TWI673237B - System and method for treating wastewater - Google Patents

Abstract

The invention provides a wastewater treatment system and method. This system includes a sedimentation tank, a purification tank, and a rear aeration tank. The purification layer includes an aeration contact area and an aquatic plant purification area. The aquatic plant purification zone comprises a porous material layer, an aquatic plant layer, at least one return pipe and an aeration device. The at least one return pipe is in communication with the aeration contact area. The method includes returning the water body of the aquatic plant purification zone to the aeration contact zone.

Description

Wastewater treatment system and method

The present invention relates to a wastewater treatment system and method, and more particularly, to a wastewater treatment system and method for improving dissolved oxygen in a water body, improving aerobic treatment efficiency, and simultaneously having anaerobic treatment.

In ecological treatment systems, pollutant removal mechanisms include sedimentation, adsorption, filtration, nitrification, denitrification, plant absorption, and biological transformation processes, but the environments created by different types of ecological treatment systems are not the same. Not all mechanisms work properly in different types of ecological treatment systems. The reaction efficiency of various nitrogen conversion mechanisms is not the same, so the nitrogen removal efficiency of the ecological treatment system is limited. After the general pollutants enter the ecological treatment system, they are mainly removed by oxygen. The main removal mechanism of nitrogen-containing pollutants is nitrification and denitrification, which converts nitrogen-containing pollutants in wastewater into Nitrogen. When nitrification is incomplete, nitrogen-containing pollutants in water cannot be completely converted to nitrogen and removed. Therefore, when nitrification is carried out, a better effect can only be obtained when the dissolved oxygen is higher than a certain limiting concentration. In addition, it has also been found that if the content of organic carbon (organic pollutants) in the wastewater is low, it will inhibit the progress of denitration and reduce the removal efficiency of total nitrogen in the wastewater. Therefore, adding aeration equipment to the ecological treatment system It can strengthen the oxygen supply conditions and increase the dissolved oxygen in the water, which can significantly improve the removal efficiency of nitrogen-containing pollutants in the purification zone, and also increase the degradation efficiency of carbon-containing pollutants.

Summarizing the current mechanisms to deal with aquaculture water pollutants include:

1. Physical action: It is mainly used to remove suspended solids or harmful ions in the breeding water by using physical filtration, gravity separation, floating removal, physical adsorption, ion exchange, oxygen green ray resonance, carbon rod adsorption, aeration and other mechanisms.

2. Biological effect: It mainly uses microorganisms to remove organic pollutants and nitrogen-containing pollutants in water through mechanisms such as biological filtration, biochemical treatment, plant uptake, mineralization conversion, assimilation, and predation.

3. Bactericidal action: Remove possible pathogenic bacteria in the breeding system through the action mechanisms of ultraviolet and ozone sterilization, ozone oxidation and sterilization, alloy oxygen sterilization, and solar radiation sterilization.

Although the above-mentioned many technologies have been verified by practical applications, they have certain effects, but they are limited by high equipment or operating costs, high technical requirements for equipment operation expertise, and high difficulty in design and practical operation. As a result, there is still much room for improvement in water quality related issues. . Based on the above-mentioned related shortcomings, planning a wastewater treatment system with low equipment costs, low energy consumption, easy operation, and clear treatment targets is indeed one of the important topics to promote the development of China's current water treatment industry.

According to relevant research, ammonia is most threatening in aquaculture water. Therefore, many inventions have adopted a method of increasing dissolved oxygen in water in order to convert ammonia nitrogen into nitrate nitrogen which is less toxic through nitrification. However, high concentrations of nitrate nitrogen in the outdoor farms just help a large number of algae proliferation. Excessive algae often lead to biological toxicity or nighttime water reversion, resulting in deterioration of water quality or death of fish and shrimp. this In addition, aquaculture wastewater usually has a low organic carbon content, which is also not conducive to denitrification and reduces the removal of total nitrogen in the water.

A technique is known that uses a rectifier to control the circulation of the aerated water body to stabilize the water flow and improve the efficiency of purification treatment. However, the flow rate of this technology is relatively fast in the area of the rectifier tube, so the overall system is mainly aerobic treatment, and can not have both aerobic and anaerobic treatment functions.

Another technique is to use an aeration zone and a porous material wall to perform an aerobic reaction in the aeration zone and an anaerobic reaction in the porous material wall. However, the aerobic reaction time of the above system is insufficient, resulting in limited removal efficiency of pollutants in wastewater.

There is still a technology for treating wastewater with high pollutant concentrations. In the above technology, the anaerobic treatment zone is set in front of the aerobic treatment zone to perform the anaerobic treatment first. This technology returns the aerobic treated sludge to the anaerobic treatment zone and the aerobic treatment zone more regularly. However, the above methods are not effective in treating wastewater with a low concentration of pollutants.

