Laboratory and Field Evaluation of the Controlled Condensation System for S03 Measurements in Flue Gas Streams

The study reported by this paper involves the use of the Controlled Condensation System (Goksoyr/Ross Coil) for flue gas S0₃ measurements in both the laboratory and the field, under low and high mass loadings. The Controlled Condensation System cools the flue gas to below the dewpoint of H₂S0₄ but above the H₂0 dewpoint. The resulting aerosol is collected either on the coil walls or on the back-up glass frit. The laboratory recovery of the H₂S0₄ in streams of varying S0₂, H₂0, and H₂S0₄ content was found to be 95 ± 6%. A new quartz filter holder was designed to meet the filtration problems encountered in collecting S0₃ from particle laden flue gas streams. This quartz system, when heated to above 250°C, quantitatively passed the H₂S0₄ into the condensation coil. Later studies with this filter system preloaded with fly ash equivalent to a mass loading of 1.3 g/m³ yielded a 80-85% recovery of H₂S0₄. The laboratory system was simultaneously tested at a 150 megawatt, pulverized coal-fired power plant prior to and after a wet limestone FGD. The inlet grain loading to the FGD ranged from 0.06 g/m³ to 11.4 g/m³ with S0₂ concentrations as high as 4000 ppm. The average inlet H₂S0₄ value was 8.3 ppm and the outlet from the FGD was 3.1 ppm. The source fluctuation value was determined to be ±65%.     

Changes in microbiological metabolism under chemical stress

Chemical stress may alter microbiological metabolism and this, in turn, may affect the natural and engineered systems where these organisms function. The impact of chemical stress on microbiological metabolism was investigated using model chemicals 2,4-dinitrophenol (DNP), pentachlorophenol (PCP), and N-ethylmaleimide (NEM). Biological activity of Pseudomonas aeruginosa was measured in batch systems, with and without stressors at sub-lethal concentrations. Stressor DNP, between 49 and 140 mg l(-1), and PCP, at 15 and 38 mg l(-1), caused decreases in biomass growth yields, but did not inhibit substrate utilization rates. These effects increased with stressor concentrations, showing as much as a 10% yield reduction at the highest DNP concentration. This suggests that a portion of carbon and energy resources are diverted from growth and used in stress management and protection. Stressor DNP, between 300 and 700 mg l(-1), and PCP at 85 mg l(-1) caused decreases in growth yields and substrate utilization rates. This suggests an inhibition of both anabolism and catabolism. Stressor NEM was the most potent, inhibiting biological activity at concentrations as low as 2.7 mg l(-1). These findings will ultimately be useful in better monitoring and management of biological treatment operations and contaminated natural systems.     

Analysis of marine sediment, water and biota for selected organic pollutants

The concentrations of various organic pollutants (benzo(a)pyrene (BaP), hexachlorobenzene (HCB) and pentachlorophenol (PCP)) were determined in samples of water, sediment and biota (flounder, killifish, shrimp, crabs and squid) from San Luis Pass, Texas. Sediment was also analyzed for polychlorinated biphenyls (PCBs), phthalic acid esters (PAEs) and various pesticides. Only PCP was detectable in water. In sediment, the relative concentrations were PAEs > BaP > (PCBs HCB) > PCP. In biota, BaP was not detectable in any animal; HCB was highest in crabs and PCP was highest in all others (flounder, killifish, shrimp and squid). The relative concentrations of HCB and PCP were different in the different organisms. The differences between the relative concentrations in the biota and in sediment are discussed. The results of this study are compared to values measured at other sites. This study is part of a larger effort to identify and quantitate pollutants in various Texas estuaries and to serve as a basis for monitoring marine pollution.     

Mineral reserves: Projected lifetimes and security of supply

This article analyses the lifetimes of reserves of three dozen important minerals. Despite the high rate of their extraction in the past 30 years, the recorded reserves of these non-renewable materials were higher in 1981 than in 1950 and they seem to meet foreseeable demand for a long time to come, as indicated by the estimated static lifetime for each of the minerals covered. The dynamic nature of ‘reserves’ is emphasized: further exploration and scientific and technological advance will add to the present proven reserves, and at a higher price further resources will be ‘upgraded’ into commercially exploitable reserves. Apparent long-term security can be disturbed by natural disasters, political events or other factors, especially in the case of minerals whose reserves and production are highly concentrated in one country. However, any such interruption in the continuity of supply is likely to be short-lived.     

Different patterns of growth and nitrogen uptake in two clones of marineSynechococcus spp.

