CN114590874B - Dual electrochemical treatment method and device for landfill leachate reverse osmosis concentrated solution - Google Patents

Dual electrochemical treatment method and device for landfill leachate reverse osmosis concentrated solution Download PDF

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CN114590874B
CN114590874B CN202111452494.3A CN202111452494A CN114590874B CN 114590874 B CN114590874 B CN 114590874B CN 202111452494 A CN202111452494 A CN 202111452494A CN 114590874 B CN114590874 B CN 114590874B
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reverse osmosis
electroflocculation
treatment
concentrated solution
unit
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CN114590874A (en
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佐藤雄梧
陈光浩
曾谦
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Hong Kong University of Science and Technology HKUST
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    • C—CHEMISTRY; METALLURGY
    • C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F1/00—Treatment of water, waste water, or sewage
    • C02F1/46—Treatment of water, waste water, or sewage by electrochemical methods
    • C02F1/461—Treatment of water, waste water, or sewage by electrochemical methods by electrolysis
    • C02F1/463—Treatment of water, waste water, or sewage by electrochemical methods by electrolysis by electrocoagulation
    • C—CHEMISTRY; METALLURGY
    • C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F1/00—Treatment of water, waste water, or sewage
    • C02F1/46—Treatment of water, waste water, or sewage by electrochemical methods
    • C02F1/461—Treatment of water, waste water, or sewage by electrochemical methods by electrolysis
    • C02F1/467—Treatment of water, waste water, or sewage by electrochemical methods by electrolysis by electrochemical disinfection; by electrooxydation or by electroreduction
    • C02F1/4672—Treatment of water, waste water, or sewage by electrochemical methods by electrolysis by electrochemical disinfection; by electrooxydation or by electroreduction by electrooxydation
    • C—CHEMISTRY; METALLURGY
    • C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F2103/00—Nature of the water, waste water, sewage or sludge to be treated
    • C02F2103/06—Contaminated groundwater or leachate
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02A—TECHNOLOGIES FOR ADAPTATION TO CLIMATE CHANGE
    • Y02A20/00—Water conservation; Efficient water supply; Efficient water use
    • Y02A20/124—Water desalination
    • Y02A20/131—Reverse-osmosis
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02W—CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO WASTEWATER TREATMENT OR WASTE MANAGEMENT
    • Y02W10/00—Technologies for wastewater treatment
    • Y02W10/10—Biological treatment of water, waste water, or sewage

Abstract

The invention belongs to the field of environmental engineering, and more particularly provides a double electrochemical treatment method of landfill leachate reverse osmosis concentrated solution, which comprises the following two steps: (1) Introducing the landfill leachate reverse osmosis concentrated solution into an electric flocculation unit to perform electric flocculation treatment on the landfill leachate; (2) Introducing the reverse osmosis concentrated solution of the garbage leachate subjected to electric flocculation into an electric oxidation-electric flocculation unit and simultaneously carrying out electric oxidation-electric flocculation treatment; the electroflocculation unit and electrooxidation-electroflocculation unit comprise two or more anodes and cathodes connected in series, wherein the cathode of the electrooxidation-electroflocculation unit is aluminum. The invention also provides a corresponding treatment device for the landfill leachate reverse osmosis concentrated solution. The invention can not only realize the removal of high-concentration COD, greatly improve the biodegradability of ROLC, but also effectively prevent toxic Pb from Ti/PbO under the conditions of short time, low energy consumption and no addition of any chemical reagent 2 And (5) dissolving the anode.

Description

Dual electrochemical treatment method and device for landfill leachate reverse osmosis concentrated solution
Technical Field
The invention belongs to the field of environmental engineering, and particularly relates to double electrochemical treatment of landfill leachate reverse osmosis concentrated solution.