Based on the current aquaculture market demand considerations and the future development trend of organic aquaculture, it is urgently needed to propose a wastewater treatment system that can remove suspended solids, organic pollutants and nitrogen-containing pollutants in wastewater, and solve the problem of optimal nutrition of environmental water bodies. And issues related to aquaculture water. At the same time, this system has the characteristics of low equipment cost, low operating cost, low energy consumption and easy operation, thereby reducing water quality control drugs and promoting the long-term development goal of organic aquaculture, and enhancing the added value of aquaculture.

One aspect of the present invention is to provide a wastewater treatment system, It can increase the amount of dissolved oxygen in the system to improve the effect of aerobic treatment.

Another aspect of the present invention is to provide a wastewater treatment method, which is performed using the above-mentioned wastewater treatment system.

According to the above aspect, a wastewater treatment system is proposed. In some embodiments, the wastewater treatment system includes a sedimentation tank, a purification tank, a rear aeration tank, a first connection unit, and a second connection unit. The top of the sedimentation tank is covered with a heat insulation plate, and a first water outlet is provided on a side wall of the sedimentation tank. The purification tank includes a contact aeration zone and an aquatic plant purification zone. The contact aeration zone is provided with a first aeration device. The aquatic plant purification zone includes a porous material layer provided on the bottom, an aquatic plant layer provided on the porous material layer, at least one return pipe, and a second aeration device. The at least one return pipe has a first end opening and a second end opening. The first end opening is in communication with the porous material layer, and the second end opening is in communication with the contact aeration zone. The second aeration device is in communication with at least one return pipe. The side wall of the purification tank adjacent to the aeration zone is provided with a first water inlet, and the side wall of the purification tank adjacent to the aquatic plant purification area is provided with a second water outlet. The first connection unit is used to connect the first water outlet and the first water inlet. The rear contact aeration tank includes a third aeration device, and a second water inlet is provided on a side wall of the rear aeration contact tank. The second connection unit is used to connect the second water outlet and the second water inlet.

According to some embodiments of the present invention, the porous material layer includes gravel, rubber chips, bricks, hearths, or a combination thereof.

According to some embodiments of the present invention, the porosity of the porous material layer is 45% to 55%.

According to some embodiments of the present invention, the porous material layer has a depth, and a first end opening of at least one return tube and a top of the porous material layer The distance is between 55% and 65% of the depth.

According to some embodiments of the present invention, the purification tank has a length, the contact aeration area accounts for 15% to 20% of this length, and the distance between the first end opening of the at least one return pipe and the contact aeration area is 19% to 22% length.

According to some embodiments of the present invention, a sludge pipe is provided at the bottom of the sedimentation tank, and the contact aeration zone includes a contact material.

According to the above aspect of the present invention, a wastewater treatment method is proposed. In some embodiments, the method includes: first, providing a wastewater treatment system and wastewater as described above. Next, the wastewater is caused to flow into a sedimentation tank to perform a sedimentation treatment to form coarsely treated water. Then, the rough treatment water is flowed into the contact aeration area of the purification tank to perform contact aeration treatment to form contact aeration water. After that, the aerated water is allowed to flow into the porous material layer of the aquatic plant purification zone of the purification tank for purification treatment. The purification treatment includes subjecting the aerated water to aerobic treatment to form a first treated water. The purification treatment further includes subjecting at least a portion of the first treated water to at least one circulating treatment, wherein the at least one circulating treatment includes returning at least a portion of the first treated water to the contact aeration zone and sequentially perform Contact aeration treatment and aerobic treatment to form circulating treated water. The purification treatment further includes performing anaerobic treatment on other parts of the first treated water and the circulating treated water to form a second treated water. Then, the second treatment water is caused to flow into the post-contact aeration tank to perform post-contact aeration treatment to form purified water.

According to some embodiments of the present invention, the aerobic treatment is performed in a porous material layer having a length of 19% to 22% of the length of the purification tank from the contact aeration zone.

According to some embodiments of the present invention, the purification treatment further includes sedimentation Treatment, filtration treatment and adsorption treatment.

According to some embodiments of the present invention, the flow rate of the operation of returning at least a portion of the first treated water into the contact aeration zone is 2500 liters / day to 3000 liters / day.

