Electrodisinfection of real swine wastewater for water reuse

Environmental Chemistry Letters - Swine production generates large volumes of wastewater, rich in organic matter, nutrients and pathogens. Electrodisinfection is used to remove organic matter and...     

SCR performance on a hydrogen reformer furnace

In late 1993, Air Products and Chemicals, Inc. began operating a new steam-methane reformer at the Tosco Refining Co.'s Avon refinery in Martinez, CA, to provide hydrogen and steam to the refinery under a long-term supply agreement. The hydrogen plant--owned, operated, and maintained by Air Products--includes a selective catalytic reduction (SCR) unit on the reformer-furnace flue gas for environmental control. SCR is a commercially proven process capable of abating emissions of nitrogen oxides (NOx) to extremely low levels; however, documented experience in a refinery setting has been limited. This paper discusses performance of the SCR, primarily during its first two years of operation; it incorporates theory and prior research findings sufficient to understand the relationship between key system variables and SCR performance. Test results demonstrate that NOx, ammonia (NH3) slip, and carbon monoxide (CO) emissions are in compliance with permit limits. NOx removal efficiency is nearly linear with the inlet NH3:NOx molar ratio up to almost 90% NOx conversion, where ammonia slip begins to rise steeply. The stoichiometric reaction ratio of NH3 to NOx is close to the theoretical 1.0. Catalyst life is estimated at four years, in line with published figures for SCR catalysts in clean-gas service.     

A case study on project-level CO2 mitigation costs in industrialised countries: the Climate Cent Foundation in Switzerland

This paper analyses CO₂ emissions reduction costs based on project data from the Climate Cent Foundation (CCF), a climate policy instrument in Switzerland. Four conclusions are drawn. First, for the projects investigated, the CCF on average pays €63/ton. Due to the Kyoto Protocol, the CCF buys reductions only until 2012. This cut-off increases reported per ton reduction costs, as the additional lifetime project costs are set in relation to reductions only until 2012, rather than to reductions realised over the whole lifetime. Lifetime reduction costs are €45/t. Second, correlation between CCF's payments and lifetime reduction costs per ton is low. Projects with low per ton reduction costs should thus be identified based on lifetime per ton reduction costs. Third, the wide range of project costs per ton observed casts doubts on the widely used identification of the merit order of reduction measures based on average per ton costs for technology types. Finally, the CCF covers only a fraction of additional reduction costs. Decisions to take reduction efforts thus depend on additional, non-observable and/or non-economic motives. Any generalisation of results has to consider that this analysis is based on prospective costs of a sub-sample of projects in Switzerland.     

The economics of harem maintenance in the sac-winged bat, Saccopteryx bilineata (Emballonuridae)

Saccopteryx bilineata has a polygynous mating system in which males defend females in a harem territory. Harem defense and courtship include energetically costly flight maneuvers and hovering displays. We tested if (1) harem males have a greater field metabolic rate than non-harem males or females and if (2) the field metabolic rate of harem males is correlated with the number of females in a harem territory. We measured the energy budget in 32 S. bilineata with the doubly labeled water method and compared these estimates with behavioral observations in the daytime roost. Among adult bats, field metabolic rate varied with body mass by an exponent of approximately two. We found no significant difference in field metabolic rate or mass-specific field metabolic rate between harem and non-harem males. The mass-specific field metabolic rate of harem-males increased with harem size. The latter finding supports the hypothesis that the energy costs of courtship display and territorial defense influence the energy budget of harem males. Overall, field metabolic rates of S. bilineata were lower than those of similarly sized bats of the temperate zone and only 2.3 times above the basal metabolic rate recorded for this species. We suggest that male S. bilineata did not take advantage of their metabolic capacity because a prudent allocation of energy to activities of harem maintenance is an adaptive strategy for males in this mating system.