anaerobically-digested-sludge bio-drying
The ADS was collected from a 12 L mesophilic anaerobic digestion reactor, which was operated at 35±1 oC using batch mode in the laboratory condition until the biogas stopped (about 25 days) according to the reference (Li et al., 2014). The VS removal rate, average biogas production and methane content was 44.3%, 0.854 L gVS-1removal and 56.2% to 67.3%, implying that the reactor performance is normal and representative. The raw sludge for the anaerobic digestion reactor were collected from the Anting WWTP in Shanghai, China. WR using as bulking materials were collected from a flour mill factory in Shanghai suburb, China.  Bio-drying experiments were performed in insulated reactors composed of insulated polystyrene foam material (Fig. 1). The lab-scale reactors were designed according to the references (Chowdhury et al., 2014; Ge et al., 2014), and 45 cm in inner height, 25 cm in inner length and 18 cm in inner width, and 45 mm of wall thickness, with an effective volume of approximately 20 L. A perforated baffle with 2-mm mesh was fixed above the bottom to support the material and facilitate aeration. An air inlet was installed at the bottom and the air outlet located on the top. The aeration rate was 250 L h-1, with 10 min run/20 min stop during the entire bio-drying process. The ratio of ADS/WR was 5:1 and chosen on the basis of the references (Banegas et al., 2007; Zhao et al., 2011; Zhao et al., 2010). Total weight of the feedstock was about 4.2 kg. The material was turned every 3 days to homogenize the materials. All the experiments were duplicated. The experimental period was 18 days.