CN105836884A - Denitrification Phosphorus Removal Device and Method for Removing N2O - Google Patents

Abstract

The invention discloses a device and a method for removing phosphorus and N2O by means of denitrification, and belongs to the field of technologies for treating sewage and protecting environments. The device comprises an urban sewage raw water tank, a denitrification phosphorus removal SBR (sequencing batch reactor), a magnetic stirrer, an N2O micro-electrode, an N2O online monitoring system and an urban sewage water outlet tank. The method includes allowing urban sewage to flow into the denitrification phosphorus removal SBR, stirring the urban sewage in an anaerobic manner for 1-2 h, sufficiently releasing the phosphorus, simultaneously storing COD (chemical oxygen demand) in the sewage as PHA (polyhydroxyalkanoate), adding N2O solution into the denitrification phosphorus removal SBR and stirring the urban sewage under an oxygen deficient condition for 2-3 h by the aid of a denitrification phosphorus removal electron acceptor which is N2O; precipitating the urban sewage for 30-45 min and then draining water into the water outlet tank. Sludge needs to be discharged from the denitrification phosphorus removal SBR on time, so that the sludge concentration of the reactor can be maintained in the ranges of 2500-4000 mg/L, and the SRT (sludge retention time) is 16 d. The device and the method have the advantages that the N2O can be economically, easily and efficiently removed, and the COD and the P in the sewage can be simultaneously removed; the traditional denitrification phosphorus removal electron acceptor is replaced by the N2O and does not need to be acquired by means of aeration, and accordingly energy consumption can be reduced.

Description

Denitrification Phosphorus Removal Device and Method for Removing N2O

technical field

The invention relates to a device and a method for denitrification phosphorus removal and _N2O removal, and belongs to the technical field of sewage treatment and environmental protection.

Background technique

Nitrous oxide (N ₂ O) is regulated by the Kyoto Protocol including carbon dioxide (CO2), methane (CH4), hydrofluorocarbons (HFCs), perfluorocarbons (PFCs) and sulfur hexafluoride (SF6) One of the six greenhouse gases (greenhouse gases, GHGs). N ₂ O exists in the atmosphere in measure, but its warming potential is 298 times that of CO ₂ . The properties of N ₂ O release sources related to human activities can be divided into chemical and biological processes. Sources of N ₂ O release from chemical processes consist of oxidative combustion, incineration, industrial production, and atmospheric deposition. The N ₂ O released from biological processes mainly comes from agricultural soils, marine microorganisms, compost storage ponds, and nitrogenous waste and wastewater treatment processes. Nitrogenous wastewater includes urban sewage, landfill leachate and industrial wastewater. At present, the contribution of N ₂ O to the global atmospheric greenhouse effect has reached 5-6%. Therefore, how to effectively control and remove N ₂ O has become a difficult problem in research today when the global warming effect is gradually increasing.

In the current research on N2O removal, there are mainly direct catalytic decomposition methods of _N2O . It means that at high temperature, one or more metal oxide catalysts such as NiO, Fe ₂ O ₃ , Al ₂ O ₃ , CuO, MoO ₃ , or one or more zeolite catalysts loaded with iron can directly convert N2O catalyzes the following reaction: 2N ₂ O→2N ₂ +O ₂ . This method is considered to be a promising treatment method because it does not introduce impurities and does not produce secondary pollution. But it requires high temperature and catalyst, and the cost is high.

In the sewage biological denitrification phosphorus removal process, the nitrate (NO ₃ ^- ) is first reduced to nitrite (NO ₂ ^- ) during the denitrification phosphorus removal process using nitrate (NO ₃ ^- ) as the electron acceptor. Then nitrite (NO ₂ ^- ) is reduced to nitric oxide (NO), then nitric oxide (NO) is further reduced to nitrous oxide (N ₂ O), and finally nitrous oxide (N ₂ O) is reduced It is nitrogen (N ₂ ). In this reduction process, it can be found that N ₂ O is an intermediate product of denitrification and phosphorus removal, and it can also be used as an electron acceptor for denitrification and phosphorus removal. The bacteria that reduce N ₂ O to N ₂ are Nos, which is N The removal of ₂ O provides a new idea.

