The biological treatment of pulp and paper mills effluents results in the production of waste secondary sludge which is hard and costly to dewater and dispose. Secondary sludge, which is structurally comparable to the municipal sewage sludge, is composed of microbial cells, organic woody materials, and ash. In this work, the use of this waste biosolid as renewable and cost-cutting filler in the composite industry is proposed. Moreover, the effect of enzymatic treatment of the waste biosolid on the final properties of the manufactured biocomposite is studied. The high protein content of the secondary sludge (35 ± 5%) and the surface thermodynamics measured by Inverse Gas chromatography (IGC) led us to choose Nylon 11 as the main polymeric matrix. The biocomposites samples produced by compounding and injection molding of different mixtures of dried secondary sludge and Nylon were tested. The results of mechanical strength tests showed that a 10% sludge content does not lead to any significant deterioration of either tensile or flexural strengths. Therefore, it is concluded that the secondary sludge may be used as filler to reduce the cost while maintaining the mechanical properties of Nylon. Enzymatic modification of the waste biosolid to advance its application from cheapening filler to reinforcing filler has also been proposed in this work. Lipase and laccase utilized for the modification of the sludge in order to reduce the hydrophobicity and increase the molecular weight, respectively. Lipase application did not lead to any significant changes in either tensile or flexural strengths. This is attributed to the rather low content of lipids in the sludge. On the other hand, enzymatic modification of the sludge by laccase which increases the molecular weight of the existing lignins, resulted in significant improvement of the flexural strength of the manufactured biocomposite.

The biological treatment of pulp and paper mills effluents results in the production of waste secondary sludge which is hard and costly to dewater and dispose. Secondary sludge, which is structurally comparable to the municipal sewage sludge, is composed of microbial cells, organic woody materials, and ash. In this work, the use of this waste biosolid as renewable and cost-cutting filler in the composite industry is proposed. Moreover, the effect of enzymatic treatment of the waste biosolid on the final properties of the manufactured biocomposite is studied. The high protein content of the secondary sludge (35 ± 5%) and the surface thermodynamics measured by Inverse Gas chromatography (IGC) led us to choose Nylon 11 as the main polymeric matrix. The biocomposites samples produced by compounding and injection molding of different mixtures of dried secondary sludge and Nylon were tested. The results of mechanical strength tests showed that a 10% sludge content does not lead to any significant deterioration of either tensile or flexural strengths. Therefore, it is concluded that the secondary sludge may be used as filler to reduce the cost while maintaining the mechanical properties of Nylon. Enzymatic modification of the waste biosolid to advance its application from cheapening filler to reinforcing filler has also been proposed in this work. Lipase and laccase utilized for the modification of the sludge in order to reduce the hydrophobicity and increase the molecular weight, respectively. Lipase application did not lead to any significant changes in either tensile or flexural strengths. This is attributed to the rather low content of lipids in the sludge. On the other hand, enzymatic modification of the sludge by laccase which increases the molecular weight of the existing lignins, resulted in significant improvement of the flexural strength of the manufactured biocomposite.

The use and research of renewable fuels has become more important due to the connection between climate changes and the use of fossil fuels. With risks of decline in petroleum production derived from fossil fuels due to limitation of resources in the future, the renewable fuels are even more important in the transport sector. Research regarding gasification of biomass to create a syngas that can be upgraded to a biodiesel for cars is one of the approaches. By gasifying black liquor, it is possible to create a 100 % green fuel diesel. However, as this black liquor might be in limited quantities the idea to create a synthetic black liquor was sparked. The pulp industry where the black liquor originated from also has quantities of wastewater, containing a biomass sludge. Otherwise containing water in so large quantities that it is not possible to combust it without ending up with a negative energy output. One of the paths could be to recover the biomass from the sludge and convert it to a liquid similar to black liquor. Catalytic hydrothermal liquefaction has been recognized as a potential method. While biocrude is usually the target in hydrothermal liquefaction for direct upgrade to biofuel, the aqueous product could prove to be used for the gasification process. This would create a combined liquefaction-gasification process. Using model compounds possibly existing in the waste sludge, hydrothermal liquefaction was performed at different temperatures, together with varied alkali loads (K2CO3) and water the content to see how the different compounds reacted. Model compounds included cellulose and lignin as major compounds. Although the temperature was increased from 240 °C to 340 ° the lignin conversion was lower at 340 °C than at 240 °C. Re-polymerization took place and around 40 % of resulted in solid residue, while the remaining 60 % was partially converted to aqueous phase, oil phase or gas in the process. By not performing the hydrothermal liquefaction it is however possible to dissolve Kraft lignin directly in water and alkali. Cellulose showed an almost full conversion at 290 °C with similar results at 340 °C, with 4 – 5 % remaining as solid. At the higher temperature more gas was produced, which is not optimal for this process where liquid product is wanted. This suggest that 290 °C is enough for cellulose conversion in this process. Using an alkali load of 0.3 times the cellulose mass in the solution the final aqueous product contained about 26 % alkali, which is similar to black liquor. Increase the alkali to 0.9 times however increased the sought aqueous product, in both terms of energy and carbon content. Fiber sludge from a pulp mill, containing mainly cellulose, could therefore most likely be converted to a liquid product that is similar to black liquor for further upgrade

