Title:
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Dairy farm waste treatment by using microbial fuel cells (MFCs) and pyrolysis
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There is an estimated 20 million tonnes of slurry produced by 2 million dairy
cows each year in the UK. The suitable treatment of dairy farm waste could
address both environmental concerns and energy security. In this study, dairy
farm waste was separated into liquid slurry and solid residues, and treated by
Microbial Fuel Cells (MFCs) and pyrolysis to minimise the environmental
impact and produce bio-energy products. The effective treatment efficiencies
were achieved by using incubated slurry mixed with fresh slurry as the anodic
solution in MFC reactors. Comparing MFCs with anaerobic digestion (AD)
under anaerobic conditions, the highest COD removal efficiency (71 %) and
total nitrogen removal efficiency (17%) were obtained in MFCs operated at
25°C and 30°C for 30 days, respectively. A higher working temperature (35°C)
was found to benefit the degradation of total suspended solids (78%). The
MFCs were also found to be effective for nutrient-rich solution treatment.
Furthermore, the anodic solutions were pre-treated by BI-CHEM manure
degrader, which could significantly benefit the bio-degradation of the TSS,
COD and nitrogen removal and enhance power generation. The dairy farm
solid waste was treated by pyrolysis to produce bio-oil and biochar. The
highest oil yield of 51 % was obtained at 500°C. For a mixed feedstock of solid
waste and bone chips (up to 15%), results suggested that co-pyrolysis could
improve the biochar production yield and bio-oil quality. The optimal
concentration of bone chips for oil yield was found to be 1 O~ and the optimal
temperature was 500°C. The conversion technologies for dairy farm waste are
discussed based on the results of the experiments in this study. The potential
energy recovery of the whole treatment was 61%.
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