CN108675549A - A kind of sewage disposal system and processing method and application based on photovoltaic driving - Google Patents

Abstract

The invention discloses a photovoltaic-driven sewage treatment system, a treatment method and an application. The sewage treatment system includes sequentially connected: an anaerobic treatment unit, the anaerobic treatment unit includes a packing type baffle anaerobic reactor; a flocculation sedimentation unit; an electrochemical reaction unit; a filtration unit; the sewage treatment system also Including photovoltaic power drive unit. Since renewable photovoltaic energy is used to provide electricity, and no additional chemical reagents are needed, the treatment cost is greatly reduced; the efficiency is high, the operation is stable, and the water quality can be improved in a short time, which overcomes the traditional centralized and decentralized Due to the shortcomings of traditional treatment methods, it is very suitable for the treatment of family domestic sewage with many rural villages and scattered distribution.

Description

A sewage treatment system, treatment method and application based on photovoltaic drive

technical field

The invention belongs to the technical field of treatment of surface water polluted water bodies, and more specifically relates to a photovoltaic-driven sewage treatment system, treatment method and application.

Background technique

In the vast rural areas of our country, with the obvious improvement of working conditions and the rapid development of the rural economy, people's lifestyles have undergone significant changes and their living standards have also increased significantly. The ecological environment has brought serious threats. In some places, the waste generated by people's life has become one of the main local pollutants. For example, the widespread use of washing machines, changing bathtubs into showers, changing dry toilets into flushing toilets, etc. These high-quality lifestyles allow people to enjoy a better life, but they also generate a lot of domestic sewage. Due to the scattered villages, the drainage and sewage treatment facilities of the houses have not yet been formed. As a result, the sewage discharged by the villagers is directly discharged into nearby creeks, ponds, and rivers without treatment. If the long-term wanton discharge is not treated in time, it will seriously pollute the local area The poor ecological environment even threatens the safety of drinking water for villagers, which greatly affects the construction of village appearance and village appearance in the new socialist countryside, and also hinders the implementation of the rural revitalization strategy. For this reason, the domestic sewage that is increasingly discharged must be treated.

At present, management methods and engineering measures are mainly used to solve the domestic sewage discharged in rural areas. The management means are mainly to combine the construction of new socialist countryside and the implementation of the rural revitalization strategy, advocate the environmental protection awareness of water conservation and water recycling, and reduce the discharge of sewage from the source. Engineering measures mainly take technological measures to treat sewage, which is the most effective way. Common treatment methods include centralized and decentralized treatment forms. However, for the vast rural areas, it is difficult to build and promote centralized sewage treatment facilities due to the large number of villages, scattered distribution, and limited investment in treatment funds. Therefore, decentralized sewage treatment technology has become the main means of rural sewage treatment in some places and has attracted the attention of environmental protection workers. At present, traditional decentralized sewage treatment includes oxidation ponds, septic tanks, and land treatment systems. Oxidation ponds have limited removal of organic matter and nitrogen and take a long time to process. Poor operation will affect the appearance of the village; septic tanks are often used as sewage pretreatment systems, and their effluent still has high concentrations of suspended solids, BOD ₅ , Nitrogen, phosphorus and pathogenic bacteria cannot be directly discharged into the water body, so they cannot be used alone; the constructed wetland system is a new type of ecosystem formed by simulating the principle of the land treatment system. To degrade pollutants in water, it has low investment and low operating cost, and can remove nitrogen and phosphorus well. However, the treatment speed is slow, it is obviously affected by seasons, and improper operation will cause groundwater pollution. In addition, combined with the water quality characteristics of domestic sewage, some common treatment units (such as flocculation treatment units) in centralized processes have good effects and are very suitable for treating domestic sewage discharged from rural areas. However, the operating cost restricts the use of these treatment units. The domestic sewage treatment method suitable for rural decentralized households has also been the focus of attention of environmental protection workers.

