Study on the gaseous emissions from a landfill

The Science of the Total Environment, 127 (1992) 201-210 Elsevier Science Publishers B.V., Amsterdam

201

Study on the gaseous enfissions from a landfill M. Loizidou ~ and E.G. Kapetanios b "Athens National Technical University, Chemical Engineering Dept., Zographou Campus, 5, Iroon Polytechniou Str., Athens, Greece bAssociation of Municipalities of the Attica Region, 46, Methonis Sir., 10o~i Ad~,;s, Greece (Received July 12th, 1991; accepted September 3rd, 1991)

ABSTRACT Emissions from landfills contain a variety of compounds, organic and inorganic, which can create problems with human health. Here we examine the pollutants methane, hydrogen ,mlphite, mercaptans, sulphur dioxide, nitrogen dioxide and certain volatile organic compounds (VCLCs) that are expected to be found in landfill emissions, in order to assess the environmental impact on the surrounding area. Results indicatethat the concentrations in ~he landfill itself are quite high and m most cases above the ambient air quahty limits, while for the surroundiag area they are l.qw. The problem is created by H2S and the mercaptans which, although in low content, have a distinct odour and cause problems to the neighbouring dv,:!!!ngs.

Key words: landfill emissions; gaseous pollutants; biogas emissions

INTRODUCTION

In most cases landfills have n,,t,...,been designed r-vr-~-j~'r'~n~l~........ few the collection and disposal of gaseous emissions and leachates. The landfill is a reactor that processes the waste mainly anaerobically. The fill material undergoes a number of simultaneous physical, chemical and biological changes (Klein, i972; Mantell, 1975; Cheremisinof and Morressi, 1976; Chian et al., i977). The biological decay of the organic material which occurs results in the evolution of gases and liquids. Gas emission from landfills has been reported by various researchers (Mertz, 1964; Farquhar and Rovers, 1973; De Walle et al., 1978; McBean and Farquhar, !980; Tanasci, 1982; Baker and Mackey, 1985; AI Omar and Faiq, 1987; Briggs, 1987; Gardner et al., 1988, Gardner and Probert, 1989); They are very complex, but the main compounds are methane and carbon dioxide of about 50% and 40%, respectively.

202

m. LOIZIDOU AND E.G. KAPETANIOS

The qualitative and quantitative characteristics of the gas emission vary greatly from one landfill to the other, depending on many factors. These inelude the type of waste, landfill age and climatological co!lditions. It is not easy to predict emissions from a landfill but measurements have to be performed in order to provide more precise information ~,~ assess the envirc.~mental problems for the surrounding area. For this particular work a study was carried out for the ;~i;aseous emissions from a landfill in the Athens area. The aim is to evaluaV~i~'the extent of the environmental problem, by measuring a number of polluting compounds such as hydrogen sulphide, mercaptans, due to their unpleasant odour, sulphur dioxide, nitrogen dioxide, as well as some volatile organic compounds (VOCsL EXPERIMENTAL PROCEDURES Seven sampling sites were chosen as shown in Fig. 1; sites 1, 2 are in the landfill area itself and sites 3, 4 near the boundaries. The sampling sites 5, 6, 7, 8 were ,:hosen outside the landfill, -500 m away (southwest, south, northeast, southeast, respectively), towards the residential areas. The methods employed were semi-automatic: For the determination of methane air samples were taken using aluminium lined bags which were transferred to the lab and measured by gas chromatography ccupled with F.I.D. For H2S a known o uantity of air was passed through an alkaline suspension of' cadmium hyt~roxide and the collected sulphide was determined by spectrophotometric measurement of the methylene blue produced by the reaction of N,N-dimethyl-p-phenylenediamine ~ d ferric chloride. For the mercaptans, a measured volume of air was aspirated through an aqueous soiution of mercuric acetate, acetic acid. The collected mercaptans were subsequently determined by spectrophotometric measurement of the red complex produced with N,N-dimethyl-p-phenylenediame,~e and ferric chloride. . NO2 determination were performed using the Griess-Saltzman '~eaction, while the SO2 measurements were based on the pararozalinine method. Details for the determination of CH4, H2S, mercaptans, SO2 and NO2 are found in WHO (1976); Morris, (1978). The sampling period varied initially, depending on the pollutant concentration, but an average of 1"h was found to be adequate. For each sampling day, ---8 different measurements were taken. Tables 1-5 present the average of the hourly taken concentrations as well as the number of sampling days, which were in 1989 covering May, June and October. For the estimation of the volatile organic compounds (VOCs), samples

