The diploma thesis is focused on the energy utilization of sewage sludge before and after microwave pyrolysis process. The first part of the thesis deals with sludge management, treatment of sludge and its subsequent use or disposal. In the second part of the thesis prepared and modified samples of sludge from WWTP 1 and WWTP 2 are subjected to microwave pyrolysis process. Subsequently, samples are taken for analyzes to determine the total organic carbon, the specific surface area, the heavy metal content and the calorific values. The resulting data was processed in Microsoft Office Excel and presented at work. At the end of the thesis two case studies are then proposed for a specific design of the conceptual location of microwave pyrolysis for the sludge drying process and the drying process of the sewage sludge in the direct combustion boiler room.

This master's thesis deals with the analysis of biochar extracts by separation methods. All analyzed biochar was produced from waterworks sludge by microwave pyrolysis. The aim of the thesis is the optimization of the sample preparation method and its analysis in a laboratory environment. With the ever-growing world population, the problem of a sustainable economy in both agriculture and waste management is becoming increasingly urgent. This fact has led most countries to consider promoting the so-called Circular Economy. The use of sewage sludge as a feedstock for biochar production is perfectly in line with this strategy. So far, however, the short term and the long term benefits and risks of using biochar have not been sufficiently described. Potentially hazardous organic substances were extracted from the biochar extracts by three techniques: liquid-liquid extraction, solid-phase extraction, and solid- phase micro-extraction. The obtained samples were analyzed using the GS-MS/TOF method. The individual methods were compared. Several biochar samples from WWTP Brno and WWTP Drahovice were selected and analyzed to verify the suitability of the selected sample analysis method.

Biochar is created during the pyrolysis of organic biomass. Once added into the soil, it can improve its features. Biochars made from sewage sludge have various compositions. It is because of the vast difference between entrance materials. Organic pollutants can be absorbed into its surface during the cooling proces sof pyrolysis. If released into the enviroment, these compounds can cause inhibition of plant growth, get into food chains and adversely affect living organisms. Organic pollutans are determined most often by GC/MS after organic solvent extraction.

Cette étude porte sur la compréhension et l'amélioration de la réactivité des charbons pour la catalyse de la réaction du craquage du méthane. Pour ce projet, nous avons produit des charbons à partir de la gazéification de bois de peuplier à 750°C sous vapeur d'eau. Par la suite, deux traitements de fonctionnalisation ont été appliqués. D'une part, une oxygénation en phase gaz a été réalisée pour augmenter la concentration des sites oxygénés. D'autre part, une imprégnation en phase liquide dans différentes solutions de sel de nitrate (calcium et potassium) a permis d'accroître la quantité de minéraux. Les propriétés physico-chimiques (structure carbonée, sites oxygénés, minéraux et porosité/surface spécifique) des charbons bruts et fonctionnalisés ont été caractérisées. Les résultats ont montré que les deux traitements de fonctionnalisation ont augmenté la concentration des sites actifs visés. Par ailleurs, les évolutions des propriétés texturales et de la structure carbonée lors des deux fonctionnalisations ont été mises en évidence. Les tests catalytiques du craquage du méthane sur les différents charbons, à 700°C, ont montré que les minéraux sont les sites les plus réactifs vis-à-vis de cette réaction. Les fonctions oxygénées basiques et les défauts de structure sont également des sites actifs. Une diminution de l'efficacité lors du craquage a été observée due à la désactivation progressive de la surface des biochars. Le développement d'un modèle, à l'échelle du pore, a permis de montrer que la concentration initiale de sites actifs à la surface et leur différence de réactivité étaient deux paramètres importants dans la prédiction du comportement de désactivation de la surface. / This study is focused on the reactivity of biochar to catalyze the methane cracking reaction. Biochar was produced from steam gasification of poplar wood (750°C, 30 min, 20°C/min, 90%H2O/10%N2, fluidized bed) and then functionalized by an O2 gas-phase treatment and a wet impregnation into nitrate salts solutions to increase oxygen functions and minerals (calcium and potassium) concentrations at the biochar surface respectively. A set of characterization was performed on the raw and functionalized biochars to evaluate their surface physico-chemical properties. The oxygenated functions, the mineral particles, the carbonaceous structures and the textural properties (specific surface area and porosity) were analyzed. Results showed that the two functionalization treatments increased the concentration of the targeted functions and modified the carbon structures and the textural properties as well. Methane cracking tests were then performed on the biochars to compare their activities and correlate with their physico-chemical properties. It has been highlighted the minerals particles of potassium and calcium are the main active sites of the biochar surface. In fact, the reactivity of the impregnated biochars was twice to 4 times higher than the one of the raw biochar. The porosity of the biochar is the second most important criteria to notably obtain a good dispersion of the minerals particles. Basic oxygenated functions and disordered carbonaceous structures (defaults into the graphene sheets) are reactive as well. However, coke deposition progressively deactivated the biochars surface over the reaction in any case. A model at the pore scale has been proposed to better understand the surface deactivation.

