Introduction: Evaluating the characteristics of landfill leachate is essential for understanding groundwater quality. Each landfill is unique, influenced by the type of waste deposited, the surrounding environmental conditions, and its design and management. The physicochemical properties of landfill leachate indicate the potential risk it poses to groundwater and soil, which in turn can impact the environment and public health. Landfilling—disposing of solid waste indiscriminately in open low-lying areas—is one of the major sources of environmental pollution and presents a significant threat to communities living nearby.
Materials and Methods
Study Area
The landfill studied is located in Nagaram village, Nizamabad City, covering an area of 55 acres. The site receives various types of solid waste, including domestic, municipal, industrial, agricultural, hospital, and construction and demolition waste. Additionally, it collects waste from nearby vegetable and non-vegetable markets, as well as slaughterhouses. Nagaram village hosts residents from diverse income groups and contains several industries, temples, and hospitals.
Sampling and analysis of landfill leachate
Landfill leachate varied significantly with space, time, design and development of dumpsite. Samples were collected and analyzed in the dry season and wet season of the annual cycle. Since the landfill site was not equipped with a leachate collection system the leachate samples were collected at the base of the landfill randomly from 5 different locations further that were mixed before sending for analysis. After the sampling, the samples were immediately transferred to lab Stored at 40 C. The analysis was started without delay based on the priority to analyze parameters, as prescribed by the standard methods APHA (1994) The physicochemical parameters examined includes pH, electrical conductivity (EC), total dissolved solids (TDS), total dissolved volatile solids (TDVS), fixed dissolved solids (FDS), chemical oxygen demand (COD), biological oxygen demand (BOD), sodium (Na+), potassium (K+), ammonia (NH+4), nitrate (NO3−). EC and pH were recorded using a Systronics conductivity meter, mode 306 and μ pH system 361(Systronics) respectively. TDVS and FDS were estimated by using the oven-drying method. The estimation of COD was done by reflux titrimetry, while BOD was calculated by oxygen determination by Winkler titration. Na+ and K+ by flame photometry (Systronic-128), while NH+4, NO3− were determined by using Perkin-Elmer UV/VIS Lambda 2 spectrophotometer. The concentrations of chromium (Cr), copper (Cu), nickel (Ni) and lead (Pb) were determined by using an atomic absorption spectrometer (AAS).
All the experiments were carried out in triplicate and the results were found reproducible within ± 3% error. The data were statistically analyzed by setting up and calculating a correlation matrix for the various parameters using the Statistical Package for Social Sciences (SPSS) software package.
Results
Landfill leachate samples were collected at the dumpsite of Nagaram. The sampling was done for complete two seasons of the annual cycle, i.e. dry season January to May and wet season June to December.
Table 1: Characteristics of Landfill leachate in dry and wet seasons
| Parameters | Nagaram | Standards at SW Disposal | |
| S1 (dry) | S2 (wet) | ||
| Temp (°C) | 28.9 | 18.7 | – |
| pH | 4.26 | 4.94 | 5.5-9.0 |
| TDS | 27458 | 27469 | 2100 |
| BOD | 18547 | 20478 | 100 |
| COD | 23580 | 20569 | 300 |
| NH4 – N | 1958 | 2134 | 50 |
| EC | 22351 | 24781 | 1000 |
| TH | 1685 | 1988 | 250 |
| TA | 5698 | 5974 | – |
| Total Fe | 58.97 | 51.42 | – |
| Cd | 0.054 | 0.047 | 3.0 |
| Cr | 0.29 | 0.23 | 3.0 |
| Zn | 2.36 | 1.92 | 5.0 |
| Pb | 1.57 | 1.44 | 0.1 |
| Cu | 0.71 | 0.69 | – |
| Ni | 0.19 | 0.25 | – |
| Cl– | 2147 | 2596 | 600 |
| F– | 659 | 526 | – |
| Na+ | 489 | 587 | – |
| K+ | 1243 | 1345 | – |
| Ca+2 | 824 | 823 | – |
| Mg+2 | 214 | 263 | – |
| SO42- | 428 | 517 | – |
| NO3– | 289 | 241 | – |
| NO2– | 69 | 52 | – |
| Phenols | 0.041 | 0.035 | – |
| Silicon (Si) | 210 | 184 | – |
Leachate Pollution Index:
LPI values indicate the contamination potential due to leachate produced from the landfill sites in the particular areas and act as an important tool for identifying and measuring the hazards caused due to percolation of the leachate in soil strata as well in aquifers. The characteristics of leachate changes over time, the LPI value will also differ. Hence, the LPI value would correspond to the leachate samples analyzed at a particular time for a specific landfill site. The LPI is calculated using the equation:
LPI = Σni=1 Wi x Pi
Where: LPI= the weighted additive leachate pollution index; n= number of leachate pollutant variables used in calculating LPI; Wi= the weight for the ith pollutant variable; Pi= the sub-index value of the ith leachate pollutant variable.
