Download or read book Identification and Correlation of Disinfection Byproducts and Total Organic Halogen Precursors in a Biofilm Matrix written by Mohd Yahya Khan and published by . This book was released on 2014 with total page 91 pages. Available in PDF, EPUB and Kindle. Book excerpt: Disinfection by-products (DBP) formation in drinking water systems is a persistent issue for water utilities. Although DBP formation is complex due to the multitude of chemical and biological interactions that occur, unremoved natural organic matter (NOM) entering the water distribution system is generally regarded as the primary precursor for DBP formation. In addition, NOM also provides nutrients that support microbial growth and persistent biofilm formation. Biofilm formation is widespread within the water distribution system due to the continuous influx of unremoved NOM. Biofilm and its associated extracellular polymeric substances (EPS) provide a dynamic repository for organic matter accumulation, and can act as a DBP precursor. Trihalomethanes (THMs) and Haloacetic acids (HAAs) represent the major classes of regulated DBPs, yet there are several others that form due to the complex interaction between the organic matter and the disinfectants. The unknown total organic halogens (UTOX) is believed to contain toxicologically vital compounds. Until recently, there have been no reliable studies analyzing the relative contributions of biofilm and its associated DBP precursors to DBP formation and speciation, and how these different precursors contribute to the total organic halogen (TOX) formation. This work seeks to abridge this knowledge gap by analyzing the DBP formation from chlorination of biofilms in simulated water distribution systems. The results of this study provide critical information about potential contributions of biofilms to the formation of DBPs and UTOX in the distribution systems and can help water utilities better control the levels of both regulated and unregulated DBPs while at the same time reducing health risks associated with DBPs. To help elucidate this interaction, heterotrophic plate counting (HPC) of bacterial colonies in different pipe materials under different chlorine residuals were conducted. Additionally, DBP and TOX formation tests were conducted and correlated with parallel factor analysis (PARAFAC) of fluorescent dissolved organic carbons. The obtained results suggest that depending on the pipe material, the accumulation of organic matter in biofilm matrix contributes significantly towards DBP formation. Corrosion of iron pipes provides not only more opportunity for growth of biofilm, but also increased adsorption sites for humic substances, both of which lead to increased DBP and UTOX formation. Overall, strong evidence of biofilm contribution to DBP formation in drinking water distribution systems suggests that water utilities need to carefully consider biofilm eradication methods to minimize the subsequent formation of toxic compounds.