Health risks from protozoa in potable reuse: Implications of Florida's data set

Abstract

Over the past two decades, 292 Florida water reclamation facilities (WRFs) have collected reclaimed water protozoa data. This paperexamines the data set, which includes more than 1,800 observations of each protozoan, including Cryptosporidium and Giardia. This study considers the occurrence of protozoa across WRFs and the potential implications for potable reuse. Quantitative microbial risk assessment was conducted for reclaimed waters from 20 WRFs to assess the necessary log reduction credit to treat water from each facility for Cryptosporidium and Giardia. These results are compared with advanced treatment trains based on either reverse osmosis or ozone with biologically active filtration.

Introduction to the topical collection on potable reuse

“…Nearly 300 such facilities in Florida have been collecting data on waterborne pathogens for more than two decades, generating more than 1,800 observations each for Giardia , Cryptosporidium , and other protozoa. MacNevin and Zornes (2020) used this database to conduct quantitative microbial risk assessment (QMRA) and provide a detailed assessment of the concentrations of Cryptosporidium and Giardia present in raw and treated wastewater, the variability in these concentrations, and the log reduction values (LRVs) that advanced treatment processes need to achieve public health goals. Bailey, Casanova, and Sobsey (2020) also used QMRA to evaluate proposed potable reuse guidelines in North Carolina and found that the proposed regulations may not sufficiently protect public health, potentially resulting in a need for additional treatment.…”