Saitama University, JAPAN 2 Center for Environmental Science in Saitama, Japan 3 University of Peradeniya

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1 Identification of Temporal Variability of Contamination in Perched Water and Groundwater at an Open Dumpsite in Sri Lanka, using Leachate Pollution Index (LPI) Udayagee Kumarasinghe 1, Y.Inoue 1, T. Saito 1, M.Nagamori 2, M.I.M. Mowjood 3, Ken Kawamoto 1,4 1 Graduate School of Science and Engineering Saitama University, JAPAN 2 Center for Environmental Science in Saitama, Japan 3 University of Peradeniya Peradeniya, SRI LANKA 4 International Institute for Resilient Society Saitama University, JAPAN kawamoto@mail.saitama-u.ac.jp Abstract: Open dumping of municipal solid waste is a common practice in Sri Lanka. The leachate produced from these dumpsites indiscriminately pollutes the surface water and groundwater. Mitigation of the risk through implementation of treatment systems requires information on the leachate quality and its variability over the time. In this study, an open dumpsite was selected from wet zone of the Sri Lanka and its perched waterinside waste layer and groundwater quality was monitored for one year (May 213 to April 214) and leachate pollution index (LPI) was used to quantify and compare the leachate contamination potential of the particular dumpsite. Dumpsite is located near to right bank of MahaweliRiver, in UdapalathaPradeshiyaSabhaCentral Province of Sri Lanka. This site has been running for about 7 years and abandoned in 211. Dump site has two sections, old and new with the age of 7 and.5 years, respectively. Two types of boreholes, groundwater borehole (BH) and perched water borehole(pbh) were made by rotary boring.the perched water and groundwater samples were collected with one month interval and samples were analyzed for 14 parameters under three different categories. Overall and sub-indices of LPI was calculated to observe temporal variability of risk of groundwater contamination. Both groundwater samples (BH and BH6) showed constant and low LPI values except for the initial stage of the monitoring and those constant values were similar to those for the control (BH8).Similar behavior was observed in perched water collected from old section of the dumpsite, in contrast, new section showed a little increase of the LPI over the time.perched water had an increasing trend of LPI with respective to the inorganic contaminants. There is no considerable different observed, in perched water and groundwater, with respect to the presence of heavy metals.reduction of LPI exhibitedthe PBH3 in old section may be due to high dissolution of the pollutants over the time. No correlation was observed between LPI and amount of rainfall received over the time. This variability should be taken into consideration in design and development of mitigation measures for the impact of open dumpsite. Key words: Open solids waste dumps, perched water, groundwater, contamination, leachate pollution index (LPI). 1. INTRODUCTION Uncontrolled landfills are places where solid wastes are disposed openly. Most commonly, riverbanks swamp/marshy lands are used for uncontrolled land filling by many municipalities. Even though the uncontrolled landfills require least development and operational costs, it is a threat to both social and environment in developing countries (Maheeset al., 211). Among many other factors, the most severe problem is caused by the leachate generated at the open dumpsites. Leachate is coming out from the wastes layers at waste decomposition, and it is consist with high concentrated salts as well as dissolved organic matter, trace metals, xenobiotic compounds (Koh, et al., 24). Since the open dumpsites are lack with leachate trapping mechanisms and liner systems, there is a risk of groundwater and surface water contamination by leachate. The leachate quality is greatly varies from dumpsite to dumpsite, and even at the same dumpsite with the time. The quality of leachate depends on many factors such as type of dumped wastes, 126

2 management practices before and after dumping, climatic factors, age of the dumpsite etc. The level of contamination is directly depends on the severity of leachate quality and the resulted risk can be minimize by applying field scale treatment mechanisms such as permeable reactive barriers. In order to dothat, the leachate should be well characterized and their seasonal variations should be properly observed. The Leachate Pollution Index (LPI)can be used for risk assessment due leachate contamination. LPI is a tool used to quantify the leachate contamination potential quantitatively and comparatively(kumar and Alappat, 25a).Sub-indices of LPI describe the dominating pollutants presence in the leachate and the impact from each pollutant type (Kumar and Alappat, 25b). Analysis of leachate pollution potential of a particular landfill is important to characterize leachate into different groups with the temporal and spatial variations. Sewwandiet al., (213) found that there is a huge variation of the LPI calculated for different dumpsites located in Sri Lanka. Further, in her study she prioritized the target pollutants that should be treated at the first. Thus the development of LPI is important prior to implementation of leachate treatment mechanisms and prediction of groundwater pollution. In addition LPI gives good indication of the pollution potential of different landfills in comparative analysis. This study is focused on development of LPI and assesses their temporal variability of a particular dumpsite in Sri Lanka. 2. MATERIALS AND METHODS 2.1 Site selection An uncontrolled open dumpsite was selected from Gampola Local Authority, Kandy district, Central Province, Sri Lanka( N and E).The lower boundary of the dumpsite is right bank of Mahaweli River and the upper is boundary is Public road.the dumpsite has two sections with respect to the age of usage,referredas new and old sections. Both new and old sections have been abandoned in year 211. The old section has been used for 7 years and new section used for.5 years for waste dumping. The waste dumping rate was approximately, 15-2 t/day. Figure 1 shows the location of the dumpsite and Figure 2 shows the dumpsite at the operation. Figure 1 The location of the dumpsite 127

