CN109761335A

CN109761335A - A new method for removing nitrate nitrogen from sewage

Info

Publication number: CN109761335A
Application number: CN201910224059.1A
Authority: CN
Inventors: 云玉攀; 温学友; 孙菁菁; 李景; 苗志加; 方晓峰; 万静敏; 朱振亚; 赵志瑞; 李爱国; 焦珍; 高爱舫
Original assignee: Hebei GEO University
Current assignee: Hebei GEO University
Priority date: 2019-03-22
Filing date: 2019-03-22
Publication date: 2019-05-17

Abstract

The invention discloses a kind of new methods of nitrate nitrogen in removal sewage, belong to technical field of sewage in environmental project, comprising the following steps: a certain proportion of catalyst and Fe are put into reactive tank, reaction kettle, fixed bed⁰, pH value is adjusted, starts to stir, controls the reaction time, intermittent or continous way can be used in operation mode, wherein when using continous way operation, reactor need to add equipment for separating liquid from solid, to prevent reproducibility Fe⁰And the loss of catalyst.The present invention uses Fe⁰The new method of collaboration loaded catalyst can convert nitrate nitrogen to nitrogen, and by-product ammonia-nitrogen content is then relatively low, truly realizes the removal of N element in water body.This is also that secondary effluent from sewage treatment plant causes the higher problem of total nitrogen content due to nitrate nitrogen content, provides a kind of new resolving ideas.

Description

The new method of nitrate nitrogen in a kind of removal sewage

Technical field

The invention belongs to technical field of sewage in environmental project, specifically, being related to nitre state in a kind of removal sewage The new method of nitrogen.

Background technique

With the development of industrial or agricultural, nitrate nitrogen in water body (NO₃ ^-) pollution have become environmental problem urgently to be resolved.In sewage The excessive emissions of nitrate nitrogen can directly contribute the decline of the eutrophication and water quality of water body, and pollution destroys ecological environment, thus right The production and living of the mankind cause strong influence.In addition, according to data, due to the discharge of high nitrogen content sewage, to a certain degree Groundwater azotate pollution caused by upper is more serious, and quite a lot of area nitrate content has even severely exceeded.Therefore, contain It first to be handled into municipal sewage plant before nitrogen sewage discharge to surface water body and then be discharged.And in practice, by dirt The limitation of water water quality and treatment process, denitrification effect is undesirable, and effluent nitrate-nitrogen content is often higher, and causing cannot be up to standard Discharge.Therefore, use which kind of technology that sewage effluents nitrate nitrogen is effectively reduced to reduce nitrate pollution as extremely urgent difficulty One of topic.

Currently, the common technology of removal nitrate nitrogen in water body includes: physical-chemical process, bioanalysis and chemical method.It is physico Method mainly passes through the nitrate nitrogen in the effects of selective penetrated property of selective absorption and film removal water body.Its shortcoming is that cannot The nitrate nitrogen in water body is completely removed, the transfer or concentration of pollutant only has occurred；Biochemical method is at present using more one Kind denitrogenation technology.Although its removal effect is preferable, low, complex process larger by water quality impact etc. that there is anti-shock loadings Disadvantage；Chemical method includes active metal reduction method and catalytic reduction method.Active metal reduction method utilizes active metal (such as Fe⁰) also Nitrate nitrogen in original removal water body.Its shortcoming is that the by-product of reaction need to carry out secondary treatment based on ammonia nitrogen；And it is catalyzed also Former rule is mainly with hydrogen or organic acid etc. (such as HCOOH) for reducing agent, under the effect of the catalyst, catalysis reduction removal nitre State nitrogen.Its shortcoming is that (hydrogen gas amount, operation pressure etc.) higher to operating condition, organic acid then decompose not exclusively, Yi Zao At secondary pollution etc..

Summary of the invention

It is an object of the invention to propose a kind of new method for removing nitrate nitrogen in sewage.This method uses reproducibility iron Simple substance (Fe⁰) the new catalytic denitrification method of loaded catalyst is cooperateed with to handle the nitrate nitrogen in sewage.In relevant research, Fe⁰Be widely used in the processing of nitrate nitrogen in water body, although preferable denitrification effect can be obtained, its react after by-product with Based on ammonia nitrogen, total nitrogen content is not effectively reduced in water body.And use Fe⁰Cooperate with the new method of loaded catalyst then can be by nitre State nitrogen is converted into nitrogen, and by-product ammonia-nitrogen content is then relatively low, truly realizes the removal of N element in water body.This Also cause the higher problem of total nitrogen content due to nitrate nitrogen content for secondary effluent from sewage treatment plant, provide a kind of new solution Certainly thinking.

