Specific energy consumption of membrane bioreactor (MBR) for sewage treatment

This paper provides an overview of current electric energy consumption of full-scale municipal MBR installations based on literature review and case studies. Energy requirements of several MBRs were linked to operational parameters and reactor performance. Total and specific energy consumption data were analysed on a long-term basis with special attention given to treated flow, design capacity, membrane area and effluent quality. The specific energy consumption of an MBR system is dependent on many factors, such as system design and layout, volume of treated flow, membrane utilization and operational strategy. Operation at optimal flow conditions results in a low specific energy consumption and energy efficient process. Energy consumption of membrane related modules was in the range of 0.5-0.7 kWh/m(3) and specific energy consumption for membrane aeration in flat sheet (FS) was 33-37% higher than in a hollow fibre (HF) system. Aeration is a major energy consumer, often exceeding 50% share of total energy consumption. In consequence, coarse bubble aeration applied for continuous membrane cleaning remains the main target for energy saving actions. Also, a certain potential for energy optimization without immediate danger of affecting the quality of the produced effluent was observed.     

Law and Defeasibility

The paper consists of three parts. In the first part five kinds of defeasibility are distinguished that is ontological, conceptual, epistemic, justification and logical defeasibility. In the second part it is argued that from these, justification defeat is the phenomenon that plays a role in legal reasoning. In the third part, the view is defended that non-monotonic logics are not necessary to model justification defeat, but that they are so to speak the natural way to model this phenomenon.     

Voltage control with on-load tap changers in medium voltage feeders in presence of distributed generation

This paper discusses voltage regulation on medium-voltage feeders with distributed generation (DG) using on-load tap changer (LTC) and line drop compensation (LDC). The analysis shows that LTC is robust against DG, whereas DG can affect the effectiveness of the voltage regulation provided by LDC. However, with proper coordination between DG and LDC, it is possible to ensure voltage regulation without unnecessarily restricting the integration of DG. It is shown that, while lowering the LTC setting can increase the DG integration limit, even higher increase can be obtained by activating the LDC feature, which is present in most LTCs, but often not used. LDC regulation is also compared with other alternatives such as using a DG unit with voltage control capability and installing a line voltage regulator.     

食品的固态发酵

许多传统食品发酵过程采用了固态发酵(ＳＳＦ)。对于若干种酶、香味、色泽、抗氧剂和其它促进健康物质来说,业已证明,与深层发酵(ＳＭＦ)相比,ＳＳＦ可给予更高的得率或更佳的产品混合物。除此之外,ＳＳＦ可减少发酵过程中的产品损耗和伴生的废料,降低下游的加工成本(去除水分)     

Effect of fermented feed on the susceptibility for Campylobacter jejuni colonisation in broiler chickens with and without concurrent inoculation of Salmonella enteritidis

Fermented liquid feed (FLF) protects broiler chickens against colonisation with Salmonella. While Campylobacter causes more disease cases in humans than Salmonella, the effect of FLF on Campylobacter was assessed. The fermented liquid feed is a moistened feed with a high number of lactobacilli, a high concentration of lactic acid, and a pH of 4. In three experiments Campylobacter was orally applied to individually housed 9-day-old broiler chickens. A significant reduction of susceptibility, as determined by cloacal swabs, was observed. At any moment where an animal has not started to shed Campylobacter yet, the probability to start shedding Campylobacter in a subsequent small time interval was nine times as high for the control chickens than for the animals that were fed FLF. FLF did not consistently change the Campylobacter colonisation level in the caeca. It was concluded that FLF could reduce the probability of introduction of Campylobacter in broiler flocks. In an experiment where some chickens were simultaneously inoculated with Salmonella enteritidis and Campylobacter, no interaction on susceptibility or caecal colonisation level was observed.     

Calculation of the redox potential of the protein azurin and some mutants

Azurin from Pseudomonas aeruginosa is a small 128-residue, copper-containing protein. Its redox potential can be modified by mutating the protein. Free-energy calculations based on classical molecular-dynamics simulations of the protein and from mutants in aqueous solution at different pH values were used to compute relative redox potentials. The precision of the free-energy calculations with the lambda coupling-parameter approach is evaluated as function of the number and sequence of lambda values, the sampling time and initial conditions. It is found that the precision is critically dependent on the relaxation of hydrogen-bonding networks when changing the atomic-charge distribution due to a change of redox state or pH value. The errors in the free energies range from 1 to 10 k(B)T, depending on the type of process. Only qualitative estimates of the change in redox potential by protein mutation can be obtained.     

Validation of macroscopic attenuated total reflection-Fourier transform infrared imaging to study dissolution of swelling pharmaceutical tablets

Macroscopic attenuated total reflection (ATR) infrared imaging is applied to study the dissolution of realistically sized hydroxypropyl methylcellulose (HPMC) tablets. The water intake into in situ compacted tablets and pre-compacted tablets was studied as a function of compaction pressure. Rigorous analysis of the imaging datasets show that the speed of water intake into HPMC tablet is approximately 4 microm/min and is hardly affected by the studied range of compaction pressures or the type of ATR crystal used (diamond or ZnSe). This constant speed of water intake implies that leakage ('creeping') of water into the space between the tablet and the ATR crystal does not occur. It is shown that the radius of the HPMC tablet initially expands to twice the original radius due to swelling.     

Real-time PCR detection of ruminant DNA

To control the spread of bovine spongiform encephalopathy, several DNA methods have been described for the detection of the species origin of meat and bone meal. Most of these methods are based on the amplification of a mitochondrial DNA segment. We have developed a semiquantitative method based on real-time PCR for detection of ruminant DNA, targeting an 88-bp segment of the ruminant short interspersed nuclear element Bov-A2. This method is specific for ruminants and is able to detect as little as 10 fg of bovine DNA. Autoclaving decreased the amount of detectable DNA, but positive signals were observed in feeding stuff containing 10% bovine material if this had not been rendered in accordance with the regulations, i.e., heated at 134 degrees C for 3 instead of 20 min.