General Sewage Technology

Prevention of wastewater by means of a closed production cycle with integrated water-re-use treatment plants in a paper factory

Zülpich Papier GmbH, which has been operating under complete effluent free conditions for 25 years, was forced to conside this technology concept because the concentration of odourous compounds in the process water had largely increased during the last few years. To maintain a closed system, an internal anaerobic/aerobic process water treatment plant was installed. A part of the total process water stream is pretreated in an UASB reactor and after aerobic treatment in an aeration tank followed by sand filtration, it is reused as process water. The efficiency of the in-line plant as well as the main improvements on the characteristics of process water, paper and exhaust was controlled in an extensive monitoring program. Within a few weeks after start-up, the in-line process water treatment plant had already reached the forecast efficiency. The organic load of process water (measured as COD) was reduced by 75 percent. The reduction of odourous low molecular fatty acids totals 95 percent.  

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Source:  Environmental library of the Federal Environment Agency (UBA)