Background
The garbage percolate is from sanitary landfill and garbage incinerator, and is a pollutant containing high concentration organic matter, inorganic salt and heavy metal. By 2025, global landfill leachate yields are expected to exceed 3.3 hundred million tons (Abunama et al, 2018; costa et al, 2019). In addition, landfill aging can produce more difficult to dispose of leachate, which is conventionalBiological methods cannot handle (Renou et al, 2008). In pollution control Standard for landfill sites (GB 16889-2008) published and implemented in China 2008, the Biochemical Oxygen Demand (BOD) in landfill leachate is controlled 5 ) Strict emission standards are put forward by indexes such as Chemical Oxygen Demand (COD), ammonia nitrogen, total Nitrogen (TN), heavy metals and the like, and the requirement must reach 100mg L -1 COD threshold of (c). To meet the standard of compliant discharge, landfill leachate treatment processes typically employ Reverse Osmosis (RO) or other techniques (99.8% removal). However, RO produces a concentrate, called landfill leachate reverse osmosis concentrate (roc), as a byproduct of membrane separation (10% to 60% of the original feed volume). ROLC concentration can be as high as 20 times that of the original percolate, and biodegradability (BOD 5 COD) as low as 0.01 (Zhou et al, 2011). ROLC also contains emerging contaminants such as pesticides, endocrine disrupting chemicals, drugs, nanomaterials, etc. (Joo and Tansel, 2015).
Methods of handling ROLC fall into four categories: (a) recharging; (b) curing (e.g. cement); (c) Evaporative crystallization, and (d) Advanced Oxidation Process (AOP). Recharging of the ROLC can inhibit the biological treatment process of the permeate and can place additional burden on the membrane process (Talalaj and Biedka, 2015). An increase in contaminant concentration will result in membrane fouling within the system, requiring high maintenance and replacement costs (about $ 1,700 per membrane element) (Avlonitis et al, 2003; renou et al, 2008; shi et al, 2019). While the curing process may be used to produce materials such as cement, the energy consumption and binder cost for partial vaporization can be as high as $93 per ton of ROLC (henderych et al, 2019). Evaporation techniques are typically mechanical vapor recompression and submerged combustion evaporators, however, they produce additional residue and little ammonia is removed from the roc (Ye et al, 2017; zhang et al, 2019). AOP, on the other hand, undergoes partial or complete oxidation of refractory organics by the generation of highly reactive free radicals (e.g., hydroxyl and sulfate groups and reactive chlorine) (Deng and Ezyske,2011; yang et al, 2015). However, limitations of AOP include: (1) The need for continuous input of chemicals such as pH modifiers and hydrogen peroxide, (2) incomplete oxidation of the compound may lead to toxic byproducts (Gautam et al, 2019).For example, in the prior art patents dealing with landfill leachate, the modified electro-Fenton (electro-Fenton) method is dominant. While the Fenton process is effective in generating OH radicals, the patent containing the Fenton process requires an optimization of the process by adjusting the pH from about 8.5 to 3-4 by strong acid alkalinity adjustment (Labiadh et al, 2016). The average cost of added sulfuric acid, iron and hydrogen peroxide was estimated to be $ 3.7/m 3 (Wu et al.,2020)。
The electrochemical method can generate the oxidant in situ without adding chemicals, and the process is simple to operate and easy to maintain, and is gradually applied to the field of landfill leachate treatment. Previously, zhou et al (2016) successfully treated ROLC (COD removal rate 87.5%) with Boron Doped Diamond (BDD) anodes in 6 hours. Although BDD has high oxygen evolution overpotential, hydroxyl radical can be generated to rapidly degrade pollutantset al 2005), but is very conductive and produces toxic chlorinated byproducts such as chlorate and perchlorate (a->et al.,2010)。Ti/PbO 2 Has good conductivity and oxygen overpotential, is another widely used anode, but the toxicity of lead (Pb) precipitation affects its applicability (Panizza and Cerisola, 2009).
Therefore, there is a need in the art for an effective method of treating ROLC that is simple in configuration, does not require the addition of chemical reagents to adjust pH, simultaneously can rapidly and efficiently reduce COD, total Organic Carbon (TOC), total Nitrogen (TN) and color in ROLC, and effectively prevents dissolution of lead in the anode.
