Off-Site Lime Stabilisation as an Option to Treat Pit Latrine Faecal Sludge for Emergency and Existing On-Site Sanitation Systems

Wilson Greya,Grover Mamani,Jan Spit,Bernard Thole,Catherine Anderson,Flavius Kamwani

doi:10.1155/2016/2717304

Abstract

Off-site lime stabilisation for treating faecal sludge was assessed by undertaking small-scale (35 L) and large-scale (600 L) field trials in Blantyre, Malawi. Hydrated lime was dosed to maintain pH 10, pH 10.5, pH 11, pH 11.5, and pH 12 depending on the buffer capacity of the faecal sludge in the four replica small-scale field trials. Significant reduction of E. coli to below the detection limit of 104 CFU/100 mL within 1 hour of treatment was reported for pH > 11. Based on the small-scale findings, large-scale field trials were conducted and greater than 3 log removal of E. coli was observed under pH 12 conditions. Therefore, based on the study, off-site lime stabilisation by dosing lime in the range of 10–35% w/w (dry solid basis), depending on the buffer capacity and solids content of the sludge to maintain pH > 11, can be used to sanitise faecal sludge during emergencies, as well as for existing on-site sanitation systems.

Highlights

In emergency situations water and sanitation are critical determinants for human survival [1]
Lime dosages are given in kilograms as well as a percentage based on dry solids (% kg lime/kg dry sludge) required to achieve respective pH conditions in each reactor
The works of Farzadkia et al suggested that 0.265 g hydrated lime added per gram of sludge is effective to stabilise wastewater sludge [8, 9]

Summary

Introduction

In emergency situations water and sanitation are critical determinants for human survival [1]. Great health risks can arise during these situations due to inadequate or unsafe excreta disposal This is especially the case in camps and urban areas following damage to existing systems, or when parts of cities receive large numbers of displaced or homeless people, thereby putting more pressure on facilities that may already be under strain [1]. In 2009, floods in the Lower Shire caused a cholera outbreak from which more than 1000 deaths were reported in Malawi (Lower Shire Valley) in addition to many more deaths on the Mozambique side of the Shire River [3]. In all these scenarios, floods destroyed homes and farms and compromised access to clean water and sanitation infrastructure.

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Results

Conclusion