People were forced to boil the drinking water over a long period. According to the Smittskyddsinstitutet the microorganism cryptosporodium was the probable cause of the outbreak. Cryptosporodium is a so-called protozoa which must have a host, a human or animal to reproduce.
In an ongoing project work Luleå University of Technology on behalf of the municipality of Östersund in trying to identify possible sources and prevent new outbreaks of the infection. It examines both the impact of snowmelt in the spring and in the rain during the summer and fall. Treatment and rainwater ports via storm drains and pipes directly into the Great Lake, Östersund municipality’s source of drinking water and bathing water, without being purified. In the samples taken investigates the presence of heavy metals, nutrients, sediment particles as well as four different indicator bacteria, natural bacteria and bacteria from feces, known as coliforms.
Generally, one can say that the higher levels of metals and particles are collected in the snow and the value of these increases dramatically during the spring snowmelt. So this is winter’s total emissions from eg industries and emissions from traffic are stored in the snow. During the summer and fall with higher temperatures and rainfall increases the amount of bacteria from eg birds, pets, livestock, vegetation and activities at campsites and in summer, as the rain washed out directly in the Great Lake via the city’s storm sewers.
– We do not measure parasites cryptosporodium says Helen Galfi, doctoral student at the Sanitary Engineering at Luleå University of Technology. Instead, it is the measurement of the four indicator bacteria is an important piece of the puzzle to see if other pathogenic bacteria or parasites may exist in the water. Any presence of cryptosporodium measured, however, the water drawn from the Great Lake to the waterworks of Östersund.
The five sampling locations are carefully selected to try to identify where in the urban potential infections or other contaminants may be generated. The selected sites are:
- Hospital District
- Bathhouse area which also includes residential and recreational areas
- A residential
- The area with camping and racetrack
Scientists have long known studies that urban areas provide a greater impact on surface water quality and the birds give maximum impact for bacteria in drinking water.
In the results presented from measurements in Ostersund confirmed that knowledge. The area around the center of Östersund where also my campus includes the highest levels of pollution in stormwater.
The project has given some new knowledge . It has for example noted that clostridia, a spore-forming living organism can survive for several months and unfriendly environments or nutrition-poor environments in the sediments of waterpipes. This means that when the snow is melting snow or ít´s raining, more organisms than expected can reach surface water sources such as the lake of Storsjön.
What are the chances that what happened in 2010 will happen again?
– In Östersund the problem is solved now with UV treatment of water in water treatment plant, but there is a possibility that similar outbreaks occur in other places in Sweden where the drinking water comes from surface water sources with the influence of human activities, says Helen Galfi, VA Technology.
The research topic Sanitary Engineering at Luleå University focuses on knowledge building around water and waste systems with starting points in sustainability and wise use of resources.
Contact at LTU