Biomedical subjects

J Alex

Publications and source records attributed to J Alex.

9 recordsLinked to original sources

PubMed2003

Progress in sensor technology--progress in process control? Part 1: sensor property investigation and classification.

To ensure correctly operating control systems, the measurement and control equipment in WWTPs must be mutually consistent. The dynamic simulation of activated sludge systems could offer a suitable tool for designing and optimising control strategies. Ideal or simplified sensor models represent a limiting factor for comparability with field applications. More realistic sensor models are therefore required. Two groups of sensor models are proposed on the basis of field and laboratory tests: one for specific sensors and another for a classification of sensor types to be used with the COST simulation benchmark environment. This should lead to a more realistic test environment and allow control engineers to define the requirements of the measuring equipment as a function of the selected strategy.

Environmental Monitoring↗

PubMed2003

Progress in sensor technology--progress in process control? Part II: results from a simulation benchmark study.

To show the impact of sensor behaviour on the control result, four strategies for aeration control are tested using different sensor characteristics. It is demonstrated, on the one hand, how an increasing response time will limit the achievable control quality and, on the other hand, how a given sensor characteristic can be taken into account for the controller design. The presented tests show that an improvement potential by control for WWTPs is available but this potential is limited compared to proper DO control with fixed set-points. To activate this control potential, sufficient control authority must be available and a careful control design is required. It can be shown that using feedback control, sensors with a small response time have significant advantages compared to conventional sensors. Using feed forward control, the improvement potential by control is considerably higher and additionally, the sensor delay can be integrated into the controller design. The presented discussion is based on simulation studies performed on a standardised benchmark case. For these tests it was necessary to include sensor models into the simulation model. It can be stated that the usage of sensor models is necessary for the application of dynamic simulation for the design and evaluation of WWTP control and in general to achieve realistic results.

Automation↗

PubMed2003

On-line measurement data of wastewater systems via WAP mobile phones.

In order to support the operation of wastewater systems a system was developed which allows us to access plant data by standard mobile devices such as WAP mobile phones. This system is suited complement the standard application of alarm and message systems based for example on SMS or pager services. This technology provides useful options for mobile remote monitoring and remote control of automated plants. This technology is particularly appropriate for the use in remote facilities where no staff is available. The technology has been implemented succesfully and shows how standard IT and Internet technologies can be utilised to support the operation of spatially distributed plants with reasonable effort. Two implementations are presented which access plant data via WAP mobile phones and via mobile pocket PCs. First application experiences are presented.

Automation↗

PubMed2003

Impacts of separate rejection water treatment on the overall plant performance.

A separate rejection water treatment appears as a high-tech unit process which might be recommendable only for specific cases of an upgrading of an existing wastewater treatment plant. It is not the issue of this paper to consider a specific separate treatment process itself but to investigate the influence of such a process on the overall plant performance. A plant-wide model has been applied as an innovative tool to evaluate effects of the implemented sidestream strategy on the mainstream treatment. The model has been developed in the SIMBA environment and combines acknowledged mathematical descriptions of the activated sludge process (ASM1) and the anaerobic mesophilic digestion (Siegrist model). The model's calibration and validation was based on data from 5 years of operating experience of a full-scale rejection water treatment. The impact on the total N-elimination efficiency is demonstrated by detailed nitrogen mass flow schemes including the interactions between the wastewater and the sludge lane. Additionally limiting conditions due to dynamic N-return loads are displayed by the model's state variables.

Ammonia↗

PubMed2002

Dead? Or just cold: profoundly hypothermic patient with no signs of life.

A 37 year old man was found in his garden cold with no signs of life. Pupils were fixed and dilated. Electrocardiography showed asystole initially. The paramedic crew started cardiopulmonary resuscitation and transferred him to the accident and emergency department. His temperature was 17.0 degrees C. Cardiopulmonary resuscitation was continued for three hours before rewarming using partial cardiopulmonary bypass. He eventually regained spontaneous cardiac output and made a full neurological recovery. Hypothermic patients with no evidence of life cannot be assumed to be dead as there is a chance of full recovery when fully warmed.

