JOURNAL OF THE AIR & WASTE MANAGEMENT ASSOCIATION, cilt.71, sa.3, ss.293-303, 2021 (SCI-Expanded)
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.