CN107720971A - Artificial swamp and its pollutant based on biomass circulating strengthen minimizing technology - Google Patents

Abstract

The invention discloses a constructed wetland based on biomass circulation and a method for enhanced removal of pollutants thereof, wherein an activated carbon layer is backfilled, and the activated carbon in the activated carbon layer is carbonized from plant residues or/and animal residues in the constructed wetland Prepared. The withered wetland plants and decayed animal residues in the constructed wetland are recovered from the constructed wetland to prepare activated carbon, and the prepared activated carbon is backfilled in the constructed wetland. Plugging of fillers reduces the capacity of constructed wetlands to treat organic wastewater and improves wetland utilization efficiency; secondly, it can solve the problem of more pollutants produced by biomass such as plant residues and animal residues in the process of decay and degradation, causing secondary pollution to organic wastewater. The problem of pollution; thirdly, the activated carbon is backfilled in the constructed wetland, which has a stronger adsorption effect on the pollutants to be treated than activated carbon from other sources.

Description

Constructed wetland and its enhanced pollutant removal method based on biomass cycle

technical field

The invention belongs to the field of sewage treatment and resource utilization and water pollution control, and in particular relates to an artificial wetland based on biomass circulation and a method for strengthening removal of pollutants thereof.

Background technique

Constructed wetland is an ecological treatment technology, which has the advantages of beautifying the landscape, maintaining ecological balance, and easy management. Constructed wetland technology has outstanding application advantages in watershed pollution control in the world, especially in developing regions, and has been widely used in the treatment of various types of sewage such as polluted river water, tail water of urban sewage plants, and dispersed domestic sewage. As the main component of constructed wetlands, wetland plants are mostly annuals, and traditional constructed wetland sewage treatment technologies have problems such as plant degradation and corruption. Wetland animals have good pollutant adsorption and degradation effects on constructed wetlands. However, the production of animal residues, such as shrimp, crab shells, and fish scales, as well as their corruption and odor will lead to deterioration of water bodies and secondary pollution. Withered wetland plants, rotting animal residues and other biomass-induced plugging of fillers and release of pollutants, and the low economic value-added of wetland plant utilization in the operation of constructed wetland projects have greatly limited its popularization and application.

There is a large amount of wetland straw produced in artificial wetlands, and there is no good treatment and utilization method at present. The most common treatment methods are natural accumulation, decay or incineration, which not only takes up space, wastes resources, but also causes environmental pollution. For wetland animal residues, there is no effective treatment method at present. Therefore, it is very important to realize the comprehensive utilization of wetland straw and the treatment and disposal of animal residues to improve the sustainable utilization of constructed wetlands.

A large number of studies have shown that adsorption is an effective technology for treating organic-contaminated wastewater. However, traditional adsorbents are expensive and difficult to recycle. When the adsorbent is saturated, it is difficult to play a corresponding role. It increases the cost of organic wastewater treatment in constructed wetlands, and it is difficult to maintain the efficiency of organic wastewater treatment in constructed wetlands.

Contents of the invention

In order to solve the above-mentioned technical problems in the prior art, the object of the present invention is to provide a constructed wetland based on biomass circulation and a method for enhanced removal of pollutants thereof. The artificial wetland carbonizes biomass such as plant straws and animal residues to prepare activated carbon, which is backfilled in the wetland matrix, thereby realizing the circulation of biomass and improving the removal effect of pollutants in wastewater.

In order to solve the above technical problems, the technical solution of the present invention is:

A constructed wetland based on biomass circulation, in which an activated carbon layer is backfilled, and the activated carbon in the activated carbon layer is prepared by carbonization of plant residues or/and animal residues in the constructed wetland.

The withered wetland plants and decayed animal residues in the constructed wetland are recovered from the constructed wetland to prepare activated carbon, and the prepared activated carbon is backfilled in the constructed wetland. Material circulation realizes the treatment and disposal of wetland plants and decayed animal residues; secondly, it can solve the problem that biomass such as plant residues and animal residues can easily cause plugging of fillers in constructed wetlands and reduce the ability of constructed wetlands to treat organic wastewater. Improve the efficiency of wetland utilization; thirdly, it can solve the problem of secondary pollution of organic wastewater caused by the production of more pollutants in the process of decay and degradation of biomass such as plant residues and animal residues.

