Syftet för studien är att ta fram möjliga avsättningsalternativ för slammet från Duvbackens avloppsreningsverk i Gävle och med stöd av en multikriterieanalys bedöma vilket alternativ som anses vara lämpligast med avseende på teknisk tillgänglighet, miljömässig hållbarhet, ekonomiskt perspektiv samt hälsa och hygien. Tre metoder har använts för studien; litteraturstudie, personlig kontakt samt multikriterieanalys. Duvbackens slam uppfyller inte dagens krav för att spridas på jordbruksmark och inte heller kraven för mindre känslig markanvändning uppnås, därmed måste andra alternativ utvärderas. De tre avsättningsalternativ som kan föreslås för slammet från Duvbacken, förutom nollalternativet är; täckningsmaterial till deponi, förbränning i kraftvärmeverk, gödsel till skogsmark och möjligen gödsel till salixodling (energiskog) det sistnämnda är möjligt endast om dispens från Länsstyrelsen kan erhållas. Dessa fyra alternativ utvärderas i en multikriterieanalys, utifrån viktningsgruppens prioriteringar. Medelvärdet för gruppens prioriteringar visar till exempel att de kriterier som anses viktiga är bland annat flexibilitet, resursutnyttjande, efterfrågan samt arbetsmiljö. De slutliga betygen blev relativt jämt fördelade för de olika alternativen, men salix fick högst slutbetyg, därefter skogsbruk, täckningsmaterial, och slutligen förbränning som fick lägst slutbetyg. Alla avsättningsalternativ har för- och nackdelar och spridning av de oönskade ämnena går inte att undkomma så länge de uppkommer från första början, därför är den bästa satsningen uppströmsarbete, e.g. att förebygga att dessa ämnen hamnar i avloppet vid källan. Slutsatser som kan dras av denna studie är att salixodling anses som det lämpligaste avsättningsalternativet för Duvbackens slam enligt utförd multikriterieanalys. I ett långsiktigt helhetsperspektiv är dock uppströmsarbete troligen den bästa investeringen. / The aim of the study is to provide and evaluate possible disposal alternatives for sludge from the wastewater treatment plant Duvbacken in Gävle by using a multicriteria analysis with respect to technical availability, environmental sustainability, economic perspective and health & hygiene. Three methods have been used in the study; literature study, personal contact and a multicriteria analysis. The sewage sludge quality today at Duvbacken does not meet national requirements to be used in agricultural purposes nor within less sensitive land use. Thus, other options should be investigated. Three deposal options have been suggested in this study by considering the legal basis and sludge quality, these are; combustion in combined heat and power plant, fertilizer to forest and fertilizer to willow (salix) cultivation, the latter is only possible if an exemption from the provincial government can be obtained. Those three alternatives, together with current landfill deposition, were evaluated in a multicriteria analysis, according to the weighting group`s priorities. The average value of the group´s priorities shows for example that important criteria seem to be flexibility, resource utilization, demand and work environment. The final results was relatively even among the options, willow got the highest rating, then forestry, then landfill cover, combustion received the lowest score. All options have pros and cons and the spreading of unwanted substances cannot be completely avoided as long as they exist in the incoming flows into the wastewater treatment plant, therefore the best investment might be upstream investigation, e.g. preventing these substances at their sources. Conclusion from this study is that willow cultivation seems to be the best disposal option for sludge from Duvbacken according to the multicriteria analysis. However, in a sustainable holistic perspective, upstream investigation would probably be the best investment.

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<p>The private sewage systems in Sweden releases around 600 tons of phosphorus per year, compared to about 350 tons from municipal sewage treatment plants, and they account for approximately 21% of the total anthropogenic discharge of phosphorus into Swedish waters. About 40% of Sweden's nearly 1 million private sewage systems are inferior with respect to emissions to surface and groundwater.</p><p> </p><p>The technology of small sewage plants is under development and knowledge of treatment effects for different solutions is poorly consolidated. Municipal authorities lack resources to keep up with the technologic development and assess the reliability of the treatment performances that suppliers report for their products. The thesis aims to conduct a market review and evaluation of wholly or partially prefabricated small sewage plants, to make it easier for municipalities and property owners to assess different technical solutions. The goal is a compilation of the products on the market, evaluated on the basis of the reliability of specified degrees of reduction.</p><p>Information on sampling procedures and test results were collected through a questionnaire to all active suppliers and the responses were then used to classify the products. The results suggest that most products have been extensively tested and shown a good cleaning ability. Those test results should be readily available to property owners and state authorities so that they do not have to make their own inquiries to verify the functionality of each product. Tests should also be entered in the central gauge database that is being constructed on behalf of the Swedish Environmental Protection Agency.</p><p>A case study was conducted in five municipalities in order to investigate how the handling of private sewage plants can be improved. The current work situation, what improvements that are demanded and what the administrators think of various suggestions for action was identified through interviews. According to the results, all administrators use the Environmental Protection Agency's general recommendations in their work though most of them experience difficulties to interpret the recommendations, and demand clearer rules and guidance. Almost all administrators want to increase the use of digital data and collaborate more across municipal boundaries. Another interesting finding is that the strategies to define the levels of environmental protection differ widely both between the five municipalities and between administrators within the municipalities. Better coordination is needed to enhance legal certainty and predictability for property owners and contractors.</p> / Kunskapscentrum Små Avlopp

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The private sewage systems in Sweden releases around 600 tons of phosphorus per year, compared to about 350 tons from municipal sewage treatment plants, and they account for approximately 21% of the total anthropogenic discharge of phosphorus into Swedish waters. About 40% of Sweden's nearly 1 million private sewage systems are inferior with respect to emissions to surface and groundwater.   The technology of small sewage plants is under development and knowledge of treatment effects for different solutions is poorly consolidated. Municipal authorities lack resources to keep up with the technologic development and assess the reliability of the treatment performances that suppliers report for their products. The thesis aims to conduct a market review and evaluation of wholly or partially prefabricated small sewage plants, to make it easier for municipalities and property owners to assess different technical solutions. The goal is a compilation of the products on the market, evaluated on the basis of the reliability of specified degrees of reduction. Information on sampling procedures and test results were collected through a questionnaire to all active suppliers and the responses were then used to classify the products. The results suggest that most products have been extensively tested and shown a good cleaning ability. Those test results should be readily available to property owners and state authorities so that they do not have to make their own inquiries to verify the functionality of each product. Tests should also be entered in the central gauge database that is being constructed on behalf of the Swedish Environmental Protection Agency. A case study was conducted in five municipalities in order to investigate how the handling of private sewage plants can be improved. The current work situation, what improvements that are demanded and what the administrators think of various suggestions for action was identified through interviews. According to the results, all administrators use the Environmental Protection Agency's general recommendations in their work though most of them experience difficulties to interpret the recommendations, and demand clearer rules and guidance. Almost all administrators want to increase the use of digital data and collaborate more across municipal boundaries. Another interesting finding is that the strategies to define the levels of environmental protection differ widely both between the five municipalities and between administrators within the municipalities. Better coordination is needed to enhance legal certainty and predictability for property owners and contractors. / Kunskapscentrum Små Avlopp

Diss. (sammanfattning) Luleå : Luleå tekniska univ., 2004. / Härtill 8 uppsatser.