3 Figure 2 Dumpsite at the operation in year Installation of monitoring wells Groundwater monitoring wells (BHs) were made using rotary boring up to the bedrock through buried waste and soil profile. Perched water monitoring wells (PBHs) inside waste layers were installed up to the original soil surface, (bottom of the waste layer) at the same transects in old and new sections. Thelocations of boreholesareshown in Figure. 3.In addition, the borehole (BH8) is installedas a control groundwater monitoring well without intrusion of contamination from the dumped waste at the site. Figure 3 Location of the leachate and groundwater monitoring boreholes at the site 2.3 Sample collection and analysis Water quality was monitored from May 213 to April 214 with one month interval. Groundwater and perched water samples were collected from both new and old sections from well BH2, PBH1 and BH6, PBH3, respectively. In addition groundwater samples were collected from BH8 also. Samples were collected into clean 1 L polypropylene bottles, preserved, stored and analyzed with standard operational procedures and analyzed for mainly three groups as organic parameters, inorganic parameters (anions and cations) and heavy metals. Laboratory analyses were done at the New Environmental Laboratory, Faculty of Engineering, University of Peradeniya, Sri Lanka and Saitama University, Japan. The analytical techniques used for the each parameter aregiven at Table

4 Table 1 Analytical technique used to measure each parameter Organic pollutants Inorganic pollutants Heavy metals Parameter Instrument Chemical Oxygen Demand (COD) HACH spectrophotometer Biological Oxygen Demand (BOD) DO meter,ad63 Adwa ph ph meter HACH Total Dissolved Solids (TDS) EC meter HACH, and conversion factor (.5) Total Nitrogen (TN) Total Organic Carbon Analyzer-LCSH/TNM-L Shimadzu Corporation Total Ammonium Nitrogen (NH + 4 -N) HACH spectrophotometer Chloride ion(cl - High Performance Liquid Chromatography, CMB- ) 2A Shimadzu corporation Fe, Cu, Zn, Pb, Ni Atomic Absorption spectrophotometer -7 Shimadzu Corporation, Japan As, Cr Inductively coupled plasma mass spectrometry, ICPM-85, Shimadzu, Japan 2.4 Collection of meteorological data Rainfalldata were collected from closer Evalgolla rain - gauge station. 2.5 Leachate characterization for leachate pollution index (LPI) Temporal variability of leachate and groundwater quality was analyzed according to sub-indices of leachate pollution index (LPI) and the overall LPI. Sub-indices of LPI consist of three main factors LPI inorganic (LP in ), LPI organic (LPI or ) and LPI heavy metals (LPI hm ). Each sub index was calculated by Eq. [1] (Kumar and Alappat, 25a) and the overall LPI was calculated using Eq. [2] (Sewwandi et al., 213). Even though, initially LPI has been developed with 18 parameters LPI can be calculated with lesser number of parameters by using Eq. [1]. In this study, 14 parameters were used for the analysis as showed in table 1. LPI = n i=1 n i=1 W i W ip i Eq. [1] LPI overall =.232 LPI or LPI in LPI hm Eq. [2] Where LPI is the leachate pollution index, w i is the weight for the i th pollutant variable, p i is the sub index score of the i th pollutant variable and n is the number of leachate pollutant variables used in calculating LPI. 3. RESULTS AND DISCUSSION 3.1 Characterization leachate with LPI Sub-indices of LPI and overall LPI calculated for a perched water monitoring well (PBH1), for the first month of monitoring (April 213) are shown in Table 2. Likewise, overall LPI and sub-indices were calculated for all other wells for each monitoring. 129