Contents of the invention

The purpose of the present invention is to propose a high-efficiency treatment method aimed at the shortage of traditional treatment methods for household domestic sewage in numerous rural villages and scattered distribution in my country. This method realizes the efficient removal of organic matter, SS, nitrogen, and phosphorus in rural decentralized domestic sewage through anaerobic treatment unit, flocculation sedimentation unit, electrochemical reaction unit and filtration unit; no additional chemical substances are required during operation, It also uses less fossil energy and has extremely low operating costs. It is very suitable for the treatment of rural decentralized single family or centralized multi-family domestic sewage.

In order to achieve the above object, the first aspect of the present invention provides a sewage treatment system based on photovoltaic drive, which comprises sequentially connected:

An anaerobic treatment unit, the anaerobic treatment unit includes a packing type baffle anaerobic reactor;

Flocculation and sedimentation unit;

Electrochemical reaction unit;

filter unit;

The sewage treatment system also includes a photovoltaic power drive unit.

As a preferred embodiment of the present invention, the packed baffle anaerobic reactor is divided into a plurality of working sections by successively arranged upper and lower baffles, more preferably 3-5 working sections, each section forms a Downflow chamber and an upflow reaction chamber;

The distance ratio between the downward flow guide chamber and the upward flow reaction chamber along the length direction is 1:5-7, and the length direction refers to the horizontal flow direction of the packed baffle anaerobic reactor;

The bottom of the upper baffle is provided with a deflector, and the angle between the upper baffle and the deflector is preferably 130-140°.

As a preferred embodiment of the present invention, a sedimentation tank is provided at the water outlet of the packing type baffle anaerobic reactor, and the generated biogas is discharged through the tank top pipeline.

The packed baffle anaerobic reactor can be regarded as a simple series connection of multiple upflow anaerobic sludge beds (UASB). Under the guidance of the upper and lower baffles, the household domestic sewage flows up and down, and passes through the Each sludge bed is in full contact with microorganisms, so that the organic matter, nitrogen, phosphorus and SS in the water body can be greatly removed. Due to the good mixing effect, the operation is stable, the treatment efficiency is high, and the shock load resistance is strong. The domestic sewage after anaerobic treatment flows into the flocculation and sedimentation unit after being adjusted by the flow meter through the photovoltaic water pump for further treatment.

As a preferred embodiment of the present invention, the flocculation-sedimentation unit includes a flocculation-settling tank provided with a plurality of anode plates 1, a plurality of cathode plates 1 and a multi-stage filter screen frame, and the first anode plate 1 enters the flocculation-settling tank close to the flocculation-settling tank. The water outlet end is arranged, the anode plate I and the cathode plate I are alternately arranged, and a multi-stage filter frame is arranged near the water outlet end;

According to the present invention, during actual operation, the flocculation and sedimentation unit is mainly composed of a cathode plate I, an anode plate I and a two-stage filter frame. Wherein, the anode plate I is close to the water inlet of the reactor, and the cathode plate I and the anode plate I are alternately inserted in parallel at a certain distance;

The two-stage filter screen frame mainly adopts an inclined insertion type frame processed by two kinds of coarse and fine filter screens. Coarse filter screen frame 28 adopts three layers of 250 purpose nylon filter cloth to process; fine filter screen frame adopts three layers of 400 purpose nylon filter cloth to process. The frames of the two filter screens can be quickly replaced, and can be recycled after washing, and the distance between them is 50-80mm when used.

By adjusting the current, the metal ions released from the anode plate I in situ undergo hydrolysis and polymerization to form a variety of hydroxyl complexes, polynuclear hydroxyl complexes and hydroxides, and thus condense and adsorb organic matter, nitrogen, and Phosphorus, SS; at the same time, the gas generated by the electrode plate will further float the condensed and adsorbed pollutant flocs to the water surface, and then filter through the two-stage filter frame, so that the organic matter, phosphorus, nitrogen, and SS in the water body can be efficiently removed; in addition, the anode The released metal ions can also directly react with phosphate to further improve the removal efficiency of phosphorus. After being treated by the flocculation and sedimentation unit, the phosphorus and SS contained in it can reach the discharge standard, and the nitrogen and organic matter may still exceed the standard.