While denitrification phosphorus removal removes N ₂ O, it also removes COD and P in sewage, which can be said to kill three birds with one stone. The method has the advantages of simple operation, low cost and no secondary pollution, and is an innovative idea. The current research has not used the denitrification phosphorus removal process to remove N ₂ O, so the application prospect is very broad.

Contents of the invention

The object of the present invention is to propose a device and method for removing N ₂ O by denitrification and dephosphorization for the removal of the greenhouse gas N ₂ O. Combining water treatment with air pollution control to achieve the removal of N ₂ O and alleviate the global greenhouse effect, while also removing COD and P in sewage. It not only saves the catalyst and heating costs of the traditional N ₂ O removal process, but also saves the aeration costs required by the traditional denitrification phosphorus removal to obtain electron acceptors. The process is simple and does not produce secondary pollution, which is an economical and environmentally friendly method.

The object of the present invention is solved by the following technical solutions: denitrification dephosphorization removes the device of N ₂ O, is characterized in that, comprises urban sewage raw water tank (1), denitrification dephosphorization SBR (2), magnetic force stirrer ( 3), N ₂ O microelectrode (4), N ₂ O on-line monitoring system (5), urban sewage outlet tank (6); urban sewage raw water tank (1) and denitrification phosphorus removal SBR ( 2) are connected; the denitrification phosphorus removal SBR (2) is connected to the N ₂ O online monitoring system (5) through the N ₂ O microelectrode (4); the denitrification phosphorus removal SBR (2) is connected to the city through the drain valve (2.5) Sewage outlet tank (6) is connected.

The denitrification dephosphorization SBR (2) is equipped with a water inlet valve (2.1), an N ₂ O solution injector (2.2), an air bag (2.3), a sampling injector (2.4), a drain valve (2.5), and a sludge discharge valve (2.6).

The treatment process of N ₂ O and urban sewage in this device is as follows: urban sewage enters the urban sewage raw water tank, enters the denitrification and phosphorus removal SBR through the water inlet pump, and anaerobically stirs for 1 to 2 hours through a magnetic stirrer to fully release phosphorus. The COD in the sewage is stored as the internal carbon source PHA; then the N ₂ O solution is added to the SBR for denitrification and phosphorus removal through the N ₂ O solution injector, and N ₂ O is used as the electron acceptor for denitrification and phosphorus removal for anaerobic stirring 2 ～3h, while monitoring the N ₂ O concentration in the mixed liquid through the N ₂ O microelectrode) and the N ₂ O online monitoring system; settling for 30～45min, the drainage ratio is 40～50%, and the drainage enters the urban sewage outlet tank. The denitrification phosphorus removal SBR is a closed system, and a 1L air bag is connected to the top of it to balance the pressure inside and outside the reactor.

The method for denitrification phosphorus removal to remove _N2O is characterized in that it comprises the following steps:

1) System startup:

Inoculate the return sludge of the A2O process from the traditional sewage plant into the SBR reactor for denitrification and phosphorus removal, so that the sludge concentration in the reactor can reach 2500-4000mg/L;

2) Runtime adjustment operation:

Urban sewage enters the urban sewage raw water tank (1), enters the denitrification phosphorus removal SBR (2) through the water inlet pump (1.1), and is anaerobically stirred by a magnetic stirrer (3) for 1 to 2 hours to fully release phosphorus, and at the same time COD is stored as the internal carbon source PHA; then the N ₂ O solution is added to the denitrification phosphorus removal SBR (2) through the N ₂ O solution injector (2.2), and the N ₂ O microelectrode (4) and N ₂ O are online at the same time The monitoring system (5) monitors the concentration of N ₂ O in the mixture, and uses N ₂ O as the electron acceptor for denitrification and dephosphorization to perform anoxic stirring for 2-3 hours until N ₂ O is completely removed. During the stirring process, the magnetic stirrer The rotation speed is 150-200r/min, just mix the solution in the reactor evenly, and it should not be stirred too fast to prevent N ₂ O from overflowing; settling for 30-45min, the drainage ratio is 40-50%, and the drainage enters the urban sewage Out of the water tank (6). The denitrification phosphorus removal SBR (2) is connected with an air bag (2.3) at the top to facilitate the balance of the internal and external pressure of the reactor. Denitrification phosphorus removal SBR needs to discharge sludge on time, so that the reactor sludge concentration is maintained at 2500-4000mg/L, and the SRT is 16d.