Preferably, the backfilling methods of the activated carbon layer in the surface flow constructed wetland include the direct mixing method, the module method and the floating ball method; the backfilling methods of the activated carbon layer in the subsurface flow constructed wetland include the module method and the floating ball method.

Further preferably, the direct mixing and adding method is to mix activated carbon with bottom mud and then backfill to obtain a mixed layer of activated carbon and bottom mud, the top of the mixed layer is a cover layer, and the bottom is a bottom mud layer. Backfilling after mixing the activated carbon and the bottom mud makes the activated carbon more stable and not easy to float and disperse.

More preferably, the thickness of the covering layer is 4-8cm, the thickness of the mixed layer is 25-40cm, and the height of the water layer is 30-50cm; preferably, the thickness of the covering layer is 5-6cm, and the thickness of the mixed layer is 26-35cm, the water layer height is 35-45cm.

The density of activated carbon is small, and when it is filled in the bottom mud, it is prone to floating phenomenon. The covering layer is spread on the mixed layer to play a covering role and prevent the activated carbon from floating out. In order to avoid affecting the adsorption effect, the thickness of the covering layer is limited. It is 4-8cm. When the thickness/height of the cover layer, the mixed layer and the water layer are set in this way, the activated carbon in the mixed layer has a better treatment effect on the organic wastewater in the water layer.

More preferably, the mass ratio of the activated carbon in the mixed layer to the bottom mud is 1:0.8-1.2.

More preferably, the substance in the covering layer is bottom mud.

Further preferably, the module method is to bury the tank containing activated carbon in bottom mud or filler, the activated carbon in the tank is divided into two layers, the upper layer is block activated carbon with a particle size of 7-8cm, and the lower layer is 10-20 mesh activated carbon, evenly perforated around and bottom of the tank.

Small granular activated carbon is easy to float in the bottom mud or filler. The block activated carbon is pressed on the top of the small granular activated carbon. On the one hand, it can press the small granular activated carbon to avoid the floating of the small granular activated carbon. The flow channel makes the surface sewage quickly reach the lower small particle activated carbon area. Under the same residence time of wastewater, the adsorption treatment effect can be improved, and the treatment effect of organic wastewater can be improved; thirdly, the upper block activated carbon can treat organic wastewater. The solid impurities can block the filter, avoid blocking the small particle activated carbon layer, and prolong the service life of activated carbon.

When the activated carbon in the tank reaches the upper limit of adsorption, the tank can be taken out as a whole, which is convenient for the recovery and replacement of activated carbon.

More preferably, the distance between the upper surface of the tank body and the upper surface of the bottom mud or filler is 4-20cm. There are roots of aquatic plants here, and the organic matter near the roots promotes the attachment and growth of microorganisms on the surface of activated carbon and improves the adsorption capacity of activated carbon.

Even more preferably, the diameter of the openings on the tank body is smaller than the particle diameter of the small activated carbon particles. Prevent small particles of activated carbon from flowing out of the tank.

More preferably, the thickness of the upper block activated carbon is 7-8cm, and the thickness of the lower layer of small granular activated carbon is 8-10cm.

Further preferably, the floating ball method is to bury hollow spheres filled with activated carbon in bottom mud or filler, the hollow spheres are connected and fixed by ropes, and a plurality of through holes are opened on each hollow sphere.

More preferably, the diameter of the activated carbon in the hollow sphere near the water inlet of the constructed wetland is 5-8 cm, and the diameter of the activated carbon gradually decreases from the water inlet to the water outlet of the constructed wetland.

Organic wastewater enters from the water inlet, flows out from the water outlet, and flows through activated carbon with gradually reduced particle size in turn. The adsorption effect of activated carbon is gradually enhanced, and at the same time, it can avoid blockage near the water inlet, which is conducive to improving the treatment effect.