Disclosure of Invention
In a first aspect, the invention provides a method for treating landfill leachate reverse osmosis concentrated solution, which is characterized by comprising the following two steps:
(1) Introducing the landfill leachate reverse osmosis concentrated solution into an electric flocculation unit to perform electric flocculation treatment on the landfill leachate reverse osmosis concentrated solution;
(2) Introducing the reverse osmosis concentrated solution of the garbage leachate subjected to electric flocculation into an electric oxidation-electric flocculation unit to perform electric oxidation and electric flocculation treatment simultaneously;
wherein the electroflocculation unit and electrooxidation-electroflocculation unit comprise two or more anodes and cathodes connected in series, wherein the cathode of the electrooxidation-electroflocculation unit is aluminum.
In one embodiment, the anode of the electrooxidation-electroflocculation unit is Ti/PbO 2 、Ti/TaO 2 Or Ti/RuO 2 Preferably Ti/beta-PbO 2 。
In one embodiment, the anode of the electroflocculation unit is aluminum, iron or stainless steel, preferably aluminum.
In one embodiment, the current density during the electroflocculation treatment and/or electrooxidation-electroflocculation treatment is 14.1mA/cm 2 。
In one embodiment, the time of the electroflocculation treatment is 30 minutes and the time of the electrooxidation-electroflocculation treatment is 180 minutes.
In one embodiment, the electrodes are spaced 10mm apart.
In one embodiment, the temperature of the electrocoagulation treatment and the electrooxidation-electrocoagulation treatment is from about 15 ℃ to about 25 ℃.
In a second aspect, the invention provides a device for treating landfill leachate reverse osmosis concentrated solution, which is characterized by comprising the following two units:
(1) The electric flocculation unit is used for carrying out electric flocculation treatment on the landfill leachate reverse osmosis concentrated solution;
(2) An electrooxidation-electroflocculation unit for simultaneously carrying out electrooxidation and electroflocculation treatment on the reverse osmosis concentrated solution of the garbage leachate after electroflocculation;
wherein the electroflocculation unit and electrooxidation-electroflocculation unit comprise two or more anodes and cathodes connected in series, wherein the cathode of the electrooxidation-electroflocculation unit is aluminum.
The invention has the beneficial effects that:
1) Provides a ROLC double electrochemical treatment method based on electric flocculation and electric oxidation-electric flocculation;
2) The ROLC processing time is greatly reduced;
3) No chemical reagent is needed to be added, so that the treatment cost of ROLC is greatly reduced;
4) Pb is prevented from dissolving from the anode, thereby reducing the formation of toxic by-products during the treatment.
Drawings
In order to more clearly illustrate the examples of the invention or the technical solutions of the prior art, the drawings used in the examples will be briefly described below, it being obvious that the drawings in the following description are only examples of the invention and that other embodiments can be obtained according to these drawings without inventive effort for a person skilled in the art.
FIG. 1 is a schematic illustration of a double electrochemical treatment (electroflocculation (EC) and electroflocculation-Electrooxidation (EO) EC ) Schematic of four specific combinations.
FIG. 2 is NIO (EC-EO EC ) The core design of (2) illustrates the two-step process of electroflocculation and electroflocculation-electrooxidation.
FIG. 3 shows the effluent in step 1 (EC) and step 2 (EO EC ) And when the waste water is not filtered, the COD removal rate and the sludge volume index are compared.
FIG. 4 shows Electroflocculation (EC) and electroflocculation-Electrooxidation (EO) at 210 minutes of performance EC ) After that, removal rates of COD, total Organic Carbon (TOC), total Nitrogen (TN) and color.
Fig. 5: (a) organic conversion in ROLC after NIO treatment; (b) biodegradability with a change in aromatic structure; (c) lead (Pb) removal and dissolution during NIO.
Detailed Description
The present invention will now be described more fully hereinafter with reference to the accompanying drawings, in which embodiments of the invention are shown. It will be apparent that the described embodiments are only some, but not all, embodiments of the invention. All other embodiments that can be obtained by a person skilled in the art based on the embodiments of the present invention are within the scope of the present invention.
As described above, the existing ROLC treatment method requires high cost, long time, addition of a large amount of chemical agent, or toxic by-products during the treatment. Accordingly, an object of the present invention is to provide a double electrochemical treatment method for ROLC capable of achieving removal of COD at a high concentration in a short time with low energy consumption without adding any chemical agent, greatly improving the biodegradability of ROLC, and effectively preventing toxic Pb from being removed from Ti/PbO 2 And (5) dissolving the anode.