100‧‧‧ wastewater treatment system

101‧‧‧ wastewater

103‧‧‧purified water

110‧‧‧ settling tank

111‧‧‧Drain pipe

113‧‧‧Insulation board

120‧‧‧ purification tank

121‧‧‧ contact aeration zone

121A, 123A, 131A‧‧‧ aeration device

121B‧‧‧Contact material

122a, 132a‧‧‧ Air Compressor

122b, 132b ‧‧‧ Submersible Motor

123‧‧‧Aquatic plant purification zone

124‧‧‧ sunshade cover

125‧‧‧ aquatic plant layer

127‧‧‧ porous material layer

127A‧‧‧Porous material particles

129‧‧‧ return tube

129A‧‧‧ first end opening

129B‧‧‧ second end opening

130‧‧‧ rear aeration tank

140‧‧‧first connection unit

141‧‧‧First Outlet

143‧‧‧First water inlet

150‧‧‧Second connection unit

151‧‧‧Second Outlet

153‧‧‧Second water inlet

160‧‧‧water level

D‧‧‧ Depth

L‧‧‧ length

200‧‧‧ Method

201‧‧‧Provide wastewater treatment system and wastewater

203‧‧‧ Allow wastewater to flow into the sedimentation tank for sedimentation treatment to form rough treated water

205‧‧‧ Flow the raw treatment water into the contact aeration zone of the purification tank to perform contact aeration treatment to form contact aeration water

207‧‧‧ The contact aeration water is flowed into the porous material layer of the aquatic plant purification zone of the purification tank for purification treatment to form a second treated water

209‧‧‧ flowing the second treated water into the post-contact aeration tank to perform post-contact aeration treatment to form purified water

301‧‧‧ aerobic treatment of contacted aerated water to form first treated water

303‧‧‧ at least one part of the first treated water is subjected to at least one cycle treatment, including returning at least part of the first treated water to the contact aeration zone, and sequentially performing contact aeration treatment and aerobic Treatment to form a loop of treated water

305‧‧‧anaerobic treatment of other parts of the first treated water and the circulating treated water to form the second treated water

401, 403, 405, 501, 503, 505, 601, 603, 605, 701, 703, 705, 801, 803, 805‧‧‧ line segments

In order to make the above and other objects, features, advantages, and embodiments of the present invention more comprehensible, the detailed description of the drawings is as follows: [FIG. 1] is a schematic diagram of a wastewater treatment system according to an embodiment of the present invention Schematic diagram; [Fig. 2] is a schematic flowchart of a wastewater treatment method according to some embodiments of the present invention; [Fig. 3] is a schematic flowchart of the purification treatment of Fig. 2; [Fig. 4] is an example and comparison Example: Biochemical oxygen demand (BOD) as a function of time; [Fig. 5] is the ammonia nitrogen (NH ₃ -N) pollutant concentration as a function of time for the examples and comparative examples; [Fig. 6] is implementation Examples and Comparative Examples with time-varying total Kjeldahl nitrogen (TKN) concentration; [Fig. 7] is the time-varying total nitrogen (TN) concentration with Examples and Comparative Examples; and [Figure 8] is the total phosphorous (TP) of the examples and comparative examples as a function of time.

The object of the present invention is to provide a wastewater treatment method and system. System, which can perform aerobic treatment and anaerobic treatment in the same system. The waste water treatment system of the present invention is provided with a return pipe to increase the amount of dissolved oxygen in the waste water and improve the efficiency of aerobic treatment. In addition, the wastewater treatment system of the present invention can plant aquatic plants in the porous material layer, which can reduce the limitation of the types of aquatic plants, and perform aerobic treatment and anaerobic treatment while using the porous material layer for sedimentation treatment, filtration treatment and Adsorption treatment can further improve wastewater treatment efficiency.

The wastewater referred to herein in the present invention may be, for example, wastewater having a low BOD (for example, less than 20 mg / L). In one example, the wastewater may be fishery wastewater, industrial and domestic mixed wastewater, and the like. The pollutants of the wastewater include suspended solids, organic pollutants and nitrogen-containing pollutants.

Wastewater treatment system

Hereinafter, the wastewater treatment system of the present invention will be described using FIG. 1. As shown in FIG. 1, the wastewater treatment system 100 includes a sedimentation tank 110, a purification tank 120, and a rear aeration tank 130. The first connection unit 140 may be connected to the sedimentation tank 110 and the purification tank 120, and the second connection unit 150 may be connected to the purification tank. 120 and rear aeration tank 130 are described below. The component symbol 160 in FIG. 1 represents the water level. The water levels in the sedimentation tank 110, the purification tank 120, and the rear aeration tank 130 are only slightly different (for example, the water level in the sedimentation tank 110 is higher than that in the purification tank 120, and the water level in the purification tank 120 is higher than Rear aeration tank 130), but this difference is not shown in FIG. 1.

As shown in FIG. 1, the wastewater 101 enters the sedimentation tank 110 of the wastewater treatment system 100. At this time, the wastewater can be referred to as inflow water. The main structure of the sedimentation tank 110 is an artificial tank. The top of the sedimentation tank 110 is covered with a heat insulation plate 113, and the bottom of the tank is helpful for collecting suspended solids. The sedimentation tank 110 includes a first water outlet 141 located on a side wall thereof, and the water system in the sedimentation tank 110 conveys the water through the first water outlet 141. He trough. In one embodiment, the bottom of the sedimentation tank 110 may be provided with a sludge pipe 111.