STUDY ON THE GASEOUS EMISSIONS FROM A LANDFILL

203

were collected for at least 48-h periods at each of the locations chosen (sites 1, 2, 3) by passing air through a collection trap containing Teaax ® adsorbent. The sample traps were thermally desorbed and measured by gas chromatography (Bozzelli and Kebbekus, 1982; Niren and Harry, 1986; Loizidou and Asimakopoulos, 1989). RESULTS AND DISCUSSION

The landfill site in the Greater ,Athens Area, is shown in Fig. 1. It has been in operation since 1972 and receives -- 3500 tons of refuse daily. The inr~in load originates from municipal refuse but also industrial wastes are disposed,

I

6

Fig. 1. Diagram of the Athens landfill and sampling sites for gas emission analysis.

204

M, LOIZIDOU AND E.G. KAPETANIOS

TABLE 1 Methane concentrations (mg/m 3) Sampling date

Sampling sites 1

20/05/89 24/05/89 29/05i89 30/05/89 06/06/~'9 13/06/89 19/06/89 21/06/89 23/06/89 30/06/89 14/10/89 20/10/89 23/10/89

2

180 200

210

110 800 600 200

3

200 850

40 12

1800

250 265 310 2800

4

6

7

8

0.8 0.6

0.8 1.0

4.5 7.5

0.8 1.0

4.5 1.0 1.1

1.1 1.0 0.8 0.8

0.3 5.2 1.2 0.9

1.3 1.1 0.8 0.6

5

6

7

8

0.02 N.D. 0.03 N.D.

N.D. N.D. N.D. N.D.

0.03 N.D. 0.01 N.D.

N.D. N.D. N.D. N.D.

15 3

60

30 25 110 33

5

5

25 18 1 5

TABLE 2 Hydrogen sulphide concentrations i mg/m 3) Sampling date

Sampling site~ 1

20/05/89 24/05/89 30/05/89 13/06/89 21/06/89 23/06/89 30/06/89 02/07/89 14/10/89 20/10/89 23/10/89 24/10/89 10/11/89 12/11/89 15/11/89

6.0 2.2

3.1 4.4 1.3 0.7 11.1 0.9 6.5 2.5 0.8

2

3.8 4.8

3.2 8.3 3.1 0.6 2.1 0.8 10.5 3.1 1.3

3

a

2.0 1.0

0.3 N.D.

0.8 2.0 0.8 0.2 0.2 N.D. i',~,9 0.08 0.1

0.08 0.07 N.D. 0.01 0.03 N.D. 0.05 0.01 N.D.

STUDY ON TPE GASEOUS EMISSIONS FROM A LANDFILL

205

TABLE 3 Mercaptafis concentrations (~g/m ~) Sampling date

Sampling sites i

12/05/89 29/05/89 30/05/89 13/06/89 14/06/89 10/10/89 20/10/89

'

1000

1100 400 300

2

800

900 1200 400

3

4

200

10

80 30 300

5

6

7

8

l0 N.D. N.D.

N.D. N.D. 21

30 N.D. N.D.

N.D. N.D. N.D.

30 N.D. 10

which are not characterised as dangerous and toxic. The landfill has no collection system for the gas produced which is emitted directty to the atmosphere, In the landfill area a significant number of people are engaged in various activities. Also, dwellings are not far from the landfill; the nearest one is < 2 k~, a¢':,ay and under certain meteorological conditions it is possible for the pollutants emitted to be transported to the residential areas (Lo~zidou et al., 1990). Complaints by the inhabitants of offending odours are quite frequent.

