Monitoring Programme Of The Restored Landfill Site At Schisto In Attica – Pireus Region

ENVIRONMENTAL MONITORING PROGRAMME OF THE RESTORED LANDFILL SITE AT SCHISTO IN ATTICA – PIREUS REGION. INTRODUCTION OF A MODERN LEACHATE TOXICITY ANALYSIS TECHNIQUE USING BIOASSAYS

Th. Lolos, G. Lolos, C Tsombanidis, K. Oikonomou, K. Raptis, G. Tavoularis

Εnviroplan S.A., 40 Ag. Konstantinou Str 15124 Marousi, Greece, http:// www.enviroplan.gr

ABSTRACT Environmental monitoring of Solid Waste Management Facilities and especially of Closed and/or (Un)controlled Solid Disposal Sites is conducted in many countries and has as target to ensure Public Health as well to avoid any kind of environmental pollution. In the present work, certain parameters are presented that were examined during the environmental monitoring of the old restored Solid Waste Disposal Site of Schisto. In particular, the main components of this work are focused on the following points: i) the chemical composition of leachates that are produced ii) checking of the degree of pollution in the underground and surface waters due to leachates iii) analysis of the quality of landfill biogas produced. Also, with the use of suitable toxicity tests the potential toxicity of both ground /surface waters and leachates has been evaluated.

KEYWORDS: Environmental monitoring; Toxicity; Leachate; Ground water; surface water; biogas 1. Introduction The subject of environmental monitoring is obligatory in the European Union according to the Directive 1999/31/EC "Sanitary Landfill of Waste", but also according to the Greek Legislation, Law 114218/97 "Framework of specifications and programs for general solid waste management" as well as Law 29407/3508/2002 "Measurements and terms for Sanitary Landfill of waste". The environmental monitoring program of the restored landfill site at Schisto includes the control of all parameters that are likely to cause environmental pollution and endanger Public Health (mainly leachate and biogas). In addition the programme also checked all environmental factors that could be influenced from the restored landfill site (mainly surface water, ground water and atmosphere), 1

as well as other parameters that concern the functional and long-term safety behavior (meteorological data, settlings, etc.). 2. General Information Waste disposal from the broad Piraeus Region until 1991 took place in the landfill site of Schisto. This landfill had operated for almost 25 years covering an area of 416.400 m2, while the waste deposited amounts to 8.176.000 tones. Until 1978 both municipal and industrial solid wastes were disposed in Schisto, followed by municipal solid waste only, until its operation was stopped in 1991. Moreover, Schisto operated without an appropriate impermeable bottom liner or an effective gas/liquid collection and treatment system for almost 25 years. From 1991 various restoration works have been executed at the site, i.e. final capping of the site, leachate / biogas management and other infrastructure works (operating facilities, environmental monitoring works, etc). In particular, two artificial lagoons for leachate collection were constructed, as well as the pipeline and the wastewater treatment plant (activated sludge method followed by artificial wetland). Moreover, biogas management works comprises of the Landfill fuel gas (LFG) extraction system consisting of 140 vertical wells, an LFG transport network leading to 23 sub-stations and then to 5 central stations, and a gas flare capable of processing 1.400Nm3/h. Monitoring works include 9 wells for off-site migration of biogas detection, 3 groundwater-monitoring wells and 50 marker posts to evaluate waste movements. The site of Schisto is now in the aftercare –maintenance period according to the requirements of 99/31 Directive. Regulations governing the disposal of solid waste in landfills specify that they must be monitored until the emission potential is so low, that do not harm the environment. The monitoring and aftercare program comprises the analysis of raw/ treated leachate quality, ground and surface water monitoring, inspection of the final cover and maintenance as required, and monitoring for any methane off-site migration. 3. METHODOLOGY The methodology that was followed in the present work is the following: CHEMICAL ANALYSIS The composition of leachates, surface and ground water was examined with scheduled (monthly) samplings in representative points in the site, during the period 01/06/2003 - 31/08/2004. Leachate samples are taken from the artificial lagoons, while samples of ground water were taken from the existing wells. Finally, 4 sampling points were used for the collection of surface water. 2

