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Slaker grits (SG) and biomass fly ash (BFA), two waste streams generated in the pulp and paper industry, are commonly disposed of in landfills, a practice with a high economic and environmental burden. In this work, their individual valorization as fillers in a commercial screed mortar formulation was evaluated in order to achieve a more sustainable management practice. The waste streams were characterized in terms of true density, particle size and morphology, and chemical and mineralogical composition. The influence of their incorporation amount (5.0, 7.5, and 10.0 wt.% of the total solids) and pre-treatment (sieving and grinding) on the fresh (workability) and hardened state (density, water absorption by capillarity, and flexural and compressive strength) properties of the mortars were assessed. The results show that the addition of 10.0 wt.% of the SG after milling and sieving (

The correct development of the composting process is essential to obtain a product of high value from organic wastes. Nowadays, some composting mixture parameters (i.e., air-filled porosity, moisture and the C/N ratio) are used to optimize the composting process, but their suitability is still debated because the literature reports contrasting results. This paper aimed to find other parameters that control the correct development of composting. The relationship between these and the compost quality was then verified. Twelve different composting mixtures were prepared using different organic wastes and bulking agents and were aerobically treated in a 300 L composter. The physico-chemical and chemical parameters of initial mixtures were analyzed, with particular regard to the total and water-extractable forms of organic C and N and their ratios and correlated with the temperature measured during composting. A positive correlation between temperature parameters during the active phase and soluble forms of N in the initial mixtures was found. A high total organic C to soluble N ratio in the composting mixtures was correlated with the low quality of the compost produced. Based on the results, a minimum content of WEN (water-extractable N) (0.4% w/w) or a TOC/WEN (total organic C/WEN) ratio in the range of 40–80 was recommended to ensure the correct development of the process and to produce compost of high quality.

The aim of the present paper is to develop a reliable and accurate model of the wastewater biochemical treatment process and to explore the behaviour through a general dynamic simulation environment, namely the INtegrated Simulation Environment Language (INSEL), for the analysis of the energy demand of the whole wastewater treatment plant. In particular, the presented model pays special attention to the chemical kinetics involved in the activated sludge process for the reduction of nitrogen and carbon compounds. According to the best practices, the plant configuration considered in this work includes the denitrification-nitrification process, performed by completely mixed reactors. In particular, the process analysed in this paper is based on the Ludzak-Ettinger process. The biological process is simulated according to the well-known method widely used in the literature, namely the Activated Sludge Model No 1 (ASM1). The model includes a set of equations for the calculation of aerobic growth of heterotrophs, anoxic growth of heterotrophs, aerobic growth of autotrophs, decay of autotrophs, ammonification of soluble nitrogen, hydrolysis of entrapped organics, and hydrolysis of entrapped organic nitrogen. All these equations, along with energy and mass balances, are solved by the explicit Euler method. The developed model is validated using literature data, showing a great accuracy (deviation below 1%). As for the temperature, results show that, between 15 and 25 °C, in the initial part of the process, transport effects dominate the consumption ones. When the temperature is higher than 30 °C, nitrate consumption is so fast that biomass growth is limited by this effect. Conversely, in case of low temperatures (5–10 °C), biomass growth is not limited by nitrate availability. Finally, results also showed that temperature significantly affects the denitrification process, whereas the effect on the oxygen is lower.

This paper is a review of 20 years of full-scale experience with the granular sludge-based ANAMMOX process. The ANAMMOX process is a biological deammonification process for energy-efficient removal of ammoniacal nitrogen, which has been successfully applied on dewatering reject liquors from biosolids sludge digesters (e.g., mesophilic anaerobic digestions, codigestion, thermal sludge hydrolysis process (THP)) and nutrient-rich anaerobically treated industrial effluents (e.g., fermentation industry, food industry). The ANAMMOX process is a continuously operated biological process using granular biomass. The highly active concentrated granular biomass allows for compact reactor systems and a fast start-up. Long term operations of various case studies show stable process performance of full-scale reactors treating municipal and industrial effluents, achieving ammoniacal nitrogen (NH4-N) removal in excess of 90% at low and high loading rates up to 2.5 kgNH4-N/(m3·d). Some special aspects (e.g., micro-nutrients, inhibition, alkalinity consumption) of treating various wastewaters are discussed in detail. The ANAMMOX process is demonstrated to be resilient in handling process upsets and off-spec wastewater composition.

