Comprehensive laboratory and pilot plant studies conducted in recent years in The Netherlands have resulted in the development of a new anaerobic treatment process, i.e. the Upflow Anaerobic Sludge Blanket (UASB) process, which was shown to be feasible for handling a large variety of industrial wastes at exceptionally high organic loading and hydraulic loading rates. So with sugar beet and potato processing wastes organic loading rates have been applied up to 30 and 45 kg COD m -3 day -1 respectively at 27-35 °C and liquid retention times of 4-8 hrs. In addition to the treatment of low strength industrial wastes the UASB-process has been investigated for its feasibility in treating domestic sewage. Results obtained in 1-2 m high UASB-reactors indicate that anaerobic pretreatment of domestic sewage may represent an attractive proposition, because it was shown that: (a) 50-80 COD-reduction could be obtained in 12-24 hrs retention time at a temperature between 13 and 30 °C; (b) the process can be combined - if required - with various simple post-treatment methods in order to achieve a 90 COD-reduction. An active anaerobic sludge can be preserved unfed for a period of one year and more, the application of anaerobic treatment for wastes of campaign industries and of domestic sewage originating from camping sites is very attractive. Moreover, the UASB process in its full-scale design is fairly simple and cheap, and the process can be well combined with other recycle methods, such as for NH +4 -N. The main features of the UASB process as well as the results obtained with the process in pilot and full-scale plants with various types of waste (e.g. of the sugar beet, potato processing industry, domestic sewage) will be described and evaluated.
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