title: Digestion of sand-laden manure slurry in an upflow anaerobic solids removal (UASR) digester.
abstract: Studies on the performance of a laboratory scale upflow anaerobic solids removal (UASR) digester were carried out using sand-laden cow manure slurries having total solids (TS) concentration as 50 and 100 g/l. Hydraulic retention time (HRT) was maintained as 32.4 days, which resulted in the volatile solids (VS) loading rates of 1 and 1.64 g/l d. The UASR system was designed to remove sand from the manure slurry, while anaerobically digesting biodegradable solids inside a single reactor. To enhance the contact of microorganisms and substrate, the liquor from the top of the digester was recirculated through the bed of settled solids at its bottom. Volatile solids reduction through this process was observed to be 62% and 68% in the case of feed slurries having TS concentration as 50 and 100 g/l (referred in the text as 5% and 10% feed slurries), respectively. The methane production rates were observed to be 0.22 and 0.38 l/l d, while methane yield was 0.21 and 0.27 l CH(4)/g VS loaded, for 5% and 10% feed slurries, respectively. This indicates that the increase in the VS loading had a positive impact on methane production rate and methane yield. It would be of interest to study the performance of a UASR digester at higher solids loadings and with longer solids retention times. Nonetheless, the presented study showed that sand-laden manure slurries can be successfully digested in a UASR digester producing methane energy equivalent to 4 kW h per m(3) of digester volume per day.
authors.affiliation: Department of Energy Environmental and Chemical Engineering, Washington University, St. Louis, MO 63130, USA. kkarim@uark.edu
authors.forename: Khursheed
authors.initials: K
authors.lastname: Karim
authors.forename: Rebecca
authors.initials: R
authors.lastname: Hoffmann
authors.forename: M H
authors.initials: MH
authors.lastname: Al-Dahhan
mesh_terms: D000693:Anaerobiosis; D001711:Biotransformation; D008372:Manure; D008697:Methane / Q000096:biosynthesis; D012822:Silicon Dioxide
chemical_list: D008372:Manure; D012822:Silicon Dioxide; D008697:Methane