Characterization and tropical seasonal variation of leachate: Results from landfill lysimeter studied
Highlights
► One open dump lysimeter and two sanitary landfill lysimeter were simulated. ► Open dump at two operating system and sanitary lysimeter having two cap liners. ► We examine performances of base in open dump and cap liner in sanitary lysimeter. ► We monitor leachate quality and quantity attributable to lysimeter operating mode. ► Investigates effect of climatic variation on leachate and lysimeter scheme.
Introduction
The term ‘landfill’ is used herein to describe a unit operation for final disposal of ‘municipal solid waste (MSW)’ on land, designed and constructed with the objective of minimum impact to the environment. This term encompasses the other terms such as ‘secured landfill’ and ‘engineered landfills’ which are also sometimes applied to MSW disposal units (Tubtimthai, 2003). The term ‘landfill’ can be treated as synonymous to ‘sanitary landfill’ of MSW, only if the latter is designed on the principle of waste containment and is characterized by the presence of a liner and leachate collection system to prevent ground water contamination. Sanitary landfill is one of the secure and safe facilities for the disposal of MSW; however, it needs high standard of environment protection in the operation of landfill (Davis and Cornwell, 1998). Moreover, it is a well-suited method for managing of MSW all over the world and to investigate the performance of sanitary landfill the behavioral patterns namely; leachate generation, landfill gas (LFG) emissions etc. are required (Visvanathan et al., 2002). Lysimeter is a simulate form of sanitary landfill in the sense of control device. The word lysimeter is a combination of two Greek words “Lusis” means “Solution” and “Metron” means “Measure” and the original aim is to measure soil leaching (Rafizul et al., 2009a). Sanitary landfill plays a significant role for the disposal of MSW in most of the developing countries like Bangladesh (Alamgir et al., 2006 and WasteSafe, 2005). Most of the landfill in developing countries does not have any liners at the base or proper top covers, which results in the potential problems of ground water/surface water contamination due to the leachate generated from solid waste landfill (Horing et al., 1999 and McBean et al., 1995). The state regulatory authorities in most of the countries around the world have framed regulations to safe guard against the contamination of groundwater sources from the leachate generated from solid waste landfill (Rafizul et al., 2011). The leachate generated from MSW disposal sites is considered as one of the highly contaminated resources from physical, chemical and biological point of view. However, the best possible knowledge of leachate characteristics at a specific site is an essential management tool. This is not only important for new containment landfill needs designed in advance, where leachate will be extracted, but also important for the old landfill where the environmental safeguards rely on the natural attenuating properties of the geological strata, to reduce the level of contaminant to environment (Robinson, 1989 and Youcai et al., 2000). In that manner leachate may pose a severe pollution threat to ground water supplies (Kelly, 1976).
Chemically contaminated leachate is one of the byproducts in landfill degradation reactions (Alamgir et al., 2006). One of the severe problems associated with the open dumping of MSW is percolation of leachate into the surrounding environment, subsequent contamination of the land and water bodies (Walker, 1969, Chian and DeWalle, 1976, Kelly, 1976, Masters, 1998 and Kumar et al., 2002). El-Fadel et al. (2002) reported that composition of landfill leachate can exhibit considerable spatial and temporal variations depending upon the site, management practices, refuse characteristics (i.e. composition and age), and internal landfill processes (hydrolysis, adsorption, speciation, dissolution, ion exchange, re-dox reactions, precipitation etc.). Moreover, the variation of leachate quality in MSW landfill can be attributed to many interacting factors such as the composition and depth of MSW; decomposition and age of MSW; degree of compaction; landfill design and operation; liner (top and base) design and operation; MSW filling procedures; the availability of moisture content; available oxygen; rate of water movement (fluid addition) and temperature (Qasim and Chiang, 1994). Therefore, it is difficult to generalize the chemical composition of leachate that posses at a particular time of sampling. In addition, leachate quality may vary from time to time and site to site due to the variables such as waste composition, temperature, moisture content, climatic changes etc. (Alkalay et al., 1998). To these endeavor, the present study was aimed to characterize the leachate and to investigate the tropical climatic influence on leachate characteristics generated from MSW deposited in open dump and sanitary landfill lysimeter and hence compared with those results of similar cases available in the literature.
Section snippets
Landfill lysimeter design and operation
Three landfill lysimeters designated as A, B and C were designed and hence constructed at KUET campus, Bangladesh based on a reference cell shown in Fig. 1, showing all the design components in details. The operational condition, liner specifications, simulation behaviour and the total weight of MSW deposited in each lysimeter are presented in Table 1. However, the detailed about landfill lysimeter design, construction and operational condition can be obtained in Rafizul et al. (2009b). The MSW
Characterization of landfill lysimeter leachate
In the laboratory, inorganic and organic compounds of leachate in terms of pH, chloride, TS, TDS, TSS, TKN, NH4-N, alkalinity, hardness, COD, conductivity, sulfate and nitrate were monitored and measured as presented in Table 2. However, the variation of inorganic and organic compounds in relation to the increasing of elapsed period, changes of climatic condition as well as open and sanitary landfill lysimeter operational condition are highlighted and hence discussed in followings.
Influence of tropical seasonal variations on landfill lysimeter operation
To investigate the variation of leachate quality in terms of pH, COD and TKN (concentration and load), conductivity, TS and chloride in relation to the changes of tropical condition, periodic monitoring of leachate quality at varying operational condition of landfill lysimeter was carried out in the laboratory. However, the entire lysimeter observation consists of dry and wet climatic condition as well as the age of MSW in lysimeter and it reveals that lysimeter operational mode played a
Conclusions
The field level landfill simulation with various top cover designs and operational condition of lysimeter greatly influences the leachate quality. Moreover, the open dump lysimeter had lower TKN, NH4-N and TKN load, while both the COD concentration and load was higher compared with sanitary landfill lysimeter. Here, it is interesting to note that chloride was increased, while pH, COD concentration, EC and TS in leachate regarding to entire lysimeter operational system were decreased during the
Acknowledgement
The authors gratefully acknowledged the financial support provided by European Commission through the project of EU- Asia Pro Eco II Programme (ASIE/2006/122-432).
References (63)
- et al.
Long Term Fate of Organics in Waste Deposits and its Effect on Metal Release
The Science of the Total Environment
(1999) - et al.
Effects of high free ammonia concentrations on the performance of anaerobic bioreactors
Process Biochemistry
(2005) - et al.
Review: biogeochemistry of landfill leachate plumes
Applied Geochemistry
(2001) - et al.
The PAF Model: an integrated approach for landfill sustainability
Waste Management
(2003) - et al.
Temporal variation of leachate quality from pre-sorted and baled msw with high organic and moisture content
Waste Management
(2002) Quality and quantity of sanitary landfill leachate
Waste Management & Research
(1983)- et al.
Anaerobic digestion of swine manure: inhibition by ammonia
Water Research
(1998) - et al.
Characterization of sanitary landfill leachates
Water Research
(1976) - et al.
Biological nitrogen removal from municipal landfill leachate: low cost nitrification in biofilters and laboratory scale insitu denitrification”
Water Research
(2002) - et al.
The effect of landfill age on municipal leachate composition
Bioresource Technology
(2008)