Elimination of beta-blockers in sewage treatment plants

beta-Blockers are used to treat high blood pressure as well as patients recovering from heart attacks. In several studies, they were detected in surface water, thus indicating incomplete degradability of these substances in sewage treatment plants (STPs). In this study, we determined the sorption coefficients (K(D)) and degradation rates of the four beta-blockers sotalol, atenolol, metoprolol and propranolol in sludge from an STP operating with municipal wastewater. The sorption coefficients (K(D), standard deviations in brackets) were determined as 0.04(+/-0.035), 0.04(+/-0.033), 0.00(+/-0.023) and 0.32(+/-0.058) Lg(-1)(COD), and the pseudo-first-order degradation rate constants were estimated to be 0.29(+/-0.02), 0.69(+/-0.05), 0.58(+/-0.05) and 0.39(+/-0.07) Ld(-1)g(-1)(COD) for sotalol, atenolol, metoprolol and propranolol, respectively. These values translate into a typical elimination in STPs (sludge concentrations of 4g(COD)L(-1) and a hydraulic retention time of 6h) of 25%, 37%, 44% and 50% for sotalol, propranolol, metoprolol and atenolol, respectively. These results are also confirmed by measurements in two municipal STPs for atenolol, sotalol and propranolol. The estimated eliminations are slightly too high for metoprolol.     

Enhanced adsorption of Cd (II) on a hydrous Al (III) floc in the presence of a modified form of polyethylenimine

A polymer modified with succinic anhydride has been investigated for the adsorption of cadmium (II) on a freshly precipitated aluminium (III) hydroxide floc. The proportion of chelate attached to the polymer is varied to determine the relationship between carboxyl and amino groups on the polyelectrolyte, in terms of enhanced adsorption of cadmium (II) on a hydrous aluminium floc. The presence of polyelectrolyte enhanced the adsorption of 3.3 ppm Cd (II) on a 333 ppm Al (III) floc at every concentration of polyelectrolyte investigated. The proportion of succinic anhydride attached to the polymer had an impact on the increased adsorption of Cd (II) on an Al (III) floc observed. A decreasing proportion of succinic anhydride to polymer resulted in a decrease in the amount of cadmium adsorbed on the floc. Above pH 8, a decrease in the % Cd (II) adsorbed on the floc and % Al (III) retained within the floc decreases with the presence of polyelectrolyte as a result of the formation of soluble Cd-Polyethylenimine-succinic acid (PEISA) complexes. When the Al-PEISA combination was applied to a complex matrix where Cd (II), Cu (II) and Ni (II) ions competed for adsorption, enhanced adsorption was observed for Cd (II) and Ni (II). At pH 7, dissolution of the floc observed with the addition of discrete chelates was not observed with the addition of polyelectrolytes.     

Semi-volatile organic compounds in the Campaspe River system (Victoria, Australia)

The levels of semi-volatile organic compounds (SVOCs) in the Campaspe River system, North Central Victoria, Australia, were monitored from January to September 1995, and the environmental trends and sources of these compounds were determined. The land use within particular catchments dictated the complexity of the SVOCs in run-off water. Run-off from native forest contained the greatest number of SVOCs. Soil and ground litter were shown to contain the greatest complexity of SVOCs, mostly terpenes. However, only a small proportion were leached by run-off with the remainder being tightly bound to the soil or volatilizing to the atmosphere. Under the prevailing drought of early 1995, the rivers contained no detectable SVOCs until the first catchment run-off after significant rainfall in May. The maximum complexity and concentration of the SVOCs coincided with extensive run-off after heavy rainfall in June, effecting a surge of SVOCs with the flood peak. Fatty acids, their amides and hydrocarbons made up the majority of the compounds identified and were in the 1-39 micrograms/l concentration range. The levels then diminished as the catchment was flushed by continual run-off. These results support Lake's 1967 hypothesis that natural floodwaters contain a signature of SVOCs entering from the catchment. The downstream passage of these compounds was obstructed by a man-made storage, Lake Eppalock, with only low concentrations of SVOCs (1-3 micrograms/l) in the outflow, displaying no correlation to run-off.     

