Fate of Fecal Indicators in Resource-Oriented Sanitation Systems Using Nitrifying Bio-Treatment.

Shervin Hashemi,Myung Joo Han ,Eun Ha Namkung

doi:10.3390/ijerph15010164

Abstract

Hygienic fecal treatment in resource-oriented sanitation (ROS) systems is an important concern. Although the addition of nitrifying microorganisms is a sustainable fecal treatment method in ROS systems, it is essential to examine the cleanliness of this method. In this study, we investigated the fate of fecal indicators in source-separated fecal samples through tracking Escherichia coli and total coliforms. The effects of adding different amounts of Nitrosomonas europaea bio-seed, along with a constant amount of Nitrobacter winogradskyi bio-seed, were studied. In intact feces samples, the pathogen population underwent an initial increase, followed by a slight decrease, and eventually became constant. Although the addition of nitrifying microorganisms initially enhanced the pathogen growth rate, it caused the reduction process to become more efficient in the long-term. In addition to a constant concentration of 10,000 cells of N. winogradskyi per 1 g feces, a minimum amount of 3000 and 7000 cells of N. europaea per 1 g feces could completely remove E. coli and total coliforms, respectively, in less than 25 days. Increasing the amount of bio-seeds added can further reduce the time required for total pathogen removal.

Highlights

Lack of access to sustainable sanitation is a result of several technical, economic, and social challenges of the current sanitation systems, and can lead to improper sanitation practices, especially in low-income countries
Resource-oriented sanitation (ROS) systems are effective in controlling open defecation, there are concerns about their hygienic conditions, especially in the case of source-separated feces [7]
The enhancement observed in the growth phase might be due to the reduction of ammonia as a result of nitrification, as the presence of ammonia limits the growth of E. coli and some other coliforms [18,21]

Summary

Introduction

Lack of access to sustainable sanitation is a result of several technical, economic, and social challenges of the current sanitation systems, and can lead to improper sanitation practices (i.e., open defecation), especially in low-income countries. Resource-oriented sanitation (ROS) systems are a sustainable solution for sanitation challenges [1,5]. Such systems are based on source-separation of urine and feces and treating them onsite to be utilized as fertilizer [1,6]. ROS systems are effective in controlling open defecation, there are concerns about their hygienic conditions, especially in the case of source-separated feces [7]. Feces naturally contains pathogens [8] In this case, it is essential to have a hygienic treatment process for source-separated feces so that it may be utilized as fertilizer

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Discussion

Conclusion