Karakterisering og rensing av tunnelvann

Abstract

This Project is a master thesis. The report is an addition to the preliminary project, which was made in the autumn of 2018. The research question of this project is: "How to solve the challenges related to polluted tunnel water?”During the project period a wide range of different methods dealingwith particle containing tunnel water has been studied. Analyses of coagulant chitosan have also been carried out. Sedimentation characteristics with a varied concentration of chitosan were analysed involvingsedimentation rate, suspended solids (SS), turbidity and particle analyses. A qualitative survey was also conducted to four respondents. All of them had both varied and relevant background in order get a wide variety of perspectives connected to the present situation, challenges and opportunities for the future.The experiments show that the optimal dosage for both sedimentation rate, suspended solids and turbidity is a chemical addition of 5 mg chitosan per litre water. The results of the analyses showed that chitosan gave a 95% purification effect with respect to SS and 96% for turbidity. Analyses of particle size distributions show that sedimentation by adding chitosan give on average 32.4% smaller particle sizes after 5 minutes of sedimentation. The result is given with respect to volume density and is comparedto a naturally sedimented sample of tunnel water. Technology is moving in the right direction with a focus on improvements related to environmental consideration in prevailing treatment methods, as well as the implementation of new methods, such as centrifugation of tunnel water. Chitosan is a coagulant that may replace some of the already existing precipitants in the future.