Water Quality Management in the Chemical Industry – BASF's Ludwigshafen Complex as an Example – Investigations, Design, Operation

Abstract

The BASF works Ludwigshafen - the largest integrated chemical complex in Europe - via re-organization of its waste water management (installation of a separate sewerage system, intra-plant measures, central chemical-mechanical-biological treatment plant) has achieved a reduction of the substance load discharged to the Rhine by ca. 98% in terms of BOD5 and by ca. 94% for COD and TOC. During many years (1961 - 1974) investigations have been carried out with pilot plants on laboratory scale (50l) as well as on semi-industrial scale (20 000 population equivalents) for selecting the suitable treatment procedure and dimensioning of the central treatment plant. The treatment procedure developed according to tests in the pilot plant (high-rate primary sedimentation to avoid activated sludge with poor settling properties, followed by an aeration stage in form of a circular basin according to the carrousel system, including a denitrification zone of variable volume) has proven successful in practice. The sludge volume index is 50 ml/g. In spite of varying nitrate concentrations the denitrification is working without problems. In the central treatment plant (dimensioning data 375 000 kg/d BOD5, ca. 100 000 kg/d NO3−, DWF 660 000 m3/d) BOD5 is degraded by 96%, COD as well as TOC by ca. 80 - 85%, while nitrate is eliminated by 95 %. It will be reported mainly on the operation experience. In addition to the central treatment facilities there are numerous decentralized measures in regard to the treatment of concentrated waste waters or waters containing poorly degradable substances like halogenated hydrocarbons and heavy metal-compounds.