Characteristics of C-, N-DBPs formation from algal organic matter: Role of molecular weight fractions and impacts of pre-ozonation

• Published in: Water research (Oxford) 2015-04, Vol.72, p.381-390
• Main Authors: Zhou, Shiqing, Zhu, Shumin, Shao, Yisheng, Gao, Naiyun
• Format: Article
• Language: English
• Subjects: Algae; Byproducts; Carbon - chemistry; Chloramines; Chlorination; Disinfection; Disinfection byproducts; Drinking Water; Extracellular organic matter; Extracellular Space - chemistry; Formations; Halogenation; Intracellular organic matter; Intracellular Space - chemistry; Microcystis; Microcystis - chemistry; Microcystis aeruginosa; Molecular Weight; N-nitrosodimethlamine (NDMA); Nanofiltration; Nitrogen - chemistry; Organic Chemicals - chemistry; Ozone; Ozone - chemistry; Pre-ozonation; Water - chemistry; Water Purification
• ISSN: 0043-1354; 1879-2448
• DOI: 10.1016/j.watres.2014.11.023

Extracellular organic matter (EOM) and intracellular organic matter (IOM) of Microcystis aeruginosa have been reported to contribute to the formation of carbonaceous disinfection by-products (C-DBPs) and nitrogenous disinfection by-products (N-DBPs). Little is known about DBPs formation from different molecular weight (MW) fractions, especially for N-nitrosodimethylamine (NDMA). This study fractionated EOM and IOM into several MW fractions using a series of ultrafiltration membranes and is the first to report on the C-DBPs and N-DBPs formation from chlorination and chloramination of different MW fractions. Results showed that EOM and IOM were mainly distributed in low-MW (100 KDa) fractions. Additionally, the low-MW and high-MW fractions of EOM and IOM generally took an important part in forming C-DBPs and N-DBPs, either in chlorination or in chloramination. Furthermore, the effects of pre-ozonation on the formation of DBPs in subsequent chlorination and chloramination were also investigated. It was found that ozone shifted the high-MW fractions of EOM and IOM into lower MW fractions and increased the C-DBPs and N-DBPs yields to different degrees. As low-MW fractions are more difficult to remove than high-MW fractions by conventional treatment processes, therefore, activated carbon adsorption, nanofiltration (NF) and biological treatment processes can be ideal to remove the low-MW fractions and minimize the formation potential of C-DBPs and N-DBPs. Moreover, the use of ozone should be carefully considered in the treatment of algal-rich water. [Display omitted] •Algal organic matters were fractionated into six molecular weight (MW) fractions.•Low-MW and high-MW fractions contributed to most disinfection by-products (DBPs).•Pre-ozonation shifted the high-MW to low-MW fractions and increased DBPs yields.