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Title: A Review of the Brogboroughand Landfill 2000 Test Cells Monitoring Data
Author: Knox Keith
Author: Environment Agency
Document Type: Monograph
Annotation: Environment Agency Project ID:EAPRJOUT_391, Representation ID: 108, Object ID: 1734
Abstract:
1.. Introduction 2. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . i-iii and Objectives . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-2 Brogborough Test Cells . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3 - 19 3 , ................................. 2.1 Introduction ......... 3 2.2 Description of the Brogborough test cells. ......................... 4 2.3 Assessment of the strengths and weaknesses: ....................... - choice of variables - construction and .management-of -the cells - monitoring 2.4 Knowledge gained from the results to date: . . . . . . . . . . . . . . . . . . . . . . . 11 - gas generation - gas quality - temperature - settlement - leachate quality 2.5. Potential to generate,useful information . . . . . - . . . . . . . . . . . . . . . . . . . 17 3. Landfill:2000 Test Cells . . . . . . . . . .. . . . . . . . . . . . . . . . . . . . . . 20 36 3.1 Introduction.. . . . . . . . . . . . , . . . . . . . 3.2 -Description-of the test cells . . . . . . . . . . . 3.3 Assessment of the strengths and weaknesses: - choice of variablesa - design and construction of the cells - monitoring of the cells: 3.4 Knowledge gained.from the results:. . . . . . - gas generation: - waste stabilization - gas quality - leachate quality. - hydraulic aspects . . . . . . . . . . . . . . . . . . . . . . 20 ,: . . . . . . . . . . . . . . . . . . . . . . 20 . . . . . . . . . . . . . . . . . . . . . . 22 . . . . . . . . . . . . . . . . . . . . . . 25 4. Microbiological Aspects of the Results .from ,Brogboroughs -: and.Landfill2000. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 37-41. 5. Usefulness of the Results in, Validating LFG Production/ Emission Models . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 42 ; 44 CWM 145/97 15.7.97.ii A Review of the Brogborough -3sLandfill 2000 Test Cells Monitoring Data 6. Comparison with Other Large-scale Test Cell Studies . . . . . . . . . . . . 43 - 57 6.1 6.2 6.3 6.4 Mountainview, California, USA .............................. Helsingborg, Sweden .................................... and lalmii, Sweden ....................................... Stockholm, Sweden ..................................... 7. Discussion i . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 58 - 62 8. Conclusions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 63 - 64 9. Recommendations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. . . : . . . 65 45 47 51 55 10. References . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 66 - 68 CWM 145/97 15.7.97.ii A Review of the Brtigborough and Landfill 2000 Test Cells Monitoring Data List of Tables Page, Naa. Brogborough Test Cells I 1. Chronological highlights in the management of the Brogborough test cells: . . . . 69 2. Chronological highlights. m-the monitoring of the Brogborough test cells., . . . . . 70 3. Choice of andvariablesexamined in the Brogborough .and Landfill 2000 test cells. 4. Strengths and weaknessesin the construction and management of the Brogborough test cells:. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 72 5. Critical aspects of the:monitoring of the Brogborough test cells. 6. Leachate quality inpumped samples from the Brogborough test cells.- . . . . . . . 74 7. Key findings from the Brogborough test cells: . . . . . . . . . . . . . . . . . . . . . 75 Landfill;,2000 . 71 . . . . . . . . . . 73 Test Cells 8.. Chronological highlights :in the management of the Landfill, 2000 test cells. .a . . . 76 9. Chronological highlights in the monitoring of the Landfill. 2000 test cells:: . . . . 77 10. Strengths and weaknessesin the monitoring of .the Landfill 2000 test cells. . . . . 77 11; Leachate quality in samples-from flooded gas probes at Landfill 2000. . . . . . . 78 12. Leachate -quality in interstitial water centrifuged from .waste samples excavated in February 1995 at Landfill 2000 . . . . . . . . . _ . . . . . . . . . . . . 78 General. ;a 13. Summary of input details for Mountainview test cells. . . . . . . . . . . . . . . . . 79 .a:I 14. Summary of results from Mountainview test cells. . . . . . . . . . . . . . . . . . . . 79 CWM 145197 15.7.97.ii A Review of the Brogborough and Landfill 2000 Test Cells Monitoring Data List of Figures Page Noa* Brogborough Test Cells 1. Layout and schematic construction details of the Brogborough test cells. ..... 80 2. Chronological summary and input details of the Brogborough test cells. ...... 81 3. Typical layout of monitoring and extraction wells, gas/temperature probes and herringbone trench system in the Brogborough test cells. ........ 82 4. Dissipation of liquid injection in Cell 3. ......................... 83 5. Leachate depths in type B and C wells. 83 6. Cumulative gas flow per tonne of waste as received. .................. 84 7. Temperature of pumped leachate samples. ......................... 85 8. Temperatures in upper (7m) gas probes. .......................... 86 9. Temperatures in middle (12m) gas probes. ....................... 86 ......................... 10. Temperatures in lower (17m) gas probes; . . . . . . . . . . . . . . . . . . . . . . . . 87 11. Mean temperatures in gas probes. