In the tropics, surface water is often the only source for drinking and industrial water. However, due to numerous releases of untreated wastewater the surface water bodies are often highly contaminated. The joint research project "Treatment of tapioca wastewater and sustainable water pollution control management of key economic zones in southern Vietnam" contributes to the improvement of surface water. This project is funded by the German Ministry of Research and Education (BMBF) and by the Ministry of Science and Technology (MOST), Vietnam.
The treatment of tapioca wastewater is the main task of the experimental component in the project. A pilot plant has been installed, operated and optimized in a midsize tapioca company in the Tay Ninh province. The wastewater treatment plant consists of an innovative combination of anaerobic and aerobic treatment schemes.
The technical components of the pilot plant were manufactured by the industrial partners in Germany, shipped to Vietnam, mounted on-site and put into operation. The University of Applied Sciences Ostwestfalen-Lippe in cooperation with the Institute for Environment and Resources, National University of HCMC, is responsible for the operation of the pilot plant and the analytical work.
In the novel treatment concept physical pre-treatment is combined with dissolved air flotation, anaerobic degradation and aerobic post-treatment. The pilot plant demonstrated its robustness and its excellent performance to remove organic matter (COD by > 98%), nutrients (Kjeldahl-N by 80-85% and total-P by 50-60%), and cyanide (total-CN by > 99%) from tapioca starch waste water.
The modelling component consists of an expert system for water pollution control management and has been developed by the University of Braunschweig in collaboration with the Vietnamese partners. In the expert system, the water balance, the transport of pollutants into the river from different sources as well as the instream water quality are simulated. In addition the experimental results from the pilot plant operation are accounted for.
The system was developed for the small catchment of the Tay Ninh river including the pilot plant, and for the large catchment of the Saigon river upstream of HCMC. The dynamics of the water and mass balance of both catchments are simulated with the SWAT model. The hydraulics and water quality of the Tay Ninh river are simulated with the 1D-HEC-RAS model. For the Dau Tieng reservoir and the Saigon river, being influenced by the tide , the 2D-CE-QUAL-W2 model was applied.
The system contains the combined models. It has a uniform operating system with menu control for input and output processes and additionally a database system for the control of project data and the storage of simulation results.
The actual state of the catchment and different scenarios were simulated with the expert system. For the numerous other tapioca factories in the catchment, fictive treatment plants with treatment efficiencies obtained in the experimental results from the pilot plant, were installed. Suitable solutions were developed under consideration of ecological and economic criteria.
The functioning expert system allows responsible Vietnamese authorities/institutions to improve the water quality of the Tay Ninh and Saigon river including the Dau Tieng reservoir. In the future, the system can be extended by the Vietnamese authorities to cover the whole Dong Nai catchment.
Scheme of the expert system