911事件的警示和教训

20 0 1年 9月 11日 ,在两架被劫持的喷气式客机撞击纽约世界贸易中心 ,数千加仑燃烧着的喷气客机燃料喷洒到多个楼层之后差不多一个小时内 ,世界贸易中心仍然高耸在曼哈顿上空。当浓烟从毁坏的外墙滚滚而出并在世界贸易中心内迅速蔓延时 ,纽约市的最高建筑 ,110层双塔的 2 4 4根密密排列的钢柱仍然支撑着整个大楼。然而 ,上午 9时 5 0分 ,136 2英尺 (415米 )高的南塔突然倒塌。大约半个小时后 ,136 8英尺 (418米 )高的北塔接着倒塌。纽约世界贸易中心遭恐怖袭击倒塌事件 ,震惊世界。这起事件在许多方面给消防工作提出了警示 ,其教训也是非常…     

Mercury contamination in fish from gold mining areas in Indonesia and human health risk assessment

This study investigates the effects on fish and assesses human health hazards from mercury released in two gold mining areas in Indonesia: Tatelu (North Sulawesi Province) and Galangan (Katingan District, Central Kalimatan Province). In Tatelu, 154 fish specimens of 10 freshwater species were collected, as well as five marine species from the fish market. The mean concentration of total mercury in muscles of freshwater fish from this area was 0.58+/-0.44 microg/g, with more than 45% of fish having Hg levels above the WHO guideline for human consumption of 0.5 microg/g. In Galangan, where 263 fish specimens of 25 species were collected, the total mercury in muscles averaged 0.25+/-0.69 microg/g. Excluding data from flooded open pits in sub-area P4, mean Hg levels in fish from Galangan were 2 to 4 times lower than 0.5 microg/g, while fewer than 10% of fish from Galangan exceeded WHO guidelines. The Hazard Quotient (HQ) was applied to both areas to determine the threat of MeHg exposure for communities in both areas. The HQ is a risk assessment indicator which defines the ratio of exposure level to a single substance in relation to a reference dose. Samples from Tatelu (excluding marine species) had an HQ above one, while those from Galangan resulted in values of 2.4 for the whole area and 9.9 for sub-area P4, pointing to potentially harmful fish consumption for the local population. By using the single-compartment model to estimate mercury levels in blood and hair from daily intake dose, sub-area P4 showed the highest levels, higher than the upper limit guideline for pregnant women, but still lower than threshold levels associated with observed clinical effects.     

Fluid filling of a membrane tube with self-weight

The filling of a membrane tube with self-weight by a fluid is studied theoretically for the first time. The fundamental problem depends on two non-dimensional parameters, $\beta$ and $\gamma$ which represent the importance of internal pressure and membrane self-weight respectively. The nonlinear equations are solved by an efficient numerical integration method. It is found that membrane self-weight has considerable effect on the tube geometry and the tension of the membrane at low filling pressures.     

Mesure en place de la permeabilite des sols fins

Bulletin of Engineering Geology and the Environment - La mesure en place de la perméabilité k des sols fins est un moyen d'améliorer la prévision des vitesses de tassement...     

Geomechanical model simulation for the varied rock formations of the Kadana dam foundation,Gujarat, India

Bulletin of Engineering Geology and the Environment - Precambrian layered rocks consisting of quartzites, phyllites and metagreywackes of the Aravallis having a large variation in thickness,...     

Oxygen transfer in a rotating disc treatment plant

In this paper experiments are described in a bio-disc pilot plant. A new method has been developed for a reproducible measurement of the thickness of the waterfilm on the rotating discs. The results were used to calculate the oxygen transfer coefficient into water (K_L). The values of K_L, calculated in this way, appeared to be considerably higher than experimental K_L-values, which is mainly due to the fact that the water layer on the rotating disc is outdistanced by the disc. This effect has not been taken into account in the literature so far.     

Dynamic analysis and optimal feedback control synthesis applied to biological waste treatment

The dynamics and optimal feedback control of biological waste treatment processes are examined. Modern feedback control theory is applied and results are obtained for both proportional and proportional plus integral control. A dynamic mathematical model of the system is developed by employing a Monod kinetic model, which is modified to account for endogenous metabolism, and a complete mixing flow model in the growth chamber. The feedback control is implemented via the flow rate so as to maintain desired effluent concentrations. External disturbances which cause changes in substrate concentration and/or cell concentration are considered and optimal control effort is applied. Results are also presented for impulse and step changes in the influent substrate concentration. It is found that by changing the values of the weighting factors in the objective function, it is possible to obtain good control of either the effluent substrate concentration or cell concentration.