Bacteria Removal from Stormwater Runoff Using Tree Filters: A Comparison of a Conventional and an Innovative System

Abstract

Non-point source pollution of stormwater contributes high contaminant loads into surface water bodies and poses a threat to the ecosystem, public health and economy. Although (pre)treatment standards have not been introduced at the federal level, Rhode Island (RI) has set minimal contaminant reduction standards for stormwater using structural best management practices (BMP). As BMP performance depends highly on geographical location and climate, and the Northeastern United States experiences broad ranges of temperatures throughout the year along with long intermittent periods between precipitation events, stormwater treatment can be challenging. In this field study, two tree filters were evaluated: a conventional unit (CTF) with sand/shale mix as filter media, and a modified tree filter (ITF) with an added layer of red cedar wood chips amended with 3-(trihydroxysilyl)propyldimethyloctadecyl ammonium chloride. Both BMPs were monitored for 346 days primarily for Escherichia coli and polycyclic aromatic hydrocarbons (PAH). Both tree filters met or outperformed RI's standards for bacteria removal (60%) and TSS (85%), making them a good choice for BMP use in this climate. Total suspended solids, E. coli, PAHs, nitrate, and phosphate removal is higher in ITF. A controlled field scale tracer test using E. coli confirmed these results.

Efficiency of Private Household Sand Filters in Removing Nutrients and Microbes from Wastewater in Finland

“…It has been found that these treatment units also reduce the number of bacteria and viruses [22]. There can also be antimicrobial amended layer added to the sand filter system [36,37]. In larger treatment units, such as public buildings e.g., schools and hotels or where the systems are shared between several households, disinfection of effluent can be a good option; it has been recommended that peracetic acid is a good choice as a disinfectant [8].…”

Managing Uncertainty in Runoff Estimation with the U.S. Environmental Protection Agency National Stormwater Calculator

“…In particular, runoff from residential and commercial parcels and properties can constitute a considerable proportion of stormflow volume, yet holds much potential for management with LID and GI techniques applied to parcels, neighborhoods, and in right‐of‐way areas (Green et al ., ; Shuster and Rhea, ; Herrmann et al ., ; Jarden et al ., ; Schifman et al ., ; Shuster et al ., ). Any type of GI installation is a hydrologic intervention, and more often than not, requires hydrologic modeling to support the planning and design process.…”

Indicator and Pathogen Removal by Low Impact Development Best Management Practices

“…Other media amendments, such as expanded shale (ES) and red cedar wood chips (RC), have also been investigated as potential biofilter amendments. Like other amendments described above, the introduction of ES and RC for microbial removal is inspired by their promise in removing organic contaminants and heavy metals from urban stormwater [68][69][70]. The efficacies of these amendments are found to be dependent on the influent microbial concentration.…”

“…Importantly, the effectiveness of antimicrobial modification depends on the antimicrobial loading (mg/g of filter media), temperature, and the residence time of stormwater. Recently, a full-scale field-study with TPA-modified RC and ES was attempted [69] using a tree box filter-a biofilter installed beneath a tree. Unlike the laboratory-scale study, TPA-modified biofilters in the field did not demonstrate any Water 2016, 8, 600 9 of 24 significant improvement of E. coli removal compared to the biofilters containing unmodified RC and ES, possibly due to reduced hydraulic residence time (too short for antimicrobial action to occur).…”