Optical purifies sewage
Municipal sewage treatment plants employ various additives to improve the performance of their sewage purification processes. In particular, it is important to neutralise acidic components and stabilise the calcium balance. To this end, Vereinigte Kreidewerke Dammann collaborated with the sewage treatment plant in Peine in a project in which calcium carbonate from chalk - Optical - was used on an industrial scale for the first time.
The municipal sewage treatment plant in Peine treats the sewage of roughly 85,000 inhabitants and has to purify some 15,000 m³ sewage per day. Since early 2005, approx. 1.5 t fine chalk from Söhlde per day has been added to the feed channel of the biological treatment stage.
The impact of aggressive carbon dioxide has declined significantly as a result, because it reacts with the chalk. Soluble calcium hydrogencarbonate is formed, which not only improves the calcium balance, but also buffers the purified water against acid influences. Part of the chalk is not dissolved and forms a supporting skeleton for the bacteria used in biological purification.
The chalk also demonstrates its positive effect at the end of the treatment chain, when the activated sludge is dewatered and comes to be disposed of/utilised. As a result of the residual chalk, the sludge can be dewatered much better, resulting in lower disposal/utilisation costs. The chalk thus makes an attractive contribution to environmental protection. The natural calcium carbonate is easy and safe to handle, and helps reduce the operating costs of municipal sewage treatment plants. These positive characteristics add up to competitive advantages, offering potential customers an outstanding alternative to conventional products.