The examined parameters for the determination of chemical composition according to the environmental terms requirements were: (a) physical parameters: pH, temperature, conductivity, turbidity, total solids, suspended solids, dissolved solids (b) organic parameters: dissolved oxygen, biochemical oxygen demand (BOD5), chemical oxygen demand (COD), total organic carbon (TOC), organic nitrogen (c) chemical parameters: ammonium, nitrous, nitric ions, phosphorus, chlorides, fluorine, phenols, arsenic, cadmium, copper, lead, mercury, nickel, zinc, cobalt. The methods of analysis were based on the Standard Methods for the Examination of Water and Wastewater by APHA, AWWA, WEF. Sampling is consistent with ISO 5667-11 and 5667-2 methods. TOXICITY TESTS Leachates arising from waste disposal sites contain toxic substances. Chemical analysis can detect only a small percentage of the total chemical substances, while it cannot take into account their synergistic action [2,7]. On the contrary, toxicity tests assess toxicity typically not detected with chemical analysis, since they take into account all additive effects from the various compounds to a living species. Therefore, these tests are considered particularly valuable as far as environmental samples are concerned. In most toxicity tests, toxicity is reported as LC50 or EC50, meaning the lethal or effective concentration that affects 50% of the population. The smaller the indicator LC50 or EC50 is, the more toxic is the sample, since lower concentration of the toxic sample is required in order to have a 50% effect to the associated population. For the evaluation of the relevant samples reported above, Daphnia magna species was used. The Daphnia magna belongs to shellfishes and is on top of the food chain (consumers). It regards a widespread species for toxicity tests, and it is certified test according to OECD 202. Toxicity is determined after counting the number of dead organisms in the sample after keeping the samples for 24 and 48 hours in constant temperature and absence of light. BIOGAS MEASUREMENTS Determination of biogas qualitative characteristics was carried out with a gas portable instrument (GA 94 Geotechnical Instruments) measuring CH4, CO2, O2, N2, H2S, CO, HCN , H2, SO2, NO2, and Cl2 in biogas collection and control sub and central stations. For evaluating the presence of air pollutants in the boundary of the site, arising from any biogas losses, gas wells have been manufactured, in order to sample and analyze the biogas.

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4. RESULTS LEACHATE Leachate characteristics from lagoons A and B is presented in the following table. Table 1: Monitoring Leachate Quality MEAN VALUE PARAMETER Temperature pH O.R.P. Conductivity (250C) Turbidity Total Solid Dissolve Solids Suspended Solids D.Ο. BOD5 COD TOC Kjeldahl-N ΝΗ4+ ΝΟ2T.P. T.P. PO43ClSO42FPhenol CNAs Cd Cu Cr Pb Hg Ni Zn Co

UNIT °C V μS/cm NTU mg/l mg/l mg/l mg /l mg /l mg /l mg C/l mg /l mg /l mg /l mg /l mg /l mg /l mg /l mg /l mg /l mg /l mg /l μg /l μg /l mg /l μg /l μg /l μg /l μg /l mg/l μg /l

Sample Α

Sample B

19,4 8,80 0,04 10.860 n.d. 6.114 6.039 75 0,75 95,73 1.603 297,1 14,73 370,6 <0,03 <0,4 16,83 41,44 2.239 54,33 0,08 0,28 <0,002 <0,5 6,04 129,73

21 8,84 0,03 10.434 n.d. 5.772 5.709 63 0,73 105,07 1.612 295,8 14,73 367,1 <0,03 <0,4 17,94 44,23 2.421 54,13 0,11 0,35 <0,002 <0,5 5,81 141,17

557,33 216,9 1,27 144 0,22 25,31

521,87 255,2 1,18 166,2 0,17 27,21

* Not detected

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pH values were found to be alkaline (8,80-8,84) which mainly can be considered a characteristic of the anaerobic phase. Leachate samples had a variable organic load, which contribute to a high COD value, but with BOD5 values less than 105mg/l, indicating an advance state of degradation. Moreover, the changes in leachate biodegrability are mainly reflected by BOD5/ COD. The BOD5/ COD ratio varying from 0,06 to 0,07. This fact suggest that the biochemical activity in the landfill body is in its final stage and the organic load is biologically stabilized. The NH4 concentration reaches the values between 367,1 to 370,6mg/l. Conversely, the concentration of nitrates was found to be rather low due to the stabilization process [5]. The relatively high concentrations of chloride remain constant with time, contrary to similar studies that show increasing chloride concentration with leachate age. This was explained by the fact that chlorides are not influenced by biochemical actions and accumulate inside the disposal site [4]. Finally, due to the alkaline pH a reduction of solubility can be observed. This results in low concentrations of heavy metals, which can be further explained by the formation of non-dissolvable sulphides from the reduction reactions. GROUNDWATER The uncontrolled disposal site of Schisto is currently under restoration and is located above burst and karst limestone. Initially, no bottom lining was incorporated, which is necessary in order to protect from leachate pollution. In the following tables, the average value of various characteristics is presented per sampling place. The pH of groundwater is neutral (7,05-7,67). The presence of nitrogen compounds suggests pollution of organic origin. Also, samples from wells have ammonium concentration higher than 0,5 mg/l, which is the maximum permissible value of potable water in EU. The BOD5 constitutes an important parameter that can be used to make statements about the organic load in water, whereas COD determines almost all organic compounds present. BOD5 expresses the quantity of oxygen consumed by bacteria during the first 5 days for the decomposition of organic pollutants. The concentration of BOD5 for the water samples does not exceed 40 mg/l, that is the maximum value for irrigation water according to the Ministry of Agriculture. COD ranges from 30,8-254,5 mg/l, and W3 having the highest COD value. An oily supernatant phase was recognized in the W3 samples, the presence of which was not resulted from the operation of the uncontrolled site (possibly an accidental spill).

