Bulking in activated sludge plants treating paper mill wastewaters

As part of a larger project to examine the causes of bulking in activated sludge plants treating wastewaters from paper mills, two laboratory-scale activated sludge plants were run in parallel. This was to evaluate the impact of variable environmental and operational parameters on the sludge ecology, and in particular, on the filamentous bacteria in the sludge. A survey of paper mills in the UK showed that there was a significant difference between the activated sludge plants at the paper mills using virgin fibre and those using recycled fibre. An examination of samples from activated sludge plants at the paper mills showed that there did not appear to be any significant correlation between filament abundance and the settlement characteristics as measured by stirred specific volume index (SSVI). The surface charge carried by the sludge particles was also measured and it was found that this parameter was better related to the SSVI. Similar results were found for samples from the laboratory plants. Seven different sets of operational conditions were applied to the laboratory-scale plants. These were aimed at simulating the conditions noted for the full-scale plants during the mill survey. The effects of low dissolved oxygen and low organic loading rates were examined. The effect of inorganic sulphur compounds and volatile fatty acids was studied. A change in raw material from virgin fibre to recycled fibre (corrugated paper) caused an immediate and continuous deterioration in settlement. Divalent cations, calcium and magnesium, were found to be successful in controlling settlement in the final clarifier.     

Discussant's Comments: Locational Disadvantage,Outer Suburbia and Urban Myths

I'll start by suggesting some things about which we might all agree, then move on as rapidly as possible to things that at least some of you will disagree with. The transition point will no doubt come earlier for some than for others.     

Liposome‐Supported Peritoneal Dialysis for the Treatment of Hyperammonemia‐Associated Encephalopathy

Hyperammonemia can lead to cerebral dysfunction, encephalopathy, coma, and death if not treated adequately. The poor prognosis associated with this condition reflects the unmet medical need for effective ammonia‐lowering treatments. Here, the translational potential of liposome‐supported peritoneal dialysis (LSPD), a recently‐developed detoxification strategy for the removal of small ionizable molecules like ammonia, is described. Dialysis fluids supplemented with micrometer‐sized, transmembrane pH‐gradient liposomes are prepared via an innovative, osmotic shock‐based method overcoming sterilization and long‐term stability issues. LSPD is able to sequester ammonia in healthy rats in relation to the injected dose, buffering capacity of the liposomal core, and membrane composition. In a rat model of cirrhosis, LSPD outperforms conventional peritoneal dialysis in lowering plasmatic ammonia levels and attenuating brain edema. LSPD does not trigger any hypersensitive reaction in pigs, a side effect commonly observed upon the injection of colloids in this animal model and in humans. These findings support the development of LSPD for the treatment of hyperammonemia‐induced encephalopathy.     

Economically optimal timing for crop disease control under uncertainty: an options approach

Severe large-scale disease and pest infestations in agricultural regions can cause significant economic damage. Understanding if and when disease control measures should be taken in the presence of risk and uncertainty is a key issue. We develop a framework to examine the economically optimal timing of treatment. The decision to treat should only be undertaken when the benefits exceed the costs by a certain amount and not if they are merely equal to or greater than the costs as standard net-present-value (NPV) analysis suggests. This criterion leads to a reduction in fungicide use. We investigate the effect of the model for disease progress on the value required for immediate treatment by comparing two standard models for disease increase (exponential and logistic growth). Analyses show that the threshold value of benefits required for immediate release of treatment varies significantly with the relative duration of the agricultural season, the intrinsic rate of increase of the disease and the level of uncertainty in disease progression. In comparing the performance of the delay strategy introduced here with the conventional NPV approach, we show how the degree of uncertainty affects the benefits of delaying control.     

Manchester encoding: opposing definitions resolved

Manchester encoding is widely used to provide clock and data information simultaneously via a single connection. There are two opposing-and incompatible-definitions of Manchester encoding where the rising edge in the centre of the data bit indicates either a logic “1” or alternatively a logic “0”. This paper resolves the differences and identifies the originator of the method     

An asymmetric MOSFET-C band-pass filter with on-chip charge pump auto-tuning

dissipates 2.412 mW from a 1.8 V power supply. The filter with the auto-tuning system occupies 0.592 mm2 and it can be utilized in GPS (global positioning system)and Bluetooth systems.     

The socioeconomics of food crop production and climate change vulnerability: a global scale quantitative analysis of how grain crops are sensitive to drought

Many studies warn that climate change may undermine global food security. Much work on this topic focuses on modelling crop-weather interactions but these models do not generally account for the ways in which socio-economic factors influence how harvests are affected by weather. To address this gap, this paper uses a quantitative harvest vulnerability index based on annual soil moisture and grain production data as the dependent variable in a Linear Mixed Effects model with national scale socio-economic data as independent variables for the period 1990–2005. Results show that rice, wheat and maize production in middle income countries were especially vulnerable to droughts. By contrast, harvests in countries with higher investments in agriculture (e.g. higher amounts of fertilizer use) were less vulnerable to drought. In terms of differences between the world’s major grain crops, factors that made rice and wheat crops vulnerable to drought were quite consistent, while those of maize crops varied considerably depending on the type of region. This is likely due to the fact that maize is produced under very different conditions worldwide. One recommendation for reducing drought vulnerability risks is coordinated development and adaptation policies, including institutional support that enables farmers to take proactive action.     

Field spectroscopy of estuarine intertidal habitats

The recent introduction of portable, low‐cost hyperspectral radiometers for measuring the reflectance of marine intertidal habitats has considerable promise, first as a source of reference spectra for airborne and satellite remote sensing, and second as a survey technique in its own right. This paper reports on the results of an intercalibration exercise in which two designs of commercially available instruments were used to measure reflectance spectra across a diverse, intertidal site. The substrates sampled included seagrasses, macroalgae, and sediments which varied in wetness and grain size. Spectra were compared statistically using several measures of similarity, and the results showed a high degree of correlation between the measured reflectance spectra. There were no significant differences between instruments from different manufacturers in the shape of reflectance spectra, but the signal‐to‐noise ratio varied considerably between individual instruments. Spectra measured by operators with lesser experience in field spectrometry tended to be more variable than those of more experienced operators, indicating that training and adherence to set protocols are important when implementing this method in the field situation. Spatial plots derived from field spectra showed essentially the same trends in surface features as plots created using traditional sampling and remote sensing methods. Furthermore, the use of field spectrometry as a stand‐alone, low‐cost method for rapidly mapping the distribution of major habitat types was demonstrated by the results of a survey of a large intertidal sandbank.