构造人工湿地（Constructed wetland）

1、构造人工湿地（Constructed wetland）The treatment effect of the wetland system is reduced greatly, shorten the service life of the wetland system, the general life of not more than 10 years; severe blockage, 35 caused scrap wetland treatment system.(3) the effluent suspended matter of wetland system can be s

2、eriously exceeded, especially in the artificial wetland which runs for more than one year. The reason is that a large number of microorganisms died in the wetland filling layer, which discharged the wetland system in the form of biofilm.Purification mechanism of subsurface flow constructed wetlandTh

3、e sewage from flowing through the plant growth medium, biochemical reaction produced filtration, sedimentation, adsorption and other physical and chemical effects and pollutants and matrix forms; microorganism plays an important role in the process, can maintain suitable microbial environment condit

4、ions will determine the effectiveness of the treatment.Subsurface flow constructed wetland treatment purification mechanism does not depend on a single wetland subsystem such as packing or vegetation, but on the premise of control, by matrix plant microbe compound ecological system of physical, chem

5、ical and biological effects of the integrated sewage purification.(1) removal of BOD5: in subsurface constructed wetlands, the removal of BOD5 is mainly microbial degradation. The main source of oxygen are aquatic plants (such as reed) by conducting tissue of vascular bundles, the rhizosphere oxygen

6、 delivery to the plant, a specific ecological environment, in addition to its transmission to the oxygen plant respiration needs in the rhizosphere, will spread to the filler and the liquid medium in the vicinity of the foundation, for aerobic bacteria consumption. By the decomposition of organic ma

7、tter. However, if the BOD5 in the wetland system is too high, the dissolved oxygen concentration in the influent should be increased.The removal of SS: the settlement of SS mainly depends on the physical settlement and retention. The colloidal part of SS is mainly removed by the action of microorgan

8、isms and the percolation of fillers. SS in general effluent can reach 20mg/L. Although subsurface constructed wetland has a good removal effect on SS, it is still necessary to reduce the SS content in the wetland system as much as possible, so as not to affect the treatment efficiency of the wetland

9、. The reason is discussed in more detail in this paper, but not discussed here.The removal of nitrogen mainly includes the absorption of aquatic plants, microbial nitrification, denitrification and ammonia volatilization. Aquatic plants absorb nitrogen accounted for dosing quantity of 8-16% in the s

10、ubsurface constructed wetland, aquatic plants and roots in the formation of oxygen, aerobic nitrification for micro area. At the same time away from the root around the anaerobic zone by rot debris and sewage can be used as carbon source and provides denitrification conditions, constitutes a micro e

11、cological cycle specific nitrogen removal, the removal efficiency of nitrogen. The actual operation results of sewage wetland treatment project at home and abroad show that low temperature and low oxygen restrict nitrification. The temperature required for nitrification is at least 5-7 C, which is a

12、n important limiting factor for nitrification throughout the wetland system throughout the year.The removal of phosphorus, phosphorus removal mainly includes adsorption and formation of insoluble calcium, iron, aluminum and other compounds of precipitation, the contact area is large and the packing

13、wastewater in constructed wetland, the phosphorus removal efficiency is higher, the effect is especially obvious in the wetland at the initial stage of operation.Removal of trace elements: the removal principle is similar to that of phosphorus, and the longer the percolation path of sewage in the pa

14、cking, the higher the removal efficiency.The removal of pathogenic microorganisms, the removal of the main mechanism of wetlandsystems pathogenic microorganism is the adsorption of the filler particles, the pathogenic microorganism removal rate can reach more than 99%.Characteristics of subsurface f

15、low constructed wetlandsAccording to the mechanism of sewage purification by subsurface flow constructed wetland and the actual situation of constructed engineering, subsurface flow constructed wetland has the following advantages:(1) the treatment effect is stable. Under the normal operation of the

16、 wetland system, the effluent water quality is generally better than the national standard class A, and even reaches the standard of class IV and V of surface water.Because the wetland plants can provide a part of carbon source needed for denitrification, it can make up for the shortage of the influ

17、ent carbon source, and has certain treatment effect to the sewage which is difficult to be degraded by other biological methods.(3) it has strong tolerance to fluctuation of hydraulic load and pollution load;It can start at any time after parking, and has little effect on the effluent quality.Fourth

18、, the wetland system generally does not set up two sinks, and the sludge yield of the treatment system is much less than that of other traditional treatment processes.The equipment and facilities are simple, easy to maintain and management, and the quality of staff operation is not high.The structur