Σni=1 Wi = 1
If the data for all the leachate pollutant variables is not available then LPI can be calculated using the following equation:
LPI = Σni=1 Wi x Pi / Σ Wi
Where: m= number of leachate pollutant variables when data is available (m<18,Σ Wi<1)
Table 2 LPI of the leachate from Nagaram dumping site
| Parameter | Sampling conc.’s | Individual pollution rating (pi) | Weightage (wi) | Overall pollution rating (wi×pi) | |||
| S1 | S2 | S1 | S2 | S1 | S2 | ||
| pH | 4.26 | 4.94 | 31 | 14 | 0.055 | 1.705 | 0.77 |
| TDS | 27458 | 27469 | 63 | 63 | 0.050 | 3.15 | 3.15 |
| BOD | 18547 | 20478 | 66 | 68 | 0.061 | 4.026 | 4.148 |
| COD | 23580 | 20569 | 83 | 81 | 0.062 | 5.146 | 5.022 |
| NH3 – N | 1958 | 2134 | 100 | 100 | 0.053 | 5.3 | 5.3 |
| TKN | – | – | – | – | – | – | – |
| Total Fe | 58.97 | 51.42 | 6 | 5 | 0.045 | 0.27 | 0.225 |
| Cr | 0.29 | 0.23 | 5 | 5 | 0.064 | 0.32 | 0.32 |
| Zn | 2.36 | 1.92 | 6 | 6 | 0.056 | 0.336 | 0.336 |
| Pb | 1.57 | 1.44 | 10 | 9 | 0.063 | 0.63 | 0.567 |
| Cu | 0.71 | 0.69 | 6 | 6 | 0.05 | 0.3 | 0.3 |
| Ni | 0.19 | 0.25 | 6 | 6 | 0.052 | 0.312 | 0.312 |
| Cl– | 2147 | 2596 | 16 | 19 | 0.048 | 0.768 | 0.912 |
| Hg | – | – | – | – | – | – | – |
| As | – | – | – | – | – | – | – |
| Phenol | 0.041 | 0.035 | 5 | 5 | 0.057 | 0.285 | 0.285 |
| Cyanide | – | – | – | – | – | – | – |
| TC* | 6.5 x 106 | 8.6 x 106 | 100 | 100 | 0.052 | 5.2 | 5.2 |
| Total value | 0.768 | 27.748 | 26.847 | ||||
| LPI | 36.130 | 34.957 | |||||
| LPI (Mean of two samplings) | 35.543 | ||||||
These LPI values are much higher than the standard LPI value of the treated leachate disposal limit of 12.561 to disposable solid waste (3,5). Higher values (35.543)of LPI signify that leachate produced from dumping sites of Nagaram of Nizamabad is highly contaminated and proper treatment techniques must be ensured before discharging the leachate.
