CN101020184A - Technological process of back pouring percolate to speed stabilization of old landfill site - Google Patents

Abstract

The present invention relates to the technological process of back pouring percolate to old landfill site for speeded stabilization and belongs to the field of environment protection technology. The technological process includes setting rain way guiding and draining facility in landfill site and sealing simply, and back pouring percolate through horizontal blind ditch with storage tank of polyethylene to speed the garbage stabilization. The technological process can speed the degradation of organic matter in the landfill site and makes it possible to omit special percolate treating facility.

Description

The back pouring percolate to speed stabilization of old landfill site process

Technical field

The invention belongs to environmental technology field, be specifically related to a kind of back pouring percolate to speed stabilization of old landfill site method, this method is carried out leachate recirculation in old soot, proposed to recharge the recycling mode of unit based on level, the even distribution of percolate is recharged in realization, improve the moisture content of rubbish, quicken the stabilisation process of old refuse landfill, and reduce the percolate pollutional load by recharging, improve leachate quality, and utilize the moisture holding capacity of landfill yard rubbish and the generation that the closing engineering reduces percolate, finally realize the rapid stabilization of old soot rubbish and the target that percolate directly discharges.

Background technology

At present, the main processing mode of China's domestic waste is sanitary landfills.Simple and easy landfill yard accounts for more than 80% of China's sanitary filling field sum, and wherein most of old soot faces to close or be about to and closes.Lacked necessary seepage control measure and gas collection facility owing to build originally, percolate that old soot produces and landfill gas to environment structure potential threat, percolate seepage meeting contaminated soil and underground water, the migration of landfill gas then may cause the regional area methane concentration to reach explosion limit and blast.In a word, old soot need take measures necessary to quicken its stabilisation before closing, reduces its long-term environmental risk.

Whether the stabilization technology of refuse landfill according to aerobic aerobic stabilization technology and the anaerobism stabilization technology of being divided into.For aerobic stabilization technology, more existing both at home and abroad laboratory scale researchs by aerobic aeration technology, are accelerated the stabilisation of rubbish.The result shows that aerobic landfill can improve the degradation rate of rubbish really.But for the rubbish of the hundreds thousand of cubic meters in old soot down to millions of cubic metres, the operating cost of technology such as aerobic ventilation is inevitable quite high, has hindered its large-scale application.The anaerobism stabilization technology mainly is under anaerobic to pass through enhancements, accelerates the stabilisation process of rubbish.

In addition, the processing of percolate is the difficult problem that old soot faces.Old soot percolate is the component complexity not only, and the water quality and quantity amplitude of fluctuation is big, and biodegradability is relatively poor, and ammonia nitrogen concentration is higher.Existing leachate treatment technology mainly contains: (1) biologic treating technique, and as activated sludge process (2) physical chemistry treatment technology, as electrochemical process, membrane technology and evaporation process technology etc.Because old soot percolate biodegradability is poor, traditional biologic treating technique such as activated sludge process etc. are difficult to reach the requirement of processing effluent quality.Physical chemistry treatment technology treatment effect is better, but construction and operating cost are higher.In addition, old soot closes the back owing to take the end covering and have rainwater guide facility, and the percolate generation reduces year by year, if adopt the conventional treatment technology, if percolate output does not reach the designing requirement of percolate treatment facility, cause the idleness of equipment and the wasting of resources easily.

Therefore, demand seeking the stabilisation process that a kind of suitable technology is quickened its rubbish urgently before current old soot closes, reduce the discharge rate and the concentration of percolate, can utilize the useful condition of creating simultaneously again for the soil of landfill yard.

Summary of the invention

Purpose of the present invention is exactly in order to overcome the above problems, recharge the unit based on the percolate level, the water distribution uniformity of percolate is recharged in realization, quicken the rapid stabilization of old soot rubbish, the discharge capacity and the concentration of percolate are all reduced greatly, this technology construction is simple, convenient, with low cost, has vast market and uses and promotional value.

