CN103449658B - Sewage treatment method - Google Patents

Abstract

The invention relates to a sewage treatment method; the domestic sewage enters an oil separation tank through a mechanical grid and then enters a hydrolysis acidification tank to decompose macromolecular organic matters in the sewage into micromolecular organic matters and remove part of COD; the sewage enters a primary sedimentation tank, and the sludge is concentrated and then discharged into a sludge storage tank; the upper clarified liquid enters an anoxic biochemical tank; sewage and nitrifying liquid which flows back from the aerobic biochemical tank generate denitrification reaction in the anoxic biochemical tank, effluent enters the aerobic biochemical tank for aerobic biochemical reaction, and the other part enters the secondary sedimentation tank through an overflow weir flow; concentrating the sludge, discharging into a sludge storage tank, and making the upper clarified liquid flow into a clean water tank; part of sludge in the sludge storage tank flows back to the hydrolysis acidification tank; conveying clear water to a biological activated carbon reactor, and enabling outlet water to flow to an ozone contact tank for recycling after disinfection; the method has stable treatment effect, less sludge production and natural return of excess sludge; the treated sewage is reused for landscape water and greening water; not only saves the pollution discharge cost, but also reduces the environmental pollution.

Description

A kind of sewage treatment method

Technical field:

The invention relates to a treatment method for distributed domestic sewage, in particular to a treatment method for domestic sewage in sanatoriums, large hotels, leisure resorts, villas in scenic spots, expressway service areas, and the like.

Background technique

my country's "Water Pollution Prevention Law" stipulates that the sewage discharged from residential areas, tourist attractions, resorts, sanatoriums, airports, railway stations, economic development zones and other scattered crowd settlements that cannot be included in the urban sewage collection system and industrial wastewater from independent industrial and mining areas Standardized discharge should be treated locally. Nursing homes, large hotels, large restaurants, leisure tourism resorts, scenic villas, and expressway service areas are all distributed domestic sewage discharge sources. Nursing homes, resorts, and mountain villas are generally located near mountains and rivers, far away from cities, and cannot be connected to urban drainage pipe networks. In addition, sensitive water bodies are also involved, so the discharge standards are very high. If the discharge meets the standards, the investment in sewage treatment facilities will be large, and the operating costs will increase accordingly.

The water quality of distributed domestic sewage such as nursing homes generally includes kitchen and restaurant drainage; bathing, washing, laundry drainage and toilet drainage. The water volume changes greatly, the water quality is complicated, and it is difficult to handle. The quality of this kind of water changes greatly, chemical oxygen demand (COD): 300~500mg/L; ammonia nitrogen (NH ₃ -N): 20~60mg/L; total phosphorus (TP): 2.6~3.7mg/L; Substance (SS): 200~500mg/L. Since it cannot be connected to the urban drainage pipe network, even if it reaches the first-class A standard in the "Pollutant Discharge Standard for Urban Sewage Treatment Plant GB18918-2002" after biological treatment, it will have a great impact on the environment if it is discharged into the water body.

At present, this kind of sewage is mostly treated by Membrane Bioreactor (MBR) process, and after treatment, it can meet the relevant standards for discharge or reuse. Membrane bioreactor combines traditional biological treatment process and membrane separation technology. It is a water treatment technology that replaces secondary sedimentation tank and sand filter tank in traditional biochemical treatment technology by membrane filtration. The membrane bioreactor replaces the secondary sedimentation tank with a membrane unit (ultrafiltration membrane or microfiltration membrane). All suspended solids and colloids are separated and retained by the membrane, and the sedimentation of the sludge will not affect the quality of the effluent. At the same time, the membrane separation unit increases the concentration of activated sludge in the aeration tank, increases the rate of biodegradation, and reduces the amount of excess sludge generated.

The current disadvantage of membrane bioreactor (MBR) lies in the problem of membrane clogging and backwashing, which makes operation and maintenance difficult, resulting in short life of the membrane, and because the price of the membrane is relatively expensive, the operating cost is high!

The reason for the clogging of the membrane is that the nutrients in the catering wastewater are mainly oil, starch, protein, etc., which are transformed into energy and a part of itself through the decomposition and absorption of microorganisms. The normal metabolism of microorganisms will produce viscous polysaccharides, viscous polypeptide molecules and protein molecules. After the bacteria die, some of these substances can be used by other microorganisms, and some of them may exist in the activated sludge mixture. Similarly, a small amount of inorganic salts from catering wastewater will be partly ingested by microorganisms such as bacteria, and the rest will also exist in the activated sludge mixture. These components remaining in the sludge mixture eventually reach the membrane surface and form a gel layer that clogs the membrane.

CN1994937 introduces a hotel sewage air flotation-oxygen-enriched biological treatment and reuse method. Its technological process is as follows: the sewage passes through the regulating tank, anaerobic hydrolysis tank, air flotation tank, oxygen-enriched biological contact oxidation tank, activated carbon filter tank, and chlorine dioxide disinfection tank to reach the target of reuse water. In the process, polyaluminum chloride needs to be added for coagulation, and after air flotation, a large amount of scum is produced. Contamination of solid waste.

