Advanced treatment of pit lakes using limestone and carbon dioxide

摘要

In Lusatia (Germany) a lot of pit lakes were flooded due to rising groundwater over the last few years. Many of the newly developed lakes are affected by an inflow of potentially acidic groundwater from the adjacent overburden dumps. Therefore, technical treatments are necessary for a sufficient water quality. Liming is the most widely used treatment. At present various liming procedures are used. However, the most of them have a relatively low buffering capacity i.e. less than 0.3 mol/m~3. This leads to, repeated treatments at short intervals being necessary.A significantly higher buffering capacity can be achieved by the use of limestone and carbon dioxide. In 2015 a pilot treatment was conducted within the pit lake "Scheibe", one of the largest pit lakes in Lusatia with a volume of 110 Mm~3. The input of limestone and carbon dioxide was carried out with two underwater nozzle pipelines. This technology has already been used for the primary neutralization of Lake Scheibe (Strzodka et al. 2013). In this paper we will present this new treatment concept in detail and the results of the pilot test.