Reduction of pathogens, indicator bacteria, and alternative indicators by wastewater treatment and reclamation processes

Abstract

The need for alternative sources of water, especially for non-potable purposes, has been met in many states in the US and throughout the world through the use of reclaimed wastewater. Wastewater contains a wide variety of microbial pathogens that may pose a risk to human health if not properly controlled; however, there are currently no national standards for microorganisms or consistent treatment requirements in the US with regards to reclaimed water. Besides the routine monitoring for TC and FC bacteria that has been used for assessing water quality, several types of alternative microorganisms have been suggested as indicators of water quality, fecal pollution, and public health risks. These include enterococci, Clostridium perfringens, and coliphage among others. This project evaluated the removal of both indicators (TC and FC, enterococci, C. perfringens and coliphage) and pathogens (enteroviruses, Giardia spp. and Cryptosporidium spp.) at 3 water reclamation facilities with varying treatment designs and operations. The facilities evaluated range in size from 20 to 44 million Liters per day capacity, with both shallow and deep bed sand/anthracite filters. Differences also existed in the disinfection processes for the 3 reclamation plants. The TC and FC showed a 5 to 7 log reduction throughout the treatment processes with no detectable levels in the final effluent. However, even though the alternative indicators (enterococci, C. perfringens and coliphage) showed reductions that varied from 2 to 6 logs, some levels of these indicators were consistently detected in 2 of the 3 facilities in the final reclaimed effluent. Both Cryptosporidium spp. and Giardia spp. were detected in the final effluent in all 3 facilities, even when no indicators were present. Virus detection was seasonal, and associated with cooler temperatures and less disinfection. The results of this study indicate that differences in filter design, operations, and disinfection approaches were responsible for differences in inter and intra facility water quality variability.

Near Real-Time Flow Cytometry Monitoring of Bacterial and Viral Removal Efficiencies during Water Reclamation Processes

“…This observation is not surprising since dual media filters, using an anthracite coal layer followed by a sand layer, are designed to reduce particles greater than the average pore size of 1.05-1.15 mm. Therefore, they are not effective at removing much smaller microorganisms including viruses and bacteria [7,21].…”

Removal of pathogenic bacteria from sewage-treated effluent and biosolids for agricultural purposes

“…seas, rivers, oceans and surface water) started to represent health risks for humans due to the disposal of treated sewage contaminated with pathogenic bacteria (Wen et al 2009;Garcia-Armisen et al 2011). A wide variety of microbial pathogens that may pose a risk to human health are known to be abundant in the treated sewage and considered the major source of faecal contamination in aquatic ecosystems (Scott et al 2003;Tyagi et al 2006).…”

Sewage-fed aquaculture: a sustainable approach for wastewater treatment and reuse

“…In addition, the human faecal material is generally considered to be of greater risk to human health as it is more likely to contain human enteric pathogens (Scott et al 2003). The detection of these micro-organisms in treated wastewater indicates a public health risk that exists with reuse of secondary treated wastewater.…”

“…To meet the demand of the hour, the effluent reuse in recent times has been looked up as a prospective alternative to cope up with the increasing water stress (Jamwal and Mittal 2010). The reclaimed water is suitable for several applications, including irrigation, toilet flushing, cleaning, industrial application and environmental augmentation (El-Gohary et al 1998;Scott et al 2003;Chiou et al 2007). Due to its stable quantity, reclaimed water from domestic sewage treatment plants (STPs) could be a reliable alternative water resource.…”