Adult↗

PubMed2002

Pollution based real time control of wastewater systems.

Wastewater systems are traditionally built as static systems to handle a design load. The real load varies, though, and hardly ever equals the design load. This implies that wastewater systems hardly ever operate in an optimum way, especially during wet weather. Real time control (RTC) of regulators can improve the operation by better fit of the system to the actual state and load. RTC based on pollutant concentrations together with hydraulic conditions (pollution based real time control, PBRTC) is investigated in this paper to assess the potential pollutant load reduction on receiving waters at wet weather without expansion of transport or storage capacity. Both CSOs and WWTP effluents contribute to the pollutant discharges to receiving waters and both are considered. Three cases are studied to assess the potential benefit of PBRTC. Giving priority to the most polluted wastewater for treatment and storage in branched interceptor systems can reduce CSO discharge loads by more than 20%. Biological WWTPs and especially activated sludge plants are more complex and less stable than chemical precipitation plants during and after high pollutant and hydraulic load. Biological plants can hence profit more from PBRTC than chemical precipitation plants. Receiving waters that are sensitive to acute effects caused by intermittent discharges can benefit more from PBRTC than receiving waters with problems connected to long-term accumulation of pollution.

Chemical Precipitation↗

PubMed2002

Model structure identification for wastewater treatment simulation based on computational fluid dynamics.

The objective of this presented project is to use the results of an CFD simulation to automatically, systematically and reliably generate an appropriate model structure for simulation of the biological processes using CSTR activated sludge compartments. Models and dynamic simulation have become important tools for research but also increasingly for the design and optimisation of wastewater treatment plants. Besides the biological models several cases are reported about the application of computational fluid dynamics ICFD) to wastewater treatment plants. One aim of the presented method to derive model structures from CFD results is to exclude the influence of empirical structure selection to the result of dynamic simulations studies of WWTPs. The second application of the approach developed is the analysis of badly performing treatment plants where the suspicion arises that bad flow behaviour such as short cut flows is part of the problem. The method suggested requires as the first step the calculation of fluid dynamics of the biological treatment step at different loading situations by use of 3-dimensional CFD simulation. The result of this information is used to generate a suitable model structure for conventional dynamic simulation of the treatment plant by use of a number of CSTR modules with a pattern of exchange flows between the tanks automatically. The method is explained in detail and the application to the WWTP Wuppertal Buchenhofen is presented.

Algorithms↗

PubMed2002

Improved design and optimization of aeration control for WWTPs by dynamic simulation.

This paper introduces a model library based on the simulation environment MATLAB/SIMULINK which allows the simulation of the aeration system of an wastewater treatment plant (WWTP). The model library presented covers all parts of an aeration system starting with the compressor set over the common air rail, flow resistances through pipes, controllable valves, aeration membranes and ending last not least with the controllers involved. The main objective of the development of the simulation system is the design, test and the support of the installation of more predictable and efficient control concepts for the aeration system in WWTPs. An example is given to demonstrate the application of the simulation system and to promote a control scheme with a flexible reference value for the pressure at the common air rail based on a most open valve (MOV) concept.

Air Pressure↗

PubMed2002

Status and future trends of ICA in wastewater treatment--a European perspective.

The status of instrumentation, control and automation (ICA) within the European wastewater community is reviewed and some major incentives and bottlenecks are defined. Future trends of ICA are also discussed. The information is based on a COST 624 workshop and a non-exhaustive survey with regard to ICA carried out in 13 European countries during March 2001. The level of instrumentation (type of sensors, usage frequency, etc.) and how these instruments are used for on-line control purposes are presented for each individual country (Austria, Belgium, Czech Republic, Denmark, Finland, France, Germany, Netherlands, Romania, Slovenia, Spain, Sweden and Switzerland). The most common types of applied real-time control in wastewater treatment plants are given. One conclusion of the paper is that sensors no longer represent the main bottleneck for on-line control, rather the lack of plant flexibility is more troublesome. Moreover, the current transitional phase of the wastewater industry in Europe represents a unique opportunity to apply ICA on a large scale. The driving forces are simply too strong to ignore.

Automation↗