activated sludge system for further treatment. The concentration of inflow COD is 400 mg/L and the volume of treated liquid is 5% of that of biochemical effluent; after 18 hours of treatment, the removal percentage of outflow COD is 65%. The repeated experiments have proven that the treated liquid can be channeled back to the biochemical system of biochemical effluent treatment for further biodegradation so that the recycled treatment of the highly concentrated desorption liquid can be obtained.

Embodiment 4

(5) Channeling the resin-desorption liquid through a nanofiltration membrane and the nanofiltration retentate (TOC=3500 mg/L, pH=9.5-10) is therefore obtained; adding in 2% (by weight) of PAC solution for coagulation-precipitation, and the supernatant so obtained is subject to ozone oxidation process wherein the concentration of ozone is 10 mg/L; after 5 hours of ozone reaction, adding NaOH solution to the oxidation liquid to generate another around of coagulation-precipitation and to adjust pH value at 9.0; after 0.5 hour of precipitation, the removal percentage of TOC in the treated liquid is 70% and the ratio of BOD.sub.5/COD.sub.cr increases to 0.45. After the NaOH coagulation process mentioned above, channeling the treated liquid to an activated sludge system for further treatment. The concentration of inflow COD is 400 mg/L and the volume of treated liquid is 5% of that of biochemical effluent; after 18 hours of treatment, the removal percentage of outflow COD is 65%. The repeated experiments have proven that the treated liquid can be channeled back to the biochemical system of biochemical effluent treatment for further biodegradation so that the recycled treatment of the highly concentrated desorption liquid can be obtained.