Article

Algal-derived organic matter as precursors of disinfection by-products and mutagens upon chlorination

Croucher Institute for Environmental Sciences and Department of Biology, Hong Kong Baptist University, Kowloon Tong, Hong Kong, PR China.
Water Research (Impact Factor: 5.32). 01/2011; 45(3):1454-62. DOI: 10.1016/j.watres.2010.11.007
Source: PubMed

ABSTRACT Algal-derived organic materials (including algal cells, hydrophilic and hydrophobic proteins) from Chlamydomonas sp. (a common green alga in local reservoirs), were chlorinated in the laboratory (20 °C, pH 7, Cl(2)/DOC ratio of 20 mg Cl(2) mg(-1)). Levels of disinfection by-products and mutagenicity (via Salmonella T100 mutation assay, -S9) over 2 h of chlorination time were determined. The hydrophilic proteins were more effective precursors of chloroform (35.9 μmol L(-1) at 120 min), 35 times greater than that from the hydrophobic proteins; whereas the hydrophobic proteins were more potent precursors of direct-acting mutagens (maximum level of 50.1 rev μL(-1) at 30 s) than the hydrophilic proteins (maximum level of 3.38 rev μL(-1) at 60 min). The mutagenicity of the chlorinated solutions generally reached a peak level shortly after chlorination and then declined afterwards, a pattern different from that of chloroform generation. The results indicate that algal hydrophilic proteins, containing low aromaticity and difficult to be removed via coagulation/flocculation, are important chloroform precursors. It is also suggested that hydrophobic organic intermediates with low molecular weight formed during chlorination may serve as the direct-acting mutagens.

0 Followers
 · 
87 Views
  • [Show abstract] [Hide abstract]
    ABSTRACT: This study was performed to illustrate the effects of preoxidation by potassium permanganate on the fluorescence spectrum of Microcysis aeruginosa, a kind of blue-green algae. The results showed there were four dominate excitation/emission (Ex/Em) wavelength pairs, 230/334, 280/312, 280/334 and 620/642 nm/nm in the fluorescence spectra of algae and their derived organic matters (AOM). Coagulation resulted in desorption of the organic matter adsorbed in algae cells and produced two new fluorophores centered at 275/460 and 400/460 nm/nm. Potassium permanganate preoxidation could reduce the fluorescence intensity of algae and dissolved algal organic matters effectively and the descent rate increased with increasing potassium permanganate dosage.
    07/2011; DOI:10.4028/www.scientific.net/AMM.71-78.2920
  • [Show abstract] [Hide abstract]
    ABSTRACT: Cells and proteins of Chlamydomonas sp. (a common green alga in local reservoirs) were separated by ultrafiltration respectively into 3 fractions with variable molecular weights (MW: >100, 10-3 and <3 kDa). After chlorination (20°C, pH 7, Cl(2)/DOC ratio of 20 mg Cl(2)mg(-1), 120 h), levels of disinfection by-products (DBPs) and mutagenicity (via Salmonella T100 mutation assay, -S9) were analyzed. The highest yields of chloroform (2571 μmol mol C(-1)), DCAA (19,083 μmol mol C(-1)) and TCAA (4939 μmol mol C(-1)) were observed from the fraction of MW>100 kDa, while the fraction of 3-10 kDa was potent DCAN precursor. In contrast, the chlorinated MW 3-10 kDa cell fraction showed high mutagenicity (maximum level of 93 rev μL(-1) at 2 min), while the MW>100 kDa cell fraction showed low mutagenicity (maximum level of 16.6 rev μL(-1) at 7200 min) after chlorination. This indicated that unmeasured DBPs or possible interactions among the DBPs contributed to the mutagenicity. Comparing between the cell and protein fractions, the former was more potent in forming chloroform, DCAA, TCAA, DCAN and TCAN. This is the first study that fractionated algal cells and proteins were examined for DBP formation and mutagenicity.
    Journal of hazardous materials 03/2012; 209-210:278-84. DOI:10.1016/j.jhazmat.2012.01.023 · 4.33 Impact Factor
  • [Show abstract] [Hide abstract]
    ABSTRACT: Trichloromethane (TCM) is a harmful halogenated organic compound usually used in the industry and a typical disinfection by-product in the water treatment with the use of chorine as disinfectant. The degradation of TCM by peroxymonosulfate combined with UV irradiation at λ= 254 nm (UV/PMS) was investigated. Results showed that TCM was efficiently degraded by UV/PMS and about 80% of TCM was decomposed when the concentration of PMS was 0.5mM. Radical-scavenging experimental results indicated that both HO• and SO4•- might contribute to the degradation of TCM. However, HO• might first be captured by PMS to form SO5•- and then partly decomposed into SO4•-, which might react with TCM. The increased concentration of PMS led to the increased removal efficiency of TCM. Whilst, the efficiency was little affected by initial concentration of TCM, indicating that there might be competition reaction with TCM degradation for radicals.
    05/2012; 518-523:2479-2483. DOI:10.4028/www.scientific.net/AMR.518-523.2479

Similar Publications