Method for strengthening in-situ treatment of malodorous gas of sewage treatment plant by using rusted iron chips
Technical Field
The invention relates to the technical field of malodorous gas treatment, in particular to a method for strengthening the in-situ treatment of malodorous gas in a sewage treatment plant by using rusted iron chips.
Background
By 2016 years, the accumulated domestic sewage treatment plants are about 4000 seats, and the sewage treatment capacity reaches 1.7 billion cubic meters per day. A large amount of malodorous gas is generated in the sewage treatment process, which may cause displeasure of workers of sewage treatment plants and peripheral residents and even influence the health of the people, and cause serious environmental problems.
The main points of malodorous gas generated in the sewage treatment process are a pretreatment unit (a grating and a grit chamber), an aeration unit of a biological unit and a sludge treatment unit (a gravity concentration tank and a mechanical dehydration machine room). The generated malodorous gas is treated with NH3And H2S is the main one, and the main one is eight kinds of malodors determined in the emission Standard of malodorous gas pollutants (GB14554-1993) in ChinaThe two most important of the gaseous pollutants.
The most used in-situ treatment method for malodorous gas generated by sewage treatment plants at home and abroad is a terminal biological method. The aeration type activated sludge process is one of terminal biological processes, and has the advantages of high treatment efficiency and no restriction by floor area factors compared with other biological processes. However, the method usually adds powdered activated carbon into the activated sludge to improve the impact load resistance and the capability of decomposing malodorous substances, and the application of the process is limited by the defects of high cost and difficult recovery of the added activated carbon.
When rusted iron chips exist in a sewage system, the following reaction can be carried out to strengthen the capacity of treating pollutants in sewage. NH (NH)4 +Removing: (1) fe on rusted iron chip surface2O3And NH4 +The dissimilatory iron reduction is coupled with the ammonia nitrogen oxidation reaction to generate Fe2+And NO2 -/N2/NO3 -(ii) a (2) At the same time, Fe2O3Will also be reduced by iron reducing bacteria to produce Fe2+;(3)NO3 -/O2Fe produced by the above reaction2+Is oxidized into Fe3+;(4)Fe3+Will react with NH4 +Carrying out iron reduction coupled with ammonia nitrogen oxidation reaction. H2And (3) S removal: (1) fe3+Can be reacted with S2-Carrying out oxidation-reduction reaction to generate an S simple substance; (2) fe2+And S2-A FeS precipitate formed. Because the rusty iron chips are rich in content and low in price, if the rusty iron chips are used for replacing active carbon, the development of the technology for treating malodorous gas by an aeration type activated sludge method is promoted.
Patent CN104923068A reports a method for treating malodorous gas, which comprises introducing malodorous gas into a biochemical aeration tank through an aeration device, and contacting microorganisms in the tank to remove malodorous gas. However, the aeration unit of this method is not closed, the gas discharged from the unit has a risk of secondary pollution, and the malodorous gas aeration device used increases the operation and maintenance costs.
Patent CN107162192A reports a waste gas treatment process of biochemical sewage treatment system, in which malodorous gas generated in an anaerobic tank is introduced into an aerobic tank through an exhaust fan, the malodorous gas is removed and discharged from the aerobic tank, but the gas discharged from the aerobic tank has a risk of secondary pollution, and the exhaust fan increases the operation and maintenance costs.
Patent CN106587344A reports an anaerobic built-in rusty iron chip reactor for efficiently removing ammonia nitrogen and a process for treating ammonia nitrogen wastewater by the reactor.
Patent CN103420480A reports an anaerobic iron salt biological denitrification process, which enhances the denitrification efficiency of sewage by adding iron salt, but the technology is not applied to ammonia-containing waste gas treatment.
Patent CN105771554A reports an in-situ denitrification method for ammonia-containing waste gas and a denitrification device used by the same, which can treat ammonia-containing malodorous gas generated in situ, but the method needs additional culture of nitrosation-anaerobic ammonia oxidation functional bacteria, and is not suitable for in-situ treatment of malodorous gas in sewage treatment plants.
In general, according to the reported in-situ malodorous gas biological treatment method and the analysis of the condition that scrap iron is adopted to strengthen the sewage treatment capability, a process for combining the scrap iron with waste gas treated by the biological method is lacked, and a malodorous gas in-situ treatment system of an aeration type activated sludge method in an urban sewage treatment plant, which is not a system, is not formed. Therefore, a method for strengthening the in-situ treatment of the malodorous gas in the sewage treatment plant by the rusted iron chips is urgently needed to be established.
Disclosure of Invention
The invention aims to solve the defects in the prior art and provide a high-efficiency and low-energy-consumption method for in-situ treatment of malodorous gas in a sewage treatment plant.