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 87 12. Cumulative settlement in test cells. ............................. 88 13. Methane concentrations in abstracted gas. ........................ 89 Landfill 2000 Test Cells 14. Schematic layout showing gas collection and leachate recirculation pipes (after Blakey et al., 1996). . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 90 15. Cross-sections showmg construction details (after Blakey et al., 1996). . . . . . . 91 16. Schematic cross-section showing closure details (after Blakey et .aZ., 1996). 17. Locations of gas probes in test cells (after Blakey et al., 1996). . . . 92 . . . . . . . . . . 93 18. Chronological summary of Landfill 2000 test cells. . . . . . . . . . . . . . . . . . . 94 19. Temperature variations in the test cells and ambient air (after Blakey et al., 1996). 95 CWM 14.5197 15.7.97.ii A Review. of the Brogborough gi Landfill 2000 Test Cells Monitoring 20. Leachate level changes in test cells (after Blakey et al., 1996). Data ........... 96 . . . . . . . . 97 21. Major inorganic parameters in sump leachates: Cl, NH,-N, Na;K: 22. Methane .concentrations in the gas vent pipes of the test cellsa . . . . . . . . . . . . 98 (after Blakey et al. ; 1996) 23. Gas composition in the probes of Cell 1 (after Blakey et al. ,. 1996). . . . . . . . . 99. 24. Gas composition inthe probes of Cell 2 (after Blakey et al., 1996); . . . . , . . . 100 :. 25. Leachate COD- and BOD. in ,Landfill 2000 test cell sumps i (after.Blakey et al., 1996). . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 101. 26.. Cumulative gas flow measurements from. time-of-transit meters (after.Blakey et al. ;-1996) .-:; . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 102 27.a CH,:COz -ratios in vent gases from: Cells 1 and 2. . . . . . . . . . . . . . . . . . . . 103 28. CH,:CO, ratios in.gas probes in Cell 1.. ......................... 104 29. CH,:CO, ratios in gas probes in Cell 2. ......................... 104. 30. Hydrogen concentrations in gas probes in both Cells (after SBlakeyet al., 1996). . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 105, 31. Sump leachate quality trendsa in Cell F,at Landfill 2000. . . . . . . . . . . . . . . . 106 .a 32. Sump-leachate quality trends-in Cell -2 at Landfill 2000. ................ 107: 33. Lithiumconcentrations following tracer addition-at Landfill 2000. ......... 108 34. Volatile fatty acid concentrations in sump leachates at Landfill 2000::. . . . . . . . 109 General a. ; 35. CH,:CO, ratios in gas from Eastwood columns (Beaven;:1996). . . . . . . . . . . 110 36. Brogborough gas flow rates;. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11-l: 37. Gas flow.profiles at Landfill 2000 and -in lysimeter studies. . . . . . . . . . . . . . 112 :j 38. Cumulative gas flow from Helsingborg.test cells; Sweden (Meijer-et al.; 1994). . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 113 39. aMethane,flow rates from Mahnii test cells, Sweden (Nilsson et al. ;,,1994):- . . . . 113 CWM 145/97 15.7.97.ii : A Review of the Brogborough d Landfill 2000 Test Cells Monitoring Data ACKNOWLEDGEMENTSa The help of the researchers involved in the-projects reviewed in this report is gratefully acknowledged. Their willingness to spend time discussing their work was much appreciated,..particularly aMr Nick Blakey of WRc, who answered innumerable questions; Thanks are also. due to Dr Irene Watson-. Craik; of the.University of Strathclyde for enlightening discussions on landfill microbiology, to Dr Anders Lagerkvist of the University of Lulea and Lotta Retzner of RVF; Sweden, for information on the various Swedish test cell.. projects. DISCLAIMER The views expressed. in this document are. not necessarily. those of the Environment :Agency . Its .officers, services or agents accept. no liability,. whatsoever for any- loss or damage arising .from: the interpretation or use of the information, or reliance on views contained herein. KEYWORDS Test cells; landfill gas; accelerated. stabilization; leachate .:quality; waste hydraulics; gas quality; microbiology; gas modelling; landfill processes; leachate recirculation. FOOTNOTE a Since the report was first prepared it has been determined that work .will not continue at the Brogborough test cells beyond 3998. A final phase of work will be undertaken to complete the collation of all data from the cells but some of the suggested-usesof the cells given in this report would not be possible within the time now available.. CWM 145197 15.7.97.ii A Review of the-Brogborough and Landfill 2000 Test Cells Monitoring Data EXECUTIVE SUMMARY 1. This report reviews data from two field-scale .landfill test-cell projects; a namely Ekogborough and Landfill 2000. 2. These two projects were begun in.1986 and -1991respectively. The Brogborough project .. was still. continuing in 1997, while the Landfill 2000 .project was terminated in Spring 1995;; 3. Both projects were set up to accelerate waste stabilization,., Brogborough -with the intention of maximising energy recovery and .Landfill 2000 to develop a bioreactor cell .: rotation,approach to landfillaiZ in which stabilized solid residues could be recovered .and the engineered cell re-used after 3 years. 4. At Brogborough, six 15,OOOtcellswere.constructed, each measuring 40m x 25m x 20ma deep. The enhancement-techniques investigated were: - low- density tipping; mixing with 50% industrial/commercial waste; addition of sewage sludge during infilling;-4 retrospective water.addition; retrospective air injection.. 