TABLE 4 Sulphur dioxide concentrations (/~g/m3) Sampling date

Sampling sites 1

22/05/89 05/06189 15/06/89 20/10/89 23/10/89 03/11/89 04/11/89 16112/89

70 200 600 420

2

600 350 500 420 600

3

280 410 390 220 130

4

5

6

I00 47

83 38

7

8

60 29

70 31

140 180 130 300 80

?

r

210

89

178

85

,

206

M. LOIZIDOU AND E.G. KAPETANIOS

TABLE 5

Nitrogen dioxide concentrations (ttg/m 3) Sampling date

15/06/89 20/10/89 03/11/89

Sampling sites

1

2

3

4

250 90 450

380 120 470

280 i50 90

190 80 170

This work concentrates mainly on the detection of a number of micropollutants which are emitted 1o the atmosphere together with methane and which are dangerous to human health due to their toxicity or unpleasant because of tl:~eir offending odour. Tables 1-6 show the concentrations of methane, hydrogen sulphide, mercaptans, sulphur dioxide, nitrogen dioxide, dichloromethane, dichloroethe, ne, trichloroethylene, tetrachloroethylene. The assessment of

TABLE 6

Concentrations of volatile organic compounds (VOCs) (/~g/m3) VOCs

Sampling date 10/10/89

01/12/89

15/12,89

C2Cl4

12.0 8.!0 4.5 17.0

15.7 2.5 16.7 21.2

3.9 3.5 12.5 19.2

7.5 0.5 3.8 3.2

Sampling site 2 CH2CI2 C2H4C!2 C2HCI3 C2C14

17.5 14.0 7.5 21.0

14.8 9.0 23.3 24.0

5.3 3.0 5.1 55.0

9.5 6.8 16.5 14.7

4.8 5.0 2.3 7.5

7.5 2.0 3.7 6.5

2.0 0.7 2.9 13.1

4. ~ 1.0 4.5 3.8

Sampling site 1 CH2C!2 C2H4CI2 C2HCI3

Sampling site 3 CH2CI2 C2H4C12 C2HCI3 C2CI4

!3/01/90

STUDY ON THE GASEOUS EMISSIONS FROM A LANDFILL

207

the experimental results is based on the guidelines for pollutants concentration in the atmosphere given by the World Health Organisation (1987) as well as the limits set by the Occupational Safety and Health Administration (OSHA, 1981) for the working environment. Methane (CHa) concentrations in the landfill sampling sites 1 and 2 (Fig. 1) are well above the OSHA limit of 50 ppm (33.5 mg/m 3) reaching the value of 2800 mg/m 3. It should be noted that t~e sampling positions were close to the wells for methane release. The sampling points 3 and 4 which are on the boundaries of the landfill give values which are sometimes above and sometimes below the OSHA limit. For the samples taken from locations 5, 6, 7 and 8, which are some distance from the landfill, the methane concentrations are very low. The World Health Organisation (WHO, 1987) suggest that the concentration of H2S should not exceed the limit of 70 t~g/m3 for an average exposure of 30 rain. According to these guidelines, the presence of H:S in the atmosphere, at the level of 15 mg/m 3 irritates the eyes and at 70 mg/m 3 can cause severe health damage. Allowing 100 as a safety factor, the H2S limit in the atmosphere, for a 24-h exposure is 0.15 mg/m 3. At this point it must be stressed that its unpleasant odour is aoticeable at very low concentrations of --8tLg/m3. The experimental results indicate that H2S is quite high for the sampling sites 1 and 2 in the landfill (Table 2), with a range of 0.8-11.1 mg/m 3. Sampling points 3 and 4 gave much lower concentrations, but still in most cases the levels were above the limit detectable by smell. For the sampiing sites 5, 6, 7 and 8, outside the landfill (Fig. 1), the presence H2S was low and in some ,~;ases below the detection limit of the experimental method used. It is clear that although the WHO guidelines are met, the odour problem cannot be overcome. A similar pattern is shown by the mercaptar~s, the landfill showing increased concentrations varying from 300-1200/~g/m 3, the boundaries showing much lower concentrations (10-300/~g/m3). The locations outside the landfill, show, in some cases, the presence of the mercaptans with concentrations above the odour limit of 4 t~g/m3, reaching value of 30 p.g/m3. The threshold limit value given by OSHA is 20 mg/m 3. The concentrations of sulphur dioxide (SO2) for the sites 1-4, range from 70 to 600 ~g/m3, while for the sites 5-8, the presence of SO2 is much lower, 31-178 tLg/m3; generally the Athens area has increased SO2 concentrations. For SO2 the WHO (1987) guidelines suggest that for the atmosphere the average value on a yearly basis should be 40-60 tLg/m3, with an upper limit of 100-150 v,g/m3 on a 24-h basis, while the OSHA suggest 2 ppm (5.3 rag/m3). From the literature (AI Omar and Faiq, 1987) an average value of 14 mg/m 3 is given for a landfill which, is much higher than the concentrations found in this work.

