Akifumi Ogino

Life cycle emissions and cost of producing electricity from coal, natural gas, and wood pellets in Ontario, Canada.

The use of coal is responsible for (1)/(5) of global greenhouse gas (GHG) emissions. Substitution of coal with biomass fuels is one of a limited set of near-term options to significantly reduce these emissions. We investigate, on a life cycle basis, 100% wood pellet firing and cofiring with coal in two coal generating stations (GS) in Ontario, Canada. GHG and criteria air pollutant emissions are compared with current coal and hypothetical natural gas combined cycle (NGCC) facilities. 100% pellet utilization provides the greatest GHG benefit on a kilowatt-hour basis, reducing emissions by 91% and 78% relative to coal and NGCC systems, respectively. Compared to coal, using 100% pellets reduces NO(x) emissions by 40-47% and SO(x) emissions by 76-81%. At

Continuous hydrogen production from glucose by using extreme thermophilic anaerobic microflora.

160/metric ton of pellets and

Rate determination and distribution of anammox activity in activated sludge treating swine wastewater.

7/GJ natural gas, either cofiring or NGCC provides the most cost-effective GHG mitigation (

Life cycle assessment of Japanese pig farming using low-protein diet supplemented with amino acids

70 and

Nitrogen removal by co-occurring methane oxidation, denitrification, aerobic ammonium oxidation, and anammox

47/metric ton of CO2 equivalent, respectively). The differences in coal price, electricity generation cost, and emissions at the two GS are responsible for the different options being preferred. A sensitivity analysis on fuel costs reveals considerable overlap in results for all options. A lower pellet price (

Simultaneous removal of colour, phosphorus and disinfection from treated wastewater using an agent synthesized from amorphous silica and hydrated lime

100/metric ton) results in a mitigation cost of

Life cycle assessment of animal feeds prepared from liquid food residues: a case study of rice-washing water.

34/metric ton of CO2 equivalent for 10% cofiring at one of the GS. The study results suggest that biomass utilization in coal GS should be considered for its potential to cost-effectively mitigate GHGs from coal-based electricity in the near term.

Mitigation of nitrous oxide (N2O) emission from swine wastewater treatment in an aerobic bioreactor packed with carbon fibers

Continuous hydrogen production from glucose at 75 degrees C was examined at HRTs of 0.67, 1, 2, and 3 d by using extreme thermophilic microflora, which consisted of several subspecies of Caldanaerobacter subterraneus. The maximum hydrogen yield of 3.32 mol-H2/mol-glucose degraded was obtained at the highest HRT, 3 d. Both the maximum volumetric and specific rates of hydrogen production (1.22 L-H2/L/d and 4.15 L-H2/g-VSS/d, respectively) were obtained at the lowest HRT, 0.67 d. A 16S rDNA analysis showed that the community structure of the microflora did not change at any of the HRTs.

Nitrate-Removal Activity of a Biofilm Attached to a Perlite Carrier under Continuous Aeration Conditions

This paper presents a quantitative investigation and analysis of anammox activity in sludge taken from biological swine wastewater treatment plants. An incubation experiment using a (15)N tracer technique showed anammox activity in sludge taken from 6 out of 13 plants with the rate ranging from 0.0036 micromol-N(2)/g-VSS/h to 3.1 micromol-N(2)/g-VSS/h, and in a biofilm with the highest activity at 25.8 micromol-N(2)/g-VSS/h. It is notable that 9 out of 11 sludges in which the pH was maintained between 6.6 and 8.1 retained anammox activity, while those with either a lower or higher pH did not. Moreover, anammox-positive sludge had a significantly higher concentration of NO(2)(-)-N plus NO(3)(-)-N than did anammox-negative sludge. A significant difference was not observed between anammox-positive and -negative sludge regarding BOD/NH(4)(+)-N in the influent, DO concentration in aeration tanks, and the concentrations of NH(4)(+)-N, free nitric acid, and free ammonia.

Swine wastewater treatment technology to reduce nitrous oxide emission by using an aerobic bioreactor packed with carbon fibres

Livestock production is indicated to be one of the major emitters of greenhouse gases (GHG), particularly methane (CH4) and nitrous oxide (N2O), around the globe, and the reduction of these emissions is an important goal. GHG emissions as well as other environmental impacts of two pig (Sus scrofa domesticus) farming systems, one using conventional diets (CNV) and the other using low-protein diets supplemented with crystalline amino acids (LOW), were therefore evaluated by comparative life cycle assessment (LCA) focusing on manure management and by cradle-to-farm gate LCA. The functional unit was defined as one marketed pig. For the comparative LCA of manure management, the CH4 and N2O emissions from manure management of CNV were set as a baseline, and the system boundary of LOW included the CH4 and N2O emissions from manure management, and changes in the GHG emissions from feed production including amino acid manufacturing, feed transport, and the materials and energy consumed in manure management. For the cradle-to-farm gate LCA of pig farming, the evaluated system included the processes of feed production including amino acid manufacturing for LOW, feed transport, animal housing including the biological activity of the animal, and manure management. The results of the comparative LCA showed that the GHG emissions from manure management of LOW were 20% less than those of CNV, and the GHG reduction rate of LOW compared to CNV was even greater in the case of a stricter target of effluent nitrogen content. The results of cradle-to-farm gate LCA showed that LOW had lower GHG emissions, acidification potential, eutrophication potential and overall environmental impact, and slightly larger energy consumption, than CNV. The sensitivity analysis showed that LOW still had less GHG emissions than CNV, even in the least preferable case assuming a 40% lower reduction rate of nitrogen excretion.