19、es and equipment needs simple infrastructure investment and low operation cost.The wetland plants (straw, reed windmill grass etc.) can be recycled, such as paper, processed into feed and animal incineration etc.Any kind of treatment process has its shortcomings, subsurface flow constructed wetland

20、system is no exception, its shortcomings are as follows: (1) large occupation area, which limits its scope of application. (2) the decrease of temperature in winter will affect the treatment efficiency.Clogging analysis of subsurface flow constructed wetlandMain factors causing wetland filler layer

21、blockage of the influent load is not well controlled, especially a large number of SS into the filler layer, there are at the same time there are a lot of biofilm packing by microorganism together, these SS and biofilm will be deposited in the filler gap, after a period of operation there will be a

22、blockage.The packing process is generally increased with the passage of silt and sediment amount of time, the formation of sludge in the upper layer containing filler, the permeability coefficient of filler decreased significantly. It has the following two kinds of performance:First, if the horizont

23、al subsurface flow constructed wetland, is the process of gradually extending back silting, the upper filler will form the thickness of sludge layer containing 20 - 30 cm. The vast majority of sewage from the surface through the filler, subsurface flow constructed wetland becomes the surface flow we

24、tland; not only shorten the residence time, but also lost the filler on adsorption, pollutant degradation, the processing efficiency is also decreased. At the same time, the sensory effect of wetland becomes worse, and the management environment is also affected.Second, if the vertical subsurface fl

25、ow constructed wetland, it will form a sludge layer containing about 10 cm in thickness and the upper filler, the surface of the filler particle size, the smaller the particle size, the more thin layer containing sludge, showed that the more easily silted up. Under normal circumstances, the diameter

26、 of the filling surface of vertical flow constructed wetlands are relatively small, which leads to the normal operation of the filler surface will cause serious water, so that the operation of the deterioration of the environment and the processing capacity decreased, serious will affect water quali

27、ty. There are similar problems with the rapid infiltration systemThe occurrence of these conditions has brought serious negative impacts on the popularization and application of constructed wetlands.In fact, according to the water quality of different pretreatment, take reasonable measures of contro

28、l into the artificial wetland system load in a reasonable range; combined with the subsurface flow wetland system is designed to free silting form, keep the treatment efficiency of subsurface flow constructed wetland system at the same time, to maintain its original advantages.Dissolved oxygen in Co

29、nstructed WetlandsWhen using constructed wetlands to treat sewage, there are three ways of source of dissolved oxygen for degradation of pollutants:First, the sewage itself contains dissolved oxygen, which generally influent water quality and pretreatment system is related. If the influent contamina

30、nt content is high and the pretreatment facility is too simple, it is possible that the influent does not contain dissolved oxygen.Two. Plants supplement, plants normally grow by Guan Weishu to the root of the oxygen, part of it will dissolve into the sewage. However, the supply of oxygen in additio

31、n to the root needs of breathing, the remaining microorganisms for the use of oxygen is limited, if only the concentration of water pollutants is too high, it will cause root hypoxia, seriously affect the normal growth of plants.Three. Atmospheric re oxygenation. This is obvious in surface flow wetl

32、and, and subsurface flow constructed wetland can only have such functions through wetting and drying cycles.Personally, the dissolved oxygen in the constructed wetland system is generally lower than 1 mg / L when the wastewater is treated. If the effective residence time of the sewage in the wetland

33、 is less than two days, it will be lower or even zero.Recently, he shared this view with the Southern China Institute of Environmental Sciences, Professor Wang Junsan. Welcome to AC water treatment technology. QQ:714375020, TELID129256 Posts 2930 essence 1 experience 23844 gold coins 10

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35、l published in 2008-3-1 08:04 only see the authorPersonal views on artificial rapid infiltration process1, artificial rapid infiltration process should be an advanced treatment process, generally should be placed in the back end of the entire processing system, in order to ensure the quality of effl

36、uent and treatment efficiency.2, if applied in the sewage treatment, we must strengthen the pretreatment measures, it is best placed in the two stage treatment process, control the load into the system. The wastewater entering the fast infiltration tank is best to reach the level B of the urban comp

37、rehensive discharge standard. After rapid infiltration treatment, generally can reach more than one class A.3, if the sewage is by simple pretreatment (such as precipitation and hydrolysis) into the infiltration tank, it is not appropriate, because it will bring rapid infiltration pond surface sense

