Faecal Sludge Quantification, Characterization and Treatment Objectives.

Abstract

The first step in designing faecal sludge (FS) treatment technologies that will meet defined treatment objectives is to quantify and characterise the FS to be treated. Ideally, this should be carried out as part of the Feasibility Study, but is however difficult due to the lack of standardised methodologies for the quantification or characterisation of FS. This complicates the design of adequate and appropriate systems. The quantities of FS generated and the typical FS characteristics are difficult to determine due the variety of onsite sanitation technologies in use, such as pit latrines, public ablution blocks, septic tanks, aqua privies, and dry toilets. In many cities, a mixture of these technologies often exist side-by-side, and there is generally a prevalence of different technologies in different geographical regions. For example, in Bangkok, Thailand; Dakar, Senegal; Hanoi, Vietnam, and Buenos Aires, Argentina septic tanks are the predominant form of onsite FS containment technology; whereas in Kampala, Uganda; Nairobi, Kenya; and Dar es Salaam, Tanzania, various types of pit latrines are the predominant form of FS containment technology (e.g. improved and unimproved private latrines, shared and public latrines). The quantity and characteristics of FS also depends on the design and construction of the sanitation technology, how the technology is used, how the FS is collected, and the frequency of collection. All of these variables results in a significant difference in FS characteristics within cities, and within the same type of containment technology in different locations. This chapter therefore aims to provide an overview of the current state of knowledge on the quantification and characterisation of FS, to identify gaps in the existing body of knowledge, and to put these into perspective with regards to FS treatment objectives.