Accordingly, in a first aspect, the present invention provides a method for treating a landfill leachate reverse osmosis concentrate, characterised by comprising the steps of:
(1) Introducing the landfill leachate reverse osmosis concentrated solution into an electric flocculation (EC) unit to perform electric flocculation treatment on the landfill leachate reverse osmosis concentrated solution;
(2) Introducing the reverse osmosis concentrated solution of the garbage percolate after the electric flocculation into electric oxidation-electric flocculation (EO) EC ) The unit is subjected to electro-oxidation and electro-flocculation treatment simultaneously;
wherein the electroflocculation unit and electrooxidation-electroflocculation unit comprise two or more anodes and cathodes connected in series, wherein the cathode of the electrooxidation-electroflocculation unit is aluminum.
As described in the background section, landfill leachate reverse osmosis concentrate (roc) is a byproduct of reverse osmosis treatment of landfill leachate, in which the contaminant species are more extensive and the contaminant concentration may be 20 times higher than the original landfill leachate. Existing electrochemical-based landfill leachate treatment methods often require the addition of large amounts of chemical reagents to adjust the pH (e.g., the electro-Fenton process) or to produce toxic byproducts during the treatment process. To this end, the present inventors have found and/or devised a combined electrochemical treatment process that overcomes the above difficulties by combining electroflocculation with electrooxidation.
In the process, the electric flocculation takes metals such as aluminum, iron and the like as an anode, and under the action of direct current, electrons are lost from the anode to form metal cations, and the metal cations are combined with OH < - > in a solution to generate a high-activity flocculation group, so that the high-activity flocculation group has extremely strong adsorption capacity, has the coagulation and precipitation effects on colloidal impurities and suspended impurities, and can remove various pollutants in water due to the oxidation effect of the anode and the reduction effect of a cathode.
During the first EC treatment step, the refractory organics (e.g., aromatics) in the rocc can be first removed rapidly by EC using an aluminum anode, which can effectively increase the efficiency and duration of subsequent EO treatments; then in the second step EO EC EO is applied to the remaining intermediate during the treatment (EC) And (5) processing. The method can rapidly reduce COD without adding any chemical substances by utilizing high content of chloride in ROLC.
In the present invention, aluminum is used as the anode of the EC because aluminum-based EC produces larger and more resistant floccules, and aluminum hydroxide in the EC process has a strong adsorption affinity for humic acid rich in rocc.
At EO EC In the process, ti/PbO is adopted 2 As anode, because of its ratio Ti/SnO 2 Is more stable and less costly than boron doped diamond (Si/BDD). Aluminum is used as the cathode at the same time, since the amphoteric nature of aluminum allows simultaneous EC (as EO EC ). Pb anodes are susceptible to dissolution when the solution pH is < 7.2 or when it contains a reducing agent such as Natural Organic Matter (NOM). ROLC is alkaline and has a pH of usually 7.9 to 8.2, so this patent is applied to EO EC In the process, aluminum is used as a cathode, so that the alkalinity is generated to further increase the pH value of the solution, and the dissolution of Pb anode is effectively inhibited. Furthermore, prior to or during EO treatment, aluminum-based ECs can raise pH and remove NOM while maintaining high treatment efficiency.
Therefore, the inventors have found through many experiments that EC treatment before and during EO is performed by combining EC with EO, and connecting electrodes in series can significantly promote degradation of ROLC and enhance biodegradability thereof, while effectively preventing Pb from dissolving to protect Ti/PbO 2 And an anode. The inventors set this double electrochemical treatment method (EC-EO EC ) Named NIO.
Examples
Materials and methods
1. Percolate source
Landfill leachate reverse osmosis concentrate (ROLC) treated by reverse osmosis is from a certain solid waste landfill of Shenzhen in China. The properties of this ROLC are shown in Table 1.
