Vacuum-assisted thermal drying of wastewater treatment sludge

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Avşar Y. , Saral A. , İlhan F. , Akyüz B., Gönüllü M. T.

JOURNAL OF THE AIR & WASTE MANAGEMENT ASSOCIATION, vol.71, no.3, pp.293-303, 2021 (Journal Indexed in SCI Expanded)

  • Publication Type: Article / Article
  • Volume: 71 Issue: 3
  • Publication Date: 2021
  • Doi Number: 10.1080/10962247.2020.1832622
  • Page Numbers: pp.293-303


Sludge drying is one of the main problems of wastewater treatment plants. It is very important to facilitate the

drying process in terms of drying efficiency, time duration and cost of the processes, so that transportation and

dumping of sludge will accordingly be realized effectively. In this study, vacuum assisted thermal drying was

studied. Under vacuum conditions, water content of the sludge was examined easier than at atmospheric pressure in

the drying process. For this reason, time, temperature and sludge mass surface area on drying efficiency were

evaluated under two different pressure levels such as 30 mbar and 1000 mbar in this study. To optimize these

parameters, the Response Surface Methodology approach was utilized. Results showed that the effect of vacuum

condition on sludge drying was remarkable to get at least 65% of solid material ratio in sludge which is the lowest

limit value on landfilling legislation in Turkey. Data obtained from the study shows that especially at high

temperatures, contribution on sludge drying of vacuum condition is more effective in terms of drying time. Smaller

sludge surface area is also found more significant on vacuum drying.