208

M. LOIZIDOU AND E.G. KAPETANIOS

Nitrogen dioxide (NO2) w a s found to be quite high in the sites 1-4, the range being 80-470 #g/m 3 Fc,r NO2, the WHO (1987) guidelines suggest that concentrations should range from 190 to 320 #g/m 3, while OSHA suggest 4.5 ppm (8.46 mg/m 3) as a limiting value. From published data (AI Omar and Faiq, 1987) much higher NO2 average values (19 mg/m ~') were given for a landfill.

Volatile organic" compounds (VOCs) The concentrations of dichloromethane (CH2C12) in sites 1, 2 and 3 have a range of 4.8-17.5 #g/m 3 (Table 6). For CH2C12 WHO suggest that the maximum permissible limit should be 3 #g/m 3 due to the carcinogenic action of this compound. From existing data (Rettenberger, 1988), much higher values are reported, the range being 54-84 mg/m 3 for a landfill in Germany, while for urban areas the range given is 1-10 #g/m 3 (Singh, 1981). It must be stressed that the quality of the refuse is responsible for these great variations. For 1,2-dichloroethane (C2H4C12) the concentrations are found to be between 0°5 and 14 t~g/m3. WHO suggest that the concentration of this compound in the atmosphere shguld not exceed the 700/zg!m 3 limit for a 24-h exposure. Existing information (LaRegina et al., 1986) on refuse and hazardous waste landfills give very low concentrations (0.04 and 2.5 #g/m 3, respectively); Rettenberger (1988) reports much higher concentrations for a landfill in Germany, 54-84 mg/m 3. The values for urban areas vary from 0.04 to 6.3 ~g/m 3 (LaRegina et al., 1986), while background concentration is - 0 . 2 ~g/m 3 (Singh, 1982). For trichloroethylene (C2HC13) the concentrations in the atmosphere at sampling sites 1, 2 and 3 had a range of 2.3-23.3 /~/m3. The WHO guidelines suggest that this compound should not exceed 1 mg/m 3. LaRegina et al., (1986) reports values up to 103 btg/m 3 and 6.6 #g/m 3 for hazardous waste and refuse landfills re,qpectively, while Rettenberger (1988) gives the ra,~ge of 0.1-46 mg/m 3. This great diversity is indicative of the behaviour t,l each landfill. The typical concentration in the cities ~tre reported to be in the range of 0.5-3 #g/m 3, while in industrial areas the levels are somewhat higher, the average level being 6 #g/m 3 with a highest of 50 #g/m 3 (Besemer, 1984; EPA, 1985). For tetrachloroethylene (C2HC14), the values obtained are quite low, the range being 3.2-55 #g/m a at the three samp!:ing sites (Table 6). The guidelines of WHO suggest that this pollutant should not exceed the li~:it of 5/~g/m 3. For hazardous waste landfills the maximum reported cop.ceatration is 57.6 tzg/m3 (LaRegina, 1986), while for refuse landfills the concentra-