Contents of the invention

The purpose of the present invention is to provide a decentralized treatment method for domestic sewage, especially a decentralized treatment method for sewage in catering and accommodation service places. This method can ensure the effective treatment of such sewage, and can safely realize sewage reuse and realize Zero discharge of sewage. After this kind of wastewater is treated, the effluent can reach the "Water Quality of Urban Miscellaneous Water for Recycling of Urban Sewage" (GB/T18920-2002). The most stringent main indicators are: five-day biochemical oxygen demand BOD ₅ ≤10mg/L; suspended solids ≤10mg/L; turbidity≤10 degrees; chromaticity≤30 degrees; pH: 6.0～9.0; total coliforms ≤3/L; smell: no unpleasant feeling; mg/L. All the effluent is reused as reclaimed water.

The effluent after sewage treatment is not only reused for domestic miscellaneous water, but the remaining reclaimed water is discharged into landscape rivers, artificial lakes or waterscape water bodies, and the water quality standard GB18921-2002 for reclaimed water used in landscape water bodies is implemented. The effluent water quality of this process has all reached the most stringent waterscape standard for ornamental landscape environmental water in the "Urban Sewage Recycling Scenery Environmental Water Quality": five-day biochemical oxygen demand (BOD ₅ ) ≤ 6; suspended solids (SS ) ≤ 10; total phosphorus (in P) ≤ 0.5; total nitrogen ≤ 15; ammonia nitrogen (in N) ≤ 5; chroma (degree) ≤ 30; ≤1.0.

The technical scheme adopted by the sewage treatment method of the present invention is: the distributed domestic sewage passes through the grid, the grease trap, the hydrolytic acidification pond, the primary sedimentation pond, the anoxic biochemical pond, the aerobic biochemical pond, the secondary sedimentation pond, Clean water pool, biological activated carbon reactor, ozone contact pool, all effluents are reused.

The specific steps are as follows:

The domestic sewage passing through the septic tank of the structure enters the wastewater treatment station through the pipeline. Because the sewage contains a certain amount of large particle suspended matter and floating matter, before the sewage enters the grease trap, these large particles and floating matter are intercepted and removed by a mechanical grille, and the sewage that has been roughly filtered by the mechanical grille enters the grease trap , and then into the hydrolytic acidification tank.

In the hydrolytic acidification tank, the macromolecular organic matter in the sewage is decomposed into small molecular organic matter, part of COD is removed, and the load of subsequent aerobic biological treatment is reduced. There is a perforated tube aerator at the bottom of the pool, and the air is introduced, which can not only prevent sludge deposition, but also play a role in homogenizing water quality and pre-aeration; a combined packing is set in the pool, and the combined packing is composed of plastic semi-soft packing and Composed of fiber soft filler. Through the action of microorganisms, it plays a certain role in hydrolysis and acidification.

The sewage in the hydrolysis acidification tank is lifted to the primary sedimentation tank through the inflow lift pump, and the sludge and water are separated. The sludge is deposited and concentrated in the sludge hopper, and is discharged into the sludge storage tank through the sludge valve by the liquid pressure. The upper clarified liquid flows into the anoxic biochemical tank by itself through the overflow weir; the sewage from the primary sedimentation tank and the nitrifying liquid returned from the aerobic biochemical tank undergo denitrification reaction in the anoxic biochemical tank, and the effluent flows into the aerobic biochemical tank by gravity . The sewage from the anoxic biochemical tank is aerated in the aerobic biochemical tank for aerobic biochemical reaction, and part of the effluent is returned to the anoxic biochemical tank as nitrification liquid through the reflux pump for denitrification; the other part flows into the secondary tank through the overflow weir. Shenchi. Sewage from the aerobic biochemical tank is separated from mud and water in the secondary settling tank, and the sludge is deposited and concentrated in the sludge hopper of the secondary settling tank, and is discharged into the sludge storage tank through the sludge valve relying on liquid pressure. The upper clarified liquid flows into the clear water tank by itself through the overflow weir. Part of the sludge in the sludge storage tank is returned to the hydrolysis acidification tank for hydrolysis to reduce the excess sludge and increase the settling performance of the excess sludge. The sludge storage tank can discharge sludge regularly, and after dehydration, the sludge returns to nature in the form of greening soil.

Both the anoxic biochemical pool and the aerobic biochemical pool are provided with combined fillers. The combined filler is composed of plastic semi-soft filler and fiber soft filler, which combines the advantages of semi-soft filler with air distribution, uniform water distribution and soft filler with large specific surface area and fast film formation.

The effluent from the secondary settling tank flows to the clear water tank by itself, and then is transported to the biological activated carbon reactor by a filter pump. The water enters from the bottom of the biological activated carbon reactor. The two biological activated carbon reactors are connected in parallel, with built-in activated carbon, and the effluent flows through the top overflow. The weir flows to the ozone contact tank.

The clean water from the biological activated carbon reactor is fully mixed and contacted with the ozone gas generated from the ozone generator in the ozone contact tank through the disinfection gas distributor in the ozone contact tank, and reused after the disinfection reaches the standard. The scope of reuse includes toilet flushing, car flushing, greening and landscape water bodies, etc.

