Sustainable Green Technologies for Environmental Management by Unknown

Author:Unknown
Language: eng
Format: epub
ISBN: 9789811327728
Publisher: Springer Singapore

7.9.4 Total Suspended Solids (TSS) Removal

The presence of suspended solids in water indicates the presence of organic matter, particulate nutrients, heavy metals and several other pollutants. Hsieh and Davis (2005) used synthetic runoff and carried out a series of twelve bioretention column tests. During the first 6-h run, sediment washout was observed and total TSS removal of 91% was noted at the end of experiment.

Field monitoring of two bioretention facilities by Davis (2007), over a period of 14 months, showed low levels of TSS removal. 54% and 59% (on a mass basis) of influent TSS was retained, respectively, in the first and second bioretention cells. Event mean concentrations (EMCs) for 23 storm events were decreased by 41% and 22% by first and second bioretention cells, respectively. Anoxic zone is included at the base of second cell. Sediment washout was also observed as TSS effluent concentrations exceeded influent concentrations, mostly during first storm events following the initiation of the system.

Li and Davis (2008) investigated the filtration mechanism of bioretention cells by performing a series of bioretention column tests and field observations. In their study, they found that stratification tends to occur in the media as particulate matter is captured by bioretention media. They also observed that finer soil particles were present in the upper media and suspended solids were trapped inside the media which altered the characteristics of media and thus reduces its hydraulic conductivity. Their study also concluded that clogging may limit the useful lifespan of bioretention filter media.

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