A case study on the performance of trickling filter plants in Alpine regions: influence of seasonal variations

The increasing number of people who come to enjoy the beauty of the Alps ma kes it necessary to provide proper disposal of the wastewater produced in t he touristic resorts including huts and cabins. Advanced wastewater treatme nt is not easy to achieve because of the difficult conditions prevailing in this region. Highly variable wastewater flows, low temperature in winter, poor availability of input data for design, energy problems. and the demand for keeping costs for building and maintenance at a minimum level are the key obstacles in the process of implementing wastewater treatment facilitie s. In the past, trickling filter plants have been commonly applied, since t his technology has been assumed to provide fairly high reliability despite the aforementioned conditions. The results of a survey focusing on the effi ciency of such systems showed that to take into account only peak loads is insufficient when designing a plant. In addition, if is necessary to provid e measures to handle discontinuous load conditions by managing water distri bution to the trickling filter, and by a recirculation strategy adapted to each condition scenario. Based on the results obtained a number of process modifications are suggested. The overall performance could be enhanced cons iderably with only a few process modifications.