Reynaud, Nicolas (2009)

Thema

Classifying and monitoring DEWATS-plants in Java

Autorenreferat

The aim of this thesis was to contribute to the improvement of the dimensioning standards and procedure for Decentralised Wastewater Treatment Systems (DEWATS) implemented by the German NGO BORDA. This was achieved through a documented approach in classifying and monitoring communal DEWATS-plants. Methods and procedures to gain, record, edit and process data on parameters relevant for a performance assessment were discribed.

As an example a classification of laboratory, technical and socio-economic data was conducted for 13 communal DEWATS-plants in Yogyakarta and Central-Java (Indonesia). Laboratory, technical and socio-economic data were collected from existing documentation or during 3 months of field research in Java.

Laboratory data included pH, settable solids, total suspended solids, chemical oxygen demand (COD) and biological oxygen demand (BOD) concentrations. Samples for COD and BOD analyses were obtained from grab samples or from a specially designed flow-proportional sampler. Sludge characteristics, such as sludge height and settling-velocities from reactor compartments were investigated. Flow hydrographs were determined for the inflow and outflow from a plant. Data on the location, served community, dimensioning-parameter values and the as-built specifications were collected.

This data were used to calculate different performance indices and were compared against design criteria in order to assess performance and to guide investigations to improve performance and update the design criteria. One DEWATS plant in Yogyakarta / Java was subjected to a detailed investigation. The plant was found to be functioning well.

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