For decades, waste and other chemicals were managed in an unsustainable manner, leading to serious environmental risks. Consequently, serious measures were taken by politicians to address the severe threats to the environment. Instead of burning food waste, the process of anaerobic digestion was introduced. This process works by breaking down food waste, manure, and other nutrient-rich materials in an oxygen-free system in four stages, where bacteria use these substrates as building blocks for biogas production. Through anaerobic digestion, food waste is converted into biogas, which can replace fossil fuels, benefiting the environment. Additionally, the residues left after digestion are used as nutrients for plants. This achieves both environmental and socio-economic benefits for society and farmers. The digestion process requires inoculum, which is the source of microorganisms, as well as substrate containing nutrient-rich materials that the bacteria use for biogas production. In 2023, studies showed that the use of hydrochar led to efficient biogas production. Hydrochar is formed during the carbonization of biomass through the HTC process, resulting in gas, liquid, and a carbon called hydrochar. This study focuses on investigating the effect of hydrochar on biogas production by developing various analytical methods to study the carbon mass balance and carbohydrate levels produced in the presence of hydrochar. The study also examines other metabolites present in the solution. To achieve this result, anaerobic digestion systems were built in six reactors: two contained only inoculum, two contained inoculum with substrate and served as references, and the last two contained inoculum, substrate, and hydrochar. Three of the reactors were connected to gas bags to investigate the biogas levels produced, while the other three were connected to bubble counters. Daily samples were taken from each bottle to analyze VFA, ammonia, and total organic carbon to examine how other metabolites affect biogas production. To ensure the stability of anaerobic digestion, pH values were measured daily. The gases produced in the connected bags were analyzed daily with gas chromatography, and the results were used to measure the carbon mass balance. This involved measuring how much carbon was in the liquid at the beginning of the experiment and how much remained at the end, as well as how much biogas was produced per day. The results showed that biogas production was higher in the reactors containing hydrochar compared to the other reactors. The carbon mass balance also showed higher amounts of total organic carbon at the beginning of digestion and lower amounts remaining in the solution at the end, indicating higher gas formation. The results also showed higher carbohydrate levels, higher VFA, lower ammonia levels, and lower pH values in hydrochar reactor, indicating effective conditions for better biogas production. / <p>Rapporten har tillåtelse från ASTM International att inkludera och referera till ASTM-standarder.</p>
| Identifer | oai:union.ndltd.org:UPSALLA1/oai:DiVA.org:kau-100447 |
| Date | January 2024 |
| Creators | Qasem, Haneen noureldeen |
| Publisher | Karlstads universitet, Karlstad university |
| Source Sets | DiVA Archive at Upsalla University |
| Language | Swedish |
| Detected Language | English |
| Type | Student thesis, info:eu-repo/semantics/bachelorThesis, text |
| Format | application/pdf |
| Rights | info:eu-repo/semantics/openAccess |
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