Discussion
Physicochemical characteristics of leachate depend upon the waste composition and water content in total waste there in the dumpsite. In the dry season a high concentration of nitrate was observed in the leachate samples. The high values of TDS in leachate samples indicate the presence of inorganic materials in the samples the high COD and BOD values indicate the high organic materials in the leachate samples. The presence of nitrogen is probably due to the deamination of amino acids during the decomposition of organic material. The presence of trace amounts of lead indicates the disposal of lead batteries chemicals used for photograph processing lead-based Paints and pipes at the landfill site. LPI signifies the level of pollution concentration of a landfill. The indexing method leads to computation of a single value which varies from 5 (best value) to 100 (worst value), which expresses the overall pollution potential due to leachate contamination in form of an increasing scale index wherein higher values indicate higher levels of pollution leading to environmental degradation
Conclusion
The present study indicates that landfill leachate contains moderately high concentrations of EC, TDS, BOD, COD, sodium, potassium, ammonium, nitrate, chromium, copper, nickel, and lead, which contribute to the deterioration of groundwater and soil quality around landfill sites. Therefore, it is recommended to implement a liner system at the base of the landfill and a leachate collection system to remove leachate efficiently. Additionally, treatment measures should be designed based on scientific principles, including appropriate recycling methods. The study’s findings suggest that calculating the leachate pollution index (LPI) and monitoring its variations provides a reliable assessment method, as it reflects trends similar to individual leachate quality parameters across seasonal and site-specific variations. Overall, the results highlight the significance of evaluating LPI to assess the potential impact of pollutant discharge on aquatic resources and underscore the need for proper solid waste management in Nizamabad city.
References
1. Abu-Rukah, Y. and O. Al-Kofahi. 2001. The assessment of the effect of landfill leachate on groundwater quality – a case study El-Akader landfill site-north Jordan. J. Arid Environ. 49 – 615–630.
2. Agrawal, A., R. Pandey, and M.L. Agrawal. April 2011. “Impact of solid waste leachate on groundwater sources-a case study.” International Journal of Chemical and Environmental Engineering. vol.2(2) – 113-118.
3. Singh G., Pal Y., Juneja P., Singh A., Rameshwar R., “Solid Waste Management Scenario Of Punjab: A Case Study.‖ In: International Conference On Latest Development In Material, Manufacturing And Quality Control, 2016.
4. ASTM “Standard Test Method For Determination Of Composition Of Unprocessed Municipal Solid Waste”, D5231-92, Astm International, West Conshohocken, 2008.
5. Singh S., Raju N.J., Nazneen S., “Environmental Risk Of Heavy Metal Pollution And Contamination Sources Using Multivariate Analysis In The Soils Of Varanasi Environs, India‖, Environmental Monitoring And Assessment 187. 2015a.
6. Alloway, B.J. and D.C. Ayres. 1997. Chemical Principles of Environmental Pollution, 2nd ed., UK: Chapman and Hall.
7. Archana. and V. Dutta. 2014. “Seasonal Variations n Physico-Chemical Characteristics of leachate in Active and Closed Municipal Solid Waste Landfill sites in Lucknow, India”. G.Journal of Environmental Science and Technology. 1(4).
8. APHA.AWWA, WPCF (1995). Standard methods for the examination of water and wastewater (17th ed.). Washington DC, USA: APHA.AWWA, WPCF.
9. Baun, A., S.D. Jensen, P. Bjerg, T.H. Christensen and N. Nyholm. 2000. Toxicity of organic chemical pollution in groundwater downgradient of a landfill (Grindsted, Denmark). Environ. Sci. Technol. 34 -1647–1652.
10. Barjinder Bhalla, M.S. Saini, M.K. Jha. November – December 2012. “Characterization of leachate from Municipal Solid Waste (MSW) Landfilling Sites of Ludhiana, India: A Comparative Study. Volume 2(6)- 732-745.
11. Barjinder Bhalla, M.S.Saini, M.K.Jha. August 2013. “Effect of Age and Seasonal variations on leachate characteristics of Municipal Solid Waste landfill”. International Journal of Research in Engineering and Technology. Vol 2(8).
12. Bohdziewicz, J. and A. Kwarciak. 2008. The application of hybrid system UASB reactor-RO in landfill leachate treatment. Desalination. 222(1-3) – 128-134.
13. Chian, E.S.K. and E.B. Dewalle. 1976. Sanitary landfill leachate and their treatment, Journal of Environmental Engineering Division, ASCE, 108(EE2) – 411.