When the activated carbon reaches the upper limit of air flotation, the hollow sphere is pulled out to facilitate the recovery and replacement of activated carbon.

More preferably, the diameter of the hollow sphere is 10-15 cm, and the diameter of the through hole is 1-2 cm.

A coupling system of a constructed wetland and a microbial fuel cell, comprising the above-mentioned constructed wetland and a microbial fuel cell, the microbial fuel cell includes an anode, a cathode and a wire, the anode is embedded in the activated carbon layer, and the cathode is fixed to the dissolved oxygen in the water layer of the constructed wetland area, the anode and cathode are connected by wires.

The above-mentioned method for enhanced removal of pollutants in constructed wetlands based on biomass cycle comprises the following steps:

The plant residues and/or animal residues in the constructed wetland are recovered and carbonized to prepare activated carbon, and then the activated carbon is backfilled in the bottom mud or filler of the constructed wetland.

Preferably, the animal remains are shrimps, crab shells or fish scales.

Preferably, the backfilled activated carbon is activated carbon obtained by carbonizing plant residues or activated carbon obtained by carbonizing animal residues or a mixture of the two.

Preferably, the plant residue is harvested during the non-growth period of the plant, and converted into activated carbon by using hydrothermal carbonization technology combined with a new type of active agent.

The beneficial effects of the present invention are:

1) Compared with the traditional constructed wetland sewage treatment technology, biomass is recycled and used as filler, and refilled into the constructed wetland to realize material recycling, avoid secondary pollution, and avoid the problem of wetland blockage.

2) Use tanks, floating balls, etc. as activated carbon to add carriers, which can realize the recovery of activated carbon.

3) Biomass activated carbon is added to the coupling system of microbial fuel cell and constructed wetland to reduce the cost and increase the power production.

Description of drawings

The accompanying drawings constituting a part of the present application are used to provide further understanding of the present application, and the schematic embodiments and descriptions of the present application are used to explain the present application, and do not constitute improper limitations to the present application.

Figure 1 is a device diagram of a surface flow constructed wetland based on biomass circulation and a method for enhanced removal of pollutants implemented in the present invention.

Fig. 2 is a tank device diagram of the surface flow constructed wetland based on biomass circulation and its enhanced pollutant removal method implemented in the present invention.

Fig. 3 is a diagram of the floating ball device of the surface flow constructed wetland based on biomass circulation and its enhanced pollutant removal method according to the present invention.

Fig. 4 is a modularized device diagram of the subsurface flow constructed wetland based on biomass circulation and its enhanced pollutant removal method implemented in the present invention.

Fig. 5 is a diagram of the floating ball device of the subsurface flow constructed wetland based on biomass circulation and its enhanced pollutant removal method implemented in the present invention.

Fig. 6 is a diagram of a combination device of constructed wetland and microbial fuel cell based on biomass cycle implemented in the present invention.

Among them, 1. Bottom mud layer; 2. Mixed layer of activated carbon and bottom mud; 3. Covering layer; 4. Water layer; 5. Black algae; 6. Water outlet; 7. Water inlet; 8. Foxtail algae; 9 , tank body, 10, activated carbon; 11, hornwort algae, 12, ground nails; 13, cattail; 14, rope; 15, floating ball; 16, coarse medium layer; 17, fine medium layer; 18, gravel layer; 19, Filling ball; 20, reed; 21, surface soil layer; 22, anode; 23, cathode; 24, titanium wire; 25, external resistance.

Detailed ways

It should be pointed out that the following detailed description is exemplary and intended to provide further explanation to the present application. Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs.

It should be noted that the terminology used here is only for describing specific implementations, and is not intended to limit the exemplary implementations according to the present application. As used herein, unless the context clearly dictates otherwise, the singular is intended to include the plural, and it should also be understood that when the terms "comprising" and/or "comprising" are used in this specification, they mean There are features, steps, operations, means, components and/or combinations thereof.

