No abstract

No abstract

No abstract

Two sub‐bituminous coals, a bituminous coal and a reject coal of 55% ash were gasified with steam and air in a 0.31‐m dia. reactor operated in the fluidized and spouted bed modes. Inert beds of 1.1 mm dia. Ottawa sand and 2.1 mm dia. gravel provided stable fluidization and spouting respectively, at superficial velocities in the range 1.3–1.6 m/s. Coals of 1.19–3.36 mm diameter were fed to the gasifier at rates up to 45 kg/h and a range of air/coal ratios. For a given coal, results in the two systems were basically similar, although differences in gas heating value, gas yield and thermal efficiency were noted for some coals.

of the Strouhal number." Morrow and Kline (1971) obtained the following correlation for the Strouhal number, St, for circular cylinders in flow of water St = 0.187 -4.15/Re (50 < Re < 150) which is 7-9% below Roshko's correlation measured in air St = 0.212 -4.5/Re (50 < Re < 150)where both St and the Reynolds number, Re, are based on the cylinder diameter (Roshko, 1953). Klemp and Acrivos (1971) made a flow visualization study of vortex shedding from circular cylinders using air bubbles in oil. Morrow and Kline have noted that there is better agreement between correlations for water and oil than for either liquid with the air correlations of Roshko (1953) or the more recent one of Tritton (1959). Thus, there is a yet unclear distinction between the Strouhal number in liquids and that in air. Unfortunately, these studies ivere not being extended to higher Reynolds numbers to check if the asymptotic value of St = 0.21 for Re > 500 is the same for both air and liquids. The data of Liu, et al. (1970), indicate a lower St in water flow for Re ~7000. To the authors' knowledge there has not been a systematic study of the influence of stream turbulence on the Strouhal number of blunt bodies in liquid flow.

No abstract

The association of dyes with health related problems is not a new phenomenon. The effectiveness of carbon adsorption for dye removal from textile effluent has made it an ideal alternative to other expensive treatment methods. The preparation of activated carbon from agricultural waste could increase economic return and reduce pollution. Cassava peel has been used as a raw material to produce activated carbon. The study investigates the removal of malachite green dye from its aqueous solution. The effects of condition such as adsorbent dosage, initial dye concentration, pH and contact time were studied. The adsorption capacity was demonstrated as a function of time for malachite green from aqueous solution by the prepared activated carbon. The results showed that as the amount of the adsorbent was increased, the percentage of dye removal increased accordingly. Higher adsorption percentages were observed at lower concentrations of malachite green dye. Silver nitrate treated cassava peel showed a better performance compared to Sulphuric acid treated and raw carbons, thus making it an interesting option for dye removal textile effluent.

Eutrophication is a serious problem occurring in ponds or estuaries where fish culture is practised. A possible solution to this problem is to raise oysters in an integrated culture with fish to improve water clarity and to help remove excess nutrients. In order to determine the effects that cultured oysters have on the environment, an experimental study was performed in the Moothakunnam region of the Vembanad lake in the Ernakulam District during February-November, 2012. The study was performed in four cages (1× 1× 1 m) referred to as treatments T1, T2, T3 and T4. The four treatments used fish (Etroplus suratensis) and oysters (Crassostrea madrasensis) in the ratio of 1:0.3, 1:0.5, 1:0.7 and 1:0 respectively. Several parameters were measured and compared between the four treatments, and these included temperature, pH, salinity, dissolved oxygen, biochemical oxygen demand, chemical oxygen demand, total suspended solids, ammonia, nitrite, nitrate and orthophosphate. Results showed that the parameters, DO, BOD, COD, TSS, ammonia and orthophosphate varied with different treatments and months. However, the contents of nitrite and nitrate showed variation only with respect to months. The eutrophication index (E) values calculated for the four treatments were 9. 45 ± 4.41, 5.25 ± 3.23, 11.32 ± 6.17 and 11.52 ± 5.45 respectively. The lower E value obtained was for T2 which supports the conclusion that oysters can control eutrophication in an integrated aquaculture system. The optimal co-cultivation proportion of fish to oysters obtained from the present study was 1:0.5.