Solar drying of wastewater sludge: A review

Review on Sludge Drying Process and Dryer in Solar Energy

“…As is shown in Figure 3, the covered sludge drying device [18], the covered sludge drying plant was constructed as a tunnel type greenhouse with a roof height of 2.5 m. It was completely enclosed by two walls, 10 mm thick transparent polycarbonate sheet with light transmittance of 80%. Indoor air can be disturbed by a fan, which can draw the saturated wet air in the room.…”

“…Each year the amount of sludge production is higher than the sewage sludge disposal in recent years in China. According to the statistics, China, European Union and United States have become the countries and regions of the large amount of sewage sludge production, such as 9.18 million tons sludge in 2009 in China, in 2010 1.17 million tons sludge in EU and 8 million tons sludge in USA [1][2]. The adverse impacts also have been paid world-wide attention with the rapid increasing of sewage sludge.…”

Forced Convective Drying of Wastewater Sludge with the Presentation of Exergy Analysis of the Dryer

“…The most important producers in the world are the European Union, China and U.S with an estimated total production of 11.7 million tons, 9.18 million tons and 8 million tons of dry solids, respectively (Bennamoun, Léonard and Arlabosse 2013;Bennamoun 2012a). Managing these huge quantities of sludge is presenting real issues.…”

“…Microwave and solar energy are the two available processes to dry the wastewater sludge using radiation. However, the two techniques are still under intensive research and few works are published in this area (Bennamoun 2012a;Léonard et al 2002;Salihoglu, Pinarli and Salihoglu 2007;Slim, Zoughaib and Clodic 2008;Mathioudakis et al 2013;Domingez et al 2004, Fang et al 2013. This method presents a complicated technology that slow down its use at the industrial scale.…”

“…It was found that origin of the sludge can also affect the experimental results (Léonard et al 2004). Commonly, application of convective drying of wastewater sludge, without prior determination of the optimum drying conditions can lead to have a nonefficient process, and a non-homogeneous dried material with formation of a skin and apparition of cracks (Bennamoun, Léonard and Arlabosse 2013, Bennamoun 2012a, Tao, Peng and Lee 2005, Tao, Peng and Lee 2008, Bennamoun, Crine and Léonard 2013, Bennamoun, Fraikin and Léonard 2014, Font, Gomez-Rico and Fullana 2011.…”