267results about How to "Increase hydraulic retention time" patented technology

The present invention relates to an integrated closed loop system for aquaculture in at least one culturing tank and using continuous bioreactor technology for the biological treatment and removal of organic material, nitrogen and phosphorous, comprising: an integrated, partially or wholly closed loop system for waste water treatment, where the water contains nitrogen containing compounds and / or substances, comprising at least one production unit of such nitrogen containing compounds and / or substances and using continuous bioreactor technology for the biological treatment and removal of organic matter, nitrogen and phosphorous from the said water at continuous flow, comprising: a) at least one suspended carrier bioreactor for bacterial growth under anoxic conditions to cause anaerobic denitrification, with one or several compartments, preceding b) at least one suspended-carrier bioreactor for bacterial growth under oxic conditions to cause aerobic nitrification, c) the denitrification taking place after the production unit, and d) the nitrification taking place prior to the production unit in a by-pass mode as part of the continuous flow.

The invention discloses a sectored multi-step ecological buffer type revetment system. The revetment system is provided with at least four levels of steps, blocking walls are sequentially arranged on the outer sides of the steps, one plant planting zone is arranged in the blocking wall of each level, soil matrix is arranged in the upper layer of each plant planting zone, yellow sand, ceramsite, soft rock and zeolite are sequentially in the lower layer of the plant planting zone of each level, and emersed landscape plants and submergence-tolerant plants are arranged in the plant planting zone of each level; hydraulic drop platforms are sequentially arranged in the corresponding positions of spaced plant planting zones of the blocking walls; and one guide plate is arranged between each blocking wall and the corresponding hydraulic drop platform; the plant planting zone of the first level is connected with a farmland drainage canal and is sectored towards the downstream to form a hydraulic-drop type hierarchical structure in an open sectored shape, the sector radius is 5-8 m, and the central angle is 45 degrees-75 degrees; and the blocking wall of the last level is connected with a river channel. The sectored multi-step ecological buffer type revetment system not only has the efficacies of protecting river channel side slope, and realizing flood water drainage and water and soil conservation, but also has good purification and landscape effects.

The invention relates to a subsurface flow constructed wetland sewage treatment system by drop water aeration oxygenation, composed of drop water aeration subsurface flow constructed wetlands in one stage or multistage series. Each stage of drop water aeration subsurface flow constructed wetland comprises a bed body, an inflow barricade, an outlet barricade and a drop water baffle; wherein a plurality of deflectors, gravel fillers and emergent aquatic plants are arranged in the bed body between the inflow barricade and the outlet barricade. The invention is even in water distribution, small inwake space and uniform in water impact, residence time of sewage in the bed body is extended, blocking is difficult, thus being beneficial to improving effluent quality and biodegradation of microorganism on nutrient such as nitrogen, phosphor and the like in the sewage, and construction and running cost is low. The invention, under the joint action of the effects, can effectively degrade pollutant of urban and town domestic sewage, a small amount of industry waste water and farm drainage and is applicable to mountain land and hilly country with certain gradient.

The invention discloses a compound constructed wetland tail water treatment system, which belongs to the field of sewage treatment technology. The system mainly includes a pretreatment and a constructed wetland system. The pretreatment portion comprises an aeration oxidation pool and an ecological gravel bed; The constructed wetland system fuses a design of stabilization lagoon, which combines a vertical current constructed wetland and a surface flow constructed wetland, and a stabilization lagoon is arranged in step in series; the tail water to be treated passes the aeration oxidation pool, the ecological gravel bed, the vertical current constructed wetland, the stabilization lagoon in order, and finally passes the surface flow constructed wetland and flows out. The system combines physical, chemical and biological means organically, thereby effectively improving the tail water quality, and the water quality of water outlet basically reaches the surface water environment standard III grade, and the water outlet can directly returns to river ecological environment for supplementing water and can be used as city miscellaneous water; the invention has the advantages of low investment, simple operation, low energy consumption, high environment benefit and ecological benefit, etc.