38、 is very poor, can not be under the influence of seepage of sewage treatment efficiency, which will produce odor, cause two pollution. At the same time, this will undoubtedly increase the area of the fast infiltration tank, and lose the technical and economic advantages of the process.4, artificial

39、rapid infiltration of sensory effect is poor, at this point is not as good as vertical flow of artificial wetland system.Operation of anaerobic ponds and aeration pondsOperation of anaerobic pondThe efficiency of anaerobic pond treatment in winter is obviously decreased, and should be fully consider

40、ed in the design. The seasonal odor is more pronounced in anaerobic ponds. The operation of anaerobic ponds does not change seasonally.Operation of aeration pondThe operation of the aeration pond is basically unchanged throughout the year. In the freezing season, it is necessary to strengthen the in

41、spection of the aerator. With the decrease of temperature, the removal rate of BOD decreased significantly. In addition, with the decrease of temperature, the transfer rate of oxygen from gas phase to liquid phase also decreases, but the solubility of oxygen increases with the decrease of temperatur

42、e, which is sufficient to compensate for the low transfer rarefaction.The anaerobic pond and aeration pond with higher load have more sludge accumulation at the bottom of the pond, and must be cleaned and disposed in time, and the sludge should be emptied regularly.Change strategy of effluent from o

43、xidation pondIn view of the efficiency of oxidation pond was affected by season, water stayed in the pond longer, Tang Tang has a capacity of high embankment, flexibility, pond water discharge can make the following changes: 1. The semi continuous emissions; emissions; the intermittent emissions; II

44、 emission.Continuous emissions can be used in warmer seasons with higher efficiency. In the winter, the treatment effect is low or the critical period of the pond spring in the aerobic pond can be non drainage. The intermediate two strategies should be carried out when the maximum discharge of the r

45、eceiving and draining rivers is carried out, and the dilution effect of the large water body can be used to prevent the influence of drainage on the environment. The determination of BODSS coliform group and DO should be done before drainage.Commissioning of aerated oxidation pondBefore entering the

46、 operation, the weed at the bottom of the pond should be removed and the dike should be piled up to 0.3m above the predicted maximum water level. Check all entrances and exits control devices. Check the oxidation pond leakage and aeration device, the method is to extract the lowest depth of the wate

47、r to the oxidation pond, observe whether to maintain a certain water level, in order to prove the anti leakage of pond. When the maximum water level is reached, the aeration system of the aeration tank can be further detected.There is no need for inoculation in the oxidation ponds that are being put

48、 into operation, because suitable bacteria and algae are widely existed in this environment. Generally speaking, it is better to put into production in spring and summer. At this time, most of the biota in the oxidation ponds can be developed naturally. After production, the pond can not be drained

49、until the following conditions are met:The water level of the receiving wastewater in the 1 oxidation pond has reached the appropriate depth specified by the design;The growth of biota in the 2 ponds has been healthy;3 chemical and biological tests have been carried out and the emission standards ha

50、ve been reached.At this point, the processing system can begin to drain and enter normal operation.Daily operation management of oxidation pondMost of the problems in oxidation ponds can be avoided by proper operation. Daily management should pay attention to the following points:1 if there are scum

51、 or algae plexus, often produce odor or attract insects, literally shattered in a state of suspension.Because of the influence of the wind direction, the orientation of the pond and the position of water entering and leaving the water, a dead angle can be formed in the pond, and a fixed water sprayi

52、ng device can be installed and the water area out of the water outlet can be used to spray the dead corner area.2 when aerobic ponds and facultative ponds are in normal operation, only a small amount of sludge accumulates. The amount of sludge deposited in the anaerobic pond and aeration tank is lar

53、ge, and the volume of the deposited tank should be reserved in the design. When I was filled with sludge volume, should stop running and cleaning. The specific method used suction dredger suction, or pond water emptying, dried by manual or mechanical excavation, removal of sludge as fertilizer.3 roo

54、ted in the pond or the slope on the submerged plants can cause many side effects, should be uprooted, this plant or herbicides kill off than better, after two, the plant remains still in the pool, will produce a large number of additional BOD, and attract insects and wild animal.44 must be controlle

55、d on the Bank of the plant growth, the specific measures is to remove all trees and shrubs from the pond embankment and slope on both sides, in order to reduce leakage along the embankment at the base of the tree, but also can reduce the consumed by transpiration of plant leaves the pond water, reduce plant residues of organic load additional