5. At Landfill-:2000, two .I;000 tonne cells were constructed,.seachmeasuring 36m x 23m x 5m ~maximum depth.. The enhancement techniques used ,were: - addition of sewage sludge during filling (both cells); - addition of sewage effluent after filling;, : - recirculation of leachate (one cell only):6. Both sets of cells were .designed for containment of leachate and the collection and measurement of landfill gas... Bothsets were completed with low permeability top caps and ,in both casessome leakage of water occurred into the cells. 7. At Brogborough,. active gas. extraction was used while at Landfill a2000 only passive venting was used: 8. At Brogborough a variety of gas flow measurement techniques was-used and eventually ... venturi meters were adopted,.linked to data loggers for continuous monitoring. aFor this evaluation, weekly hot wire anemometer. data have been used for -the period before the venturis were installed, and venturi data subsequently. During the period when both methods were .in use, their results were- found to compare very well. CWM 145197 15.7.97.ii i A Review of the Brogborough and Landfill 2000 Test Cells Monitoring Data 9. At Landfill 2000, only occasional gas flow measurement was undertaken until late 1993, when continuous monitoring was installed in the non-recirculation cell. A novel time-oftravel flow meter using a thermal tracer was used. A similar flow meter was installed in the recirculation cell only in December 1994, three months before the end of the study. 10. Both projects featured a variety of strengths and weaknesses in their design, construction, management and monitoring. However, both have produced extremely valuable data showing the degree of enhancement that can be achieved at large scale using the techniques investigated. Both have also generated valuable information on landfill degradation processes and on gas generation patterns. 11. At Brogborough: - methanogenesis and gas generation began earlier and at a faster rate in cells to which sewage sludge or (to a lesser extent) non-hazardous industrial waste had been added; - gas generation rates increased steadily in all cells over a 6-7 year period and were still increasing in some cells after 8-9 years. This is contrary to the expectations from gas models, which predict maximum rates much earlier, followed by exponentially declining rates; - enhancedrates as high as 22m3 LFG/t.a were reached in a cell which had.air injected into it. This may have been partly due to improved distribution of moisture into dry wastes; - similarly high rates developed in a cell to which large volumes of water were added retrospectively. Although the enhancement took longer to develop than in the air injection cell, the high rates have been sustained for longer; - rates in the control cell have reached 13m3LFG/t.a which is above the upper end of the typical observed range for conventional landfills. 12. At Landfill 2000: - methanogenesisbecame established within one year in both cells; - enhanced rates up to 17m3 LFG/t.a developed in the cell in which leachate was recirculated at a rate equivalent to a hydraulic retention time of - 1 year in the waste mass; - even in the non-recirculation cell a gas generation rate of - 8m3LFG/t.a developed; CWM 145/97 15.7.97.ii ii A Review of the Brogborough and Landfill 2000 Test Cells Monitoring Data - the high gas generation rates were achieved in spite of unusually low temperatures (range 7-17AdegreesC; mean - 12AdegreesC) in both cells, caused by their shallow depths; - stabilization of waste was not- achieved in three years. Solid, samples in early 1995 still had biochemical methane potentials:. of76 (recirculation cell) and 161 (nonrecirculation cell) m3 LFG/dry tonne; - a significant proportion of gas generation was due to:H,/CO, utilization; - a significant .proportion of gas generation occurred in the agravel- leachate drainage layers; - high,rates.of methane generation wereaalso, able to occur :within the waste mass even a. though the .-in situ ~moisture .remained strongly. -acetogenic: This is contrary to I. conventional .expectations but is supported by similar results from test cells in Sweden. 13: The results from both sets of text cells i show that acceleration of ,degradation rates by a factor -of -2. should :be achievable at full-scale landfills using relatively simple techniques. 14. In neither study. were all factors optimised, and a greater degree of enhancement may .a be achievable. 15. The results from both sets of cells have shownthat neither temperature nor:bulk leachate composition are necessarily a good guide, to the level of-methanogenic activity. 16. No large-scale test cells .have been used to investigate accelerated.contaminant flushing, either in the UK or abroad. 17; It is recommended that the Brogborough test cells be continued as long as possible, to: - confirm the shape and duration of the .gas generation profiles; - confirm gas yields;- demonstrate the accelerated flushing bioreactor concept;, CWM 145197 15.7.97.ii .. . 111 A Review of the Brogborough and -Landfill 2000 Test Cells Monitoring Data 1.
Publisher: Environment Agency
Subject Keywords: Microbiology; Landfill gas; Test cells; Accelerated stabilization; Leachate quality; Waste hydraulics; Gas quality; Gas modelling; Landfill processes; Leachate recirculation.
Extent: 130
Permalink: http://www.environmentdata.org/archive/ealit:4422
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