The back pouring percolate to speed stabilization of old landfill site process that the present invention proposes, it is characterized in that: described process is by after being provided with rainwater guide facility and carrying out simple and easy closing in refuse landfill, adopt the leachate recirculation mode, realize handling percolate and quicken waste stabilisation;

Described leachate recirculation mode is horizontal french drain recycling mode, and the employing level recharges the unit, and it is the center with polyethylene hold-up tank (6) that each level is recharged the unit, radially is evenly equipped with some horizontal french drains;

Be promoted in the polyethylene hold-up tank (6) at landfill yard top by elevator pump behind the described leachate collection, uniform water distribution oozes to each horizontal french drain, polyethylene hold-up tank (6) works the percolate water yield and the water distribution effect regulated, the described top at polyethylene hold-up tank (6) is provided with manhole, regularly draw clearly, prevent to stop up;

Described upward the setting at polyethylene hold-up tank (6) recharged pipeline (3), and the described pipeline (3) that recharges is a polyethylene perforation floral tube; Describedly fill washing rubble water conservancy diversion layer (2) on every side recharging pipeline (3), stop up polyethylene pipe to prevent rubbish, and increase water penetration;

Describedly between intermediate cover layer (5) and washing rubble water conservancy diversion layer (2), geotextiles (4) is set, in case rainfall enters landfill yard in the non-return filling process.

The present invention has following advantage:

1, horizontal french drain recycling mode has improved the uniformity of water distribution, has quickened the stabilisation of rubbish

The horizontal french drain formula of employing of the present invention is recharged water distribution, not only easy construction, and can improve the uniformity of water distribution of leachate recirculation, and improve the moisture content of rubbish effectively, quicken the degraded of rubbish;

2, utilize the moisture holding capacity of rubbish, by recharging the outer discharge capacity that reduces percolate

Rubbish itself has certain porosity, and through the rubbish of certain hour landfill, porosity can increase, and its moisture holding capacity can increase, and therefore, the present invention can reduce the outer discharge capacity of percolate by the mode of recharging percolate.

3, reduced the organic loading of percolate

The present invention is by the mode of leachate recirculation, not only quickened the organic matter degradation in the garbage loading embeading layer, organic matter in the percolate also can be utilized by the Institute of Micro-biology in the landfill yard and obtain degraded simultaneously, thereby improves the percolate effluent quality, handles in the field of realization percolate.

4, operation is simple, need not to set up special percolate treatment facility after the processing again

This patent adopts sets up the form of horizontal french drain to carry out leachate recirculation at landfill layer top, and this mode is constructed simple, and the water quality after the processing can reach the corresponding discharge standard of country, need not to set up special percolate treatment facility again.

Description of drawings

Fig. 1 recharges the plane of unit for level of the present invention.The center is a PE percolate hold-up tank, and four levels are recharged french drain and played the water distribution effect, and percolate oozes by under the french drain, realizes water distribution uniformity.

Fig. 2 recharges the drawing in side sectional elevation (A-A section) of unit for level of the present invention.The final cover layer of rubbish is the lining that has the HDPE geomembrane, can increase the rainwash of rainfall, reduces the following of percolate and oozes.The HDPE perforation floral tube of water distribution is positioned at gravel layer, flows to horizontal french drain end for guaranteeing percolate, and the french drain hydraulic gradient is 0.03.

Fig. 3 recharges the profilograph (B-B section) of unit for level of the present invention.Shown the final tectal formation in old soot.

The specific embodiment

Below in conjunction with embodiment technical scheme of the present invention is described further:

Shown in accompanying drawing 1-3.The 1-waste layer, 2-washing rubble water conservancy diversion layer, 3-recharges pipeline, 4-geotextiles, 5-intermediate cover layer, 6-polyethylene hold-up tank.

The present invention is primarily aimed at old soot, and specific practice is by after rainwater guide facility etc. is set carries out simple and easy closing, adopts the leachate recirculation technology, the purpose that realizes handling percolate and quicken waste stabilisation.

Old soot percolate is mainly from rainfall.The empirical model that employing is verified in actual landfill yard design and construction in a large number---reasonable formula is predicted the landfill percolate generation.The reasonable formula model of percolate generation:

$Q=\frac{C\·I\·A}{1000}---\left(1\right)$

In the formula, the Q-percolate water yield, m ³/ day; The I-annual rainfall, mm; C-leaches coefficient, dimensionless number; A-landfill yard area, m ²According to domestic and foreign experience, to the landfill yard that does not close as yet, C gets 0.2; To the landfill yard that has closed, C gets 0.067.

As seen, closing back percolate generation reduces significantly.Be provided with independent percolation liquid treating system cost of investment higher and be difficult to reach the design water yield easily cause the idleness of equipment.

