Hygienisation with the use of lime In a medium-size treatment plant Sewage sludge classified as hazardous waste requires searching for advanced and more effective methods of utilization. Waste produced in treatment plants, should be subject to proper reprocessing on the grounds of health, economic and legal reasons. In treatment plants, hygienisation with the use of lime (CaO) is commonly applied. The main advantage of the aforementioned method is the growth of pH value of sewage sludge and the reduction of pathogens. Apart from this, sewage sludge hygienisation with the application of lime is characterized by the high costs associated with the acquisition of lime. Assuming the price of highly reactive lime ranging from EUR 67-82 per one tone, additional cost of approximately EUR 8600 is generated for a medium treatment plants per year. Additionally, the liming of sewage sludge requires the modernization of treatment plants and the acquisition of new equipment. But due to the fertilizing properties of aforementioned waste, the agricultural utilisation of sewage sludge is the best method for small and medium treatment plants. The financial feasibility analysis showed that the whole undertaking will pay off within 7 years. This paper presents the cost-effective analysis of sewage sludge hygienisation in medium municipal treatment plant. In this article, the main mechanism of process and the influence of liming on sewage sludge characteristics are also showed.