As a preferred embodiment of the present invention, the electrochemical reaction unit includes an electrochemical reaction cell provided with a plurality of anode plates II and a plurality of cathode plates II, wherein one anode plate II is arranged close to the water inlet end of the electrochemical reaction cell, The anode plates II and cathode plates II are arranged alternately. When the wastewater filtered by the filter frame flows through the anode plate II and the cathode plate II in sequence, the residual nitrogen in the water reacts on the surface of the anode to generate nitrogen gas and is removed, and the residual organic matter can also react on the surface of the electrode and be further removed.

As a preferred embodiment of the present invention,

Described anode plate 1 adopts aluminum plate, iron plate or cast iron plate metal electrode;

The anode plate II adopts Ti/RuO ₂ -IrO ₂ or Ti/RuO ₂ -IrO ₂ -SnO ₂ coated electrodes;

The cathode plate I and the cathode plate II adopt graphite electrodes or titanium plate electrodes.

According to the present invention, in the actual operation process, in the flocculation and sedimentation unit, the anode plate I is close to the water inlet of the reactor, and after insertion, the cathode plate I and the anode plate I are alternately inserted, and the parallel spacing is 30-50mm. The varistor I makes the current density between the two electrodes of the cathode plate I and the anode plate I 5.6˜33.0 mA/cm ² . In the electrochemical reaction unit, the anode plate II is followed by the fine filter frame, and then the cathode plate II and the anode plate II are alternately inserted after it is inserted, and the parallel distance is maintained at 20-40mm. The cathode plate II is adjusted by adjusting the sliding rheostat II The current density between the two electrodes of the plate II and the anode plate II is 8.3-41.7 mA/cm ² .

As a preferred embodiment of the present invention, the filter unit includes a filter tank, and the filter tank is provided with a plurality of filter material units composed of filter materials in different particle size ranges, and the particle size of the filter material along the water flow direction is from large to large. Minimal settings.

As a preferred embodiment of the present invention, the plurality of filter material units include a coarse filter material unit, a medium filter material unit, and a fine filter material unit;

The coarse filter unit includes limestone particles with a particle diameter of 2.5-5mm, a thickness of 150-250mm, and a porosity of 45-55%;

The medium filter unit includes biochar with a particle size of 1.5-3mm, a thickness of 200-300mm, and a porosity of 52-58%;

The fine filter material unit includes biochar with a particle size of 0.8-1.6 mm, a thickness of 250-350 mm, and a porosity of 47-55%.

Through the adsorption and interception of biochar, not only can further control various pollutants, but also control the metal ions remaining in the water due to electrode dissolution. For ease of replacement, all limestone and biochar are placed in the filter unit before use.

After the above-mentioned treatment, the sewage flows to the bottom of the filter unit by itself, and the flocs and SS remaining in the water body are adsorbed and intercepted by the above-mentioned layers of filter materials when they flow through the coarse filter unit, medium filter unit, and fine filter unit. further cleared. In addition, when the metal ions left by the electrode dissolution in the water body flow through the above-mentioned filter material layer, they will also be filtered, adsorbed and intercepted by the above-mentioned filter material layer, so as to avoid excessive metal content in the water body.

As a preferred embodiment of the present invention, the photovoltaic power drive unit includes a photovoltaic panel assembly, a photovoltaic controller, a DC-DC module, a battery pack, a light control switch, a sliding rheostat and an ammeter.