Vid skogsavverkning tas en del av de näringsämnen som trädet använt under sin tillväxttid bort från marken och förs inte tillbaka. Detta kan leda till näringsfattigare mark och lägre pH vilket leder till sämre tillväxt för träden. Skogsstyrelsen rekommenderar olika åtgärder för att motverka detta och en av åtgärderna är återföring av aska till skogen. Det finns vissa riktlinjer för vad koncentrationen av grundämnen bör vara för att detta ska anses positivt för skogen. Det har bedrivits forskning sedan 2018 för att återföra slam och aska från pappersbruk till skogen genom att föra in det i plantor som ska utsättas i skogen. Detta i form av härdade produkter som pellets eller pulver.   Fokus i denna studie är att undersöka olika askor, slam och härdade produkter som biokol för att jämföra med riktvärdena för askåterföring som Skogsstyrelsen har bestämt. Därutöver benämns några skadliga ämnen som kan ha förekommit i för höga koncentrationer. Prover förbereds genom torkning och malning av hydrokol, pyrokol, torvmark, pyrolyserad träflis, bioaska, blandslam och bioslam. Dessa pulveriserade prover analyseras sedan i en XRF-analys för att få ut koncentrationer av olika grundämnen för provernas torrsubstans.  Slam från pappersbruk visade sig innehålla lägre koncentrationer av de makronäringsämnen och spårämnen än askan, och ur näringssynpunkt vore ren askåterföring bättre. Men med ren askåterföring råder en större risk att få en högre koncentration av giftiga ämnen som vanadin och nickel vilket förekom i högre grad i askan. Andra höga halter av spårämnen var krom i ett hydrokolprov och kobolt och svavel vilket uppkom i askproverna. En blandning av aska med en andel slam bör skapa bra förutsättningar för ökad näring med liten risk för skadliga grundämnen. Denna rapport kom fram till att en blandning av ca 55 % slam och 45 % aska bör vara lämpligt för att undvika förgiftning av nickel och vanadin och samtidigt innehålla de nödvändiga näringsämnena. Genom att processa slam från pappersindustrin har det gjorts biokol prover som denna studie fått ta del av. Det visade sig att biokolet från Heinola, Finland visar på bra resultat som ger ökad tillväxt genom sitt höga fosforvärde. Att använda samma process som Heinola proverna för tilltänkta biokol bör vara att föredra / During deforestation, some of the nutrients used by the trees during the growth period are removed from the soil and not returned. This can lead to poorer content of nutrients in the soil and lower Ph, which leads to poorer growth for the trees.   The Swedish Forest Agency recommends various measures to counteract this and one of the measures is ash recycling, which there are certain guidelines for, what the concentration of elements should be for this to be considered positive for the forest.   A research project has been conducted since 2018 to return sludge and ash from paper mills to the forest by introducing it into plants to be planted in the forest. This in the form of hardened products such as pellets or powders.  This report mainly focuses on checking different ashes, sludge and hardened products such as biochar to compare with the guideline values for ash recycling that the Swedish Forest Agency has set.   In addition, this report highlights some harmful substances that may have been present in too high concentrations.  This is done by drying and grinding samples from hydrochar, pyrochar, peat soil, pyrolyzed wood chips, bioashes, mixed sludge and biosludge. These powdered samples are then run in an XRF analysis to obtain concentrations of different elements for the samples for a maximum dry content.  The sludge was found to contain lower concentrations of the useful and dangerous substances than the ashes, and from a nutritional point of view, pure ash recycling would be better. But with pure ash recycling, there is a greater risk of getting a higher concentration of toxic substances such as vanadium and nickel.  The results show hazardous elements such as nickel, chromium, cobalt, sulfur and vanadium measured in excessive doses. These occur mainly in the ash samples. A mixture of ash with a proportion of sludge should create good conditions for increased nutrition with little risk of harmful elements. As a suggestion, this report shows that a mixture of about 55% sludge and 45% ash should be suitable to avoid poisoning of especially nickel and vanadium. It turned out that the biochar from Heinola, Finland shows good results that increase growth through its high phosphorus value. Using the same process as the Heinola samples for proposed biochar should be preferred.