The invention discloses an aerobic inner loop reflux typed immobilized microbe fluid-bed reactor, which comprises the following parts: sediment area, reacting area and depositing area, wherein the bottom of depositing area possesses sludge hopper with water distributor on the top, which connects pump through inlet pipe; the support aerating pipe is set on the water distributor, which connects inlet pipe and microhole aerating machine; the reflective board is set on the support aerating pipe; the immobilized microbe fill and inner loop reflux pipe are set in the reacting area with the first and second hopper-shaped sampling holes on the top of inner loop reflux; the bottom of sludge hopper connects the first stop valve and sludge draining pipe; the outer wall of reactor bulk possesses multiple sampling holes; the top of reactor bulk connects U-shaped pipe, outlet pipe, liquid rotor flow gauge, the second stop valve and outlet tank.

The invention belongs to the technical field of environmental engineering, and relates to a device for treating wastewater, in particular to a three-dimensional electrode reactor which can effectively degrade nitrogenous organic wastewater and a treating process thereof. The main electrodes of the reactor respectively consist of two copper-zinc alloy electrodes and a titanium-iridium-platinum steady-state anode; active carbon is filled between the main electrodes; a part of active carbon is made into insulated particles through coating polyvinyl alcohol gel; and the proportion of the insulated active carbon particles to conductive active carbon particles is between 1: 6 and 6: 1. After a certain voltage is applied, the cathode undergoes nitrate reduction reaction, and the anode oxidizes ammonia nitrogen into nitrogen and mineralizes or converts COD into a simple organic matter. The existence of the filler can effectively strengthen the current efficiency of the reactor, reduce the energy consumption and improve the mass transfer efficiency; and therefore, the invention provides wastewater denitrification device and process with high current efficiency, simple operation, and capabilities of efficiently removing nitrate, ammonia nitrogen and COD and keeping energy consumption at an acceptable level.

The invention discloses a farmland non-point pollution stepped undercurrent dam ecological purification ditch system. The system has a trapezoidal ditch section; the ditch wall and ditch bottom on two sides of the ditch are provided with seepage-proofing building blocks; hexagonal hole structures are formed in the middle of the building blocks, and plants are planted on the hexagonal hole structures; the periphery of the building blocks are laid with pebbles and fibers; undercurrent dams are arranged in the ditch body in a distance of 10-20m at an interval; an intercepting plate is arranged at a part which is 1m away from the upstream of the undercurrent dam; small holes are formed on the lower part of the intercepting plate; the upstream face of the dam body of the undercurrent dam is provided with a fine grid filtering net; the lower part of the dam body is provided with a filling layer which takes gravel and ceramsite as fillings; the filler particles are gradually thinned along the water flow direction; the upper part of the dam body is provided with a clay layer; and plants are planted on the clay layer. The problem that large land is occupied in ecological engineering is solved, the system has the characteristics of high treatment efficiency, wide application range, good visual effect and the like, the water body is subjected to full-face purification at the normal water level, and the normal drainage and flood discharge functions during large-rainfall period are not influenced.

The invention discloses an ecological floating bed suitable for a high-sediment large-flow rate water body. The ecological floating bed is formed by interconnecting two floating bed units, wherein each floating bed unit comprises floating bed fixing rods, hollow PVC tubes, wave eliminating rafts and a gauze; a plurality of hollow PVC tubes are horizontally arranged and fixed by the floating bed fixing rods so as to form a floating raft; the wave eliminating rafts are arranged below the two ends of the floating raft respectively; the gauze in which hollow columnar polyvinyl chloride short corrugated tube packing is packed is hung below the floating raft; and the gauze is positioned below the wave eliminating rafts. The ecological floating bed can treat the water body which contains high sediment and high phosphorus and nitrogen concentration, is suitable for a river with large flow rate, can build a landscape effect without influencing shipping, and can produce part of economic benefits.

