title: Thermophilic anaerobic digestion of coffee grounds with and without waste activated sludge as co-substrate using a submerged AnMBR: system amendments and membrane performance.
abstract: Coffee grounds are deemed to be difficult for degradation by thermophilic anaerobic process. In this research, a 7 L AnMBR accepting coffee grounds was operated for 82 days and failed with pH dropping to 6.6. The deficiency of micronutrients in the reactor was identified. The system was recovered by supplying micronutrient, pH adjustment and influent ceasing for 22 days. In the subsequent 160 days of co-digestion experiment, waste activated sludge (15% in the mixture) was mixed into coffee grounds. The COD conversion efficiency of 67.4% was achieved under OLR of 11.1 kg-COD/m(3) d and HRT of 20 days. Tannins was identified affecting protein degradation by a batch experiment. Quantitative supplements of NH4HCO3 (0.12 g-N/g-TSin) were effective to maintain alkalinity and pH. The solid concentration in the AnMBR reached 75 g/L, but it did not significantly affect membrane filtration under a flux of 5.1 L/m(2) h. Soluble carbohydrate, lipid and protein were partially retained by the membrane.
authors.affiliation: State Key Laboratory of Heavy Oil Processing, China University of Petroleum, PR China; Department of Civil and Environmental Engineering, Graduate School of Engineering, Tohoku University, Japan.
authors.forename: Wei
authors.initials: W
authors.lastname: Qiao
authors.forename: Kazuyuki
authors.initials: K
authors.lastname: Takayanagi
authors.forename: Mohammad
authors.initials: M
authors.lastname: Shofie
authors.forename: Qigui
authors.initials: Q
authors.lastname: Niu
authors.forename: Han Qing
authors.initials: HQ
authors.lastname: Yu
authors.forename: Yu-You
authors.initials: YY
authors.lastname: Li
mesh_terms: D000641:Ammonia / Q000032:analysis; D000693:Anaerobiosis / Q000187:drug effects; D001673:Biodegradation, Environmental / Q000187:drug effects; D057919:Biological Oxygen Demand Analysis; D019149:Bioreactors; D002241:Carbohydrates / Q000032:analysis; D003069:Coffee / Q000737:chemistry*; D005227:Fatty Acids / Q000032:analysis; D005374:Filtration; D008567:Membranes, Artificial; D011506:Proteins / Q000032:analysis; D059748:Proteolysis / Q000187:drug effects; D012037:Refuse Disposal / Q000295:instrumentation* / Q000379:methods*; D012722:Sewage / Q000737:chemistry*; D012995:Solubility / Q000187:drug effects; D013634:Tannins / Q000494:pharmacology; D013696:Temperature; D014866:Waste Products / Q000032:analysis*
chemical_list: D002241:Carbohydrates; D003069:Coffee; D005227:Fatty Acids; D008567:Membranes, Artificial; D011506:Proteins; D012722:Sewage; D013634:Tannins; D014866:Waste Products; D000641:Ammonia
keywords: Anaerobic co-digestion; Coffee grounds; Membrane reactor; Sludge; Thermophilic