We grew marineSynechococcus Clones WH7803 and WH8018 at 150µE m^–2 s^–1 in dilute batch cultures with NH ₄ ⁺ as the limiting nutrient. The maximal uptake capacities for NH ₄ ⁺ and NO ₃ ^- were measured in frequent experiments during log and stationary phases of growth. Clone WH7803, originally isolated from oceanic waters, had a specific uptake rate of NH ₄ ⁺ that approximated the maximum (log phase) specific growth rate (ca ~ 0.025 h^–1). NO ₃ ^- uptake was observed only after nitrogen in the media was depleted; the NO ₃ ^– uptake capacity was ca 12% the capacity for NH ₄ ⁺ uptake throughout the nitrogen depleted period. Growth was arrested upon nitrogen depletion, but resumed soon after reinoculation into fresh media, even after 5 d of starvation. Clone WH8018, originally isolated from coastal waters, revealed a five-fold enhancement in the NH ₄ ⁺ uptake rate relative to growth rate at the time of nitrogen depletion. As nitrogen starvation proceeded, this enhancement was reduced. This clone, too, was able to take up NO ₃ ^- once nitrogen in the media was depleted, but only after ca 20 h. Growth continued for a limited period during nitrogen depletion, but nitrogen-starved cells were slow to recover upon reinoculation into fresh media. We speculate that clonal differences may reflect differences in the molecular regulation of nitrogen assimilation.     

Full-scale class A biosolids production by two-stage continuous-batch thermophilic anaerobic digestion at the hyperion treatment plant, Los Angeles, California.

The City of Los Angeles Hyperion Treatment Plant (HTP) (California) converted its anaerobic digesters to thermophilic operation to produce Class A biosolids. Phase IV tests demonstrated compliance of a two-stage, continuous-batch process with Alternative 1 of U.S. Environmental Protection Agency 40 CFR Part 503 (U.S. EPA, 1993), which defines the time-temperature requirement for batch treatment (T > or = 56.3 degrees C at 16-h holding). Fecal coliforms, Salmonella sp., viable helminth ova, and enteric viruses were not detected in biosolids in the postdigestion train, including the truck-loading facility and the farm for land application as the last points of plant control where compliance is to be demonstrated. The same results were achieved during Phase V tests, after lowering the second-stage holding temperature to 52.6 degrees C to reduce the elevated methyl mercaptan production that was observed during Phase IV. Hence, the Phase V process complied with Alternative 3 of 40 CFR Part 503. Currently, HTP operates its digesters under the same conditions as tested in Phase V. In 2003, monthly monitoring of the biosolids at the truck-loading facility and the farm for land application demonstrated consistent compliance with Alternative 3.     

Suppression of testicular steroidogenesis in rats by the organochlorine insecticide Aldrin

Treatment with Aldrin, an organochlorine insecticide, for 13 and 26 days caused suppression of 3beta-hydroxysteroid dehydrogenase (3beta-HSD) and 17beta-hydroxysteroid dehydrogenase (17beta-HSD) activities, along with accumulation of cholesterol in the testicular tissues of adult rats. The same treatment also resulted in a reduction in the nuclear diameter of Leydig cells (LCND) and diameter of seminiferous tubules. A decrease in the weight of testes, seminal vesicles and ventral prostate was also noted. HCG administration in the long-term (26 days) treatment restored the steroidogenic enzymes activity and the nuclear diameter of the Leydig cells. It also reduced the accumulation of tissue cholesterol towards the vehicle-injected controls. The inhibition of steroidogenesis in the testes possibly reflects a decrease in pituitary gonadotrophin release after the treatment with Aldrin.     

Evaluating a Canadian regional air quality model using ground-based observations in north-eastern Canada and United States

The simulated concentrations from a numerical 3-dimensional regional air quality model (MC2AQ) are compared to those of ground-based observations in north-eastern Canada and the United States. The model has oxidant chemistry for both inorganic and organic species and deposition routines driven online by a mesoscale compressible community meteorological model (MC2). A standard emission inventory of anthropogenic, natural and biogenic sources for the year 1990 for 21 atmospheric trace species was used in the simulation. The model was run for July 1999, because of the occurrence of a high ozone episode and the availability of the monitoring data for surface O3, SO2, NO, NO2 and NOx. The comparisons during the episode show that the model performs quite well for predicting concentrations and diurnal variations of the surface ozone. The predictions for other gaseous species show some discrepancies with observations, but they are consistent with the results from other models evaluated in the literature. The uncertainties in the emission inventory for these species might be the main causes of the discrepancies. Further studies are needed to improve the predictability of SO and NOx, especially as the model is developed to include particulate matter formation as a result of these gaseous precursors.