The invention discloses a treatment method for greenhouse turtle breeding wastewater. By regarding an enhanced biofiltration system and a deep fluid water planting vegetable bed as a core, organically combining biological and ecological treatment, the method comprises the following specific steps: firstly introducing the greenhouse turtle breeding wastewater into a quick sedimentation basin to remove suspension in the wastewater; then introducing the wastewater into the enhanced biofiltration system to remove degradable organic matters and pollutants such as nitrogen and phosphorus; and flowing the tail water into the deep fluid water planting vegetable bed to perform deep treatment, and further removing nitrogen and phosphorus through synergistic effect of vegetable growth absorption and microorganism at roots. According to the method, the process is simple, the management and the maintenance are convenient, the effect is stable, the operation cost is low and the economic benefit is significant.

The invention discloses an energy-saving consumption-reducing short-range nitration dephosphorizing coupling technique with synchronous denitrification and a device thereof, belonging to technical field of domestic and industrial sewage treatment. A metal carrier bed is installed in an aerobic section with integrated reaction, and is made of iron wood shaving washed through acid cleaning; and the outer part of the iron wood shaving is covered by wire netting. Under conditions of normal temperature and low dissolved oxygen, the aims of short-range nitration and synchronous denitrification can be realized; an anaerobic section is used for finishing phosphorous releasing; the aerobic section is used for finishing short-range nitration, an anoxic section is used for finishing denitrification for removing phosphorous, a fast aerobic section is used for removing remaining ammonia and nitrogen and phosphorous. The invention uses iron wood shaving with low cost to realize stable accumulation of nitrite; the aerating amount is small, the carbon source is saved, and denitrification for phosphorous removing is carried out by taking the nitrite produced via short-range nitration as electron donor, thus the nitrogen and phosphorous can be removed synchronously; and the problem that the nitrite in water could damage the environment and has toxicity is solved. The invention can realize the aims of saving energy and reducing consumption to the largest extent, and is suitable for purifying and treating domestic sewage continuously for a long time.

The invention relates to an undercurrent dam which is applied in a farmland ecological trench to intercept substances such as nitrogen, phosphor and the like. According to the invention, water permeable walls are arranged at the two sides. A gravel filter layer is arranged in the middle of the water permeable walls. A soil cover layer is disposed over the gravel filter layer. A vegetable system is planted on the soil cover layer. The undercurrent dam can be placed in a farmland drainage channel and a surface flow wetland. In the surface flow wetland system, when sewage flows through the undercurrent dam, hydraulic retention time can be effectively increased; in addition, due to the arrangement of the gravel filter layer, suspending pollutants in the water body can be settled and absorbed, and plants on the undercurrent dam can effectively absorb eutrophicated pollutants such as nitrogen, phosphor and the like in the water body. Finally, sewage treatment effect of a common surface flow wetland is increased.

The invention discloses a flow-guide type ecological floating bed suitable for a high-flow-speed water body. The flow-guide type ecological floating bed comprises a floating bed body and a floating bed fixing device, wherein the floating bed body comprises a planting matrix, side wing plates and flow guide plates, wherein the side wing plates are installed at the both sides below the planting matrix, two W-shaped flow guide plates are installed at the middles of the two side wing plates, and aquatic plants are placed on the planting matrix; the floating bed body is fixed on a riverbed by a floating bed fixing rope and a floating bed rod. The flow-guide type ecological floating bed disclosed by the invention is capable of effectively reducing the speed of a water flow at the bottom of the floating bed, protecting the formation and development of biological membrane structures on the surfaces of root systems, increasing the hydraulic retention time of the water flow in the root areas of the plants, and increasing the absorption and degradation efficiency of the root systems of the plants to pollutants in a high-flow-speed environment, as well as adaptive to the water quality purification need of the high-flow-speed water body.

This invention relates to a wastewater treatment apparatus, especially UCT-broken line flow membrane bioreactor for reclaimed water reuse. The apparatus comprises: a float valve, a punched aeration tank, a liquid flow meter, a gas flow meter, a vacuum pressure gauge, a hollow fiber membrane module, a diving reflux pump, a single-stage self-priming pump, an electronic stirrer, an aeration pump, an ORP potential tester, am oxygen dissolution tester, a water storage tank, and an adjusting pool. The membrane bioreactor is divided into an anaerobic zone, an anoxic zone and an aerobic zone at a volume ratio of 1:1:4. Two partition boards are set in the aerobic zone. The ORP probe can monitor the redox potential of the anaerobic zone and the anoxic zone, and broken line flow mode of water flow in oxygen dissolution reactor in the aerobic zone. A dump pump is used to pump water into the water storage tank via the membrane module.