TABLE 1 Properties of landfill leachate reverse osmosis concentrate (ROLC)
Parameters (parameters) Concentration of
pH 8.37±0.14
Temperature (. Degree. C.) 20.9
UV 254 Absorbance (cm) -1 ) 83.7±1.4
Color (Pt-Co) 27049±159
COD 8750±181
BOD 130.3±11.5
TOC 3576±165
TN 1086±130
NH 4 + -N 820±54
Cl - 6781.4±315
Pb 0.266±0.021
* Unless otherwise indicated, all parameters are in units of mg L -1 。
2. Electrochemical arrangement
All electrochemical tests were performed in two steps in an undivided cell (fig. 1), step 1 (electroflocculation, EC) and step 2 (electroflocculation-electrooxidation, EO) EC ) Four specific combinations of the two steps are as follows: (a) Parallel EC-EO EC (P1); (b) Tandem EC-EO EC (S1); (c) Parallel EO EC -EC (P2); (d) Tandem EO EC -EC (S2). 300mL ROLC was added per run, without changing pH or adding other chemicals. The EC unit consisted of four plates with a gap of 10mm, set to two aluminum anodes and two carbon-graphite cathodes (both 99.9% pure; 70X 100 mm). The total active surface area was determined to be 126cm 2 . Step 1 (EC) at a current density of 14.1mA/cm 2 Is carried out at room temperature for 30 minutes, which is considered to be the optimal condition in the preliminary test. EO (ethylene oxide) film EC The unit is provided with four insertion electrodes consisting of two Ti/beta-PbO 2 Anode (70×100mm;1.3mm coating thickness) and two aluminum cathodes. Step (EO) EC ) The active surface area, current density and electrode spacing were the same as those set for EC, with 180 minutes at room temperature. The effluent is not passed between step 1 and step 2Filtration, as COD, TOC and Sludge Volume Index (SVI) were found to decrease without filtration (fig. 2). A constant stirring speed of 150rpm was maintained throughout the experiment.
3. Analysis method
Throughout the experiment, at EC and EO, respectively EC Samples were taken during the process at 15 and 30 minute intervals. All EC-EO passed before further analysis EC The treated samples were all filtered through a 0.45 μm filter (Sartorius Minisart). Due to the ROLC exposure to pH, COD, TOC, dissolved Inorganic Carbon (DIC), TN and BOD 5 Influence of the measured values (APHA, 2012). The inventor aims at EC-EO EC COD, TOC, TN, color and lead dissolution of the treated samples were analyzed and the aromatic structure change and enhancement of biodegradability of the remaining organic compounds were investigated.
Intermittent pH measurements were performed using a portable multimeter (Multi 3420, wtw, germany). Using a high range (150 -1 To 1500mg L -1 ) COD sample bottles were subjected to chemical oxidation (model 45600-00, hach, USA) at 150℃for 2 hours. The COD values of all samples were determined spectrophotometrically (DR 2800, hach, USA) at 620 nm. TOC and TN were measured by combustion catalytic oxidation at 680℃using a TOC/TN analyzer (TOC-5000A, shimadzu, japan).
Ammonium (NH) 4 + ) Measurement of color and Ultraviolet (UV) absorbance was performed using spectrophotometry (JASCO V-770UV-Visible/NIR Spectrophotometer, easton, maryland, USA) (APHA, 2012). NH (NH) 4 + The concentration was determined at 425nm using Nessler reagent.
Lead (Pb) concentration was quantified using a Graphite Furnace Atomic Absorption Spectrophotometer (GFAAS) (Hitachi, ZA3000, japan) to verify Pb (II) dissolution in the treatment. The sludge produced was also acidified to verify Pb concentration. All samples were measured after acidification with 5% nitric acid.
Untreated ROLC and electrochemically treated samples were freeze-dried (-50 ℃ C., 48 hours) and uniformly ground into powder form. High resolution X-ray photoelectron spectroscopy (XPS) analysis was performed on a Kratos Analytical AXIS Ultra DLD photoelectron spectrometer. The lyophilized samples were mixed with KBr at a ratio of 1:100 and analyzed by Fourier transform Infrared Spectroscopy (FT-IR) (Vertex 70Hyperion 1000,Bruker) to determine the change in functional groups that were treated by the binding electrochemical method. All samples were measured in triplicate. The chemicals and reagents used were analytically pure and were used without further purification.