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Hard carbon is regarded as one of the most promising anode materials for sodium-ion battery. However, the ash content of the hard carbon anode inherited from the precursor have several negative impacts on the electrochemical performance of hard carbon. The traditional method utilizes strong inorganic acid washing to reduce the ash content of hard carbon. However, this method results in heavy environment pressure and safety hazards. Therefore, it’s necessary to exploring an alternative ash content removal method which is safer and environment friendly. This project develops an environmentally friendly approach to remove ash from hard carbon by using acetic acid. This approach effectively reduces the ash content and enhances the electrochemical performance of the hard carbon anode. The ash content of hard carbon decrease from 1.57 wt% to 0.655 wt% after the 4 mol /L acetic acid treatment. The two-step treatment process also studied in this project and shows a better ash removal ability than one-step treatment process. The ash content of 4 mol /L acetic acid and 20 wt% KOH only 0.28 wt%. Furthermore, the electrochemical performance of the two- step treated hard carbon exhibits notable improvements, including enhanced initial Columbic efficiency (from 84.53% to 88.11%), reversible capacity (from 244.2 mAh g-1 to 280.8 mAh g-1). The long cycle performance of chemical treated hard carbon anode need further investigations in future studies. / Hårt kol anses vara ett av de mest lovande anodmaterialen för natriumjonbatterier. Askhalten i den hårda kolanoden som ärvts från prekursorn har dock flera negativa effekter på den elektrokemiska prestandan hos hårt kol. Den traditionella metoden använder stark oorganisk syratvättning för att minska askhalten av hårt kol. Denna metod resulterar dock i hög miljöbelastning och säkerhetsrisker. Därför är det nödvändigt att utforska en alternativ metod för borttagning av askinnehåll som är säkrare och miljövänligare. Detta projekt utvecklar ett miljövänligt tillvägagångssätt för att ta bort aska från hårt kol genom att använda ättiksyra. Detta tillvägagångssätt reducerar effektivt askinnehållet och förbättrar den elektrokemiska prestandan hos den hårda kolanoden. Askhalten i hårt kol minskar från 1,57 viktprocent till 0,655 viktprocent efter 4 mol/L ättiksyrabehandlingen. Tvåstegsbehandlingsprocessen studerades också i detta projekt och visar en bättre förmåga att avlägsna aska än enstegsbehandling. Askhalten av 4 mol/L ättiksyra och 20 viktprocent KOH är endast 0,28 viktprocent. Dessutom uppvisar den elektrokemiska prestandan hos det tvåstegsbehandlade hårda kolet anmärkningsvärda förbättringar, inklusive förbättrad initial Columbic effektivitet (från 84,53 % till 88,11 %), reversibel kapacitet (från 244,2 mAh g-1 till 280,8 mAh g-1). Den långa cykelprestandan hos kemiskt behandlad hård kolanod behöver ytterligare undersökningar i framtida

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With a growing concern of climate change due to increased levels of CO2 in the atmosphere, carbon sequestration has been suggested as a possible solution for climate change mitigation. Biochar,a highly carbonaceous product produced through pyrolysis, is considered a viable option due to its content of stable carbon. This work covers the investigation of the possibility to produce biocharfrom four different feedstocks, namely peat, straw, horse manure and sewage sludge. The study includes a literature study and a five-week trial period at a 500 kW pilot plant, PYREG 500, in Högdalen. The thermal behaviour of the feedstocks, including garden waste, was investigated using thermogravimetric analysis (TGA). The TGA results were used to decide the optimal pyrolysis temperature for peat and straw at the pilot plant. The TGA results showed that the feedstocks behave differently when pyrolysed; the mass loss rate as well as the final mass loss varied. Physiochemical characterisation of the biochar was completed and the results were in agreement with previous studies. The produced biochar from straw and two types of peat had a C content above50 wt.% (76.6, 80.7, 79.2 wt.%) and low molar ratios of H/C (0.33, 0.36, 0.38) and O/C (0.032,0.023, 0.024). The pH increased as a consequence of pyrolysis and the biochars were alkaline (pH10.1, 8.5, 8.3). Polycyclic aromatic hydrocarbons (PAHs) were found in biochar from both strawand peat (8.26, 1.03, 5.83 mg/kg). In general, nutrients and heavy metals were concentrated in the biochar, except for Cd which decreased and Hg which could not be determined. The specific surface area of biochar from straw was considered small (21 m2/g) while biochar from peat had a higher specific surface area with a greater span (102-247 m2/g). The properties of the produced biochar were compared to the criteria included in the European Biochar Certificate and some of them were fulfilled, including the content of C, PAH and heavy metals. A flue gas analysis was completed when operating the pilot plant on straw pellets and it was showed that several emissions were released, including NO2, SOX, HCl and particulates, however, solely the emissions of NO2 exceed the regulations which will be applied in 2020. Regarding process design of a future pyrolysis plant, it is suggested that the means of material transport, particle separation, temperature control and quenching of biochar should be improved.

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