The purification tank 120 is a single tank and may be a rectangular tank. The purification tank 120 includes a contact aeration zone 121 and an aquatic plant purification zone 123. In addition, the purification tank 120 further includes a first water inlet 143 provided on a side wall adjacent to the contact aeration zone 121 and a second water outlet 151 provided on a side wall adjacent to the aquatic plant purification area 123 to facilitate the passage between Wastewater transportation.

The above-mentioned contact aeration zone 121 is provided with a first aeration device 121A and uniformly distributed contact materials 121B. The first aeration device 121A includes a first air compression device 122a and a first submersible motor 122b. In the present invention, the contact material 121B may be any known or commercially available contact material. For example, the contact material may be a biofilm with a large specific surface area and growth adhesion, and may be a wave plate, a honeycomb plate, or a rope. Filter media, mesh filter or float.

The aquatic plant purification zone 123 includes an aquatic plant layer 125, a porous material layer 127, at least one return pipe 129, and a second aeration device 123A. A porous material layer 127 is provided at the bottom of the aquatic plant purification area 123. The porous material layer 127 includes a plurality of porous material particles 127A and a bacterial film (not shown). The wastewater treatment system 100 may be bred for a period of time (for example, one month), so that the bacteria (for example, aerobic bacteria and anaerobic bacteria) can be grown into the above-mentioned bacteria film by using porous material particles as a carrier. Generally speaking, the porous material particles 127A adjacent to the contact aeration zone 121 are mostly covered with an aerobic bacteria film, and the porous material particles 127A remote from the contact aeration zone 121 are often covered with an anaerobic bacteria film. In one embodiment, the porous material layer 127 may include gravel, rubber chips, brick particles, hearth particles, or a combination thereof, and the average particle diameter may be, for example, 3 cm to 5 cm. The porous material particles of the above rubber slice can be formed, for example, by using waste tires by removing steel wires and slicing. The porous material particles thus formed may further Contains iron ions or ferrous ions to facilitate the removal of wastewater pollutants.

In yet another embodiment, the porous material particles 127A are stacked on each other to form irregularly sized and distributed pores. This pore can prevent the water body from generating a circulating flow (or short flow) in the porous material layer 127, and can prolong the purification treatment time. In one embodiment, the porosity of the porous material layer 127 is 45% to 55%. When the porosity is too small, the porous material layer 127 is easily blocked, and when the porosity is too large, the wastewater treatment effect is not good.

The aquatic plant layer 125 is provided on the porous material layer 127. In an example, the aquatic plant layer 125 is a planted aquatic plant in the porous material layer 127. The aquatic plants may include, but are not limited to, reeds, rushes, cattails, pennisetum, windmills, yarrow, pelagows or any combination thereof. Since a porous material layer 127 is laid on the bottom of the aquatic plant purification zone 123, in addition to the aquatic plants, other non-aquatic plants can also be selected. Therefore, the wastewater treatment system 100 of the present invention has the advantage that the types of aquatic plants are not limited.

The return pipe 129 has a first end opening 129A and a second end opening 129B. The first end opening 129A is in communication with the porous material layer 127, and the second end opening 129B is in communication with the contact aeration region 121. In some embodiments, the porous material layer has a depth D, and the first end opening 129A of the return tube 129 is 55% to 65% of the depth D from the top of the porous material layer 127. In some embodiments, the purification tank 120 has a length L, the contact aeration zone 121 occupies 15% to 20% of the length L, and the first end opening 129A of the return pipe 129 is 19% to 22 away from the contact aeration zone 121. % Of length L. When the position of the return pipe 129 is too close to the contact aeration zone 121, the time for performing aerobic treatment is too short. When the position of the return pipe 129 is too far from the contact aeration zone 121, the amount of dissolved oxygen in the wastewater cannot be effectively increased. Nor can it improve the efficiency of aerobic treatment.

The second aeration device 123A is a second air compression device. The second aeration device 123A is disposed outside the return pipe 129 and communicates with the return pipe 129 to provide air bubbles in the return pipe 129. A surge is formed by the buoyancy of the bubbles to lift the water in the return pipe 129 to the contact aeration zone 121 through the second end opening 129B. The second aeration device 123A is not provided with a submersible motor, because the bubbles treated by the submersible motor are too small, which is not conducive to the water body being lifted by the buoyancy of the bubbles.

In particular, the present invention excludes direct aeration of water bodies in the porous material layer 127. If the aeration is performed directly in the porous material layer 127, when an attempt is made to increase the amount of dissolved oxygen in the water, the bubbles generated by the aeration will block the pores of the porous material layer 127, causing the hydraulic retention time to decrease. In addition, direct aeration also causes disadvantages such as uneven dissolved oxygen, peeling of biofilm, and irregular water flow that affect the aerobic treatment effect described below.