Method of the invention mainly passes through the nitrate anion and reproducibility iron simple substance under the catalytic action of catalyst, in water body (Fe⁰) reacting is converted into N₂, to achieve the purpose that effective denitrogenation.

Technical principle of the invention is based on catalysis reaction principle.Fe⁰As the reducing agent of reaction, it acts as electronics confessions Body.And denitrification process is a typical heterogeneous catalytic reaction, on the metal active position of catalyst surface, nitrate nitrogen passes through hair Raw deoxygenation is gradually converted into nitrogen.

Its technical solution is as follows:

The new method of nitrate nitrogen in a kind of removal sewage, comprising the following steps: put into one in catalytic reduction reactor Determine the catalyst and Fe of quality⁰, pH value is adjusted, starts to stir, controls the reaction time, operation mode can be used intermittent or continuous Formula.Wherein, when using continous way operation, reactor need to add equipment for separating liquid from solid, to prevent reproducibility Fe⁰And catalyst Loss.

Step 1, starting peristaltic pump, sewage of the 300mL containing nitrate nitrogen, nitrate 22mg/L, with certain flow into Enter catalytic reduction reactor.

Step 2, the catalyst and Fe that certain mass is added into catalytic reduction reactor⁰, add catalyst and Fe⁰ Mass ratio is 5:4；

Step 3 opens full-automatic titrator, the hydrochloric acid of automatic feeding certain volume into reactor, concentration 0.5mol/ L keeps the pH value in reactor constant in 3-5；

Step 4 opens magnetic stirring apparatus, and stirring intensity control is 400r/min, and the biography of strengthen the system is intended to by stirring Matter effect, thus the generation for promoting catalysis to react, to obtain preferable denitrification effect；

After step 5, reaction 2h, reactor outlet valve is opened, the water sample of certain volume is taken out, through 0.45 μm of film mistake Filter measures nitrate nitrogen, nitrite nitrogen, ammonia nitrogen and total nitrogen concentration in water outlet, to analyze the denitrification effect of catalytic reduction reaction.

Further, the catalyst selected in step 2 is loaded catalyst, is made of catalytic active component and carrier.It urges The active component of agent load is made of major catalyst and co-catalyst.Major catalyst is mostly noble metal, as Pd, Pt, Ru, Rh, Ir etc..Co-catalyst usually has Ag, Hg, Cu, Ni, Sn, In etc..(such as Pd) adds Sn, In, Cu gold respectively in major catalyst Belong to, catalytic effect can be obviously improved.The active component of catalyst can be by the above major catalyst and co-catalyst group two-by-two It closes and constitutes.Carrier plays great function in catalysis reaction.The surface area and pore structure of carrier not only determine the work of load Property noble metal crystal grain also controls response matrix molecule, intermediate product or final product and is being catalyzed in the degree of scatter on its surface Mass transport process, surface migration and the reaction process on agent surface and the ability for reaching metal grain surface.Therefore, catalyst carrier The catalytic activity and choosing to catalyst such as itself type, composition, surface area, pore structure, thermal conductivity, heat resistance, mechanical strength Selecting property influences very big.The carrier is roughly divided into 2 classes: inorganic carrier and organic carrier.Inorganic carrier includes: γ-Al₂O₃, activity Charcoal, ZrO₂、SnO₂, ceramic membrane, SiO₂、TiO₂, ceria, hydrotalcite, diatomite, kaolin, silica gel etc..Organic carrier has Resin, high molecular polymer, fiber etc..

Further, the catalyst is single carried catalyst, that is, chooses carrier of a certain material as catalyst, The above material or its modified material (such as modification infusorial earth), or the stable, absorption property using other chemical property can be selected Well, the biggish new material of specific surface area (such as graphene).Catalyst can also be composite carried catalyst, i.e., carrier is by two Kind or two or more materials are mixed in a certain proportion processing and are made.

Further, the catalyst activity component of selection is bimetallic Pd and Cu, and Pd:Cu mass ratio is that (Pd is 3:1 5wt%).

Further, catalyst amounts 4g/L, Fe⁰Dosage is 5g/L.

Further, in step 3, pH value 4.

The invention has the benefit that

1, react more quick, reaction time is short；

2, operation is more simple, is convenient for management, and controllability is strong；

3, system catalytic activity and N₂Selectivity is higher, belongs to environmentally friendly technology.Its outstanding feature is: its Under specific reaction condition, nitrogen can be converted by the nitrate nitrogen overwhelming majority in system, by-product ammonia nitrogen concentration is relatively low, Without being reprocessed, the removal of N element in water body is truly realized, it is significant.

Specific embodiment

Technical solution of the present invention is described in more detail With reference to embodiment.

Using the secondary effluent of certain sewage treatment plant as test water, water quality indicator is as shown in table 1.

