Peer Review Report For: Chemical characterization of faecal sludge in the Kumasi metropolis, Ghana [version 1; peer review: 1 approved, 1 approved with reservations]

Background: Faecal sludge (FS) represents a huge resource, which when tapped and made use properly can be of great benefit to many. However, the key to tapping this resource lies in proper characterisation, in order to make known the constituents and thereby determine the end-use. Methods: Three sources of FS from 43 communities in the Kumasi metropolis of Ghana were characterised in terms of their total solids content, chemical oxygen demand (COD), pH, nitrogen, phosphorous and lipid contents. FS from pit latrines, public septage and private septage were analysed. Results: On average, lipid content was found to be in the range of 8.82 – 9.66% of dry FS depending on the source of FS. Total solids were between 0.79 and 4.68%, while the COD was between 9495 and 45611mg/L. Phosphorus content was in the range of 137 – 520mg/L, while nitrogen was 649 – 4479mg/L. Most FS samples were generally alkaline in nature. Conclusions: These results are amongst the first long-term characterization efforts for FS in terms of conventional and non-conventional characteristics, tailored towards typical treatment and novel resource recovery options, respectively.