Indicator and Pathogen Removal by Low Impact Development Best Management Practices

Jian Peng,A Afrooz,Megan Rippy,Yiping Cao,Stanley Grant

doi:10.3390/w8120600

Abstract

Microbial contamination in urban stormwater is one of the most widespread and challenging water quality issues in developed countries. Low impact development (LID) best management practices (BMPs) restore pre-urban hydrology by treating and/or harvesting urban runoff and stormwater, and can be designed to remove many contaminants including pathogens. One particular type of LID BMP, stormwater biofilters (i.e., vegetated media filters, also known as bioinfiltration, bioretention, or rain gardens), is becoming increasingly popular in urban environments due to its multiple co-benefits (e.g., improved hydrology, water quality, local climate and aesthetics). However, increased understanding of the factors influencing microbial removal in biofilters is needed to effectively design and implement biofilters for microbial water quality improvement. This paper aims to provide a holistic view of microbial removal in biofilter systems, and reviews the effects of various design choices such as filter media, vegetation, infauna, submerged zones, and hydraulic retention time on microbial removal. Limitations in current knowledge and recommendations for future research are also discussed.

Highlights

Urbanization, with concomitant increase in impervious surfaces, results in increased volume and rate of stormwater flow; reduces natural infiltration of stormwater; negatively impacts stream and coastal ecosystems; and often carries significant pollutant loads, including pathogens, into receiving waters [1], which provide significant values both as habitat and a recreational resource
Given the complications described above, how can hydraulic residence time (HRT) be factored into biofilter design? Here, we argue for the following two design philosophies: (1) design for scenarios that result in the smallest range of HRTs likely to be encountered in practice; and (2) assume simplified operating conditions amenable to analytical treatment
Summary and Future Research Needs biofilters are heterogeneous in several respects: (1) they are layered systems consisting of fine sand, Oursand, understanding key(see design factors that maximize stormwater microbial removal is stillof coarse and gravelof units

Summary

Introduction

Urbanization, with concomitant increase in impervious surfaces, results in increased volume and rate of stormwater flow; reduces natural infiltration of stormwater; negatively impacts stream and coastal ecosystems; and often carries significant pollutant loads, including pathogens, into receiving waters [1], which provide significant values both as habitat and a recreational resource. Stormwater reuse is becoming an increasingly attractive resource management strategy [5]. Microbial contamination, among all stormwater contaminants, is the most problematic for water reuse [6]. Low impact development (LID), a planning and environmental management practice that focuses on restoring the hydrology of an urbanized watershed to its pre-development condition, has been increasingly used to improve human water security

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