1. A method for strengthening the in-situ treatment of malodorous gas in a sewage treatment plant by using rusted iron chips comprises the following steps: the method is characterized in that the sealing of the positions of the original sewage treatment plant, which mainly generate malodorous gases, namely a pretreatment unit (a grid, a grit chamber and a sewage adjusting tank), an aeration unit for biological treatment and a sludge treatment unit (a gravity concentration tank and sludge dewatering equipment) is realized, and a corresponding on-line sensor, a rust iron scrap feeding metering pump, a pressure gauge and a flowmeter are arranged, so that the running condition of the process in the malodorous gas treatment process is monitored in a master control room;
2. the closed units are connected with gas pipelines among the closed units in a manner shown in figure 1, malodorous gas spontaneously flows under the pressure generated by the closed aeration unit, so that the malodorous gas enters from the bottom of the closed sewage regulating tank and is absorbed by sewage, sewage in which the malodorous gas is dissolved enters into a biological treatment unit in which rust iron chips are added, and is removed through biochemical reaction, and part of malodorous gas escaping from the sewage regulating tank enters from the bottom of the biological treatment aeration unit and is absorbed, absorbed and decomposed by activated sludge;
3. the top of the anaerobic tank of the biological unit is provided with a rust iron scrap feeding metering pump, and the rust iron scrap feeding metering pump is used for supplementing according to the iron loss condition of the water discharged from the aerobic tank of the biological unit;
4. the aeration unit of the biological treatment is provided with a pressure gauge and a pressure relief valve, and when the pressure in the aeration unit exceeds a safety value, the valve is opened to relieve the pressure;
5. the main foul gas generating point is provided with a foul gas on-line sensor (such as H) after being sealed2S and NH3) Judging the operation condition of the process according to the concentration of the malodorous gas monitored in real time;
6. the gas pipelines of the aeration unit, which are connected with the regulating tank and the sludge treatment unit, are provided with flow meters, so that the flow of gas can be observed in a main control room in real time.
Compared with the prior art, the invention has the following beneficial effects:
(1) no foul gas end treatment equipment is required to be installed, and the floor area condition is not limited, so that the method is suitable for the transformation of the original sewage treatment plant;
(2) the sealed aeration unit and other sealed units form pressure difference to spontaneously form gas flow, and no additional power device is needed, so that the operation cost is saved;
(3) the malodorous gas of the closed unit enters from the bottom of the sewage adjusting tank and is absorbed by the sewage adjusting tank at the first level, so that the malodorous gas is prevented from directly entering the aeration tank to impact the biological unit. A small part of escaped malodorous gas is introduced from the bottom of the aeration unit, so that the multi-stage absorption of the malodorous gas by sewage is realized;
(4) the sewage system added with the rusty iron chips strengthens the pollutant treatment capacity of the sewage system;
(5) the pressure of the closed unit, the concentration and the flow of the malodorous gas can be observed in real time in the main control room, and the stability of the process operation is guaranteed.
Drawings
FIG. 1 is a schematic view of the reinforcement of the in-situ treatment of malodorous gases from a sewage treatment plant with rust iron: 1-a gas flow meter; 2-malodorous gas on-line monitor; 3-rusty iron filings are added into a metering pump; 4-air blast aeration; 5-pressure gauge and pressure relief valve; 6-effluent sampling point (iron content determination); 7-high concentration malodorous gas flow line; 8-low concentration malodorous gas flow line.
Detailed Description
The invention is further described below with reference to examples:
(1) take the in-situ treatment of malodorous gas in the A2/O process of municipal sewage treatment plant as an example
The pretreatment units (a grid, a grit chamber and a sewage adjusting tank), the aeration tank of the biological unit and the sludge treatment unit (a gravity concentration tank and sludge dewatering equipment) are completely sealed, and a pipeline for gas flowing is arranged between the sealed units. The sealing and pipeline materials are selected by local sewage treatment plants according to the principles of environmental protection and economy, and the parameters of sewage treatment capacity, aeration quantity of the aeration units and the like are considered for determining the sealing volume, so that the malodorous gas is ensured to form proper pressure between the sealing units to drive the malodorous gas to flow.
The foul gas concentration detector is arranged in each closed unit, and the installation position is far away from the gas pipe opening and is above the highest liquid level of the sewage. The pressure value of each closed unit, the change condition of the concentration of the malodorous gas, the flow of the malodorous gas in the pipeline and the loss condition of scrap iron are observed in the control room. If the pressure of the closed unit is too high, opening a pressure release valve of the aeration tank to reduce the pressure to a safe pressure value; if the concentration of the malodorous gas is too high, the malodorous gas can not completely react in the aeration unit and escape in a large amount due to too high pressure in the closed unit, and the treatment effect of the malodorous gas can be deteriorated due to the change of water quality parameters, and corresponding measures are taken in time according to actual conditions to improve the treatment efficiency of the malodorous gas; according to the loss condition of the iron filings discharged from the aeration tank, proper amount of rust iron filings are added into the anaerobic tank for supply.
The invention is suitable for the in-situ treatment of the malodorous gas of different biological treatment processes of all municipal sewage treatment plants, and related workers can change and modify the malodorous gas according to actual conditions within the scope without departing from the technical idea of the invention through the content of the description.