The invention discloses an AOA coupled anaerobic ammonia oxidation deep nitrogen and phosphorus removal process, which comprises an anaerobic zone for internal carbon source storage and phosphate release, an aerobic zone for aerobic excessive phosphorus uptake and short-cut nitrification-anaerobic ammonia oxidation, and an anoxic zone for internal carbon source short-cut denitrification-anaerobic ammonia oxidation, wherein an active biological filler is added into the aerobic zone and the anoxic zone to enrich main functional bacteria, the anaerobic zone has long hydraulic retention time and can store an internal carbon source, the anoxic zone is located at the rear end of the aerobic zone and does not need nitrification liquid backflow, and an aeration zone is added at the rear end of the anoxic zone to improve sludge settleability. The AOA coupled anaerobic ammonia oxidation deep nitrogen and phosphorus removal process solves the problems of insufficient carbon source and incapability of synchronously and deeply removing nitrogen and phosphorus in the nitrogen and phosphorus removal process, reduces the loss of the carbon source, improves the utilization rate of the carbon source, reduces the operation energy consumption of a sewage treatment system, and bring a better application prospect to deep nitrogen and phosphorus removal of urban sewage.

The invention specifically relates to a mixed nutritional type denitrifying biological filler and a preparation and application thereof. The mixed nutritional type denitrifying biological filler adopts the technical principle that activated carbon, sulfur and solid carbon source are used as raw materials to prepare the denitrifying biological filler, and the denitrifying biological filler and anionic clay are mixed and loaded into an applicable reactor; the filter simultaneously has the heterotrophism and autrophism denitrifying effects, so that the problem of secondary pollution caused by adding of liquid carbon sources is effectively solved, and the production of sulfur autrophism byproducts is flexibly controlled.

Offshore facilities, systems, and methods for treating wastewater have been developed. An offshore wastewater treatment facility include wastewater treatment components (for preliminary treatment, primary treatment, secondary treatment, and / or advanced treatment); a means for moving wastewater from a land-based site to the facility; a means for removing treated wastewater from the facility; and a means for removing sludge from the facility. A method of treating wastewater includes: transporting wastewater from a site on land to a wastewater treatment facility located offshore in a body of water, and subjecting the wastewater to preliminary treatment, primary treatment, secondary treatment, and / or advanced treatment.

The invention discloses a multidimensional ecological drainage system for intercepting and controlling separate system rainwater pollutants into a river. The system is arranged on one side of a river bank and takes a stair-step shape along the river bank; rainwater in pipe networks flows into a first-stage water drop platform by rain-water pipes, enters a storage pond, flows into an ecological buffer zone by a second-stage water drop platform, and lastly flows into a plant growth detention pond; and the first-stage water drop platform and the ecological buffer zone are slope-shaped, and plants are planted in the plant growth detention pond. The system not only ensures drainage, but also reduces the risk that rainwater polluted run-offs directly flow into the river, reduces impact and damage to water quality of the water body in a river channel, effectively controls the pollutants in the river, effectively improves the water environment, and enhances the urban water landscape value.

The present invention discloses one kind of ventilating and baffling artificial wetland simulator with one ventilating and baffling artificial wetland body set inside an organic glass container. The ventilating and baffling artificial wetland body has a clay layer with a water distributing pipe connected through the first cut-off valve and a liquid flowmeter to a water pump in a water tank, a sandstone layer, a cinder layer, a gravel layer, a water outlet pipe with the second cut-off valve, the third baffle between the gravel layer and the cinder layer, and the second baffle between the cinder layer and the sandstone layer and with an air distributing pipe connected through a needle valve and a gas flowmeter to an air pump, the first baffle between the sandstone layer and the clay layer. The present invention is suitable for simulating sewage treatment in artificial wetland.

