Development and commissioning of decision support tools for sewerage management.

Managing sewerage systems is a highly complex task due to the dynamic nature of the facilities. Their performance strongly depends on the know-how applied by the operators. In order to define optimal operational settings, two decision support tools based on mathematical models have been developed. Moreover, easy-to-use interfaces have been created as well, aiding operators who presumably do not have the necessary skills to use modelling software. The two developed programs simulate the behaviour of both wastewater treatment plants (WWTP) and sewer network systems, respectively. They have essentially the same structure, including raw data management and statistical analysis, a simulation layer using the application programming interface of the applied software and a layer responsible for the representation of the obtained results. Four user modes are provided in the two software including the simulation of historical data using the applied and novel operational settings, as well as modes concerning prediction of possible operation periods and updates. Concerning the WWTP software, it was successfully installed in Nantes (France) in June 2004. Moreover, the one managing sewer networks has been deployed in Saint-Malo (France) in January 2005. This paper presents the structure of the developed software and the first results obtained during the commissioning phase.     

Dissolved organic carbon dynamics in the upper rhone: The influence of side-arms?

Dissolved organic carbon (DOC) dynamics were investigated over a two year period in the Upper Rhǒne River to examine the role of side-arms in providing DOC to the main channel in relation to discharge fluctuations, especially floods. Concentrations of DOC are shown to remain low in space and in time (average 1.5 mg ^?1) and to be more related to global hydrological events (precipitation) than to any local flushing for backwaters during floods. The results do not support the general assumption that side-arms are the providers of DOC to the main channel.     

DURATION MOMENTS AND YIELD CURVE MOVEMENTS

In this paper we will analyze the relationship between the value and duration moments of a cash flow and movements in the yield curve. We will show that for changes in the yield curve which can be related to tⁿ , the 1st order changes in the net present value of a cash flow are linearly dependent on the n + lth duration moments, and that the 2nd order changes are dependent on the sum of duration moments of order 2 n + 1 and 2 n + 2. We will use this relationship to tilt tracking portfolios so as to protect them against specific changes in the yield curve.     

Significant Issues for the Future of Product Innovation

The value of a technology strategy has been increasingly discussed by R&D personnel and those involved in product development and business planning efforts. In this issue Albert Rubenstein and Americo Albala elevate this discussion by showing the importance of preparing a firm to compete by stressing the development of important, relevant technologies. Discovery and development must be channeled into areas that will be needed to support business initiatives likely to occur in the future. Albala stresses the importance of this change for the development of economies in nations that have been disappointed by the lack of success of importing technologies from more developed nations, while Rubenstein maintains that the pace of marketplace change requires a technology strategy in order to reduce the misapplication of scarce resources within the firm and the possibility of being blindsided by competitive developments. These essays continue a year-long series of contributions that the editor-in-chief solicited from members of the editorial board. Members were asked to reflect upon changes and opportunities that they see influencing our profession during the coming decade. Both of these short essays are designed to introduce new perspectives. It is not essential that you agree with the recommendations, but we hope that you are stimulated as you reflect on the issues they raise.     

MODELING THE TERM STRUCTURE FROM THE ON‐THE‐RUN TREASURY YIELD CURVE

We propose a new model to estimate the term structure of interest rates using observed on‐the‐run Treasury yields. The new model is an improvement over models that require a priori knowledge of the shape of the yield curve to estimate the term structure. The general form of the model is an exponential function that depends on the estimation of four parameters fit by nonlinear least squares and has straightforward interpretations. In comparing the proposed model with current yield‐curve‐smoothing models, we find that, for the data used, the proposed model does best overall in terms of pricing accuracy both in sample and out of sample. JEL classification: E43, G12     

Application of a multi-channel system for continuous monitoring and an early warning system.

A multi-channel continuous toxicity monitoring system developed in our laboratory, based on two-stage mini-bioreactors, was successfully implemented in the form of computer-based data acquisition. The multi-channel system consists of a series of a two-stage minibioreactor systems connected by a fiber optic probe to a luminometer, and uses genetically engineered bioluminescent bacteria for the detection of the potential toxicity from the soluble chemicals. This system can be stably and continuously operated due to the separation of the culture reactor from the test reactor and accomplish easy and long-term monitoring without system shut down by abrupt inflows of severe polluting chemicals. Four different recombinant bioluminescent bacteria were used in different channels so that the modes of the samples toxicities can be reasonably identified and evaluated based upon the response signature of each channel. The bioluminescent signatures were delivered from four channels by switching one at once, while the data is automatically logged to an IBM compatible computer. We also achieved the enhancement of the system through the manipulation of the dilution rate and the use of thermo-lux fusion strains. Finally, this system is now being implemented to a drinking water reservoir and river for remote sensing as an early warning system.     

Monitoring of human enteric viruses and coliform bacteria in waters after urban flood in Jakarta, Indonesia.

Floodwaters in Kampung Melayu village, Jakarta, Indonesia, as well as river water and consumable water (including groundwater and tap water) samples in flooded and non-flooded areas, were quantitatively analysed to assess occurrence of viruses and total coliforms and E. coli as bacterial indicators after flooding event. High numbers of enterovirus, hepatitis A virus, norovirus (G1, G2) and adenovirus were detected at high concentration in floodwaters and waters sampled from Ciliwung River which runs across metropolitan Jakarta and is used widely for agriculture and domestic purposes by poor residents. One out of three groundwater wells in the flooded area was contaminated with all viruses tested while no viruses were found in groundwater samples in non-flooded areas and tap water samples. The results revealed that human enteric viruses, especially hepatitis A virus and adenovirus, were prevalent in Jakarta, Indonesia. This study suggested that flooding posed a higher risk of viral infection to the people through contamination of drinking water sources or direct contact with floodwaters.     

Boosting nitrification by membrane-attached biofilm.

Nitrification is a key step for reliable biological nitrogen removal. In order to enhance nitrification in the activated sludge (AS) process, membrane-attached biofilm (MAB) was incorporated in a conventional activated sludge tank. Simultaneous organic carbon removal and nitrification of the MAB incorporated activated sludge (AS + MAB) process was investigated with continuous wastewater treatment. The effluent TOC concentration of AS and the AS + MAB processes were about 6.3 mg/L and 7.9 mg/L, respectively. The TOC removal efficiency of both AS and AS + MAB were above 95% during the wastewater treatment, indicating excellent organic carbon removal performance in both processes. Little nitrification occurred in the AS process. On the contrary, successful nitrification was obtained with the AS + MAB process with nitrification efficiency of about 90%. The volumetric and surface nitrification rates were about 0.14 g/Ld and 6.5 g/m2d, respectively. The results clearly demonstrated that nitrification in the conventional AS process was boosted by MAB. Furthermore, the microfaunal population in the AS + MAB process was different from that in the AS process. The high concentration of rotifers in the AS + MAB process was expected to decrease the generation of excess sludge in the process.