5 Index Table 2 Sub-indices and overall LPI calculated for PBH1 for April 213 Parameter Pollutant concentration (mg/l) Sub-index value (P i ) Weight factor (w i ) W i P i LPI org BOD COD LPI in ph TDS 1.24* TN NH4 + -N Cl LPI hm Total Fe Cu Zn Pb Ni As Cr LPI overall =.232 LPI or LPI in LPI hm 6.66 The temporal variability of LPI are shown in figure 4 (a), (b), (c),(d) and (e)for PBH1, PBH3, BH2, BH6and BH8,respectively. Temporal variability and monthly rainfall were also compared in the same figures. A rapid increase of LPI in was observed in perched water collected from new section. The organic pollutant levels also showed an increase. The pollution potential from heavy metal was not showed a significant different from leachate and groundwater. Both groundwater samples (BH2 and BH6) showed a reducing trend of leachate pollution indices at the beginning and become stable. Perched water monitoring well at the old section of the dumpsite (PBH3), also showed the similar trend but it was not observed in leachate monitoring well located in the new section (PBH2). No temporal variability was observed in any LPI indices calculated for the groundwater monitoring well located at the out of the dumpsite (BH8). 13

6 5 5 LPI (a) PBH1 (Perched water at New-section) (b) PBH3 (Perched water at Old-section) 5 5 LPI (c) BH2 (Groundwater at New-section) 5 4 LPI (d) BH6 (Groundwater at Old-section) (e) BH8 (Control) Figure 4 Temporal variations of LPI indices and rainfall Figure 5 shows the comparative illustration of the temporal variability of LPI overall in monitoring wells. As shown LPI overall calculated for the groundwater monitoring wells,(bh2 and BH6) showed constant and low LPI values except for the initial stage of monitoring and those constant values were similar to those for the control (BH8). The slightly higher LPI values observed at BH2 and BH6 at the initial stage of monitoring might be caused by physical disturbance from installing monitoring wells. Even though LPI overall at the PBH3 shows slight difference from the BH8, it is greatly varied at the PBH1.Reduction 131

7 of LPI exhibited PBH3 in old section may be due to the complete dissolution of the pollutants over the time. Dumpsite requires close attention on inorganic ion removal when installing leachate treatment system, especially for the leachate collected from the new section. Since the threat of heavy metal contamination is similar at the both section for perched water and groundwater it can be used the same heavy metal removal techniques. Mar 214 Feb 214 Apr 214 May Jun 213 Jun 213 Jul 213 BH2 BH6 PBH1 PBH3 BH8 Dec 213 Oct 213 Sep 213 Aug 213 Jul 213 Figure 5 Temporal variations of LPI overall There was no significant relationship betweenlpi overall and the monthly precipitation. Since the dumpsite is located in the wet zone of the country, and there are no clear climatic seasons presence in temperate countries, the quality of leachate may not be severally depend on the amount of rainfall received. In addition, leachate generation process takes required several days; quality of leachate cannot be interpreted with the monthly rainfall. 4. CONCLUSIONS There is a risk of groundwater contamination by the generated leachate at the particular dumpsite, since the heavy metals and other contaminants presence in the groundwater and leachate. Risk of groundwater contamination is reduced with the time, and the sub-indices and overall leachate pollution indices are reduced. Leachate generated at the new section of dumpsite showed increment of the leachate pollution index especially with respect to the inorganic ions. Reduction of LPI exhibitedthe PBH3 in old section may be due to the fully dissolution of the pollutants over the time. No correlation was observed within LPI and amount of precipitation. This may be due to the site located at wet zone in Sri Lanka where no significant different seasons found.it would be necessary to compare LPI overall with the daily precipitation. LPI is an effective tool, that can be used to analyze leachate in qualitatively rather using raw data. LPI categorize the leachate according to the severity of pollution level, so selection of specific treatment mechanism to the particular group is simple. ACKNOWLEDGEMENT This study was funded by the SATREPS Project of the Japanese International cooperation Agency (JICA) and Japan Science and Technology agency (JST).The study was supported by Mr. N.T.B. Madhusanka, Mr. YohanJayawardhane, Mr. IshankaWimalaweera and Ms. WageeshaPremarathne. 132

8 REFERENCES Koh, I., Chen-Hamacher X, Hicke K, Thiemann W. (24).Leachate treatment by the combination of photochemical oxidation with biological process.journal of Photochemistry, Photobiology Chemistry, 162: Kumar D. and Alappat B. (25a).Evaluating leachate contamination potential of landfill sites using leachate pollution index. Clean Technologies and Environmental Policy. vol. 7, n. 3, Kumar D. and Alappat B. J. (25b).Analysis of leachate pollution index and formulation of subleachate pollution indices. Waste Manage. Res., vol. 22, Mahees, M.T.M, C. Sivayoganathan, B.F.A. Basnayaka. (211). Consumption, Solid Waste Generation and Water Pollution in PingaOya Catchment area, Tropical Agricultural Research 22 (3): Sewwandi, B.G.N., K. Takahiro, K. Kawamoto, S. Hamamoto, S. Asamoto and H. Sato.(213). Evaluation of leachate contamination potential of municipal solid waste dumpsites in Sri Lanka using leachate pollution index.sardinia, 14 th international waste management and landfill symposium, Forte village resort, Italy, 3th October 4 th September