The rear aeration tank 130 is an artificial tank. The rear aeration tank 130 may be connected to the purification tank 120 through a second connection unit 150 provided with a valve, through the second water outlet 151 on the side wall of the purification tank 120 and the second water inlet 153 on the side wall of the rear aeration tank 130. To allow the water body to enter the rear aeration tank 130 from the second connection unit 150. A third aeration device 131A is provided in the rear aeration tank 130, and the third aeration device 131A includes a third air compression device 132a and a second submersible motor 132b. The function of the rear aeration tank 130 is mainly to increase the dissolved oxygen content of the treated water by the aeration effect of the third aeration device 131A, so as to meet the requirements of the subsequent use of the pool (ie, post aeration treatment). The water treated through the above process is referred to herein as purified water 103.

In a preferred embodiment, the above-mentioned first connection unit 140 The upper and lower positions of the second connection unit 150 in the wastewater treatment system 100 are arranged diagonally (as shown in FIG. 1) to control the flow of water. In the embodiment of the present invention, the first connection unit 140 is disposed near the top of the tank of the wastewater treatment system, and the second connection unit 150 is disposed near the bottom of the tank of the wastewater treatment system.

In this embodiment, since the first water outlet 141 of the first connection unit is closer to the position where the wastewater flows into the sedimentation tank 110, in order to prevent the wastewater that has just flowed in from flowing out of the sedimentation tank 110 before the sedimentation treatment is fully performed, A vertical baffle (not shown) is set between the wastewater inlet position of the sedimentation tank 110 and the first water outlet 141, but the sedimentation tank 110 is not completely separated into two spaces so that the rough treated water after sedimentation can pass through. It is input to the purification tank 120.

It is to be noted that the first air compression device 122a, the second air compression device, and the third air compression device among the first aeration device 121A, the second aeration device 123A, and the third aeration device 131A used in the present invention 132a is provided outside the purification tank 120 and the rear aeration tank 130, and any conventional air compression device can be used. Specific examples may include, but are not limited to, reciprocating air compressors, rotary air compressors, or centrifugal air compressors.

The first submersible motor 122b and the second submersible motor 132b are stirred at high speed by the turbine fan blades to make tiny bubbles from the air input from the air compression device, which can greatly increase the rate of dissolved oxygen and the amount of dissolved oxygen in the water. Prolongs air bubbles in water. At the same time, the fan blades of the turbine also fully mix the gas and water, so a better aeration efficiency can be achieved. Compared with the floating boat type aeration motor, the present invention can achieve better aeration efficiency by cooperating with the air compression device and submerged aeration motor installed outside the tank.

Wastewater treatment method

The wastewater treatment method using the wastewater treatment system 100 will be described below. Please refer to FIG. 1, FIG. 2 and FIG. 3 at the same time, wherein FIG. 2 is a schematic flowchart of a wastewater treatment method 200 according to some embodiments of the present invention, and FIG. 3 is a schematic flowchart of the purification treatment of FIG. 2.

As shown in step 201, a wastewater treatment system 100 and a wastewater 101 are first provided. Next, as shown in step 203, the wastewater 101 is caused to flow into the sedimentation tank 110 to perform a sedimentation treatment to form coarsely treated water. In the above-mentioned sedimentation treatment, a large volume of suspended solids, such as sediment, will settle to the bottom of the sedimentation tank 110 by physical sedimentation, and be discharged through the sludge pipe 111. The coarsely treated water after the precipitation treatment is discharged through the first water outlet 141 and flows to the purification tank 120 through the first water inlet 143.

Next, as shown in step 205, the rough treated water is caused to flow into the contact aeration zone 121 of the purification tank 120 to perform contact aeration treatment to form contact aerated water. The contact aeration treatment includes aeration treatment and contact oxidation treatment. In the aeration treatment, a first aeration device 121A is used to increase the amount of dissolved oxygen in the wastewater to form aerated water. The contact oxidation treatment is a nitrification process using nitrifying bacteria, wherein the contact material 121B is used as a substrate so that the nitrifying bacteria used for the contact oxidation treatment adhere to and grow. In one embodiment, the contact aeration treatment is aerobic treatment, which uses aerobic nitrifying bacteria in wastewater with a relatively high amount of dissolved oxygen and cooperates with the contact material 121B as a substrate to perform processes including nitrification and contact oxidation. In order to remove nitrogen-containing pollutants and organic pollutants in wastewater and form contact with aerated water. At the same time, in order to improve the treatment efficiency of nitrifying bacteria, a sunshade cover 124 may be provided above the contact aeration zone 121. The nitrifying bacteria referred to herein may be self-operating nitrifying bacteria or heterotrophic Nitrifying bacteria.