The output DC voltage and current of photovoltaic panel components fluctuate due to light conditions, so the DC-DC module stabilizes the voltage or stabilizes the current to supply power to the processing unit. In order to ensure that the system can work normally at night and in weak light, a photovoltaic controller and a battery pack are used to store the remaining electrical energy, and the battery pack is used to provide power to the processing unit through a light control switch at night and in weak light. After being adjusted by the two sliding rheostats, the photovoltaic power drive unit can simultaneously supply power to the flocculation sedimentation unit and the electrochemical reaction unit.

According to the present invention, in the actual operation process, the photovoltaic panel assembly is composed of 4 to 8 250W photovoltaic panels connected in parallel, and its parameters are: working voltage 34.9V, working current 6.0～7.8A; The DC-DC module is connected. The photovoltaic controller is mainly to ensure the normal charging and discharging function of the battery pack, and has the protection functions of preventing the battery pack from overcharging, over-discharging, open circuit, overload, anti-reverse charging, and output short circuit; preventing reverse connection of solar panels and reverse connection of the battery pack Function: balanced charging, temperature compensation and other functions, its parameters are: solar panel voltage ≤ 50V, rated working voltage 12/24V, rated working current 50-60A. The DC-DC module mainly converts the DC voltage or current output by the photovoltaic panel that changes with light into a stable DC voltage or current, and its parameters are: input voltage 7-36V, output voltage 2-30V, output current 0-36V 8A. The storage battery pack consists of 2-4 maintenance-free lead-acid batteries with a capacity of 12V and 150-250AH connected in series and parallel, mainly to store the remaining electric energy and realize power supply to the processing unit at night and under weak light. The light control switch has the following functions: automatically cut off the battery pack to supply power to the processing unit under strong light; and at night and under weak light (less than 80-130W/m ² ), the photovoltaic panel cannot provide power to the processing unit through the DC-DC module. The battery pack is automatically restored to provide electric energy when the power is on; its parameters are: working voltage 24V, rated current 10-20A.

A second aspect of the present invention provides the treatment method of the sewage treatment system, the treatment method comprising:

After the sludge is inoculated in the packed baffle anaerobic reactor, the wastewater passes through the anaerobic treatment unit, the flocculation sedimentation unit, the electrochemical reaction unit and the filtration unit in sequence.

As a preferred embodiment of the present invention, the hydraulic retention time is 4-7d, and the volume load is 3-6kg COD _Cr /(m ³ ·d).

The third aspect of the present invention provides the application of the sewage treatment system in treating domestic sewage of rural distributed households.

Compared with prior art, the beneficial effect of the present invention is:

1) Since renewable photovoltaic energy is used to provide electricity, and no additional chemical reagents are needed, the treatment cost is greatly reduced; the efficiency is high, the operation is stable, and the water quality can be improved in a short time, which overcomes the traditional centralized And the deficiencies of decentralized treatment methods, it is very suitable for the treatment of domestic sewage in rural areas with many scattered households;

2) The use of packing type baffle anaerobic reactor can greatly remove organic matter, nitrogen, phosphorus and SS in the water body, and has stable operation, high treatment efficiency, strong impact load resistance and lower energy consumption; in flocculation In the precipitation unit, the metal ions formed by the dissolution of the electrodes are generated in situ and the energy is continuously released into the sewage, the utilization efficiency of metal ions is high, and less sludge is generated; in the electrochemical reaction unit, organic matter and nitrogen are further treated, and No sludge is produced. The battery pack is charged during the day and the external power supply is automatically performed at night or in weak light; the filter frame can be replaced quickly, and can be recycled after washing.

3) The use of limestone and bio-carbon filter materials can better avoid excessive metal ion content in the water body and significant changes in the pH value of the water body after organic matter, nitrogen, phosphorus, and SS are removed.

Other features and advantages of the present invention will be described in detail in the detailed description that follows.

Description of drawings

Fig. 1 shows a schematic diagram of a photovoltaic-driven sewage treatment system according to an embodiment of the present invention.

