Diss. Linköping : Univ., 2005.

In Sweden there are about 750 000 house holds that have on-site sewage systems (OSS). Approximately 40-60% of these are not approved by todays standards. The OSS releases every year large amounts of nutrients that contribute to eutrophication of the marine environment and emissions also contributes to an increased risk of the spread of infectious agents. Municipalities have a central role to ensure that the OSS’s are living up to both national and regional environmental objectives. Today there are no legal requirements on how municipalities should ensure that the OSS’s complies with current regulations. Each municipality is responsible to adapt their work to the requirements of the Environmental Code. This study examines how ten Swedish municipalities are working with OSS and what the differences are in their approach to this problem. The study presents what is needed for a sustainable upgrade or replacement rate for OSS’s. The study is divided into two parts , the first part summarizes the guidance for municipalities to inspect the OSS and that is available from the govermental agencies and which was considered to be relevant to this study. In the second part , ten Swedish municipalities were interviewed , using so -called semi-structured interviews. The conclusion is that if municipalities are to achieve a sustainable upgrade or replacement rate, more guidance materials on how municipalities should evaluate old facilities are required. More stricter guidelines are also needed to enforce political decisions in order to allocate more resources for the continuing work of OSS but also by setting clearer objectives with which municipalities are enforced to comply.

<p>The purpose with this project was to invent a product that secures buildings sewer</p><p>systems against rats. The problem was presented to us by a local building maintainer in</p><p>Halmstad, who had experienced big problems with rats in his real estate. The project has</p><p>been carried out by Per Johansson, Robert Lidén and Niclas Nilsson under our own</p><p>auspices. We are primarily sponsored by AMLI Business Partner but also by</p><p>Innvationsgruppen, Halmstad Fastighets AB and Anticimex.</p><p>To be able to secure a whole building with only one product we came to the conclusion</p><p>that the product must be placed in the horizontal sewer pipe that connects with the</p><p>municipal sewer system. Our goal was to invent a product that prevent rats from passing</p><p>and at the same time not affect the water flow. We have succeeded in meeting our goal</p><p>and can in this report present a well functioning product named RatStop.</p><p>We have confirmed the market and can see a high potential in the product. The problem</p><p>is big in Sweden and enormous worldwide. The project group has to find sponsors for</p><p>production, marketing and further development of complementing concepts. Therefore</p><p>we now search for business partners.</p><p>We have used dynamic product development and all the tools combined with it during the</p><p>development. Especially meetings with competent persons have given us much, like</p><p>insight in the market, facts in different subjects and feedback on our idea and product.</p><p>We have learned a lot and we will benefit from this in the future. We believe in our</p><p>product and we will continue to work with it under the newly started company, Ratcon.</p><p>Hopefully our product will be available on the market within a year.</p>

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The purpose with this project was to invent a product that secures buildings sewer systems against rats. The problem was presented to us by a local building maintainer in Halmstad, who had experienced big problems with rats in his real estate. The project has been carried out by Per Johansson, Robert Lidén and Niclas Nilsson under our own auspices. We are primarily sponsored by AMLI Business Partner but also by Innvationsgruppen, Halmstad Fastighets AB and Anticimex. To be able to secure a whole building with only one product we came to the conclusion that the product must be placed in the horizontal sewer pipe that connects with the municipal sewer system. Our goal was to invent a product that prevent rats from passing and at the same time not affect the water flow. We have succeeded in meeting our goal and can in this report present a well functioning product named RatStop. We have confirmed the market and can see a high potential in the product. The problem is big in Sweden and enormous worldwide. The project group has to find sponsors for production, marketing and further development of complementing concepts. Therefore we now search for business partners. We have used dynamic product development and all the tools combined with it during the development. Especially meetings with competent persons have given us much, like insight in the market, facts in different subjects and feedback on our idea and product. We have learned a lot and we will benefit from this in the future. We believe in our product and we will continue to work with it under the newly started company, Ratcon. Hopefully our product will be available on the market within a year.