Example 1

As shown in Figure 1, the surface flow constructed wetland is bottom mud layer 1, activated carbon and bottom mud mixed layer 2, overburden layer 3, water layer 4, black algae 5, and foxtail algae 8 from bottom to top. The constructed wetland adopts intermittent flow, and the hydraulic retention time is 3 days. Bottom mud layer 1 is covered with bottom mud, which is taken from about 10cm below the surface of the bottom mud layer, about 5m away from the shore, and passed through a 200-mesh sieve to remove impurities. The thickness of the layer is about 25cm. Activated carbon is prepared from a mixture of black algae and shrimp, ground into powder and mixed with the bottom mud at a ratio of 1:1, and spread on the bottom mud layer 1 with a thickness of about 30cm. The covering layer 3 has the same composition as the bottom mud layer 1, and is spread flat on the mixed layer 2 of activated carbon and bottom mud to play the role of covering, preventing the activated carbon from floating out and affecting the adsorption effect. The thickness of this layer is about 5cm. The water layer 4 is a water body polluted by pollutants, and the height of the water layer 4 is about 40 cm. The submerged plants were planted interspecifically with Hydragala 5 and Foxtail Algae 8 at a ratio of 1:1. The black algae 5 selects a well-growing strain with a length of about 30 cm, adopts the cutting method, inserts the root in the matrix, and the main part of the plant is in the water. Select 7-10cm of foxtail algae 8, and plant it in the bottom mud layer 1 by cutting method.

Example 2

As shown in Figure 2, the surface flow constructed wetland adopts the simplest structure, which consists of bottom mud layer 1, water layer 4, and hornwort 11. The constructed wetland adopts intermittent flow, and the hydraulic retention time is 3 days. The bottom mud layer is bottom mud, which is taken from about 10cm below the surface of the bottom mud. The mud is taken from the point about 5m away from the shore, passed through a 200-mesh sieve to remove impurities and large particles, and spread on the bottom layer with a thickness of about 25cm. Activated carbon is prepared from a mixture of hornwort algae and crab shells. Hornwort is planted in the bottom mud by cutting method.

In particular, there are two ways to add activated carbon in this embodiment. One is the modular method. The module is made of a PVC tank body 9, and holes are evenly punched around the tank body 9 and at the bottom. The lower layer is covered with 10-20 mesh small granular activated carbon, and the upper layer is covered with block activated carbon (particle size is 7-8cm). The tank body 9 is placed about 5 cm below the surface of the bottom mud layer 1, where there are roots of hornwort 11, and the organic matter near the roots promotes the growth of microorganisms on the surface of the activated carbon and improves the adsorption capacity. The upper layer of massive activated carbon can allow the surface flow sewage to reach the lower small particle activated carbon area quickly, improving the adsorption treatment effect, and can also reduce the problem of surface flow artificial wetland surface blockage. After the activated carbon reaches the upper limit of adsorption, the whole tank is lifted out and replaced, which is easy to operate.

As shown in Figure 3, another addition method is the float method. Adopt the polyethylene floating ball 15 of about 12cm in diameter, the spheroid is punched the hole of about 1.5cm in diameter evenly, and 10-20 mesh gac granules are placed in the floating ball. The floating balls 15 are connected with ropes 14 and placed about 5 cm below the surface of the bottom mud layer 1. The number of activated carbon floating balls to be added can be flexibly selected according to the concentration of pollutants and the size of the wetland. The starting end and the tail end of the whole set of floating balls are connected on the ground nail 12 with a rope 14, and the ground nail 12 is fixed on the wetland bank. After the activated carbon adsorption reaches the upper limit, it can be taken out and replaced as a whole. The plants were hornwort 11 and Typha 13 evenly inter-planted at a ratio of 1:1. Near-natural wetlands are similar to surface flow wetlands, and can be added in the same way.

Example 3

As shown in FIG. 4 , the subsurface constructed wetland consists of a coarse medium layer 16 , a fine medium layer 17 and cattails 13 . Activated charcoal is made from a mixture of cattails and earthworms. Activated carbon is added in a modular fashion. The stainless steel tank body 9 is evenly perforated around and at the bottom, block activated carbon is placed in the front end, and 10-20 mesh small particles in the rear end. The tank body 9 is placed about 15cm away from the surface filler.