Explanation of reference signs:

1-biogas outlet, 2-sewage water inlet, 3-filler baffle anaerobic reactor, 4-filler baffle anaerobic reactor outlet, 5-photovoltaic water pump, 6-flow meter, 7- Sliding rheostat I, 8-ammeter I, 9-DC-DC module, 10-photovoltaic panel assembly, 11-photovoltaic controller, 12-battery pack, 13-light control switch, 14-sliding rheostat II, 15-ammeter II, 16-reaction tank outlet, 17-filter tank outlet, 18-fine filter unit, 19-medium filter unit, 20-coarse filter unit, 21-filter cleaning drain, 22-filter, 23- Filter tank water inlet, 24-reaction tank cleaning outlet, 25-anode plate II, 26-cathode plate II, 27-fine filter screen frame, 28-coarse filter screen frame, 29-cathode plate I, 30-anode plate I , 31-reaction tank water inlet, 32-floating water inlet.

Detailed ways

Preferred embodiments of the present invention will be described in more detail below. Although preferred embodiments of the present invention are described below, it should be understood that the present invention can be embodied in various forms and should not be limited by the embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the scope of the invention to those skilled in the art.

Example 1:

This embodiment provides a photovoltaic-driven sewage treatment system and method. First, a set of photovoltaic-driven rural household sewage treatment facilities based on decentralized rural households is built in the laboratory. As shown in Figure 1, the sewage treatment system based on photovoltaic drive mainly includes anaerobic treatment unit, flocculation sedimentation unit, electrochemical reaction unit, filtration unit and photovoltaic power drive unit. Wherein, the anaerobic treatment unit adopts the packing type baffle anaerobic reactor 3, thereafter with a settling tank; the flocculation settling unit mainly consists of the cathode plate 129 in the reaction tank, the anode plate 130 and the two-stage filter frame (coarse filter Net frame 28 and fine screen frame 27) form; Electrochemical reaction unit is mainly made up of cathode plate II 26, anode plate II 25 in the reaction tank; Filtration unit is mainly made up of the coarse filter material unit that places from bottom to top in the filter tank 22 20. The medium filter material unit 19 and the fine filter material unit 18 are formed; the photovoltaic power supply driving unit is composed of a photovoltaic panel assembly 10, a photovoltaic controller 11, a DC-DC module 9, a storage battery pack 12, a light control switch 13, a sliding rheostat 17, Sliding rheostat II 14, ammeter I 8 and ammeter II 15 etc. constitute. The specific operation steps are as follows:

(1) Start-up and operation of the packing type baffle anaerobic reactor: the packing type baffle anaerobic reactor 3 is divided into 3 to 5 working sections by the upper and lower baffles, and a downward flow is formed in each section chamber and an upward flow reaction chamber, and the distance ratio between the two chambers along the length direction is 1:5 to 1:7, and a 45° deflector is set at the bottom of the upper baffle. Through sludge inoculation and step-by-step debugging, when the hydraulic retention time HRT is 4-7d and the volume load is 3-6kg COD _Cr/ (m3·d), the removal rates of COD and BOD are both above 75%, and then turn to into the formal operation stage. By adjusting the flow rate of the sewage water inlet 2, the water flow velocity in the upstream reaction chamber is 0.3mm/s-0.5mm/s. The waste gas is discharged from the biogas export port 1, and the sewage is treated by the packed baffle anaerobic reactor 3, so that the organic matter, nitrogen, phosphorus and SS in the water body can be greatly removed, and then flow into the subsequent sedimentation tank for further treatment .

