Sammendrag
Many municipalities, among them the Trondheim municipality, is considering reusing sand for icy roads that is gathered from roads, foot paths and bike paths. In order to reuse this sand in an environmentally and economically acceptable fashion, washing the sand is being discussed. In cooperation with Trondheim municipality this task has primarily seen on contamination being supplied to sand for icy roads as well as the washing of the sand. In addition there is a consideration concerning contamination and washing of “gatefei*”. Certain materials connected with environmental concerns have been analyzed in the washing water and fine-grained materials from the washing water from the sand and “gatefei” at nine different storages in Trondheim, in addition
the main storage in Tiller. The storages that samples were collected from were: Solbakken skole, Ny–Jordveien, Granåsen gård, Være vestre, Blomsterbyen, Kyvannet, Kongsvegen, Fossgrenda and Buran operation station. The sand for icy roads is eventually gathered in the main storage in Tiller. Potential sources of metals added to the sand for icy roads and “gatefei” have also been discussed.
Sand for icy roads and “gatefei” is washed with ion exchange water, with and without added nitric acid (HNO3). Fine-grained materials from the washing water was dried and decomposed with the help of UltraClave. The washing water and the decomposed dust samples were analyzed with ICP-MS. The elements that are focused on in this thesis are the elements that are associated with environmental aspects, like magnesium, iron, zinc, vanadium, manganese, chlorine, bromide, arsenic, lead, cadmium, mercury, copper, chromium and nickel. The results of the analysis show that the amount of chlorine was consistently high in the washing water in both the sand for icy roads and “gatefei” from the storages. Arsenic and copper stood out in the washing water from both the sand of the icy roads and “gatefei”, where the amount of arsenic and copper were within the classification of condition (III) and (IV) in the washing water from the sand and “gatefei” from multiple storages and sand from the main storage in Tiller. In the dust from the washing water from the sand for icy roads and “gatefei” iron and magnesium were the dominating elements. The amount of magnesium was within the VI classification of condition (V) (in accordance to the English limit values) in the dust from the sand for icy roads and “gatefei” from all the storages and the main storage in Tiller. The amount of chromium, nickel, copper and zinc dominated among the heavy metals in the dust from the sand for icy roads and “gatefei”. It was observed that the amount of arsenic, chromium and manganese were within the classification of condition (III) in the dust from the sand for the icy roads at one or more storages. In the dust from the “gatefei” the amount of manganese were within the classification of condition (III) in multiple storages. The traffic is probably the main source of the metals that is added to the sand for icy roads while it is on the road. The high amount of chlorine is most probably from the use of road salt during the winter, or salt added to the sand for icy roads to prevent freezing while in storage. Much of the results from “gatefei” show the same tendencies, as the sand for icy roads, and many of the sources for contamination in “gatefei” is probably the same as the sand for icy roads.
*Gatefei: A mixture of sand, soil and gravel
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