Occurrence and Treatment of Micropollutants in Landfill Leachate

Micropollutants have emerged as a new challenge to the scientific community over the past decade. This chapter discusses the occurrence of various micropollutants in landfill leachate. Phthalic acid esters (PAEs) are one of the most investigated compounds in landfill leachate and are therefore given special focus in this chapter. The potential treatment options for these micropollutants are discussed with relevance to the estrogenicity potential of micropollutants. The potential of leaching of micropollutants from landfill sites is discussed to emphasize on the requirements of appropriate liners to avoid such exposure to the surrounding environment. Biological treatment in particular membrane bioreactors have been successfully used to remove some of the micropollutants. Advanced oxidation processes such Fenton and photo-Fenton have limited application reported in literature whereas other physic-chemical processes such as coagulation and adsorption have been demonstrated to be effective in the removal of micropollutants.

Introduction to Solid Waste and Its Management

Municipal Solid Waste (MSW) disposal has become an increasingly serious problem in many parts of the world. In general, greater economic prosperity and a higher percentage of urban population correspond to a greater amount of solid waste produced. However, less effort has been exerted in the proper management of solid wastes produced by urban dwellers, particularly in developing countries. This chapter introduces the basic MSW rules. MSW composition, production, and collection are also highlighted. Furthermore, the concept of landfilling and waste decomposition is discussed in this chapter.

Leachate Treatment

Landfilling is one of the most important methods for disposal of solid waste in many countries. One of the most obvious problems associated with the landfilling practice is the generation of leachate. This chapter reviews case studies on the on-site treatment of leachates using various technologies in selected European and Asian countries. It was shown that the generation of leachate varies widely in both quantity and quality in European and Asian countries. Biological treatment and membrane technology show very high efficiencies in treating leachate generated from Odayeri landfill (in European side of Turkey) and Komurcuoda landfill (at Asian side of Turkey). Leachates from Arpley landfill (UK) and Bukit Tagar landfill (Malaysia) were successfully treated using sequence batch reactor (SBR). Fairly good treatment efficiencies were obtained using constructed wetlands (CWs) in treating Gdansk-Szadolki landfill leachate in Poland. Furthermore, the use of coagulation, filtration and membrane technologies has been proven effectively in treating Nonthaburi landfill leachate in Thailand.

Biological Treatment Technology for Landfill Leachate

Biological process for environmental preservation and treatment is not a new technology. It was used a decade ago until now. The most important tools in biological processes are the microorganism and upstream instruments (bioreactor, pond and others) to run the process. Furthermore, the efficiency of the process depends on many factors such as temperature, pH, type of microorganism, conditions, and other nutrients. To understand the factors that will affect the process, mechanisms of microorganisms to treat or protect the environment must be considered. For leachate treatment, biological process is one of the most widely used techniques for low cost and environmentally friendly.

Leachate Pollution and Impact to Environment

Pollution prevention is a step towards obtaining a green environment, and no amount of effort in that direction should be considered too great. To this effect, the pollution by leachate and the resultant impact on the environment is discussed in this chapter. Types and sources of pollution, their transfer and effect have been discussed, so as to give a background understanding on pollution and hence provide a platform for its control. The age old waste disposal practice of open dumps and landfilling is discussed, highlighting the dangers of indiscriminate waste dumping and uncontrolled landfilling practices. Although other sources of leachate generation are highlighted, the chapter focuses on leachates from municipal landfills and the effect of its migration. Engineered landfills also known as sanitary landfills have performed better in curtailing the movement of leachates, hence the use of artificial liners or low permeability soils such as the well compacted clayey soils, to eliminate or minimize leachate migration.

Leachate Generation, Transport, and Control

This chapter will discuss in detail on the primary aspect influencing leachate generation, transport and control within the landfill area. The leachate generation will look into the various factors that contribute toward increment and reduction of water balance in the landfill cell cause by the physical, chemical and biological activities. The topic will include discuss on common methods and models for estimating water input and transformation into/inside the landfill layer. Meanwhile, leachate transport part would emphasis on the leachate movement and mobility due to the effect of waste percolation, moisture field capacity and the gravity pull. Dominant flow type and the effect upon solute transport as well as other landfill components would be emphasize within the discussion. Lastly, this chapter will elaborate on the conventional and advanced techniques that being utilized for the control of the leachate for further treatment system or as beneficial advantages in the landfill management system.

Legislation for Solid Waste Management

The legal and institutional framework, as well as the international trends in solid waste management, serves as the basis for the formulation of a policy framework that seeks to improve solid waste management (SWM) practices in the future. Recently, SWM has become a global concern, especially for urban environments such as Malaysia, whose economy could potentially be adversely affected. To address these issues, the authors has reviewed several laws, including the Federal Constitution 1957; Local Government Act (Act 171) 1976; Town and Country Planning Act (Act 127) 1976; Environmental Quality Act (Act 127) 1974; Street, Drainage, and Building Act (Act 133) 1974; and Solid Waste and Public Cleansing Management Act 2007. Relevant international norms and principles at the federal, state, and local levels have also been reviewed. Exploring this topic generates an overview of SWM implementation in the context of Malaysia and the rest of the world.

Polishing Of Landfill Leachate

This chapter deals exhaustively with the various techniques employed in polishing landfill leachate, the role, importance and effects of polishing leachate and the use of constructed wetlands with many examples from some countries where it has worked with considerable success. Types, forms and functions of wetlands in leachate polishing were also dealt with while the chapter also provides information on the advanced treatment wetlands technology being employed now for polishing landfill leachate; its design considerations and future projections. The role of bioremediation and aquatic plants in leachate treatment was also considered and reviewed while projected futuristic outlook of polished landfill leachate was examined.

Integrated Leachate Treatment Technology

In this chapter, the performance of combined treatment of municipal landfill leachate is reviewed. Although individual physico-chemical treatments are suitable for the removal of heavy metals and hydrolyzation of some organic compounds, a combination of two physico-chemical treatments or physico-chemical and biological is required for optimum treatment of stabilized landfill leachate. A combination of two physico-chemical treatments can give optimum results in removal of recalcitrant organic compounds from stabilized leachate, as reflected by a significant decrease of the COD values after treatment. On the other hand, a combination of physico-chemical and biological treatments is required to achieve effective removal of NH3-N and COD with a substantial amount of biodegradable organic matter. In many cases, physico-chemical treatments are suitable for pre-treatment of stabilized leachate. The objective of this paper is to highlight various types of integrated leachate treatments as it has been difficult to get optimum efficiency from single approached treatment.

Composition of Leachate

Solid waste is an important environmental problem in both developing and developed countries. Management of Municipal Solid Waste (MSW) is one of the main modern environmental issues in municipal areas because of both its huge amount and variety of constituents. Information on characteristics of MSW is important for the formulation of new waste management policy. Landfill leachate is defined as an aqueous effluent produced when water percolates through the waste in a landfill. The nature of landfill leachate depends on the type of MSW being dumped, landfill age, moisture content, seasonal weather variations, site hydrology, the stage of decomposition in the landfill and pH. Produced leachate could contain large amounts of contaminants measured as COD, BOD5, NH3–N, heavy metals, phenols, phosphorus etc. Obviously, as landfill age increases, the biodegradable fraction of organic pollutants in leachate decrease as an outcome of the anaerobic decomposition occurring in landfill site. Thus, mature or stabilized leachate contains much more refractory organics than young leachate.