The invention discloses an aerobic inner loop reflux typed immobilized microbe fluid-bed reactor, which comprises the following parts: sediment area, reacting area, depositing area from upwards to downwards, wherein the sludge hopper is set in the depositing area with water distributor on the top; the support pipe is set on the water distributor with reflective board on the upper end; the fixed microbe fill and inner circulation reflux pipe are set in the reacting area; the first and second hopper typed baffles are set on the upper end of inner circulating reflux pipe; three-phase separator is set on the connecting part of first hopper typed baffle and reactor bulk, which connects the second draining pipe, second gas rotor flow meter and second needle valve and water tank through gas chamber; several sampling holes are set on the external wall of reactor bulk, which connects outlet pipe, liquid rotor flow meter, second stop valve and outlet tank through U-shaped pipe.

The invention discloses a multi-medium tidal flow artificial wetland device and method. The artificial wetland device comprises anti-seepage layers, a water distribution tank and a filter tank, wherein the water distribution tank is formed by separating a tank body by virtue of the anti-seepage layers and internally provided with a porous polyurethane material and a water inlet pipe is arranged at the upstream side of the water distribution tank; the upstream side of the filter tank is communicated with the downstream side of the water distribution tank through a plurality of communication pipes, a multi-medium filtering material layer is arranged in the upstream space inside the filter tank and the downstream space inside the filter tank forms a water collecting tank. According to the multi-medium tidal flow artificial wetland device, by the inter-coordinated physical, chemical and biological actions of the multi-medium filtering material, wetland plants and efficient microbes, the media adsorption, ion exchange, co-precipitation, and efficient microbial adsorption reduction, fixed and biological extraction are organically combined so that the heavy metals in micro-polluted water are effectively removed and the secondary pollution of the heavy metals is prevented.

The invention relates to a method for ecologically improving the water quality of a water delivery type lake. In the method, frame outlines of water-permeable diversion piers, water-permeable spur dikes and water-permeable diversion walls are respectively formed in the lake; rubbles are arranged outside wood piles; gabions are arranged on the inner sides of the wood piles; gravels are filled among the gabions to form the water-permeable diversion piers, the water-permeable diversion walls and the water-permeable spur dikes; the water-permeable diversion piers are arranged at an inlet of the lake; and the water-permeable spur dikes and the water-permeable diversion walls are continuously staggered along the direction of water current. According to the method, the defects that the engineering quantity is large, the treatment expense is high, secondary pollution is easily caused, the symptoms not the causes are addressed, and the like are overcome; the water-permeable diversion piers, the water-permeable spur dikes, the water-permeable spur dikes and the water-permeable diversion walls are sequentially arranged in the lake, so that a water body in the lake is fully exchanged, the hydraulic retention time is prolonged, the water quality purification is enhanced, the silt settling effect is improved and the flow speed is reduced; the method can be used for creating environments which are more suitable for organisms to live in, enriching species and facilitating the recovery of a biological system; and the method has the advantages of simpleness for operation, convenience for construction, stable functions and low construction cost.

The invention discloses a bidirectional flow internal circulation type PS advanced oxidation reactor and a sewage treatment method. The bidirectional flow internal circulation type PS advanced oxidation reactor comprises a reactor, wherein an inner barrel and an outer barrel which are staggered up and down and are concentric to each other are arranged in the reactor; the upper end of the inner barrel is open; the lower end of the inner barrel is connected with the bottom of a reactor tank; the upper end of the outer barrel is connected with the top of the reactor tank; the lower end of the outer barrel is open; the bottom of the reactor tank is provided with a power-free self-priming backflow system and an umbrella-shaped conical water distributor; the lower end of a catalyst dosing pipe which stretches to the bottom from the top of the reactor tank is correspondingly communicated with an umbrella-shaped conical medicine distributor; the umbrella-shaped conical medicine distributor is positioned in a water-distributing mixed area of the reactor; the reactor also comprises a circular water distribution baffle, a water inlet mixing device and a secondary dosing device. The reactor is small in height-diameter ratio, the reaction space is fully utilized, the capacity load rate is high, the power consumption is low, the unreacted pollutants and agents are repeatedly treated in the power-free backflow system, the agent utilization rate is improved, the agent consumption and energy consumption are reduced, and the cost is reduced.