In addition, the rubbish in old soot is through the degraded of long period, and porosity increases, and has certain moisture holding capacity.Specific retention refers to that through soil or the retainable volumetric(al) moisture content of rubbish after the long-term gravity drainage, the listless humidity of withering refers to by lowest volume water-retention value remaining in soil behind the plant evaporation or the discarded object.These two water content all recently define with volume.Specific retention and to transfer the difference between the listless humidity be exactly available moisture or moisture holding capacity in soil or the rubbish.The specific retention of rubbish changes with the size of impressed pressure and the degree of decomposition of rubbish, and its value is 22.4%～55%, and the specific retention of compacting clay liner is about 35.6%.The listless humidity of withering of rubbish is about 8.4%～17%, and the listless humidity of withering of compacting clay liner is about 29%.It is 7.7% that the rubbish that is adopted in HELP model specification 3 is transferred listless humidity.Influence principal element the forming of rubbish specific retention by burden pressure, compacting mode and rubbish.In general, if the composition of rubbish remains unchanged, then its specific retention will reduce along with the increase of burden pressure and compaction.Organic component such as paper, hardboard, textile etc. are many in the rubbish, and its specific retention is also high more.According to external relevant result of study, the specific retention of rubbish is on average got 33cm/m, and the average initial water content of solid waste can be assumed to be 12cm/m.On average, can absorb moisture 21cm/m.

1 hectare of area of estimation highly is about for the amount that the landfill unit of 10m can hold percolate:

$Q_c=10000{\mathrm{<figure-callout\; id="2"\; label="m"\; filenames="A20071006445500081.png,A20071006445500091.png"\; state="\{\{state\}\}">m</figure-callout>}}^2\&times;\frac{21\mathrm{cm}}{m}\&times;10m=21000{\mathrm{<figure-callout\; id="3"\; label="m"\; filenames="A20071006445500091.png"\; state="\{\{state\}\}">m</figure-callout>}}^3$

By the aforementioned calculation result as seen, the moisture holding capacity of rubbish is considerable.Old soot need not to be provided with big regulating reservoir.

The infiltration coefficient leachate recirculation amount of rubbish is decided according to the burden requirement of landfill yard optimum operation, and it is fixed also can to come according to the aerogenesis situation of landfill yard.According to having achievement in research, average osmotic coefficient k=1.5 * 10 of rubbish both at home and abroad ^-4～1.1 * 10 ^-3Cm/s gets 2 * 10 ^-4Cm/s.Percolate can be considered as flow event recharging of landfill yard, meets Darcy's law.Only consider the seepage flow of vertical direction, the seepage flow flow velocity

$q=k\frac{H+L}{L}---\left(2\right)$

In the formula, k is an infiltration coefficient, cm/s; H is the percolate depth of accumulated water, m; L is the rubbish body thickness, m.According to the Field Research situation, get H=0.6 m, L=10m.

The percolate level is recharged the horizontal projected area of ditch and is calculated:

$A=\frac{100\&CenterDot;Q}{\mathrm{qT}}---\left(3\right)$

In the formula, Q is the leachate recirculation amount, m ³Q is the seepage flow flow velocity, cm/s; T gets 1d for recharging the duration.Satisfy and recharge on the long-pending basis of horizontal groove face, how main consideration realizes recharging the water distribution uniformity of percolate.Recharge the shortcoming that the influence area is little, water distribution is even inadequately, difficulty of construction is big for overcoming vertical shaft, adopt horizontal french drain recycling mode.For easy and simple to handle, the introducing level is recharged the notion of unit.It is the center with polyethylene (PE) hold-up tank that each level is recharged the unit, radially is evenly equipped with some horizontal french drains, sees accompanying drawing 1～accompanying drawing 3.Be promoted in the polyethylene hold-up tank at landfill yard top by elevator pump behind the leachate collection, uniform water distribution oozes to each horizontal french drain.The effect of geotextiles is to prevent that rainfall enters landfill yard in the process of recharging.The polyethylene jar plays regulates the percolate water yield and water distribution effect, and tank deck is provided with manhole, regularly draws clearly, prevents to stop up.Recharging pipeline is the polyethylene perforation floral tube of filling the washing rubble on every side.The effect of washing rubble is to prevent that rubbish from stopping up polyethylene pipe, increases water penetration simultaneously.