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Chloride concentration ranges from 36-684,67 mg/l. These relatively high concentrations can possibly be attributed not only to leachate effects, since the possibility of sea penetration to groundwater cannot be excluded. Table 2: Monitoring Groundwater Quality MEAN VALUE PARAMETER

UNIT W1

W2

W3

18,31

20,7

19,03

7,05

7,27

7,67

0,35

-0,043

0,09

Conductivity (25 C) μS/cm 3.327

659,2

2.159

Turbidity

NTU

17,04

12,98

21,35

Total Solid

mg/l

2.531

422

1.531

Dissolve Solids

mg/l

2.446

412

1.481

Suspended Solids

mg/l

85

10

50

D.Ο.

mg /l

1,64

2,46

0,99

BOD5

mg /l

18,51

1,89

9,99

COD

mg /l

103,01

30,8

254,5

TOC

mg C/l 20,33

3,6

n.d.*

Kjeldahl-N

mg /l

0,56

0,1

0,51

ΝΗ4+

mg /l

2,28

0,6

6,31

ΝΟ2-

mg /l

2,20

0,12

3,21

ΝΟ3-

mg /l

252,27

4,55

12,65

Τ-Ρ

mg /l

0,02

0,035

0,03

mg /l

0,07

0,068

0,06

Cl-

mg /l

684

36

340

SO42-

mg /l

405

47,2

415,2

F-

mg /l

<0,025

<0,025

0,05

CN-

mg /l

<0,002

<0,002

<0,002

As

μg /l

<0,5

<0,5

<0,5

Cd

μg /l

0,43

16

0,52

Cu

mg /l

3,34

1,5

1,26

Cr

μg /l

13,19

1,54

<0,6

Temperature

°C

pH O.R.P.

V 0

PO4

3-

6

Pb

μg /l

<0,5

0,54

1,13

Hg

μg /l

<0,04

<0,04

0,80

Ni

μg /l

<0,6

1,15

<0,6

Zn

mg /l

25,85

0,17

0,07

Co

μg /l

0,72

<0,4

<0,4

* Not detected

SURFACE WATER Samples from surface water (rain) were taken from four different points collected in suitable bottles. The surface water pH is slight alkaline (7,86-7,99), whereas the conductivity is particularly low (725-301 mS / cm). The BOD5 value in the samples ranges from 8,1-65,5 mgO2 / l. Also, the content in ammonia and nitric ions ranges between 0,07-1,4 mg / l and 1,2-1,8 mg / l respectively. The overall concentrations implies that no mixing of rain water with leachate takes place. BIOTESTS Because of the unknown toxicity of the samples under examination, a preliminary test was done, so as to find the toxicity level (range finding test), consisting of 5 dilutions with four repetitions per dilution. After asserting toxicity levels for the samples, subsequent final testing (definitive test) followed, from which the EC50 indicator was derived. Statistical processing of results proceeded with the help of PC statistical program SPSS (probit analysis). Table 3: EC50 & NOEC Toxicity Testing 24h & 48h Sample leachate W1 W2 W3

Test 24h EC50 (ml/l) NOEC (ml/l) 156 264

60 125 125 <125

Test 48h EC50 (ml/l) NOEC (ml/l) 151 454 656 <125

60 <125 <125 <125

As expected, leachate sample is the most toxic. Leachate toxicity is a function of mainly ammonia, alkalinity and COD content [8]. In particular, ammonia directly affects Daphnia species, while alkalinity rises ammonia toxicity [6]. Another author relates toxicity to chloride, ammonia and hardness content [1]. In similar studies, the important role of zinc and organic compounds to the toxicity of Daphnia species is documented.