(2) Preparation of the flocculation sedimentation unit: in the reaction tank, insert the anode plate 130 near the water inlet 31 of the reaction tank, and then alternately insert the cathode plate 129 and the anode plate 130 in parallel, so that the horizontal distance between adjacent plates is 30-50mm; insert the coarse filter frame 28 and the fine filter frame 27 obliquely in sequence downstream of the last cathode plate I 29, and ensure that the inclination distance is 50-80mm. Wherein, cathode plate 1 29 adopts graphite or titanium plate electrode, anode plate 1 30 adopts aluminum plate, cast iron plate or iron plate electrode; Coarse filter screen frame 28 adopts three layers of 250 mesh nylon filter cloth to process; Fine filter screen frame 27 It is made of three layers of 400-mesh nylon filter cloth. After completing the above tasks, adjust the reaction tank water outlet 16 and the reaction tank water inlet 31, and connect the reaction tank water inlet 31, the flow meter 6, the photovoltaic water pump 5, the packing type baffle plate anaerobic reactor in sequence through the hose The water outlet 4 and the floating water inlet 32 are connected.

(3) Preparation of the electrochemical reaction unit: in the reaction cell, insert the anode plate II25 near the side of the fine filter frame 27, then alternately insert the cathode plate II 26 and the anode plate II 25 in parallel, so that the horizontal distance between the adjacent pole plates is 20-40mm. Among them, the cathode plate II 26 uses graphite or titanium plate electrodes, the anode plate II 25 uses Ti/RuO ₂ or Ti/IrO ₂ or Ti/RuO ₂ -IrO2 coated electrodes, and the end of the electrochemical reaction unit close to the filter unit is also equipped with The reaction tank cleans the drain port 24 .

(4) Preparation of the filter unit: the coarse filter material unit 20 , the medium filter material unit 19 and the fine filter material unit 18 are placed in sequence from bottom to top in the filter tank 22 . Wherein, the coarse filter unit 20 is equipped with limestone particles with a particle diameter of 2.5 to 5 mm, the thickness is 150 to 250 mm, and the porosity is 45 to 55%; the medium filter unit 19 is equipped with biological particles with a particle diameter of 1.5 to 3 mm. Carbon granules, the thickness is 200～300mm, and the porosity is 52～58%. The fine filter material unit 18 is equipped with biochar particles with a particle size of 0.8～1.6mm, the thickness is 250～350mm, and the porosity is 47～50%. 55%. After the above-mentioned filter material is placed, adjust the water outlet 17 of the filter tank and the cleaning drain 21 of the filter tank, and connect the water outlet 16 of the reaction tank with the water inlet 23 of the filter tank through a hose.

(5) Pre-wiring of the photovoltaic power drive unit: the photovoltaic panel assembly 10 composed of 4 to 8 250W photovoltaic panels provides energy for the flocculation sedimentation unit and the electrochemical reaction unit. After the photovoltaic panel assembly 10 is connected in parallel, as shown in Figure 1 As shown, it is divided into two lines of connection, one way first connects the positive and negative poles of the input terminal of the DC-DC module 9 to the positive and negative poles of the photovoltaic panel assembly 10 in parallel, and then connects the negative poles of the output terminal of the DC-DC module 9 to the sliding rheostat 1 in turn. 7. The ammeter I 8 is connected in series with the cathode plate I 29, and the positive pole of the output terminal is temporarily disconnected from the anode plate I 30; in addition, the negative pole of the output terminal of the DC-DC module 9 is also connected to the sliding rheostat II 14 and the ammeter II 15 at the same time After being connected in series, it is connected to the cathode plate II 26, and the positive pole of the output terminal is also temporarily disconnected from the anode plate II 25; the other way first connects the input terminal of the photovoltaic controller 11 to the positive and negative poles after the parallel connection of the photovoltaic panel assembly 10, and then Connect the positive and negative terminals of the maintenance-free lead-acid battery with a capacity of 12V and 150-250AH in series and then connect them in parallel, and connect the positive and negative terminals of the battery pack 12 connected in parallel to the output terminal of the photovoltaic controller 11 and the input of the light control switch 13 respectively. After that, the negative pole of the output terminal of the light control switch 13 is also connected with the cathode plate I 29 after being connected in series with the sliding rheostat 7 and the ammeter I 8 on the one hand; It is connected with the cathode plate II 26, and the positive pole of the output end of the light control switch 13 is temporarily disconnected from the anode plate I 30 and the anode plate II 25.