Then, as shown in step 207, the aerated water is caused to flow into the porous material layer 127 of the aquatic plant purification zone 123 of the purification tank 120 to perform a purification treatment to form a second treated water. Referring to FIG. 3, the purification process includes the following steps 301, 303, and 305. First, as shown in step 301, the aerated water is subjected to aerobic treatment to form a first treated water. The aerobic treatment is performed by contact aeration water with a high dissolved oxygen amount flowing in from the contact aeration zone 121 in a porous material layer 127 adjacent to the contact aeration zone 121, for example, in the return pipe 129 and the contact aeration zone 121 Between areas. This aerobic reaction may be, for example, nitration. However, because the porous material layer 127 is not supplied with oxygen and its resistance is large, the flow velocity of the water body is reduced (while turbulence can also be reduced), the dissolved oxygen contacting the aerated water in the porous material layer 127 has a fast consumption rate and aerobic Poor processing performance.

In order to improve the efficiency of aerobic treatment, the wastewater treatment system 100 of the present invention is provided with a return pipe 129. As shown in step 303, the circulation process is performed at least once using the return pipe 129. This circulating treatment includes allowing at least a portion of the first treated water to be returned to the contact aeration zone 121, and performing contact aeration treatment and aerobic treatment again to form a circulating treated water with a higher dissolved oxygen content and increase the water flow rate. In order to continue to contact the high oxidation efficiency of the aeration zone and improve the removal efficiency of organic pollutants and nitrogen-containing pollutants.

The first treated water that has not been refluxed and the recycled treated water in step 303 may be subjected to an anaerobic treatment, as shown in step 305. This anaerobic treatment is because the amount of dissolved oxygen in the water gradually decreases as the water flows toward the second water outlet 151, so the main reaction in the porous material layer 127 is converted into an anaerobic reaction, such as denitration.

In one embodiment, the purification treatment may further include a sedimentation treatment, a filtration treatment, and an adsorption treatment. The porous material particles 127A of the porous material layer 127 can adsorb undissolved nitrogen-containing pollutants, organic pollutants, and suspended solids in contact with the aerated water.

In one embodiment, the purification treatment may further include a biological treatment using the aquatic plant layer 125. The biological treatment includes aerobic reactions such as mineralization, nitrification, and assimilation of organic matter through rhizomes or sandy soil at the bottom of the plant. At the same time, biological treatment can also include the uptake of aquatic plants, which is beneficial to the removal of nitrogen-containing pollutants, organic pollutants and heavy metals. In another example, the purification treatment in the purification tank 120 may also include the radiation of sunlight and the predation of protozoa to remove pathogenic bacteria.

Thereafter, as shown in step 209, the second treated water is caused to flow into the post-aeration tank 130 to perform post-contact aeration treatment to form purified water 103.

Examples

The embodiment uses a wastewater treatment system 100 similar to that shown in FIG. 1 for wastewater treatment. The purification tank 120 of the embodiment is a single tank, and the length, width, and height of the tank are 186cm, 47cm, and 41cm, respectively. The lengths of the contacting aeration zone 121 and the aquatic plant purification zone 123 are 30cm and 156cm, respectively. The porous material The particle size of the porous material particles (gravel) of the layer 127 is about 3 to 5 cm, and the porosity is 45.7%. The inlet flow rate of the wastewater treatment system of the embodiment is planned to be 101 liters / day, the water depth is about 36 cm, the hydraulic retention time is 1.42 days, and the hydraulic load is 0.116 m ³ / m ² / day. The contact aeration zone 121 was continuously aerated, and its average dissolved oxygen amount was 4.75 mg / L. The average dissolved oxygen content of the second treated water flowing out of the purification tank 120 was 0.7 mg / L. Three return pipes 129 are disposed at a distance of 0.38 m from the contact aeration zone 121 and a depth of 0.22 m. The total return flow of the three return tubes 129 is 2940 L / day.

Comparative example

The specifications of the wastewater treatment system of the comparative example are substantially the same as those of the embodiment, but the wastewater treatment system of the comparative example does not include an aeration zone and a return pipe, and the entire purification tank is composed of a gravel layer planted with hoe grass. The system of the comparative example had a total tank porosity of 41.1%, a hydraulic retention time of 1.28 days, and a hydraulic load of 0.116 m ³ / m ² / day.

The evaluation methods and evaluation results of the present invention are performed in accordance with the testing methods announced by the Environmental Protection Department of the Executive Yuan. The relevant evaluation results are described later.

1. Organic pollutant removal efficiency

The removal efficiency of organic pollutants as referred to herein in the present invention is based on the view of Biochemical oxygen demand (BOD). Biochemical oxygen demand is the amount of dissolved oxygen required by aerobic microorganisms in water to oxidize organic pollutants into inorganic substances within a certain period of time. The inflow area of the comparative example refers to the inflow at the same position of the aeration area corresponding to the example.

Please refer to Table 1 and Figure 4. Table 1 describes the average concentrations of biochemical oxygen demand of the systems of the examples and comparative examples at different sampling points and their corresponding removal rates. FIG. 4 shows the biochemical oxygen demand concentration values over time for the examples and comparative examples, where line segment 401 represents the inflow water, line segment 403 represents the embodiment, and line segment 405 represents the comparative example.