Sewage flows in from the water inlet, first passes through the filtration and adsorption of plants, and then passes through the front-end block activated carbon area. Large pieces of activated carbon can not only absorb and treat pollutants, but also allow sewage to pass through quickly to avoid front-end clogging. The back-end small particle activated carbon strengthens the adsorption effect. In other embodiments, the number of modules to be added can be flexibly selected according to the size of the wetland and the concentration of pollutants. Activated carbon can be replaced as a whole when the adsorption limit is reached.

Example 4

As shown in FIG. 5 , the subsurface constructed wetland consists of a gravel layer 18 , a topsoil layer 21 and reeds 20 . Activated charcoal is made from a mixture of reeds and fish scales. Activated carbon is placed in the packing ball 19 of about 12cm in diameter, and the floating ball is evenly punched with holes about 1.5cm in diameter. Packing balls 19 are placed directly between the gravel block gaps, at about 15 cm from the packing surface, and are connected with ropes 14 . Filler ball 19 two ends are fixed on the ground nail 12 with rope, and ground nail 12 is fixed on the wetland bank. In the packing ball 19 close to water inlet 7, gac is lumpy, about 6cm long. The closer to the water outlet, the smaller the gac in the filler ball 19. Sewage enters from the water inlet, flows out from the 6 outlets, and flows through smaller and smaller activated carbons in turn, the adsorption effect is gradually enhanced, and at the same time, the front end is prevented from being blocked. Activated carbon adsorption reaches the upper limit, directly pull out and replace.

Example 5

As shown in Figure 6, the surface flow constructed wetland is composed of bottom mud layer 1, water layer 4 and black algae 5. The constructed wetland adopts intermittent flow, and the hydraulic retention time is 3 days. The matrix layer is the bottom mud of the Xiaomeihe River, which is collected from about 10cm below the surface, and the mud is taken from the point about 5m away from the shore, and passed through a 200-mesh sieve to remove impurities and large particles, with a thickness of about 25cm. Activated carbon is prepared from a mixture of black algae and earthworms and mixed with bottom mud at a ratio of 1:1. The water layer 4 is a water body polluted by pollutants, and the height of the water layer 4 is about 40 cm. The submerged plants are black algae. Select a well-growing plant with a length of about 30 cm. Using cutting method, the root is inserted into the bottom mud, and the main part of the plant is in the water.

A microbial fuel cell is introduced, and the material of the anode 22 and the cathode 23 is carbon felt. The anode 22 is buried in the mixed layer 2 of activated carbon and bottom mud. The cathode 23 is suspended in the body of water. The cathode 23 and the anode 22 are connected by a titanium wire 24 and connected to an external resistor 25 . The resistance value of the external resistor 25 is 1000Ω. The addition of activated carbon can effectively improve the pollutant removal effect from two aspects. One is to improve the adsorption effect and remove pollutants by adsorption. Second, the addition of activated carbon improves the conductivity of the sediment and enhances the power production of the entire system. The anode degrades more contaminant contaminants for better removal.

Sewage flows into the constructed wetland, and a small part of the pollutants are first removed by wetland plants and animals through adsorption and metabolism. Subsequently, the sewage infiltrates into the bottom mud. The sediment has a stronger adsorption capacity for pollutants, and a large amount of pollutants exist in the pore water of the sediment. Plant and animal residues are used to prepare activated carbon, which is backfilled in the sediment to absorb pollutants in the pore water of the sediment and realize a biomass cycle. In addition, the pollutants present in the pore water are utilized by the electrogenic microorganisms on the anode surface, releasing protons and electrons. Electrons reach the cathode through the external circuit, and protons reach the cathode through the sediment. At the cathode, protons, electrons, and oxygen undergo a reduction reaction, completing the circuit cycle of the microbial fuel cell. The two processes are carried out at the same time, which greatly improves the removal rate of pollutants. At the same time, realize power generation and save energy.