(6) Treatment of domestic sewage in rural decentralized households: After the first five steps are completed, place the photovoltaic panel assembly 10 under sunlight with a certain light intensity outdoors, turn on the switch of the photovoltaic water pump 5, and let the filler-type baffle plate The domestic sewage discharged by the family of six treated by the oxygen reactor 3 flows through the reaction tank and the filter tank 22 successively. After ten minutes of water coming out of the filter tank outlet 17, the DC-DC that has been disconnected in step (5) is discharged. The positive pole of the output terminal of the module 9 and the positive pole of the output terminal of the light control switch 13 are connected to the anode plate I 30 and the anode plate II 25 at the same time. The current density between I 29 and anode plate I 30 is 5.6-33.0mA/cm ² , and the sliding rheostat II14 is adjusted so that the current density between the anode plate II 25 and cathode plate II 26 is 8.3-41.7mA/cm ² . After 150 minutes, the treated sewage was sampled, and the total nitrogen content was determined by alkaline potassium persulfate-digestion ultraviolet spectrophotometry, the total phosphorus content was determined by ammonium molybdate spectrophotometry, and the COD _Cr concentration was determined by potassium dichromate method , BOD ₅ was determined by dilution and inoculation method, and SS was measured by gravimetric method. The results are shown in Table 1.

Table 1 Changes of water quality parameters before and after treatment

As can be seen from the results of Example 1: for the domestic sewage discharged by a common family of six, after 150min, after being treated by this treatment method, the treatment effect is better, and each discharge index all reaches the "Pollution by Urban Sewage Treatment Plants". It can be directly discharged into Class III surface water functional waters and closed or semi-closed waters such as lakes and reservoirs.

Embodiment 2: the operation steps are as follows:

(1), (2), (3), (4), (5) step in the present embodiment and (1), (2), (3), (4), (5) in the embodiment 1 Same; the difference is:

(6) Treatment of domestic sewage in rural decentralized households: After the first five steps are completed, place the photovoltaic panel assembly 10 under sunlight with a certain light intensity outdoors, turn on the switch of the photovoltaic water pump 5, and let the filler-type baffle plate The domestic sewage discharged by the 4 households treated by the oxygen reactor 3 flows through the reaction tank and the filter tank 22 in turn, and after ten minutes after the water outlet 17 of the filter tank is discharged, the DC-DC module that has been disconnected in step (5) The positive pole of the output terminal of 9 and the positive pole of the output terminal of the light control switch 13 are connected to the anode plate I 30 and the anode plate II 25 at the same time, the flow rate is adjusted to 1.0-1.5L/min, and timing is started; after that, the sliding rheostat 7 is adjusted to make the cathode plate The current density between I 29 and anode plate I 30 is 5.6-33.0mA/cm ² , adjust the sliding rheostat II 14 to make the current density between anode plate II 25 and cathode plate II 26 be 8.3-41.7mA/cm ² . After 150 minutes, the treated sewage was sampled, and the total nitrogen content was determined by alkaline potassium persulfate-digestion ultraviolet spectrophotometry, the total phosphorus content was determined by ammonium molybdate spectrophotometry, and the COD _Cr concentration was determined by potassium dichromate method , BOD ₅ was determined by dilution and inoculation method, and SS was measured by gravimetric method. The results are shown in Table 2.

Table 2 Changes of water quality parameters before and after treatment

As can be seen from the result of embodiment 2: for the domestic sewage discharged by common 4 households, after 150min, after being processed by this treatment method, the control effect is better, and each discharge index all reaches " urban sewage treatment plant pollutant Discharge standard "(GB18918-2002) stipulates the first-level standard requirements, and can be directly discharged into surface water Class III functional waters and closed or semi-closed waters such as lakes and reservoirs.