Experimental results
1. COD, TOC and color removal rate of four combined modes of double electrochemical treatment method
All electrode arrangements and treatment sequences, i.e. S1 (EC-EO EC In series), S2 (EO EC EC, tandem), P1 (EC-EO EC Parallel) and P2 (EO EC EC, parallel), following pseudo-primary kinetics, rapidly reduces COD in 210 minutes, in the order of effectiveness S1>S2>P1>P2. The best binding mode is S1, at 1.479 ×10 -2 Minute (min) -1 Reduces COD by 96% (figure 4) at the average removal rate constant. In contrast, the COD removal rate of S2 was reduced by 1.41 times, thereby achieving only 92% COD removal rate.
The significant reduction of COD is accompanied by a decolorization close to 100%, the rate of decolorization also follows pseudo first order kinetics, the order of efficiency being S1>S2>P1>P2. S1 reaches a decoloring rate of 99.5% within 150 minutes, and the highest average decoloring rate is 2.681 multiplied by 10 -2 Minute (min) -1 In contrast, the decolorization constants of S2, P1 and P2 were 1.12 times, 1.36 times and 23.9 times lower, respectively (i.e., 2.403X 10) -2 Minute (min) -1 、1.977×10 -2 Minute (min) -1 And 1.12X10 -3 Minute (min) -1 )。
While S1 reduces TOC by 72% (fig. 4). Other electrode arrangements reduced TOC by 61.5% (S2), 63.5% (P1) and 38.4% (P2).
2. Influence of four combinations of double electrochemical treatment methods on organic conversion and biodegradabilityThe electrochemical treatment of the tandem form (S1 and S2) by XPS analysis was found to reduce the amount of-C-OH and-C=O and significantly increase the amount of-COOH. Specifically, -COO in S1 and S2 compared to 11% in untreated controlThe highest H content was 28% and 22%, respectively. Furthermore, the electrochemical treatment method in the series form reduced the-c=o content from 10% (control) to 6% (S1) and 8% (S2), whereas the electrochemical treatment method in the parallel form increased the-c=o content by 16% (P1) and 18% (P2), respectively. Furthermore, the-C-OH content was reduced to 14% in S1 and S2 (FIG. 5), and increased to 25% in P2.
For the improvement of biodegradability, the electrochemical treatment method in the form of a series connection is superior to the electrochemical treatment method in the form of a parallel connection. Both S1 and S2 convert the roc into highly biodegradable effluent, thereby converting BOD 5 the/COD increased significantly from 0.015 to 0.53 and 0.64, respectively (FIG. 5), while the ratio of P1 and P2 remained at 0.095 and 0.035, respectively. Aromatic substitution index (UV) of P1, S1 and S2 253 /UV 203 ) From 0.42 in untreated ROLC to 0.14, 0.14 and 0.12, respectively (FIG. 5), while the aromatic substitution index of P2 was reduced to 0.28.
3. Influence of four combinations of Dual electrochemical treatment methods on Pb dissolutionDissolution of Pb prevents Ti/beta-PbO 2 Use of an anode. Dissolution of Pb can be inhibited by increasing pH, dissolved Inorganic Carbon (DIC) and free chlorine, but NOM accelerates dissolution of Pb. Accordingly, the inventors comprehensively examined Pb dissolution of the anode, pb concentration in the raw sample and the electrochemically treated sample, and the produced Pb-containing sludge. During S1, EC will first remove pre-existing Pb to undetectable levels, adsorbing 0.078mg Pb into the sludge; subsequent EO EC The process releases about 0.042mg of Pb, with 0.103mg of Pb adsorbed by the EC of the cathode, and 0.061mg of L -1 Is not removed. However, S2 releases about 2.2 times Pb (about 0.092 mg) and transfers 0.140mg Pb to the sludge, while 0.106mg L -1 The EC of the cathode remained in solution and was then ineffective for Pb removal. In addition, S1 removes about 70% of the NH4 in the ROLC + -N and reduce TN by 70%. Chloroamine can destroy PbO 2 The stability of the layer, while the reduction of nitrogen-containing species reduces the risk of chloroamine.