The device and method for denitrification phosphorus removal and _N2O removal of the present invention have the following advantages:

1) Compared with the traditional method of removing N ₂ O through high-temperature catalysis, the device and method for removing N ₂ O by denitrification and phosphorus removal do not require heating and adding catalysts, which saves costs.

2) The process is simple and easy to control, does not produce secondary pollution, and belongs to the environmental protection process.

3) Traditional denitrification phosphorus removal needs to obtain electron acceptors through aeration, and the device and method for denitrification phosphorus removal N ₂ O use N ₂ O as the electron acceptor for denitrification phosphorus removal, saving 100% aeration energy consumption, reducing the cost of wastewater phosphorus removal treatment.

Description of drawings

Fig. 1 is a schematic structural diagram of a device for denitrification phosphorus removal and N ₂ O removal according to the present invention.

In the figure, 1 is the urban sewage raw water tank, 2 is the denitrification phosphorus removal SBR, 3 is the magnetic stirrer, 4 is the _N2O microelectrode, 5 is the _N2O online monitoring system, and 6 is the urban sewage outlet tank; 1.1 is the inlet Water pump; 2.1 is the water inlet valve, 2.2 is the N ₂ O solution injector, 2.3 is the air bag, 2.4 is the sampling injector, 2.5 is the drain valve, and 2.6 is the mud discharge valve.

detailed description

Below in conjunction with accompanying drawing and embodiment the present invention will be further described: denitrification phosphorus removal as shown in Figure 1 removes the device of N ₂ O, comprises city sewage raw water tank (1), denitrification phosphorus removal SBR (2), magnetic force stirrer (3), N ₂ O microelectrode (4), N ₂ O online monitoring system (5), urban sewage outlet tank (6); urban sewage raw water tank (1) and denitrification dephosphorization SBR through inlet pump (1.1) (2) are connected; the denitrification phosphorus removal SBR (2) is connected with the N ₂ O online monitoring system (5) through the N ₂ O microelectrode (4); the denitrification phosphorus removal SBR (2) is connected with the The city sewage outlet tank (6) is connected.

The denitrification dephosphorization SBR (2) is equipped with a water inlet valve (2.1), an N ₂ O solution injector (2.2), an air bag (2.3), a sampling injector (2.4), a drain valve (2.5), and a sludge discharge valve (2.6).

The experiment uses domestic sewage from a family area of a university in Beijing. _The N ₂ O solution comes from a saturated N ₂ O solution that is blown into water by an N ₂ O gas tank. The concentration is 800-1000mgN ₂ ON/L. The concentration of liquid N ₂ O (calculated as N) is 60-80 mg/L, and the specific water quality of domestic sewage raw water is as follows: COD concentration is 120-260 mg/L, NO ₂ ^- -N concentration <0.1 mg/L, NO ₃ ^- -N The concentration is <0.8mg/L, the P concentration is 5-7mg/L, and the pH is 7-8. The test system is shown in Figure 1. The reactor is made of plexiglass. The denitrification and phosphorus removal SBR has an effective volume of 2L and a drainage ratio of 40-50%.