Combined with the treatment effects of Examples 1 and 2, it is shown that the photovoltaic-driven rural household sewage treatment method is feasible.

Having described various embodiments of the present invention, the foregoing description is exemplary, not exhaustive, and is not limited to the disclosed embodiments. Many modifications and alterations will be apparent to those of ordinary skill in the art without departing from the scope and spirit of the described embodiments.

Claims (10)

1. A sewage treatment system based on photovoltaic drive, characterized in that, the sewage treatment system includes sequentially connected: An anaerobic treatment unit, the anaerobic treatment unit includes a packing type baffle anaerobic reactor; Flocculation and sedimentation unit; Electrochemical reaction unit; filter unit; The sewage treatment system also includes a photovoltaic power drive unit. 2. The sewage treatment system according to claim 1, wherein the packing type baffle anaerobic reactor is divided into a plurality of working sections by successively arranged upper and lower baffles, forming a downward guide in each section chamber and an upward flow reaction chamber; the distance ratio between the downward flow diversion chamber and the upward flow reaction chamber along the length direction is 1:5-7; the bottom of the upper baffle is provided with a deflector. 3. The sewage treatment system according to claim 1, wherein, The flocculation-sedimentation unit includes a flocculation-settling tank provided with a plurality of anode plates 1, a plurality of cathode plates 1 and a multi-stage filter screen frame, the first anode plate 1 is arranged close to the water inlet end of the flocculation-settling tank, and the anode plate I and the cathode plate I are alternately arranged, and a multi-stage filter frame is arranged near the water outlet; The electrochemical reaction unit includes an electrochemical reaction cell provided with a plurality of anode plates II and a plurality of cathode plates II, wherein one anode plate II is arranged close to the water inlet end of the electrochemical reaction cell, and the anode plate II and the cathode plate II are arranged alternately. 4. The sewage treatment system according to claim 3, wherein, Described anode plate 1 adopts aluminum plate, iron plate or cast iron plate metal electrode; The anode plate II adopts Ti/RuO ₂ -IrO ₂ or Ti/RuO ₂ -IrO ₂ -SnO ₂ coated electrodes; The cathode plate I and the cathode plate II adopt graphite electrodes or titanium plate electrodes. 5. The sewage treatment system according to claim 1, wherein, the filter unit comprises a filter tank, and the filter tank is provided with a plurality of filter material units composed of filter materials of different particle size ranges, along the flow direction The particle size of the filter material is set from large to small. 6. The sewage treatment system according to claim 5, wherein the plurality of filter material units comprise a coarse filter material unit, a medium filter material unit, and a fine filter material unit; The coarse filter material unit includes limestone particles with a particle size of 2.5-5 mm, a thickness of 150-250 mm, and a porosity of 45-55%; The medium filter unit includes biochar with a particle size of 1.5-3mm, a thickness of 200-300mm, and a porosity of 52-58%; The fine filter material unit includes biochar with a particle size of 0.8-1.6 mm, a thickness of 250-350 mm, and a void ratio of 47-55%. 7. The sewage treatment system according to claim 1, wherein the photovoltaic power drive unit comprises a photovoltaic panel assembly, a photovoltaic controller, a DC-DC module, a battery pack, a light control switch, a sliding rheostat and an ammeter. 8. Adopt the treatment method of the sewage treatment system described in any one of claims 1-7, it is characterized in that, this treatment method comprises: After the sludge is inoculated in the packed baffle anaerobic reactor, the wastewater passes through the anaerobic treatment unit, the flocculation sedimentation unit, the electrochemical reaction unit and the filtration unit in sequence. 9. The treatment method according to claim 8, wherein the hydraulic retention time is 4-7d, and the volume load is 3-6kgCOD _Cr /(m ³ ·d). 10. The application of the sewage treatment system described in any one of claims 1-7 in the treatment of rural decentralized domestic sewage.