Thermophilic anaerobic digestion of coffee grounds with and without waste activated sludge as co-substrate using a submerged AnMBR: System amendments and membrane performance

Comprehensive monitoring and management of a long-term thermophilic CSTR treating coffee grounds, coffee liquid, milk waste, and municipal sludge

“…Researches on AD of coffee grounds showed a successful result using batch experiment in which biogas conversion of 60% (Oi et al, 1981), 84% (Kostenberg and Marchaim, 1993), and 69% (Qiao et al, 2013a) were obtained under mesophilic and thermophilic condition, respectively. However, long-term continuous experiments showed process instability due to many factors.…”

“…2. This period is shorter compared to the previous experiment using AnMBR for treating coffee grounds and sludge which required 120 days to achieve steady state condition (Qiao et al, 2013a). Laboratory and field-scale applications indicate that start-up periods ranging from three weeks to one year (Poggi-Valardo et al, 1997;Biey et al, 2003).…”

“…During the first 17 days, the reactor was fed with OLR 4.0 kg-COD/m 3 /d and subsequently it was fed with OLR 8.2 kg-COD/m 3 /d for the rest of operation time ($38 days). The substrate used for feeding within this period was supplemented with microelements (adopted from the previous research, Qiao et al, 2013a) and Na 2 SO 4 in order to improve the reactor performance and increase the process stability, especially through the propionic acid degradation. Supplementation of sulfate aimed to stimulate the growth of sulfate-reducing bacteria (SRB) which could utilize propionic acid as electron donor (Harmsen et al, 1995).…”

“…aromatic 2 compounds, polyphenols, and alkaloids could be minimized by mixing different substrates (Braun and Wellinger, 2003). Mixing coffee grounds with sludge (85:15) has been reported to result in a more stable digestion process compared to digestion of sole coffee grounds, while 15% sludge (dry basis) in the feedstock was sufficient to provide a reactor with micro elements (Qiao et al, 2013a). Another important factor about the anaerobic digestion of coffee grounds is the application of the thermophilic temperature.…”

Multiple effects of trace elements on methanogenesis in a two-phase anaerobic membrane bioreactor treating starch wastewater

“…Three dosages (0.02, 2 and 200 mg L −1 ) were used in this study (Qiang et al 2012;Qiao et al 2013) to investigate the multiple effects of TE supplementation beyond stabilization (Table 2), and mixed supplementation of the three order levels was tested. Other two groups were also studied including a recovery group (TE31) from the inhibition group TE30 and a group based on TE requirements (TE40).…”