Iron oxide is a good and inexpensive adsorbent for arsenic (As) compounds and other heavy metals in water (Fe, Cu, Cd, Pb, Ni, Zn). Waste sludge from water treatment plant, which is highly in iron content, can be considered as a great adsorbent. Utilizing this waste as material for water treatment would get benefits on not only environment but also energy, resources and social economy. This study describes experiments to produce arsenic adsorbent material from waste sludge taken from Ha Dinh water treatment plant by using glass water, Fe(NO3)3 and heat to modify and enrich iron content. This process aims to make a good material for filtration and sorption of As. Other effects of pH, time, adsorbent mass, and adsorbate concentration are also considered. The processes are successful in removing Arsenic ion clearly. Initial As sample of 1000μg/L, contact time 4 hours, material 1 g/L, the efficiency is 99.64%. Treated water is under national technical regulation on domestic water quality (QCVN 02:2009/BYT column I) –, where column I is applicable to water provision units. Research also starts to make material particles, which are more favorable to practical application. These adsorbent productions after modification are beneficial with low-cost and environmentfriendly advantages. / Oxít sắt là một chất hấp phụ tốt và rẻ trong việc loại bỏ các hợp chất asen (As) và một số kim loại nặng khác trong nước (Fe, Cu, Cd, Pb, Ni, Zn). Trong khi đó, bùn thải từ các nhà máy xử lí nước giàu thành phần sắt, có thể xem là một vật liệu hấp phụ tốt. Việc tận dụng bùn thải này làm vật liệu xử lý ô nhiễm không chỉ đem lại những lợi ích cho môi trường mà còn về mặt tài nguyên, năng lượng và kinh tế xã hội. Báo cáo này trình bày cách chế tạo vật liệu từ bùn thải của nhà máy xử lý nước cấp Hạ Đình thành vật liệu xử lý ô nhiễm asen bằng cách sử dụng thủy tinh lỏng, Fe(NO3)3 và nhiệt để biến tính làm tăng hàm lượng sắt trong bùn thải, tạo vật liệu tốt cho quá trình lọc và hấp phụ As. Các nhân tố ảnh hưởng tới hiệu suất hấp phụ như pH, thời gian, khối lượng chất hấp phụ, và nồng độ As cũng được đưa ra đánh giá. Việc loại bỏ As đạt hiệu quả rõ rệt. Với nồng độ As ban đầu là 1000 μg/L, thời gian xử lý 4 giờ, vật liệu sử dụng là 1g/L thì hiệu suất xử lý đạt 99,64%. Nồng độ As sau xử lý đạt tiêu chuẩn QCVN 02:2009/BYT, cột I – Quy chuẩn kỹ thuật quốc gia về chất lượng nước sinh hoạt, cột I áp dụng đối với các cơ sở cung cấp nước. Nghiên cứu cũng bước đầu thử nghiệm chế tạo thành viên vật liệu để thuận lợi hơn trong việc ứng dụng trong thực tiễn. Vật liệu bùn thải sau biến tính có lợi thế về chi phí thấp và thân thiện với môi trường

This doctoral thesis is focused on the possibilities of alkali-activated slag (AAS) shrinkage reduction, which would together with the use of waste sludge from waterglass production contribute to wider practical utilization of this interesting material. Besides the influence on AAS dimensional changes also effect of various factors on workability, setting time and mechanical properties was investigated. Obtained results were supported by the application of instrumental techniques like izotermal calorimetry, mercury intrusion porosimetry, scanning electron microscopy and X-ray diffraction. The results show the possibilities of reduction of AAS drying shrinkage related to its cracking tendency through the combination of increased dose of waterglass and reduced water to slag ratio (w/b), partial replacement of slag by pulverized fly ash or cement by-pass dust and application of organic admixtures, where significant effect on AAS hydration was observed. On the basis of the obtained results concrete mixtures, where the whole activator was replaced by the waste sludge form waterglass production, were designed and optimized in terms of shrinkage, mechanical properties and price. Selected concretes were also tested in semi-operating conditions.