According to Table 1 and FIG. 4, the removal rate of the biochemical oxygen demand of the system of the embodiment is 77.7%, which is much higher than the 34.5% of the system of the comparative example. Obviously, setting the contact aeration zone and the return pipe to increase the dissolved oxygen amount at the front end of the porous material layer and extend the aerobic treatment time can effectively improve the removal rate of biochemical oxygen demand.

2. Removal efficiency of ammonia nitrogen pollutants

The removal efficiency of the ammonia nitrogen pollutants referred to in the present invention is to evaluate the removal rate of the sum of molecular ammonia (NH ₃ ) and ion ammonia (NH ₄ ⁺ ). The inflow area of the comparative example refers to the inflow at the same position of the aeration area corresponding to the example.

Please refer to Table 2 and Figure 5. Table 2 describes the average concentrations of ammonia nitrogen pollutants and the corresponding removal rates of the systems of the examples and comparative examples at different sampling points. FIG. 5 shows the concentration of ammonia nitrogen pollutants as a function of time in the examples and comparative examples, where line segment 501 represents the inflow water, line segment 503 represents the embodiment, and line segment 505 represents the comparative example.

According to Table 2 and FIG. 5, it can be known that the system of the embodiment has no effect on ammonia nitrogen pollution. The removal rate was 97.5%, which was much higher than the 12.8% achieved by the comparative system. Obviously, setting the contact aeration zone and the return pipe to increase the amount of dissolved oxygen at the front end of the porous material layer and extend the aerobic treatment time can effectively improve the removal rate of ammonia nitrogen pollutants. In particular, after contacting the aeration zone, adding a return pipe to increase the dissolved oxygen at the front end of the porous material layer in the aquatic plant purification zone can further improve the removal rate of ammonia nitrogen pollutants to 97.5%.

3. Total Kjeldahl nitrogen removal efficiency

Nitrogen-containing pollutants in general waste water include Organic nitrogen, Ammonia-nitrogen (NH ₃ -N), Nitrite-nitrogen (NO ₂ ^-- N), and Nitrate-nitrogen ; NO ₃ ^-- N). The mechanism for removing the above substances is mainly the decomposition of organic nitrogen into ammonia nitrogen by oxidation, the conversion of ammonia nitrogen to nitrite nitrogen by nitrification, and the oxidation of nitrite nitrogen to nitrate nitrogen. The sum of organic nitrogen and ammonia nitrogen is called total Kjeldahl nitrogen ( Total Kjeldahl nitrogen; TKN).

Please refer to Table 3 and Figure 6. Table 3 describes the average Kjeldahl nitrogen concentrations and removal rates of the systems of the examples and comparative examples at different sampling points. FIG. 6 shows the total Kjeldahl nitrogen concentration values over time for the examples and comparative examples, where line segment 601 represents the inflow water, line segment 603 represents the embodiment, and line segment 605 represents the comparative example.

According to Table 3 and FIG. 6, the removal rate of the total Kjeldahl by the system of the example is 89.9%, which is much higher than the 28.9% of the comparative example system. Obviously Ground, the contact aeration zone and the return pipe are provided to increase the dissolved oxygen amount at the front end of the porous material layer and extend the aerobic treatment time, which can effectively improve the total Kjeldahl nitrogen removal rate.

4. Total nitrogen removal efficiency

The total nitrogen (TN) removal efficiency referred to in the present invention is to evaluate the removal rate of the sum of the three nitrate nitrogen, nitrite nitrogen, and total Kjeldahl nitrogen in the wastewater.

Please refer to Table 4 and Figure 7. Table 4 describes the average total nitrogen content and removal rate of the systems of the examples and comparative examples at different sampling points. FIG. 7 shows the total nitrogen content concentration over time for the examples and comparative examples, where line segment 701 represents inflow water, line segment 703 represents the embodiment, and line segment 705 represents a comparative example.

According to Table 4 and FIG. 7, it can be known that the removal rate of the total nitrogen by the system of the embodiment is 86.4%, which is much higher than the 29.7% of the system of the comparative example. Obviously, setting the contact aeration zone and the return pipe to increase the dissolved oxygen amount at the front end of the porous material layer and extend the aerobic treatment time can effectively improve the total nitrogen removal rate.

5.Removal efficiency of phosphorus-containing pollutants

Phosphorus is a common water-contaminated nutrient salt. Its main removal mechanisms are plant absorption, medium adsorption, precipitation, and incorporation, and biological reactions convert phosphorus into insoluble substances and precipitate in sediment. Therefore, if you want to remove phosphorus, you must achieve regular removal by harvesting plants and removing sediment. The inflow area of the comparative example refers to the same position of the aeration area of the corresponding example. Home inflow.

