Purpose – To determine the influence of alkali components (especially Ca compounds) on the hematite phase formation during thermal processing of sewage sludge and the observation of transformations proceeding at different ratios of Ca to FePO 4 . Design/methodology/approach – The model compositions were heated to temperatures of 600°C and 950°C, then calcined within 3 hours without mixing. Cooled products were subjected chemical analysis regarding the content of phosphorus that was soluble in cold water, 0.4 per cent HCl, 2 percent citric acid and aqua regia as well as crystallographic identification. Findings – On calcining at 600°C, CaO reacts with FePO 4 , forming hydroxylapatite. The hematite phase which is insoluble in mineral acids crystallizes above 600°C. Further increasing the calcining temperature leads to transformations resulting in Ca 9 Fe(PO 4 ) 7 and hematite formation. Molar ratios of CaO to FePO 4 · 2H 2 O of 1.0 and 2.0 lead to hematite phase formation and increase the availability of phosphorus compounds (characterized by phosphate solubility in 0.4 percent HCl and 2 percent citric acid) in compositions after calcining. Practical implications – The addition of CaO to sewage sludge before the combustion process should be beneficial from the point of view of further extraction of phosphorus compounds from the ash obtained. Suitable CaO addition favours iron binding into the hematite phase and raises the solubility of the phosphorus compounds in the ashes formed. Originality/value – This paper is a new source of information which complements existing knowledge about phosphorus recovery from sewage sludge.
Management of Environmental Quality: An International Journal – Emerald Publishing
Published: Dec 1, 2005
Keywords: Waste management; Sewage
It’s your single place to instantly
discover and read the research
that matters to you.
Enjoy affordable access to
over 18 million articles from more than
15,000 peer-reviewed journals.
All for just $49/month
Query the DeepDyve database, plus search all of PubMed and Google Scholar seamlessly
Save any article or search result from DeepDyve, PubMed, and Google Scholar... all in one place.
Get unlimited, online access to over 18 million full-text articles from more than 15,000 scientific journals.
Read from thousands of the leading scholarly journals from SpringerNature, Elsevier, Wiley-Blackwell, Oxford University Press and more.
All the latest content is available, no embargo periods.
“Hi guys, I cannot tell you how much I love this resource. Incredible. I really believe you've hit the nail on the head with this site in regards to solving the research-purchase issue.”Daniel C.
“Whoa! It’s like Spotify but for academic articles.”@Phil_Robichaud
“I must say, @deepdyve is a fabulous solution to the independent researcher's problem of #access to #information.”@deepthiw
“My last article couldn't be possible without the platform @deepdyve that makes journal papers cheaper.”@JoseServera