Embodiment 1

Certain bioreactor landfill pilot plant test of south

Since 2002, Tsing-Hua University is a research object with the testing column of 4 30t of certain landfill yard of south, carried out the stabilisation research of pilot-scale anaerobic type bioreactor landfill, adopt the difference amount of recharging and recharge frequency, under the research leachate recirculation condition, testing column goes out to flow the degraded situation of leachate quality situation of change, landfill gas production and landfill waste.The actual Shenzhen's house refuse weight in wet base that records consists of: the kitchen surpluss 67.01%, bamboo wood 3.71%, fabric 2.30%, paper 2.62%, foam 1.76%, metal 0.86%, plastics, rubber 19.90%, glass, pottery 1.83%.Easily biodegradable organicses such as the plain and hemicellulose of the main fibre-bearing of rubbish from cooking, through one to two year be that degradable finishes, and organic matters such as bamboo wood are based on the lignin of difficult degradation.

Three are recharged testing column R1, R2, R3 and recharge 1.6m weekly respectively ³, 0.8m ³, 0.2m ³Percolate, contrast blank post R4 and recharge 0.1m weekly ³Clear water.Test lasted more than 2 years, and the result shows that recharging has tangible removal effect to organic pollution in the percolate.After recharging for 30 weeks, three BOD that recharge post ₅Average removal rate is respectively 91.2%, 87.2% and 85.2%, and the highest single-revolution clearance reaches 97.4%, 98.5% and 97.7% respectively.Recharge when proceeding to for 44 weeks, recharge post and go out to flow percolate BOD ₅/ COD mean value is 0.07, BOD ₅/ TN mean value is 0.13, BOD ₅/ TP mean value is 11.After the 50th week, respectively recharge the COD of post percolate water outlet _CrBe lower than 1000mg/L, BOD ₅Be lower than 300mg/L, reached " integrated wastewater discharge standard " (GB8978-1996) three grades of discharge standards.As seen, be that the bioreactor landfill technology of core has good percolate treatment effect to recharge.

The accumulative total generation that recharges post R1 to the 45 all landfill gas of the amount of recharging maximum can reach 9494.5L, is respectively R2, R3, R4 landfill gas output 12.63,20.91,77.19 times.The ratio of cellulose (C), hemicellulose (H) content and lignin (L) content to the rubbish drops to 0.53 of latter stage from 2.18 of the landfill initial stage, the palliating degradation degree that easily biodegradable organics in the rubbish is described is than hardly degraded organic substance height, and the stable degree of rubbish increases substantially.

Embodiment 2

Certain old soot closing training works of south

Certain refuse landfill of south, the length of service 10 years, garbage loading embeading total amount 1,730,000 m ³, landfill yard area 8.15 ten thousand m ²This refuse landfill was closed in 2005, adopted the HPDE film as the surface anti-seepage layer, had an internal drainage and cut big vast job facilities, and gas directing system is arranged.

According to in-situ data, adopt 7 levels to recharge the unit and carry out leachate recirculation.Process is lasted 1 year recharging, and the result shows that the percolate effluent quality has reached sewage comprehensive discharge country grade III Standard, and the palliating degradation degree of rubbish significantly improves.

Claims (1)

1, back pouring percolate to speed stabilization of old landfill site process, it is characterized in that: described process is by after being provided with rainwater guide facility and carrying out simple and easy closing in refuse landfill, adopt the leachate recirculation mode, realize handling percolate and quicken waste stabilisation;

Described leachate recirculation mode is horizontal french drain recycling mode, and the employing level recharges the unit, and it is the center with polyethylene hold-up tank (6) that each level is recharged the unit, radially is evenly equipped with some horizontal french drains;

Be promoted in the polyethylene hold-up tank (6) at landfill yard top by elevator pump behind the described leachate collection, uniform water distribution oozes to each horizontal french drain, polyethylene hold-up tank (6) works the percolate water yield and the water distribution effect regulated, the described top at polyethylene hold-up tank (6) is provided with manhole, regularly draw clearly, prevent to stop up;

Described upward the setting at polyethylene hold-up tank (6) recharged pipeline (3), and the described pipeline (3) that recharges is a polyethylene perforation floral tube; Describedly fill washing rubble water conservancy diversion layer (2) on every side recharging pipeline (3), stop up polyethylene pipe to prevent rubbish, and increase water penetration;

Describedly between intermediate cover layer (5) and washing rubble water conservancy diversion layer (2), geotextiles (4) is set, in case rainfall enters landfill yard in the non-return filling process.

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