Unsafe sanitation systems poses a risk for pathogen transmission, wherefore it is important to both inactivate pathogens present in human excreta and conduct safe sanitation systems from use to end-use. The Peepoo toilet, using ammonia sanitisation, have been suggested as a low-cost sanitation solution and is implemented in schools in Kibera, an urban slum in Kenya. This master thesis aim to study the inactivation efficiency of ammonia sanitisation when treating human excreta with urea, and to quantify the risks of exposure to microbial hazards from the Peepoo sanitation system using faecal indicator bacteria. Excreta was collected from four schools in Kibera. After adding urea to mimic the inactivation of the Peepoo in the laboratory, the inactivation rate was correlated to temperature and free ammonia concentration for Campylobacter spp., Escherichia coli and Enterococcus spp.. Campylobacter spp. and E. coli both had a high inactivation rate even at low temperature and low addition of urea. Inactivation rate of Enterococcus spp. was lower and close to zero when 1.87 % urea was added for 15 °C. For Enterococcus spp. a lag-phase was observed, which was not affected by temperature but by concentration of free ammonia. For investigated bacteria, inactivation rate increased with increased temperature and free ammonia concentration. Along the Peepoo management chain, several hazardous events were identified such ascontamination during usage, handling and transportation. Sampling showed a higher contamination of Enterococcus spp. than of E. coli. Enterococcus spp. was used as a faecal indicator for Ascaris and E. coli was used as an indicator of E. coli O157:H7 in a quantitative microbial risk assessment (QMRA). Through the QMRA, the risk of infection of Ascaris and E. coli O157:H7 for one exposure event was simulated based on a Exponential and a Beta-Poisson dose-response model respectively. The risk of infection of Ascaris was around 12 % regardless of where exposure occurs, if Ascaris eggs were present. For risk for infection with E. coli O157, the simulated risks were below 10 % at almost all exposure points, with most of the high risk exposure points located in the schools. There are risks of pathogen transmission in the Peepoo management chain that should be further investigated. Ammonia sanitisation permits a high degree of microbial inactivation but to secure a safe end-product it is recommended to be kept in room temperature (24.05±0.62 °C) or higher.

Avloppsslam innehåller näringsämnen, som bör återföras till naturen för att skapa ett så kallat näringskretslopp. Genom att optimera hygieniseringen av avloppsslam med effektivare behandlingsmetod kan avloppsslam bli mer lämpligt att avsättas ur ett bättre ekonomiskt- och miljömässigt perspektiv. Syftet med arbetet var att undersöka och bedöma om effektiviseringav befintlig slambehandling är möjlig för att uppnå tillräcklig hygienisering. Utifrån den effektiviserade slambehandlingsmetoden utreda möjliga avsättningsalternativ som lämpar sig bäst för avloppsslammet i Avesta kommun. En litteraturöversikt utfördes för att öka kunskapen och förståelsen av avloppsslam, desshantering och avsättning. Fallstudien är utformad med kvalitativ metod och informationen har inhämtats från vetenskapliga artiklar, myndigheter, rapporter, examensarbeten och personligkontakt som komplement för att erhålla en god förståelse. Uppgradering av mesofil rötning av avloppsslam vid 37 °C till termofil rötning, 55 °C – 65 °C innebär förhöjd temperatur; det kräver mer energi och ökade energikostnader. Komponenter av den mesofila rötningsprocessen kommer att behöva uppgraderas eller bytas ut och därför tillkommer extra kostnader som också behöver ses över. Fördelarna med termofil rötning inkluderar kortvariga uppehållstider, mindre rötkammare och slammet blir tillräckligt hygieniserat. Ett framtidsscenario är framtaget utifrån effektiviserad slambehandling där två avsättningsalternativ är mest lämpliga för avloppsslammet i Avesta kommun. Gödsel till produktiv mark är ett av de föreslagna alternativ som tillåter fosforn återvinnas och återanvändas. Om inte termofil rötning som effektivisering hade erhållit tillräcklig hygienisering borde andra komplementerande processer ha införts, exempelvis komposteringstrumma eller pastörisering. En fullständig kostnadsjämförelse mellan befintlig slambehandlingsmetod och mer effektiviserad slambehandlingsmetod är dock nästan omöjlig att utföra då alla kostnader beror på val av komponenter och faktorer. Denna fallstudie bidrar med ett underlag som kan ge större möjligheter för Avesta Vatten och Avfall AB att välja den mest lämpliga avsättningen för avloppsslammet i Avesta kommun i framtiden. / Sewage sludge contains nutrients, which should be returned to nature to create a so-called nutrient circulation. By optimizing sanitisation of sewage sludge with effective treatment methods, sewage sludge can be more appropriately disposed from a better economic- and environmental perspective. The aim of this work was to investigate and judge the efficiency of existing sludge treatment is possible to achieve a sufficent sanitation. Based on the streamlined sludge treatment method investigate the disposal options that is best suited for sewage sludge in Avesta town. A literature review was conducted to increase the knowledge and understanding of sewage sludge, its treatment and disposal. The case study is formed with qualitative method and information which has been collected from the scientific articles, authorities, reports, theses and personal contact as a complement to obtain a good understanding. Upgrading of mesophilic digestion of sludge at 37 ° C to thermophilic digestion at 55 ° C - 65 ° C means increased temperature; this requires more energy and hence increases energy costs. Components of the mesophilic digestion process need to be upgraded or replaced and therefore additional costs should also be considered. The advantages of the thermophilic digestion include short residence time, smaller digester and sludge becomes sufficiently disinfected. A future scenario is developed based on more efficient sludge treatment where two disposal options are most appropriate for the sewage sludge in Avesta town. Returning digestate to productive land is one of those suggested alternatives that allows phosphorus to be recovered and recycled. If not thermophilic digestion as streamlining is not effective enough for sufficient sludge sanitation, other complementary processes have to be introduced, for instance, composting drum or pasteurization. A full cost comparison between the existing sludge treatment and more efficient sludge treatment method is, however, almost impossible to be performed when all costs depend on the choice of components, factors and so on. This case study contributes with first-hand information that can provide greater opportunities for Avesta Vatten och Avfall AB to select the most appropriate options for sewage sludge disposal in Avesta town in the future.