Biomedical subjects

J G Langeveld

Publications and source records attributed to J G Langeveld.

6 recordsLinked to original sources

PubMed2005

Wastewater planning in Djenné, Mali. A pilot project for the local infiltration of domestic wastewater.

The city of Djenné (Mali) is famous for its mosque which is the world's largest adobe building. Djenné is considered to be one of the most interesting cities in Western Africa from an architectural point of view. Since 1988, Djenné is listed as a UNESCO World Heritage Site. In the 1990s, a drinking water supply network was provided by foreign development organisations. However, no facilities were provided for the disposal of wastewater, resulting in an increase of waterborne diseases. This paper describes the urban drainage problem in Djenné and discusses the systematic evaluation of possible solutions and the subsequent pilot project for the local infiltration of sullage. The infiltration of sullage proved to be an appropriate technology for solving the urban drainage problem in Djenné.

Cities↗

PubMed2005

Advection-dispersion modelling tools: what about numerical dispersion?

In general the transport of dissolved substances and fine suspended particles is governed by the one-dimensional advection-dispersion equation. In order to model the transport of dissolved substances and fine suspended particles, the advection-dispersion equation is incorporated into commonly used urban drainage modelling tools such as InfoWorks CS (Wallingford Software, United Kingdom) and MOUSE (DHI Software, Denmark). Two examples show the use of InfoWorks CS and MOUSE using standard model settings. Modelling results using tracer experiments show that numerical model parameters need to be altered in order to calibrate the model. Using tracer experiments as a model calibration tool, it is shown that a non-negligible amount of dispersion is generated by InfoWorks CS and MOUSE and that it is in fact the numerical dispersion that is calibrated.

Calibration↗

PubMed2005

Suspended solids transport: an analysis based on turbidity measurements and event based fully calibrated hydrodynamic models.

Modelling suspended solids transport is a key issue for predicting the pollution load discharged by CSOs. Nonetheless, there is still much debate on the main drivers for suspended solids transport and on the modelling approach to be adopted. Current sewer models provide suspended solids transport models. These models, however, rely upon erosion-deposition criteria developed in fluvial environments, therewith oversimplifying the sewer sediment characteristics. Consequently, the performance of these models is poor from a theoretical point of view. To get an improved understanding of the temporal and spatial variations in suspended solids transport, a measuring network was installed in the sewer system of Loenen in conjunction with a hydraulic measuring network from June through December 2001. During the measuring period, 15 storm events rendered high-quality data on both the hydraulics and the turbidity. For each storm event, a hydrodynamic model was calibrated using the Clemens' method. The conclusion of the paper is that modelling of suspended solids transport has been and will be one of the challenges in the field of urban drainage modelling. A direct relation of either shear stress or flow velocity with turbidity could not be found, likely because of the time varying characteristics of the suspended solids.

Calibration↗

PubMed2003

Interactions within the wastewater system: requirements for sewer processes modelling.

Today's focus on wastewater system optimisation necessitates the development of knowledge on the interactions between sewer systems and wastewater treatment, since these interactions have often been neglected in the past. In this paper the question is discussed to what extent it is favourable and possible to include dynamic changes of wastewater quality in wastewater system optimisation studies. The sensitivity of the wastewater treatment works to influent fluctuations proved to be the key issue in determining which sewer processes are involved in the dynamic interactions between sewer systems and treatment works. The preliminary results show the importance of a good description of the transport processes involving the double and suspended fractions.

Models, Theoretical↗

PubMed2002

Increasing wastewater system performance--the importance of interactions between sewerage and wastewater treatment.

The necessity to assess sewer systems and wastewater treatment plants (WWTPs) as integral parts of the wastewater system has been well known for several years and discussed in many conferences. Until recently, sewer systems and WWTPs were improved (or optimised) separately or independently, which resulted in suboptimal solutions. Nowadays, in The Netherlands as well as in other European countries, a trend can be recognised towards more integral solutions. Nevertheless, due to a lack of knowledge on the interactions between the sewer systems and the WWTPs the implementation of this way of thinking in practice takes a long time. This paper describes the results of two cases in which the interactions between sewerage and wastewater treatment are incorporated within the optimisation of a wastewater system. The first case illustrates the importance of taking the interactions into account, while the second case shows how to deal with the interactions within a wastewater system optimisation study. It is concluded that the combination of total wastewater system analysis, incorporating the interactions within the wastewater system, with efficient search algorithms is expected to be very valuable in future wastewater system optimisation studies.

Algorithms↗

PubMed1992

Isolation of sequences from a random-sequence expression library that mimic viral epitopes.

We describe the use of random peptide sequences for the mapping of antigenic determinants. An oligonucleotide with a completely degenerate sequence of 17 or 23 nucleotides was inserted into a bacterial expression vector. This resulted in an expression library producing random hexa- or octapeptides attached to a beta-galactosidase hybrid protein. Mimotopes, or antigenic sequences that mimic an epitope, were selected by immunoscreening of colonies with monoclonal antibodies, which were specific for antigenic sites on the spike protein of the coronavirus transmissible gastroenteritis virus. We report one mimotope for antigenic site II, eight for site III and one for site IV. The site III and site IV mimotopes were closely similar to the corresponding linear epitopes, localized previously in the amino acid sequence of the S protein. An alignment of the site II mimotope and the sequence of the S protein around Trp97, which is substituted in escape mutants, suggests that this mimotope mimics a conformational epitope located around residues 97-103. Applications of mimotopes to epitope mapping, serodiagnosis and vaccine development are discussed.

Amino Acid Sequence↗