Browsing by Author "Hurme, Markku, Docent, Aalto University, Department of Biotechnology and Chemical Technology, Finland"

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  • Material and energy balance of solid recovered fuel production
    (2015) Nasrullah, Muhammad
     School of Chemical Technology | Doctoral dissertation (article-based)
    The quality of solid recovered fuel (SRF) holds the key to its market demand and utilization for power production. However, the lack of consistency in the quality and availability of SRF may limit its applications in power producing industries. In the SRF production, proper sorting of input waste's components into the relevant output streams is a decisive factor in defining the quality and yield of the SRF. The objective of this research work was to establish the material and energy balance of SRF production based on an in-depth analysis and detailed evaluation of physical and chemical characteristics of the input and output streams and waste components produced in industrial-scale SRF production. The SRF was produced from three different types of waste materials: commercial and industrial waste (C&IW), construction and demolition waste (C&DW) and municipal solid waste (MSW). In the case of SRF produced from MSW, higher yields of material were recovered in the form of SRF as compared with that recovered from C&IW and C&DW. Of the MSW input to the process, 72 wt. % was recovered as SRF, equivalent to 86 % energy recovery. In the case of SRF produced from C&IW, a higher mass fraction of the input chlorine (Cl), lead (Pb) and mercury (Hg) was found in the SRF as compared with the SRFs produced from C&DW and MSW, namely 60 %, 58 % and 45 %, respectively. The SRF produced from CDW was found to contain the lowest mass fraction of the input chlorine, lead and mercury in comparison with the SRFs produced from C&IW and MSW, namely 34%, 8% and 30%, respectively. In each case of the SRF production, a higher mass fraction of the input cadmium (Cd) was found in the SRF than in the other output streams. Among the waste components, rubber, plastic (hard) and textile (synthetic type) were identified as the potential sources of polluting elements and potentially toxic elements (PTEs). In C&IW, C&DW and MSW, rubber was measured to contain 8.0 wt. %, 7.6 wt. % and 8.0 wt. % of chlorine, respectively. In C&DW, plastic (hard) and textile (especially synthetic type) were measured to contain 7.0 wt. % and 3.8 wt. % of chlorine respectively. The results of this thesis can be used by the SRF manufacturers and users in order to enhance and implement their understandings about the quality and yield of SRF and the research institutes/organisations to make use of the generated data, in waste management and waste-to-energy related modelling and decision making tools.
  • Proof of concept of black liquor valorisation by partial wet oxidation
    (2016) Hassan, Raja Muddassar
     School of Chemical Technology | Doctoral dissertation (article-based)
    In today's pulp and paper industries, large quantities of black liquor are produced when wood or non-wood lignocellulosic feedstocks are digested with cooking chemicals to separate cellulose fibres from lignin, hemicellulose and other degraded components. Although black liquor is considered to be a waste product, it is rich in both dissolved organic components from wood and added cooking chemicals. In order to recover these cooking chemicals and generate energy from the dissolved organic compounds, it is common practice to burn black liquor in a recovery boiler. However, this is not always the case; for example in developing countries, where small-scale non-wood pulping mills tend to lack spent liquor treatment facilities, the resultant spent liquor is discharged into the environment without effective treatment. The aim of this thesis is to prove the concept of using partial wet oxidation (PWO) for the treatment of lignocellulosic-rich waste streams in order to produce chemicals on laboratory scale. In particular, the effluent from wood and non-wood pulping mills - i.e. black liquor - is investigated as a raw material for the PWO process in order to produce valuable chemical feedstocks and thus improve the profitability of pulping mills. Moreover, the data produced by this research will contribute by providing a much-needed estimate of the commercial feasibility of the PWO concept. The study consists of an investigation into the process concept, optimization of operating conditions, and the effect of numerous variables on the process yield in PWO. In addition to the PWO research, the concept of catalytic partial wet oxidation (CPWO) is studied. Fruthermore, the effect on lignin is studied by treating concentrated black liquors in a two-stage process comprising carbonation before PWO of the liquid phase. The experiments were carried out in a 100ml AISI 316 SS bench-scale high-pressure reactor. Feedstocks studied in this study included the following: wheat straw black liquor (WSBL), Kraft black liquor (KBL), hydrolysate from pulp bleach (HLP), and hydrolysate from wood (HLW). Additionally, spruce sawdust with a particle size of less than 1.5 mm was also used as feedstock for the PWO process. Analysis of the products from PWO was performed using the following methods: COD, TOC, pH, solid concentration, high performance liquid chromatography (HPLC), capillary electrophoresis and lignin properties. In this study, typically formic acid, acetic acid and lactic acid were determined quantitatively. Nevertheless, for some cases, more detailed analysis for some other carboxylic acids were also performed.