The advanced treatment adopted by this device is a biological activated carbon reactor with built-in activated carbon. After the sewage is treated through the traditional secondary treatment, although most of the suspended solids and organic matter are removed, there are still traces of suspended solids and dissolved harmful substances. compounds such as nitrogen and phosphorus. The bottom aeration operation mode is adopted to further remove COD, N, P and other compounds, so that the effluent can meet the reuse standard. Activated carbon can be granular activated carbon and columnar activated carbon, preferably granular activated carbon.

The disinfectant used in this device is ozone. Ozone is a strong oxidant that can quickly react with most organic matter and microorganisms in wastewater to deodorize, decolorize, sterilize, remove phenol, cyanide, iron, manganese, and reduce COD and BOD ₅ etc. have a significant effect.

Beneficial effects of the invention: (1) simple operation, low maintenance cost, and easy automatic operation; (2) stable treatment effect, less sludge production, and the remaining sludge is used for greening soil by returning to nature. (3) It is well coordinated with the environment, and the treated sewage can be reused for landscape water and green water. It not only saves a lot of sewage charges, but also reduces environmental pollution, and has high economic and environmental benefits.

Description of drawings

Figure 1 is a schematic diagram of the process flow.

Detailed ways

Example 1

The water quality of certain nursing home wastewater is shown in Table 1, and the process flow system of Fig. 1 of the present invention is adopted for processing, and the processing results are as shown in Table 1.

Table 1 Water quality characteristics and treatment effect of sewage in a sanatorium (mg/L)

Example 2

Table 2 shows the water quality index before treatment and the effluent effect after treatment of a hotel's catering wastewater.

Table 2 Water quality characteristics and treatment effect of catering wastewater in a hotel (mg/L)

Example 3

Table 3 shows the water quality index before treatment and the effluent effect after treatment of catering wastewater in a tourist resort.

Table 3 Water quality characteristics and treatment effect of catering wastewater in a tourist resort area (mg/L)

Claims (5)

1. a sewage water treatment method, is characterized in that:

First sanitary sewage through structures septic tank enters oil trap after mechanical grille coarse filtration, then enters hydrolysis acidification pool;

At hydrolysis acidification pool, the larger molecular organics in sewage is decomposed into small organic molecule, remove part COD;

Sewage rises to preliminary sedimentation tank by inlet water lifting pumps in hydrolysis acidification pool, carries out mud-water separation, and mud deposits concentrated in sludge bucket, relies on liquid pressure to enter storage basin by sludge valve; Top clear liquor is flow automatically and is entered anoxic biochemistry pool by overflow weir; , there is anti-nitration reaction in the sewage coming from preliminary sedimentation tank and the nitrification liquid refluxing from aerobic biochemical pool, water outlet gravity flow enters aerobic biochemical pool in anoxic biochemistry pool;

The sewage aeration in aerobic biochemical pool coming from anoxic biochemistry pool carries out aerobic biochemical reaction, and a water outlet part is back to anoxic biochemistry pool as nitrification liquid by reflux pump, carries out anti-nitration reaction; Another part is flow automatically and is entered second pond by overflow weir;

The sewage coming from aerobic biochemical pool carries out mud-water separation in second pond, and mud deposits concentrated in the sludge bucket of second pond, relies on liquid pressure to enter storage basin by sludge valve, and top clear liquor is flow automatically and entered clean water basin by overflow weir;

Part sludge reflux in storage basin, to hydrolysis acidification pool, is hydrolyzed, and mud is after dehydration, to afforest with native mode back to nature;

The water outlet coming from second pond flows automatically to clean water basin, then be transported to biological activated carbon reactor with filtration pump, water enters from the bottom of biological activated carbon reactor, the parallel connection of two biological activated carbon reactors, built-in gac, water outlet flows automatically to ozone contact tank by top overflow weir;

The clear water coming from biological activated carbon reactor in ozone contact tank, with the ozone gas producing from ozonizer by sterilizing gas divider in ozone contact tank fully mixing contact, sterilize after up to standard and carry out reuse.

2. method according to claim 1, is characterized in that: at the bottom of hydrolysis acidification pool, be provided with perforated pipe aerating regulation device, pass into air, prevent sludgd deposition, homogenizing water quality and preaeration; In hydrolysis acidification pool, be provided with combined stuffing, combined stuffing is made up of plastics semi soft packing and fiber soft-filler, by microbial process, plays acidication effect.

3. method according to claim 1, is characterized in that: built-in combined stuffing in anoxic biochemistry pool, combined stuffing is made up of plastics semi soft packing and fiber soft-filler.

4. method according to claim 1, is characterized in that: built-in combined stuffing in aerobic biochemical pool, combined stuffing is made up of plastics semi soft packing and fiber soft-filler.

5. method according to claim 1, is characterized in that: the built-in gac of biological activated carbon reactor, and bottom adopts aeration operation scheme, and gac is granular active carbon and columnar activated carbon.