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Wastewater reuse is being increasingly emphasized as a strategy for conservation of limited resources of freshwater and as a mean of safeguarding the aquatic environment due to contaminants present in wastewater. Although secondary and tertiary treated wastewater is often discharged into surface waters, it cannot be reused without further treatment. One of the parameters of concern for human and environmental health is components of organic matter originating from wastewater treatment plant (WWTP) effluents. This effluent organic matter (EfOM) should be carefully characterized in order to find an optimum treatment method for water reuse. This review presents the components of EfOM present in WWTP effluents and various treatment methods that may be employed for reduction of EfOM. These processes include flocculation, adsorption, biofiltration, ion exchange, advanced oxidation process, and membrane technology. The removal efficiency is discussed in terms of removal of total organic carbon, endocrine-disrupting chemicals (EDCs), pharmaceuticals and personal care products (PPCPs), different polarity fractions (such as hydrophobic and hydrophilic), and molecular weight distribution of organic matter.
KEYWORDS: adsorption, advanced oxidation process, biofiltration, biologically treated sewage effluent, characteristics, effluent organic matter, flocculation, ion exchange, membrane technology, molecular weight distribution, treatment, wastewater reuse
1. INTRODUCTION
Wastewater treatment is employed as an action to protect the quality of limited freshwater resources and therefore make it more acceptable for beneficial reuse. However, achieving this objective remains elusive, as the total discharge of biologically treated sewage effluent (BTSE) is continually on the rise due to increasing population and urbanization. Wastewater reclamation has been recognized as one of the most effective ways of increasing the availability of limited freshwater, and at the same time, the use of reclaimed water
can reduce the demand for freshwater. For the purpose of wastewater reclamation/reuse, it is imperative to study the characteristics of effluent organic matter (EfOM) in the BTSE in detail in order to design effective treatment methods.
2. CHARACTERIZATION OF EFFLUENT ORGANIC MATTER IN WASTEWATER
2.1. Overview of EfOM
The systematic treatment of wastewater was started in the late 1800s and early 1900s (Tchobanoglous and Burton, 1991). For the last two centuries, wastewater treatment has continually been developed to meet strict disposal standards. Recently, wastewater for reuse is being increasingly emphasized as a strategy for conservation.
Although many previous researchers have...