Variation and removal of 2-MIB in full-scale treatment plants with source water from Lake Tai, China

摘要

2-Methylisoborneol (2-MIB) is one of the most common taste and odor (T&O) compounds in waterbodies and causes complaints from drinking water consumers. This is a case study of two water treatment plants taking the raw water from Lake Tai, the third largest lake in China. The relationships between the 2-MIB concentration and algae density, light change and nutrients of the raw water for the most recent four years were comprehensively investigated. The yearly variation pattern of the 2-MIB concentration in the raw water is closely related to the algae cell density. Both values reached peaks in July or August with concentrations as high as similar to 500 ng/L and similar to 1000 X 10(4) count/L, respectively. For the diurnal 2-MIB variation, the concentrations increase from 5 to 6 am, reach a peak value at similar to 12 p.m., and then gradually decrease and achieve the lowest value at night. These results further confirm that 2-MIB is highly related to algae cell activity (e.g., photosynthesis). In addition, 2-MIB exists both inside and outside algae cells (i.e., intracellular and extracellular or bound and dissolved 2-MIB, respectively), and the percentage of the extracellular/dissolved portion was as high as 60% during the study period. Conventional water treatment processes (usually referrings to coagulation sedimentation and sand filtration, CSF) in WTPs have extremely unstable 2-MIB removal efficiencies (from -20% to 95%), which is mainly related to the existing forms of 2-MIB. The intracellular/bound portion can be effectively removed by CSF, especially sand filtration, while advanced water treatment processes are required to remove the dissolved 2-MIB. An ozone-activated carbon process is recommended, and the 2-MIB removal rate can reach 100%. This research has great theoretical and engineering value for treating water containing T&O compounds. (C) 2019 Elsevier Ltd. All rights reserved.