Direct thermal drying of sludge using flue gas and its environmental benefits

ABSTRACT

This paper reported a sludge disposal technology that uses 100–200°C flue gas to dry sludge through a systematic analysis of the relationship between sludge drying rate/temperature and moisture content. Using this direct drying technology, the sludge drying capacity for the dryer tested can reach 86 tons d⁻¹ at 160°C. The experimental results show this technology can also preserve 95% calorific value in the sludge, and remove 16–42% PM_2.5, 26–55% PM₁₀, and 7–25% SO₂ from the flue gas. The exhaust gas from the sludge dryer consists mainly of chain alkanes while benzenes only 9.65% when dried at 100°C.

KEYWORDS:

• Drying
• PM_2.5 and PM₁₀
• sewage sludge
• SO₂

Additional information

Funding

This research is supported by National Program on Key Technology Research and Development (grant number: 2012BAC15B03), Key Technologies R&D Program of Zhejiang Province (grant number: 2005C13005), and Key Scientific and Technological Program of Zhejiang Province (grant number: 2005C23051). CL also acknowledges the financial support from Shenzhen Science and Technology Innovation Committee (ZDSYS201602261932201). Additional Support was provided by Southern University of Science and Technology (G012966001).