Please refer to Table 5 and Figure 8. Table 5 describes the average concentrations and removal rates of phosphorus-containing pollutants at different sampling points of the systems of the examples and comparative examples. FIG. 8 shows the time-varying concentration values of phosphorus-containing pollutants in the examples and comparative examples, where line segment 801 represents the inflow water, line segment 803 represents the embodiment, and line segment 805 represents the comparative example.

According to Table 5 and FIG. 8, the removal rate of the phosphorus-containing pollutants by the system of the example was 25.7%, which was higher than that of the system of the comparative example by 12.9%. Obviously, the system of the present invention can also improve the removal rate of phosphorus-containing pollutants.

In addition, the nitrites and nitrates of the system of the present invention do not accumulate during wastewater treatment.

By using the wastewater treatment system of the present invention, by setting a return pipe in the aquatic plant purification zone with a porous material layer at the bottom, a part of the aerobic treated water body is returned to the contact aeration zone to increase the amount of dissolved oxygen in the water body . According to this, the efficiency of aerobic treatment can be effectively improved, thereby improving the overall efficiency of wastewater treatment. In addition, the wastewater treatment system of the present invention has the advantages of simple operation and low cost, which is beneficial to fish farming or other industries that require wastewater treatment.

Although the present invention has been disclosed as above in the embodiments, it is not intended to be used. To limit the present invention, anyone with ordinary knowledge in the technical field to which the present invention pertains can make various modifications and retouches without departing from the spirit and scope of the present invention. Therefore, the protection scope of the present invention shall be regarded as the attached application. The patent scope shall prevail.

Claims (8)

A wastewater treatment system includes: a sedimentation tank, wherein a heat insulation plate covers the top of the sedimentation tank and a first water outlet is provided on one side wall of the sedimentation tank; a purification tank having a length, and the purification tank includes : A contact aeration zone comprising a first aeration device; and an aquatic plant purification zone comprising: a porous material layer located at the bottom of one of the aquatic plant purification zones, wherein the porous material layer has a depth; An aquatic plant layer is provided on the porous material layer; at least one return pipe has a first end opening and a second end opening, wherein the first end opening is in communication with the porous material layer, and the second end opening is in communication with the porous material layer; The contact aeration zone is in communication, the distance between the first end opening and the contact aeration zone is 19% to 22% of the length, and the distance between the first end opening and a top of the porous material layer A depth of 55% to 65%; and a second aeration device in communication with the at least one return pipe, wherein a side wall of the purification tank adjacent to the contact aeration zone is provided with a first water inlet and is adjacent to The aquatic plant purification zone A second water outlet is provided on a side wall of the purification tank; a first connection unit is used to connect the first water outlet and the first water inlet; a rear contact aeration tank includes a third aeration device, wherein A second water inlet is provided on one side wall of the rear contact aeration tank; and a second connection unit is used to connect the second water outlet and the second water inlet. mouth. The wastewater treatment system according to item 1 of the patent application scope, wherein the porous material layer comprises gravel, rubber chips, bricks, hearths, or a combination thereof. The wastewater treatment system according to item 1 of the patent application scope, wherein a porosity of one of the porous material layers is 45% to 55%. The wastewater treatment system according to item 1 of the scope of the patent application, wherein a bottom of a sedimentation tank is provided with a row of mud pipes, and the contact aeration zone includes a contact material. A wastewater treatment method includes: providing a wastewater treatment system and a wastewater as in any of claims 1 to 4 of the scope of patent application; allowing the wastewater to flow into a sedimentation tank to perform a sedimentation treatment to form a coarsely treated water; The raw treated water flows into a contact aeration zone of a purification tank to perform a contact aeration treatment to form a contact aerated water; the contact aerated water flows into a porous material in a purification zone of an aquatic plant in the purification tank In the layer, a purification treatment is performed, wherein the purification treatment includes: performing aerobic treatment on the contact aerated water to form a first treatment water; and subjecting at least a portion of the first treatment water to at least one cycle Place Treatment, wherein the at least one circulation treatment includes returning the at least a part to the contact aeration zone, and sequentially performing the contact aeration treatment and the aerobic treatment to form a circulation treatment water; and making the first treatment water; Performing an anaerobic treatment on the other parts of the treated water and the circulating treated water to form a second treated water; and flowing the second treated water into the post-contact aeration tank to perform a post-contact aeration treatment A purified water is formed. The wastewater treatment method according to item 5 of the scope of the patent application, wherein the aerobic treatment is performed in the porous material layer at a distance of 19% to 22% of the length of the purification tank from the contact aeration zone. The wastewater treatment method according to item 5 of the scope of patent application, wherein the purification treatment further includes a sedimentation treatment, a filtration treatment, and an adsorption treatment. The wastewater treatment method according to item 5 of the scope of patent application, wherein one of the operations for returning the at least part to the contact aeration zone has a flow rate of 2500 liters / day to 3000 liters / day.