The specific implementation includes the following steps:

1) System startup:

Inoculate the return sludge of the traditional sewage plant A2O process into the SBR reactor for denitrification and phosphorus removal, so that the sludge concentration in the reactor can reach 3500mg/L;

2) Runtime adjustment operation:

Urban sewage enters the urban sewage raw water tank (1), enters the denitrification phosphorus removal SBR (2) through the water inlet pump (1.1), and is anaerobically stirred by a magnetic stirrer (3) for 1 to 2 hours to fully release phosphorus, and at the same time COD is stored as the internal carbon source PHA; then the N ₂ O solution is added to the denitrification phosphorus removal SBR (2) through the N ₂ O solution injector (2.2), and the N ₂ O microelectrode (4) and N ₂ O are online at the same time The monitoring system (5) monitors the concentration of N ₂ O in the mixture, and uses N ₂ O as the electron acceptor for denitrification and dephosphorization to perform anoxic stirring for 2-3 hours until N ₂ O is completely removed. During the stirring process, the magnetic stirrer The speed is 150-200r/min, just mix the solution in the reactor evenly, and it should not be stirred too fast to prevent N ₂ O from overflowing; settling for 30-45min, the drainage ratio is 40-50%, and the drainage enters the urban sewage Out of the water tank (6). The denitrification phosphorus removal SBR (2) is connected with a 1L air bag (2.3) at the top to facilitate the balance of the internal and external pressure of the reactor. Denitrification phosphorus removal SBR needs to discharge sludge on time, so that the reactor sludge concentration is maintained at 2500-4000mg/L, and the SRT is 16d.

The test results show that after the operation is stable, the concentration of N ₂ O in the denitrification dephosphorization SBR reactor water is 0-2mg/L, the concentration of COD is 35-40mg/L, NO ₂ ^- ~N<0.1mg/L, NO ₃ ^- ~N<0.5mg/L, P<0.5mg/L.

The above are specific embodiments of the present invention, which are convenient for those skilled in the art to better understand and apply the present invention, but the implementation of the present invention is not limited thereto, so those skilled in the art can make simple improvements to the present invention. Within the protection scope of the present invention.

Claims (2)

1. denitrification dephosphorization removes N₂The device of O, its feature includes: municipal sewage raw water box (1), denitrification dephosphorization SBR (2), magnetic stirring apparatus (3), N₂O microelectrode (4), N₂O on-line monitoring system (5), municipal sewage go out Water tank (6)；Municipal sewage raw water box (1) is connected with denitrification dephosphorization SBR (2) by intake pump (1.1), Denitrification dephosphorization SBR (2) passes through N₂O microelectrode (4) and N₂O on-line monitoring system (5) connects, denitrification Dephosphorization SBR (2) is connected with municipal sewage water tank (6) by draining valve (2.5)；

Described denitrification dephosphorization SBR (2) is provided with water intaking valve (2.1), adds N₂O solution injector (2.2), airbag (2.3), sampling injector (2.4), draining valve (2.5), mud valve (2.6).

2. the method applying device as claimed in claim 1, it is characterised in that comprise the following steps:

1) system starts:

By traditional wastewater factory A₂O process reflows sludge seeding is in denitrification dephosphorization sbr reactor device, in making reactor Sludge concentration reaches 2500～4000mg/L；

2) regulation operation when running:

Municipal sewage enters into municipal sewage raw water box (1), enters denitrification dephosphorization SBR by intake pump (1.1) (2), stirring 1～2h by magnetic stirring apparatus (3) anaerobism, the COD in sewage saves as internal carbon source PHA simultaneously； N subsequently₂O solution is by adding N₂O solution injector (2.2) adds, simultaneously in denitrification dephosphorization SBR (2) Pass through N₂O microelectrode (4) and N₂N in O on-line monitoring system (5) monitoring mixed liquor₂O concentration, with N₂O makees Electron acceptor for denitrification dephosphorization carries out anoxia stirring 2～3h to N₂O is removed completely, in whipping process, and magnetic Power agitator speed is 150-200r/min,；Precipitation 30～45min, draining ratio is 40～50%, is drained into city City's sewage water tank (6)；Denitrification dephosphorization SBR (2) is connected with airbag (2.3) and is easy in balanced reaction device at top External pressure；Denitrification dephosphorization SBR needs spoil disposal on time, makes reactor sludge concentration maintain 2500～4000mg/L, SRT is 16d.