The above descriptions are only preferred embodiments of the present application, and are not intended to limit the present application. For those skilled in the art, there may be various modifications and changes in the present application. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principles of this application shall be included within the protection scope of this application.

Claims (10)

1. A constructed wetland based on biomass circulation, characterized in that: an activated carbon layer is backfilled therein, and the activated carbon in the activated carbon layer is prepared by carbonization of plant residues or/and animal residues in the constructed wetland. 2. The constructed wetland according to claim 1, characterized in that: the backfill method of the activated carbon layer in the surface flow constructed wetland comprises direct mixing and adding method, module method and float method; the backfill method of the activated carbon layer in the subsurface flow constructed wetland comprises module method and float method. 3. The constructed wetland according to claim 2, characterized in that: the direct mixing and adding method is backfilling after mixing activated carbon and bottom mud to obtain a mixed layer of activated carbon and bottom mud, and the top of the mixed layer is a covering layer, bottom mud layer; Preferably, the thickness of the covering layer is 4-8cm, the thickness of the mixed layer is 25-40cm, and the height of the water layer is 30-50cm; preferably, the thickness of the covering layer is 5-6cm, and the thickness of the mixed layer is 26-40cm. 35cm, the water layer height is 35-45cm; Preferably, the mass ratio of activated carbon in the mixed layer to the bottom mud is 1:0.8-1.2; Preferably, the substance in the covering layer is bottom mud. 4. The artificial wetland according to claim 2, characterized in that: the module method is to bury the tank body containing activated carbon in bottom mud or filler, the activated carbon in the tank body is divided into two layers, the upper layer is Block activated carbon with a particle size of 7-8cm, the lower layer is 10-20 mesh activated carbon, and the surrounding and bottom of the tank are uniformly perforated; Preferably, the distance between the upper surface of the tank body and the upper surface of the bottom mud or filler is 4-20cm; Preferably, the diameter of the openings on the tank body is smaller than the particle diameter of the small particle activated carbon; Preferably, the thickness of the upper block activated carbon is 7-8cm, and the thickness of the lower layer of small granular activated carbon is 8-10cm. 5. The artificial wetland according to claim 2, characterized in that: the floating ball method is to bury the hollow spheres equipped with activated carbon in the bottom mud or filler, and the hollow spheres are connected and fixed by ropes, and each hollow sphere A plurality of through holes are provided on the top. 6. The constructed wetland according to claim 5, characterized in that: the diameter of the activated carbon in the hollow sphere near the water inlet of the constructed wetland is 5-8 cm, and the diameter of the activated carbon between the water inlet of the constructed wetland and the water outlet gradually decreases. Small. 7. The constructed wetland according to claim 6, characterized in that: the diameter of the hollow sphere is 10-15 cm, and the diameter of the through hole is 1-2 cm. 8. A coupling system of a constructed wetland and a microbial fuel cell, characterized in that: it includes the constructed wetland and the microbial fuel cell described in any one of claims 1-7, the microbial fuel cell includes an anode, a cathode and a wire, and the anode is embedded in the The activated carbon layer and the cathode are fixed in the dissolved oxygen area of the water layer of the constructed wetland, and the anode and cathode are connected by wires. 9. The method for enhanced removal of pollutants in constructed wetlands based on biomass circulation according to any one of claims 1-7, characterized in that: comprising the steps of: The plant residues and/or animal residues in the constructed wetland are recovered and carbonized to prepare activated carbon, and then the activated carbon is backfilled in the bottom mud or filler of the constructed wetland. 10. The method according to claim 9, characterized in that: the animal remains are shrimp, crab shells or fish scales. Preferably, the backfilled activated carbon is activated carbon obtained by carbonizing plant residues or activated carbon obtained by carbonizing animal residues or a mixture of the two; Preferably, the plant residue is harvested during the non-growth period of the plant, and converted into activated carbon by using hydrothermal carbonization technology combined with a new type of active agent.