The invention discloses a permeable reactive barrier system and a method for in-situ remediation of petroleum hydrocarbon in groundwater by an enhanced anaerobic biotechnology, and belongs to the field of groundwater remediation. Groundwater containing the petroleum hydrocarbon flows through a permeable reactive barrier along the water flow direction, nitrate-reducing bacteria and sulfate-reducing bacteria formed by microorganisms under anaerobic conditions are utilized to degrade the petroleum hydrocarbon in groundwater, and accordingly the purpose of remediation of the petroleum hydrocarbon polluted groundwater is achieved. The permeable reactive barrier system and the method effectively solve the problems of low efficiency and high power consumption in a method for in-situ remediation of the petroleum hydrocarbon in the groundwater with the aid of indigenous microbial flora, and have the advantages of low acting time, high remediation efficiency, strong operability and good remediation effect.

The invention discloses a construction method of a lake water purification system. The method includes the steps of: (a) site surveying; (b) site construction; (c) precipitation zone configuration; (d) aeration zone configuration; (e) compounding zone configuration; (f) ecological planting zone configuration; (g) floating island unit establishing; and (h) regional beautification. The method provided by the invention has the advantages of simple construction, short construction period and cost saving, and after construction, the purification system has the functions of water storage, flood control, and water and air purification, can protect biodiversity, adjust microclimate and improve environmental quality, thus laying the foundation for water quality improvement of regional lake water.

Disclosed is a method for in-situ remediation of mercury pollution in underground water with magnetite and bauxite slag.The method includes: crushing and sieving natural magnetite slag and natural bauxite slag for standby application; excavating a trench in the lower reach of the underground water pollution plume in the direction vertical to the underground flow, putting uniformly mixed permeable reactive barrier filling materials into the trench, and performing even compaction to obtain a permeable reactive barrier.The magnetite and bauxite can effectively remove mercury in underground water, and meanwhile, acidic mercury-polluted underground water tends to be neutral in pH value after flowing through the reactive barrier.Using the underground water for desorption of active materials loaded with mercury, the results show that the magnetite and bauxite mixture has good stability and safety as the mercury remediation material, and cannot cause secondary pollution to the underground water.By adding a certain proportion of sand, on the premise that usage of the active materials is not increased, thickness of the barrier body can be increased, hydraulic retention time is prolonged, and more construction expense of the PRB (permeable reactive barrier) is saved.

The invention discloses a method and device for staring and stably maintaining short-cut nitrification and denitrification by controlling different anoxic and aerobic volume ratios. The method includes the following steps that firstly, sludge is cultivated and acclimated; secondly, short-cut nitrification and denitrification are started, wherein by controlling the DO concentration of an aerobic zone and adjusting the volume ratio of an anoxic zone to the aerobic zone to be 5:3-6:2, a short-cut nitrification and denitrification system is started; thirdly, short-cut nitrification and denitrification are stably maintained, wherein according to inflow water quality changes and daily monitoring conditions, short-cut nitrification and denitrification are stably maintained by adjusting the DO concentration of the aerobic zone and changing the volume ratio of the anoxic zone to the aerobic zone. After the system runs stably, the ammonia and nitrogen removing rate reaches 91.35%, and the accumulation rate of nitrite in water flowing out of an aerobic pond is 91.15%. Short-cut nitrification and denitrification are started and stably maintained in the continuous flow A / O technology, and the problem that short-cut nitrification and denitrification are difficult to start and stably maintain in a continuous flow urban domestic sewage treatment system is solved.