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As far as ground water is concerned, the greatest toxicity is posed by W3, while no toxicity was observed for the W1 and W2 samples, 24h test. Toxicity however was present for the 48 h tests. Finally, no toxicity was observed in any of the rain water samples, therefore these are characterized as non toxic. BIOGAS Production of gas (biogas) is one main phenomenon that takes place in Landfill Sites due to aerobic or anaerobic processes. During aerobic digestion of organic compounds CO2, water and energy is produced. This is promoted mainly by air intrusion to the waste top layer and air already present. Fermentation in anaerobic conditions takes place in four stages: initially the undissolved compounds are hydrolysed. In the second stage organic matter is degraded to intermediate products such as organic acids, alcohols, CO2, H2 or H2O. In the third stage alcohols and fatty acids are further degraded to acetic acid, H2 and CO2 and finally CH4, CO2, H2S, H2 is produced. Figure 1: Main components of biogas composition (mean values) 60 50 40 30 20 10 0

A

B

C1

C2

D

CH4

55,0

40,2

32,0

41,8

26,9

CO2

40,1

32,4

34,5

36,8

20,8

O2

1,7

10,8

2,7

4,8

13,5

N2

3,2

16,6

30,8

16,6

38,8

Figure 2: Secondary components of biogas composition (mean values) 70,0 60,0 50,0 40,0 30,0 20,0 10,0 0,0

A

B

C1

C2

D

H2S

6,4

4,3

19,7

2,3

0,3

CO

15,7

2,4

4,0

1,1

6,4

H2

65,6

0,3

8,7

11,6

50,1

HCN

51,4

8,1

63,9

4,4

1,3

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5. CONCLUSIONS Leachate originating from the restored, uncontrolled disposal site at Schisto contain a high amount of organic load, mainly not biodegradable. At the same time, the inorganic load (consisting to a large degree of chloride and ammonium) was also measured to be high.. The accumulative and additive effect of the pollutants was evaluated with the use of biotests. Leachate presents a high toxicity, as expected. Biogas consists of methane and carbon dioxide in high concentrations and nitrogen, oxygen, hydrogen sulfide, CO, hydrogen, cyanides to a lesser extent. Other gases were not detected. Biogas with fraction of methane higher than 40% could be pumped from about 60% of the wells. Finally, no biogas escapes could be detected in the surroundings of the site. 6. BIBLIOGRAPHY 1. Assmuth, T., Penttilae, S. (1995). ‘’Characteristics, Determinants and Interpretations of acute Lethality in Daphnids exposed to complex waste leachates Aquatic Toxicology 31:124141. 2. Baun, Anders, Jensen, Susan D., Bjerg, Poul L., Christensen, Thomas H., Nyholm, Niels. (1998). Toxicity of Organic Chemical Pollution in Groundwater Downgradient of a Landfill (Grindested, Denmark). Dissertation, Technical University of Denmark. 3. Chian, E.S.K., DeWalle, F.B.,1976. Sanitary landfill leachates and their treatment. J. Environ. Eng. Div.(Proc. Am. Soc. Civil Eng.) 102 (EE2), 411-431. 4. Chu, L.M., Cheung, K.C., Wong, M.H., 1994.Variations in the chemical properties of ladfill leachate. Environ. Manage. 18 (1), 105-117. 5. Clement, B., 1995. Physico-chemical characterization of 25 French landfill leachates. Proceedings of Sardinia 95, 5th International Landfill Symposium, CISA, Cagliari (Italy), 315-325. 6. Clement, B., Janssen, C., Le Du-Delepierre, A. (1996) Estimation of the hazard of Landfills through toxicity testing leachates : 2 Comparison of phisio-chemical characteristics of landfill leachates with their toxicity determined with a battery of tests Chemosphere 35: 2783-2796 7. Galassi, S., Battaglia, C., Vigano, L. (1988) A Toxicological Approach for Detecting Organic Micropollutants in Environmental Samples. Chemosphere 17: 783-787. 8. Lambolez, L., Vasseur, P.,Ferard, J.F., Gibert, T., (1994). The environmental risks of industrial waste disposal : An experimental approach including Acute and Chronic Toxicity studies. Ecotoxicology and Environmental Safety, 28:317-328 9