Rent vatten är en förutsättning för allt liv på jorden men utsläpp av föroreningar från mänskliga aktiviteter snedvrider ekosystemen med allvarliga konsekvenser som följd. Bristfällig rening och utsläpp av obehandlat avloppsvatten till naturen orsakar syrebrist och övergödning i vattenmiljöer. I svenska städer renas avloppsvatten i kommunala reningsverk genom mekanisk, biologisk och kemisk rening. Utanför städerna där kommunal anslutning inte är möjlig finns små anläggningar, så kallade enskilda avlopp, som renar avloppsvatten från en enskild fastighet eller ett mindre antal hushåll. Avloppsvatten från bensinstationer renas ofta i enskilda avloppsanläggningar där små reningsverk blir en allt vanligare reningsmetod. Reningsverken dimensioneras utifrån en branschgemensam definition av hushållsavlopp, vilken kan avvika starkt från det avloppsvatten som produceras i fastigheten till följd av avsaknad av bad-, disk- och tvättvatten. Framförallt är höga halter av organiskt material och kväve orsaker till skillnaderna. Naturvårdsverkets krav för utsläpp från enskilda avlopp förväntas vara uppfyllda även för avloppsvattnet från bensinstationer, trots att förutsättningarna i avloppet skiljer sig avsevärt från de som ligger till grund för kraven. I utredningen ingår tre små reningsverk som renar avloppsvatten med höga halter organiskt material från bensinstationer. De två reningsverken med biofilmsprincip har problem att klara kraven för rening av kväve. Dessutom undersöks inverkan av en reservoar och hypotesen är att den genomsnittliga reningsgraden ökar då reservoaren utjämnar de starkt varierande flödena. I reningsverket med aktivt slam uppstår problem med att det aktiva slammet dör och avger fräna lukter. Prover togs och analyserades vid samtliga reningsverk. Utredningen syftar till att finna orsakerna bakom de nedsatta reningsgraderna och föreslå åtgärder. De frågor som ställs är hur kvävereningen fungerar i biofilmsanläggningarna och hur den kan förbättras samt vad orsakerna är till varför det aktiva slammet dör och hur det kan undvikas. Resultaten pekade på fosforbrist i reaktorerna på biofilmsanläggningarna, vilket hämmade mikroorganismernas aktivitet vid reduktion av organiskt material som försvårade möjligheterna till kvävereduktion. Storleken på tankarna var sannolikt för små eller för få i förhållande till den höga organiska belastningen. Reservoaren i biofilmsanläggningen hade enligt utredningen en utjämnande effekt på reningsgraden av kväve och fosfor, men hade ingen påverkan på reduktionen av organiskt material. I aktivslamanläggningen orsakade den höga halten organiskt material syrebrist, vilket tillsammans med sulfat från fällningskemikalien ledde till bildandet av illaluktande vätesulfid samt det giftiga och svarta järnsulfid. För att öka reningsgraden av kväve i biofilmsanläggningarna föreslås att fosforreduktionen placeras efter den biologiska reningen och tillsats av en annan typ av flockningsmedel i slamavskiljaren rekommenderas för att underlätta reduktionen av organiskt material. För att undvika sulfidbildning i aktivslamanläggningen krävs en ökad syresättning. En kloridbaserad fällningskemikalie förordas framför en sulfatbaserad, eftersom tillgång till sulfat möjliggör bildandet av sulfider. / Clean water is essential for all life but emissions of pollutants from human activities are disturbing the balance in ecosystems leading to severe consequences. Poor treatment of domestic wastewater can cause anoxic waters and eutrophication in aquatic environments. In Swedish cities, domestic wastewater is treated in municipal wastewater treatment plants through mechanical, biological and chemical treatments. Where connection to the municipal wastewater treatment plants is not available, the wastewater from a single or a few households are treated in decentralized treatment plants. Wastewater, mainly from toilets, on gas stations is a typical example of individual sewage and decentralized treatment plants are becoming more common. The decentralized treatment plants are dimensioned based on an industry-wide definition of domestic sewage, which can differ greatly from the sewage produced in gas stations because of the lack of diluting bathing and washing water. The high concentration of organic matter and nitrogen is mainly the explanation to the differences. Regulation for emissions from domestic wastewater that has been made by the Swedish Environmental Protection Agency applies to this special wastewater even though the preconditions in the wastewater are significantly different from the ones that form the basis for the requirements. This study includes three decentralized treatment plants treating domestic wastewater with a high organic load having problems to meet the requirements of the authorities. Two of the treatment plants are based on the principle of fixed biofilm and is investigated because of their inadequate reduction of nitrogen. The difference between the two plants is a reservoir and a hypothesis is that it has a positive effect of the total reduction rate by smoothing of the incoming flow. The third treatment plant is a batch reactor with activated sludge that now and then has problems with pungent odors and dead activated sludge colored black. Samples were taken and analyzed at all treatment plants. The questions posed are how the reduction of nitrogen is working in the biofilm plants and how it can be improved, as well as the question about the reasons behind the dead sludge in the batch reactor with activated sludge and how it is prevented. The effect of the reservoir on the reduction rate is also investigated. The results revealed a lack of phosphorus in the bioreactors with fixed biofilm, which inhibited the microbial activity and thus the reduction of organic matter and nitrogen. The size of the reactors was at the same time probably too small relative to the organic load. The investigation showed that the reservoir in the biofilm plant had a positive effect on the reduction rate for total nitrogen and phosphorus. The high concentration of organic matter caused poor oxygen exchange in the batch reactor with activated sludge, leading to the formation of toxic hydrogen sulfide and iron sulfide. The sulfides explained the bad odors and why the activated sludge died. The proposed action for the biofilm plant is to place the reduction of phosphorus after the biological treatment, for example filtration. In the batch reactor with activated sludge is increased oxygen exchange suggested, in combination with a new precipitation chemical that is not based on iron sulfate, but chloride, because access to sulfate enables the formation of sulfides.

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