1 sewage quality of table

Test choose catalyst carrier be diatomite, modification infusorial earth, graphene, active component be Pd-Cu (Pd: Cu mass ratio is 3:1, Pd, 5wt%), three kinds of catalyst amounts are 4g/L, Fe⁰Dosage be 5g/L, reaction temperature is Room temperature (20 DEG C), system pH be 4.2, stirring intensity 400r/min, reaction time 2h.

It is tested according to the above-mentioned operating procedure enumerated, test result is as shown in table 2 below.

The analysis of 2 effluent quality of table

The study found that carrying out denitrogenation processing to secondary effluent of municipal sewage plant using this method, three kinds of catalyst are equal Preferable denitrification effect can be obtained, the nitrate in water outlet reduces obviously, and the total nitrogen of system has significant decrease, is lower than The 15mg/L of discharge standard can reach discharge standard.Wherein, Pd-Cu/ graphene catalytic effect is best, Pd-Cu/ diatomite Effect is worst, and has a certain upgrade to the catalyst effect after diatomite modified.

It is the good denitrification effect of guarantee in the present invention (with catalytic activity and N₂Selectivity is measured), reaction need to be suitable for Operating condition under carry out, influence factor include: catalyst load active component constitute (such as Pd:Cu mass ratio), carrier kind Class, Fe⁰Dosage, pH value, reaction time, stirring intensity, catalyst amounts, carrier: active component mass ratio etc..For screening Suitable reaction condition, first by Plackett-Burman experimental design and analysis, from influence catalytic reduction it is numerous because In element, main affecting factors are chosen；Then by response surface analysis, Box-Behnken experimental design is carried out, is obtained by fitting Test data, establish even experiment design, and carry out conspicuousness etc. and examine, using optimal setting, find the anti-nitre of catalysis Change the optimum reaction condition of reaction.

In the reaction system established according to the present invention, react as follows:

Using the reactive hydrogen [H] generated deoxygenation can occur for nitrate nitrogen, gradually be reduced to N₂:

e^-+H⁺→H

e^-+H₂O→OH^-+H

In the present invention, suitable acid condition is most important for the conversion of nitrate nitrogen to nitrogen, H⁺Concentration is excessive, raw At NH₄ ⁺It can increase, system catalytic activity and N₂Selectivity can reduce；H⁺Less, catalysis reaction is slower, and denitrification effect is poor；This Outside, suitable H⁺Concentration can also Accelerating reduction Fe⁰Corrosion, to promote the reduction of nitrate nitrogen.

The foregoing is only a preferred embodiment of the present invention, the scope of protection of the present invention is not limited to this, it is any ripe Know those skilled in the art within the technical scope of the present disclosure, the letter for the technical solution that can be become apparent to Altered or equivalence replacement are fallen within the protection scope of the present invention.

Claims

1. a novel method for removing nitrate nitrogen in sewage, is characterized in that, comprises the following steps:

Step 1, start the peristaltic pump, 300mL of sewage containing nitrate nitrogen, the nitrate nitrogen concentration is 22mg/L, enter the catalytic denitrification reactor at a certain flow rate;

Step 2, adding a certain mass of catalyst and Fe ⁰ to the catalytic denitrification reactor, and the mass ratio of the catalyst and Fe ⁰ added is 5:4;

Step 3. Turn on the automatic titrator, automatically add a certain volume of hydrochloric acid into the reactor, the concentration is 0.5mol/L, and keep the pH value in the reactor constant at 3-5;

Step 4. Turn on the magnetic stirrer, and the stirring intensity is controlled to be 400r/min;

Step 5. After 2 hours of reaction, open the outlet valve of the reactor, take out a certain volume of water samples, filter them through a 0.45 μm membrane, and measure the concentrations of nitrate nitrogen, nitrite nitrogen, ammonia nitrogen and total nitrogen in the effluent to analyze the catalytic reduction reaction denitrification effect.

2 . The novel method for removing nitrate nitrogen in sewage according to claim 1 , wherein the catalyst selected in step 2 is a supported catalyst, which is composed of catalytically active components and a carrier. 3 .

3 . The new method for removing nitrate nitrogen in sewage according to claim 2 , wherein the catalyst is a single carrier catalyst or a composite carrier catalyst. 4 .

4. The new method for removing nitrate nitrogen in sewage according to claim 2, wherein the selected catalyst active components are bimetallic Pd and Cu, and the Pd:Cu mass ratio is 3:1.

5. The novel method for removing nitrate nitrogen in sewage according to claim 1, wherein the catalyst dosage is 4g/L, and the ^FeO dosage is 5g/L.

6 . The new method for removing nitrate nitrogen in sewage according to claim 1 , wherein, in step 3, the pH value is 4. 7 .