S1 (series EC-EO compared to other binding modes EC NIO) is the only binding modality suitable for inhibiting Pb dissolution. Thus, the first and second substrates are bonded together,the inventors have further used NIO to treat reverse osmosis concentrates of landfill leachate from different batches in a domestic landfill.
Results of NIO treatment of ROLC (5 months 2019) of landfill
Before NIO: after NIO:
COD 13593mg L -1 COD 560mg L -1
TOC 3992mg L -1 TOC 1041mg L -1
TN 901mg L -1 TN 311mg L -1
color 29110Pt-Co Color 193Pt-Co
NH 4 -N 650mg L -1 NH 4 -N 163mg L -1
8210mg L of chloride -1 Chloride 3921mg L -1
ROLC of NIO to landfill site (month 6 2019)) Processing the result
Before NIO: after NIO:
COD 8750mg L -1 COD 380mg L -1
TOC 3576mg L -1 TOC 999mg L -1
TN 1083mg L -1 TN 323mg L -1
color 27030Pt-Co Color 133Pt-Co
NH 4 -N 820mg L -1 NH 4 -N 240mg L -1
Chloride 6781mg L -1 Chloride 3728mg L -1
Results of NIO treatment on ROLC (month 8 2019) to generate a landfill
Before NIO: after NIO:
COD 6697mg L -1 COD 401mg L -1
TOC 3129mg L -1 TOC 813mg L -1
TN 864mg L -1 TN 211mg L -1
color 24800Pt-Co Color 35Pt-Co
NH 4 -N 750mg L -1 NH 4 -N 213mg L -1
Chloride 7120mg L -1 Chloride 4128mg L -1
As shown by the above results, the NIO achieved similar COD removal of about 95% regardless of the initial COD loading (about 6700 to 14000 difference). NIO has proven to be a promising alternative, effectively treating ROLC into biodegradable compounds.

Claims (5)

1. The treatment method of the landfill leachate reverse osmosis concentrated solution is characterized by comprising the following two steps:
(1) Introducing the landfill leachate reverse osmosis concentrated solution into an electric flocculation unit to perform electric flocculation treatment on the landfill leachate reverse osmosis concentrated solution;
(2) Introducing the reverse osmosis concentrated solution of the garbage leachate subjected to electric flocculation into an electric oxidation-electric flocculation unit to perform electric oxidation and electric flocculation treatment simultaneously;
wherein the electric flocculation unit comprises two anodes and two cathodes which are connected in series, and the anode of the electric flocculation unit is aluminum;
wherein the electro-oxidation-electro-flocculation unit comprises two anodes and two cathodes which are connected in series, the cathodes of the electro-oxidation-electro-flocculation unit are aluminum, and the anodes of the electro-oxidation-electro-flocculation unit are Ti/PbO 2 。
2. The method of claim 1, wherein the anode of the electrooxidation-electroflocculation unit is Ti/β -PbO 2 。
3. A method according to claim 1 or 2, wherein the current density during the electroflocculation treatment and/or electrooxidation-electroflocculation treatment is 14.1mA/cm 2 。
4. A method according to claim 1 or 2, wherein the time of the electroflocculation treatment is 30 minutes and the time of the electrooxidation-electroflocculation treatment is 180 minutes.
5. The device for treating the landfill leachate reverse osmosis concentrated solution is characterized by comprising the following two units:
(1) The electric flocculation unit is used for carrying out electric flocculation treatment on the landfill leachate reverse osmosis concentrated solution;
(2) An electrooxidation-electroflocculation unit for simultaneously carrying out electrooxidation and electroflocculation treatment on the reverse osmosis concentrated solution of the garbage leachate after electroflocculation;
wherein the electric flocculation unit comprises two anodes and two cathodes which are connected in series, and the anode of the electric flocculation unit is aluminum;
wherein the electrooxidation-electroflocculationThe unit comprises two anodes and two cathodes connected in series, wherein the cathode of the electro-oxidation-electro-flocculation unit is aluminum, and the anode of the electro-oxidation-electro-flocculation unit is Ti/PbO 2 。
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