THESIS
2016
xviii, 121 pages : illustrations (some color) ; 30 cm
Abstract
Urine source separation offers good opportunities for nutrients recovery from human urine. A
previous study on seawater-catalyzed urine phosphorus recovery (SUPR
®) utilizing seawater
as precipitant recovered more than 95% of the phosphorus from fresh urine as struvite within 6
h, allowing efficient and economic phosphorus recovery from human urine. SUPR effluent,
containing limited phosphorus but abundant organic matters, ammonia, sulfate and inorganic
carbon, presents not only a challenge for conventional wastewater treatment but also a potential
resource for energy and nutrients recovery. Microbial fuel cell (MFC) is an emerging
technology capable of converting chemical energy from organic or inorganic matters into
electricity with electroactive bacteria as catalyst. This stud...[
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Urine source separation offers good opportunities for nutrients recovery from human urine. A
previous study on seawater-catalyzed urine phosphorus recovery (SUPR
®) utilizing seawater
as precipitant recovered more than 95% of the phosphorus from fresh urine as struvite within 6
h, allowing efficient and economic phosphorus recovery from human urine. SUPR effluent,
containing limited phosphorus but abundant organic matters, ammonia, sulfate and inorganic
carbon, presents not only a challenge for conventional wastewater treatment but also a potential
resource for energy and nutrients recovery. Microbial fuel cell (MFC) is an emerging
technology capable of converting chemical energy from organic or inorganic matters into
electricity with electroactive bacteria as catalyst. This study, is therefore, aimed at investigating
the feasibility and performance of treatment and energy recovery of SUPR effluent by MFC.
Besides high concentrations of nutrients, SUPR effluent also has high pH and salinity.
Feasibility tests showed that under such conditions, bicarbonate buffer had desirable buffering
effectiveness and was applicable in MFCs. Higher COD concentrations could result in higher
power outputs and substrate removal rates, while sulfate did not exert negative effects. Under
low organic substrate condition, high concentrations of ammonia significantly inhibited MFCs’ performance. Reducing ammonia concentration to a low level recovered the reactor from failure.
Under high organic substrate condition, deterioration caused by ammonia inhibition was
alleviated. The long-term operation of MFCs fed with synthetic high strength influent was
feasible and stable, with a maximum power density of 50.3 W/m
3, a COD removal rate of 454.0
g/m
3·d
-1 and an ammonia removal rate of 297.3 g N/m
3·d
-1 achieved. The continuous flow MFC
fed with the same influent presented a maximum power density of 17.2 W/m
3, a COD removal
of 43.2% and a total ammonia removal of 8.1% under 50 Ω after the optimization of external
resistance. The variation from synthetic to real effluent of SUPR was less influential on
continuous flow MFC than on batch mode MFCs, with a maximum power density of 22.0 W/m
3
obtained under batch mode and 14.2 W/m
3 obtained under continuous flow mode respectively.
Microbial community analysis revealed the dominance of Geoalkalibacter in the anodic
biofilms with the abundance varying with MFCs’ performance. Nitrifying bacteria, sulfate-reducing
bacteria and sulfur-oxidizing bacteria were all found but existed in low abundances.
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