The invention relates to a composite filter tank for internal electrolysis and denitrification, and application thereof. The filter tank sequentially comprises a water distribution area, an iron-carbon doping area, a filler area, a supporting layer and a water collecting area from top to bottom, wherein perforating and water collection plates are respectively arranged on the top parts of the iron-carbon doping area, the filler area, the supporting layer and the water collecting area; a funnel-shaped slope with the gradient being 5 percent is arranged on the bottom part of the water collectionarea; a water inlet is formed in the upper part of the water distribution area; a back washing water outlet is formed in the lower part of the water distribution area; a water outlet, a back washing water inlet and a disturbance water inlet are formed in the bottom part of the water colleting area. According to the composite filter tank for internal electrolysis and denitrification, and the application thereof provided by the invention, on one hand, the problems that an existing deep-bed filter tank is low in simultaneous phosphorus and nitrogen removal efficiency and the operation cost is greatly increased since an external carbon source needs to be fed during an operation process is solved, and on the other hand, the problem that after the deep-bed filter tank is operated for a certain time, a filter material is easy to harden so as not to be easy to back wash is solved.

The invention discloses a wavy subsurface-flow constructed wetland landscape water body treatment system and method. The system combines a horizontal subsurface-flow constructed wetland with a vertical subsurface-flow constructed wetland to form a wavy subsurface-flow constructed wetland. By means of regularly arranging upper clapboards and lower clapboards inside the wetland and replacing a horizontal flow state with a wavy flow state, sludge flows in a plurality of modes which are connected in series and alternate in upstream and downstream flows, so that organic nutrient substances are sufficiently degraded to remarkably promote deposition of phosphorus; the sludge is repeatedly subjected to anaerobic and aerobic treatment, so that removing of nitrogen can be facilitated; appropriate limestone is added into the filler of the wetland to release Ca<2+>, so that phosphorus in the sludge generates insoluble deposition of calcium phosphate, and thus the removal rate of phosphorus is increased. Due to the adoption of modes, such as intermittent water distribution, water inflow to a water distribution pipe by forming openings in the bottom as well as serial or parallel operation of a plurality of wavy subsurface-flow constructed wetlands, the bed body of the constructed wetland plays a relatively large efficiency, the removal rate of nitrogen phosphorus and organic matters is increased and the sludge treatment capability is enhanced.

The invention discloses a method for efficient removal of heavy metals in farmland irrigation water by a plant pond, a constructed wetland and an adsorption tank. The method is mainly characterized in that farmland in which natural water inlet and outlet can be realized by difference of elevation is selected according to farmland irrigation ditch distribution conditions to form a 'plant pond, constructed wetland and adsorption tank' integrated purification process, aquatic plants such as typha and hydrilla are planted in the plant pond and the constructed wetland, and the adsorption tank is filled with industrial and agricultural wastes such as straws high in heavy metal adsorption capacity to purify heavy metal pollution in the farmland irrigation water. The aquatic plants can not only prevent short circuit of water flow but also improve purification efficiency; the adsorption tank can further improve purification efficiency to guarantee that heavy metals in the farmland irrigation water reach the standard. By adoption of the method, heavy metal pollution in the farmland irrigation water can be efficiently eliminated while pollution of N, P and the like can be cleared, and the heavy metal content of the farmland irrigation water can reach the standard all year round.

The invention discloses an ecological multidimensional retention system for rainwater drainage on a bank side of a river. A primary ecological buffer zone, a first-layer ecological retention system, a second-layer ecological retention system, a third-layer ecological retention system and a secondary ecological buffer zone are orderly arranged on the upstream side of a river embankment along the slope of the bank side; the three layers of ecological retention systems are in concentric semi-annular radial form and of ditch type structures; each ecological retention system is provided with a planting soil layer, a packing layer and a gravel layer, and plants good in stress resistance and prosperous in root system are planted on the ecological retention system; herbaceous plants are planted in the two ecological buffer zones. The ecological multidimensional retention system is capable of reducing the pollution load due to the fact that rainwater runoff is directly discharged into receiving water by use of the retention spaces; due to closure and adsorption by use of a filter material and purification of rainwater runoff pollution by use of the plant root system, partial heavy metal ions, pathogens and the like can be removed; the ecological multidimensional retention system is suitable for any rainwater volume and water quality and has a good landscape effect.