Mexican Kisses : Habanera

https://digitalcommons.library.umaine.edu/mmb-ps/3020/thumbnail.jp

L\u27 Affinite : Valse lente

https://digitalcommons.library.umaine.edu/mmb-ps/2041/thumbnail.jp

Evaluation of the toxicity of contaminated sediments in the James River, Virginia

The Virginia State Water Control.Board, in cooperation with the Department of Chemical Oceanography of the Virginia Institute of Marine Science has recently conducted periodic chemical surveys of organic pollutants in the sediments of the upper James River. The August 1983 survey showed elevated concentrations of polycyclic aromatic hydrocarbons (PAH) at Stations ·4 and 7 (Figure 1 and Table 1). Although the reported concentrations were approximately one order· of magnitude lower than those reported in contaminated areas of the Elizabeth River, they were deemed high enough to warrant_ further study based on reported toxicity of Elizabeth River sediments (Hargis et al. 1984; Roberts et al. 1985). The purpose of the present-study was to determine if the sediments from these two sites were contaminated to the extent that they would be acutely toxic to fish

Semi-continuous anaerobic digestion of the marine micro-algal species I. galbana and D. salina grown under low and high sulphate conditions

Anaerobic digestion of marine micro-algae is a necessary step for their incorporation into the future portfolio of biofuels. Digestion of marine feedstocks can pose operational issues associated with competition and toxicity to the microbial consortium. This research examined the marine species Isochrysis galbana and Dunaliella salina continuously cultivated in a tubular photobioreactor using a low sulphate medium; D. salina was also cultivated with a high sulphate medium (4.7 g SO4 L−1). Harvested micro-algal biomass was used as feedstock in semi-continuous digestion with a salt-adapted inoculum. Stable operation was achieved with reasonable specific methane production (SMP)despite a short (15-day)retention time. SMP for I. galbana and D. salina was 0.244 and 0.233 L CH4 g−1 volatile solids (VS), with VS destruction 32% and 48% respectively. SMP ranged from 62 to 94% of the biochemical methane potential, but was only 32–49% of theoretical methane yields, indicating pre-treatments may be beneficial. Changing from low to high sulphate D. salina reduced the SMP to 0.193 L CH4 g−1 VS with a rise in H2S production. Under semi-continuous digestion, evidence for sulphide precipitation and oxidation was observed, which were not seen in batch analyses. This highlights the importance of conducting continuous rather than batch studies, to avoid overlooking these effects.</p

Comparative testing of energy yields from micro-algal biomass cultures processed via anaerobic digestion

Although digestion of micro-algal biomass was first suggested in the 1950s, there is still only limited information available for assessment of its potential. The research examined six laboratory-grown marine and freshwater micro-algae and two samples from large-scale cultivation systems. Biomass composition was characterised to allow prediction of potentially available energy using the Buswell equation, with calorific values as a benchmark for energy recovery. Biochemical methane potential tests were analysed using a pseudo-parallel first order model to estimate kinetic coefficients and proportions of readily-biodegradable carbon. Chemical composition was used to assess potential interferences from nitrogen and sulphur components. Volatile solids (VS) conversion to methane showed a broad range, from 0.161 to 0.435 L CH4 g?1 VS; while conversion of calorific value ranged from 26.4 to 79.2%. Methane productivity of laboratory-grown species was estimated from growth rate, measured by changes in optical density in batch culture, and biomass yield based on an assumed harvested solids content. Volumetric productivity was 0.04–0.08 L CH4 L?1 culture day?1, the highest from the marine species Thalassiosira pseudonana. Estimated methane productivity of the large-scale raceway was lower at 0.01 L CH4 L?1 day?1. The approach used offers a means of screening for methane productivity per unit of cultivation under standard conditions