Removal of Emerging Contaminants from Water and Wastewater Using Nanofiltration Technology

1. Introduction

Emerging contaminants (ECs) can be broadly defined as any synthetic or naturally occurring chemicals but cause known or suspected adverse ecological and(or) human health effects. This ever-increasing contaminants pose potential environmental and health threat to the living organism (Bolong, Ismail, Salim, & Matsuura, 2009). In some cases, due to low concentration emerging contaminants have likely existed for a long time, which may not be detected until new analytical methods are developed. Hence, some ECs are not necessarily new chemicals, which are from municipal, agricultural, and industrial wastewater sources and pathways (Petrović, Gonzalez, & Barceló, 2003).

There are two reasons why emerging contaminants are of continued concern for the health and safety of consuming public. The first one is the trace level of most ECs with concentration at μg/L or ng/L, and broad range of physiochemical characteristics, which make both detection and elimination extremely difficult (Richardson & Ternes, 2005); And the second one is the adverse health and environmental effects of ECs even at a low concentration. Some intermediate metabolites or transforming products of ECs (especially for endocrine disrupting chemicals) exhibit biologically active effect as well (Diamanti-Kandarakis et al., 2009).

The main issue of ECs is nonexistence of limiting regulations, especially for new compounds, by-products, pharmaceuticals as related to the water and wastewater treatment industry. The first Contaminant Candidate List (CCL) was created in 1998 by United States Environmental Protection Agency (US EPA) for contaminants that are currently not subject to any proposed or promulgated national primary drinking water regulations. Even through many efforts have been devoted, there is limited number of contaminants with Maximum Contaminant Level (MCL) regulated by US EPA.

The main groups of ECs are described in Table 1.