Reuse of Treated Wastewater in Industrial Symbiosis

Abstract

Many regions around the world suffer from occasional or permanent droughts. Recent years have shown that although Sweden is not a water scarce country, it is vulnerable to dry peri- ods. As drinking water is applied in not only households, but within agriculture and indus- tries, this thesis explores the opportunities to achieve an improved management of water re- sources, by investigating the possibilities to reuse treated wastewater.
By collaborating with water associations and industries around Sweden, a categorization of the main water consuming applications within industries was established. These were found to be cooling water, boiler feed, the washing of vehicles and water for recreational purposes. The reuse within agriculture and directly at the wastewater treatment plant were also investi- gated although mainly through literature.
It was found that a large interest in the topic is present within the industries and the environ- mental incitement is strong. It was though also communicated that the environmental benefits alone will not be motivation enough, the economical incitement dominates, since drinking water is easily accessible at a relatively low cost.
Further, this study proposes processes, which could be installed in the wastewater treatment plant, to achieve the water qualities required by the industries. The proposed processes in- clude activated carbon, reverse osmosis, nano-, micro- and ultrafiltration, ozonation and the disinfection processes ultraviolet light and chlorination. The instalment of nanofiltration showed a reduction or elimination of most substances, relevant for the categories for imple- mentation. The remaining processes have abilities to reduce or eliminate some substances and it was further investigated if a combination of processes could be beneficial.
For a more holistic approach, the legal aspects and costs were looked into, with the conclusion that clarifying definitions about treated wastewater are needed, as it has the possibility not to be seen as waste, but as a bi-product of the treatment process. Depending on the classification, the possibilities of reusing treated wastewater change.
The range of costs is large, depending on mainly the process which needs to be installed at the treatment plant and the connecting pipe systems, since local differences may have large ef- fects.
In conclusion, the reuse of treated wastewater does have potential and with the interest and motivation by industries, it seems like a promising option for the future of water.

Popular Abstract

Drinking water is currently used for many applications, which do not require as high of a qual- ity. At the same time, treated wastewater is discharged into the environment without being fur- ther used. To connect those two topics, this thesis, in collaboration with VA SYD, explores the possibilities for a more conscious water usage.
The reuse of treated wastewater has been done in several countries around the world. These regions suffer from occasional or permanent droughts, and recent years have shown that even northern Europe can experience water shortages. Sweden does not suffer from water scarcity, but reoccurring droughts, have caused for discussions around the usage of drinking water.
With the help from seven other water associations around Sweden, this thesis looked into, if industries have the possibility and motivation, to use another type of water than drinking water, with a focus on treated wastewater. It was found, that there is a great interest and industries are eager to rethink their water usage. As not all processes in industries have the same water quality requirements, it was further looked into, how these differ. The seven main water reuse possi- bilities are cooling water, recreational purposes, cleaning of vehicles, boiler water, food indus- try and process water, wastewater treatment plants and agriculture. As wastewater treatment plants are not designed for the reuse of treated wastewater, additional processes need to be installed to achieve the required qualities. Since wastewater is defined as waste, so is treated wastewater. In order to be able to reuse the water, an end-of-waste procedure could be a solution to re-classify wastewater as a bi-product of an industry. This would enable the water to be reused for other purposes, instead of being discharged into the environment.
The costs to go through with a wastewater reuse project, depend on the location of reuse and the required water quality. To install processes and connect the wastewater treatment plant with the industry can range greatly, due to regional, local and individual circumstances. Industries work towards environmentally benefitting solutions but without an economical benefit of reus- ing treated wastewater, it seems unlikely for them to contribute to the investment. Drinking water is comparably cheap and easily available in Sweden and for industries to invest in the project, more benefits need to become clear.
Concluding, it was found that industries in Sweden have noticed the water issues and the dry summers during the past years. This has contributed to more awareness and environmental thinking around their water usage. As processes exist to fulfill the quality requirements of the industries, the reuse of wastewater could become a valuable option in the future.

• author: Bürger, Greta
• supervisor: Åsa Davidsson
• organization: Chemical Engineering (M.Sc.Eng.)
• course: VVAM01 20191
• year: 2019
• type: H2 - Master's Degree (Two Years)
• subject: Chemistry
• keywords: Wastewater, Reuse, Symbiosis, water engineering, environmental engineering, vattenförsörjningsteknik, avloppsteknik
• report number: 2019-3
• language: English
• id: 8988015
• date added to LUP: 2019-07-04 16:46:31
• date last changed: 2019-07-04 16:46:31