STUDY ON THE GASEOUS EMISSIONS FROM A LANDFILL

209

tions range from 0.02-4 mg/m 3 (Rettenberger, 1988) and 44.3 #g/m 3 (LaRegina, 1986). For urban areas the concentration range is reported to be 1.9-2.9 #g/m 3 and for rural areas 0.27-1.4 #g/m 3 (LaRegina, 1986). Global background levels of tetrachloroethylene are around 0.2/zg/m 3 (EPA, 1985). CONCLUSIONS

The emissions from the landfill contain a variety of compounds, organic and inorganic, which in most cases are in high concentrations and above the limit set by International Organisations for ambient air quality. These compounds include methane, sulphur dioxide and nitrogen dioxide. The high concentrations found in the landfill itself decrease rapidly in the surrounding area, but still some substances are problematic. TLc pollutants, hydrogen sulphide and metcaptans, though detected in low concentrations outside the landfill area, they are present in the surrounding area above the odour limit, thus are unpleasant to neighbouring residents. The volatile organic compounds measured, are found in quite low concentration and their value is low compared with what is found in other landfills at an international level. This is expected because the landfill receives mainly domestic refuse. REFERENCES

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Gardner, N. and S.D. Probert, 1989. Combustible gas production from domestic municipal and industrial refuse deposited in landfill sites. Appl. Energy, 34: 21-34. Klein, S.A., 1972. Anaerobic digestion of solid wastes. Compost Sci., 11: 6. LaRegina, J:, W. Bozelli, R. Harkov and S. Gianti, 1986. Volatile organic compounds at hazardous waste sites and a sanitary landfill in N. Jersey. Environ. Progr. 5 (1): 18-27. Loizidou, M. and D.N. Asimakopoulos, 1989. Volatile organic compounds in the indoor en= vircnment. Technical report prepared for the Ministry of Health, Welfare and Social Security, Athens. Loizidou, M., D.N. Asimakopoulos, G. Kallos, D.P. Lallas and E.G. Kapetanios, 1990. Environmental impact assessment of the gaseous emissions of the Liosia landfill. Technical Report, Athens University. Mantell, L.C., 1975. Solid wastes: Origin, Collection, Processing and Disposal, John Wiley and Sons, N.Y. McBean, E.A. and G.J. Farquhar, 1980. An examination of temporal/spatial variations in landfill-generated methane gas. Water, Air Soil Pollut., 13: 157-172. Mer~z, R.C., 1964. Investigation to determine the quality and quantity of gases produced during refuse decomposition. Final report, California Water Quality Control Board, Uaiversity of Southern California, Report No. 99-10, L.A. Morris, K., 1978. Methods of air sampling and analysis. American Public Health Association, 1015 Eighteenth Str. N.W. Washington DC. 20036, APHA Intersociety Committee. Niren, L.N. and E.R. Harry, 1986. Guidelines for monitoring indoor air quality. EPA 600/$4-83-046. OSHA (Occupational Safety and Health Administration) (1981). Federal Register 40,23072. Rettenberger, G., 1988. Gaseous emissions from landfi~is. !SWA 88 Proc. of the 5th Inter. Solid Wastes Conf. Schafer, M. end H.J. Schroter, 1988. Adsorptive removal and recovery of halo~arbons from land fill gas. ISWA 88 Proc. of the 5th Inter. Solid wastes Conf. Shen, T.T. and T.L Tofflemiri, T.J., 1980. Air pollution aspects of land disposal of toxic wastes. J. Fnviron. Eng. Div. ASCE, 106(EEl), 211-226. Singh, H.B., 19$1. Measurement of sorae potentially hazardous organic chemical in urban environment. Atmos. Environ., 15: 601-612. Singh, H.B., 1982. Distribution of selected gaseous organic mutagens and suspect carcinogens in ambient air. Environ. Sci. Technol., 16: 872-880. Tanasci, B.S., 1982. Wastes management. J. Inst. Waste Manage., October" 500. WHO, 1976. Selected methods of measuring air pollutants. Geneva. WHO, 1987. Air quality guidelines for Europe, European Series, No. 23.