The process of pelleting miscanthus biomass often encounters issues related to the low durability of the obtained pellets and high energy inputs. To solve these issues, the use of copra meal as a supplement is proposed. This paper presents the results of research on energy parameters of miscanthus biomass pellets supplemented with copra meal in terms of energy consumption in the pressure agglomeration process. As part of this research, the energy parameters of miscanthus biomass, copra meal biomass, and their blends were characterized. Next, the raw materials were used for the production of pellets in the pressure agglomeration process. The investigations included proximate and ultimate analysis and estimation of heating values. Moreover, the total fat content, mechanical durability, kinetic strength, and bulk density were determined, and the energy consumption in the pelleting process was assessed. The results indicate that the energy consumption in the miscanthus biomass pelleting process can be substantially reduced by adding copra meal as a biocomponent. When the copra meal addition did not exceed 30%, the pellets exhibited over 95% durability, over 1200 kg∙m−3 density, and over 417 kg∙m−3 bulk density. Given the 44% reduction in energy consumption in the pellet production process and the energy efficiency of 4815 Wh·kg−1 determined in this study, copra meal may be an interesting material for use as an additive in the production of miscanthus biomass pellets.

(1) Background: sewage sludge is a by-product of wastewater treatment, which needs to be managed appropriately, e.g., in composting processes. The application of municipal sewage sludge composts (MSSCs) as a soil amendment is a potential way to effectively manage sewage sludge. (2) Methods: this paper presents the results of a vegetation pot experiment undertaken to assess the suitability of Dactylis glomerata L. and MSSC in the aided phytostabilization technique when applied on soils from an area effected by industrial pressure; this is characterized by high levels of heavy metal (HM). The contents of HMs in the test plant (the roots and above-ground parts), as well as in the soil and MSSC, were determined via an atomic spectrometry method. (3) Results: the application of MSSC positively contributed to an increased production of plant biomass and an increase in the pH in the soil. Concentrations of Cu, Cd, Pb, Zn, and Cr were higher in the roots than in the above-ground parts of Dactylis glomerata L. The addition of MSSC contributed most significantly to the considerable reduction in Ni, Pb, and Zn contents in the soil after the experiment. (4) Conclusions: MSSC can support the phytostabilization of soils contaminated with high levels of HMs.

Synthetic gas generated from the gasification of biomass feedstocks is one of the clean and sustainable energy sources. In this work, a fixed-bed downdraft gasifier was used to perform the gasification on a lab-scale of rice husk, sawdust, and coconut shell. The aim of this work is to find and compare the synthetic gas generation characteristics and prospects of sawdust and coconut shell with rice husk. A temperature range of 650–900 °C was used to conduct gasification of these three biomass feedstocks. The feed rate of rice husk, sawdust, and coconut shell was 3–5 kg/h, while the airflow rate was 2–3 m3/h. Experimental results show that the highest generated quantity of methane (vol.%) in synthetic gas was achieved by using coconut shell than sawdust and rice husk. It also shows that hydrogen production was higher in the gasification of coconut shell than sawdust and rice husk. In addition, emission generations in coconut shell gasification are lower than rice husk although emissions of rice husk gasification are even lower than fossil fuel. Rice husk, sawdust, and coconut shell are cost-effective biomass sources in Bangladesh. Therefore, the outcomes of this paper can be used to provide clean and economic energy sources for the near future.

To reduce the use of commercial conventional inorganic fertilizers, the possibility of using pulp and paper industry wastes in agriculture as an alternative source of nutrients is recently under study and discussion. This work aimed to evaluate the effect of sodium lignosulfonate application to soil on photosynthetic leaf nutrient (N, P, K, Ca, Mg, Fe, Mn, and Na) and water use efficiency. A pot culture experiment was conducted with cucumber seedlings, using five lignosulfonate concentrations (0, 1, 2.5, 5, and 10 vol. %) in sandy soil under sufficient or low nutrient availability for plants. The impact of nutrient availability on the plants’ physiological traits was stronger than the lignosulfonate impact. Under sufficient nutrient availability, the lignosulfonate application resulted in decreased photosynthetic N, P, K, Ca, Mg, Fe, and Na use efficiency. Cucumber growth and development, and photosynthetic nutrient, water, and light use efficiency were significantly reduced with a nutrient deficiency. The sodium lignosulfonate application was not successful in eliminating the negative effects of nutrient deficit on cucumber seedlings.

This study analyzes the effects of N fertilizer application rates on profitability of growing switchgrass and using the feedstock in a pyrolysis biorefinery facility to create a source of sustainable aviation fuel (SAF) supply in Tennessee. Switchgrass (Panicum virgatum L.) is a perennial bunchgrass native to North America with traits suitable for biofuel and co-product production. Previous chemical analysis has shown that ash content in switchgrass is related to the amount of nitrogen applied to the field, while at the biorefinery level, the percentage ash content reduces the biorefinery fuel output. To obtain optimal nitrogen (N) application rates for the switchgrass producers and the biorefinery, a two-part analysis is employed. First, a partial budgeting profitability analysis is conducted for this cropping enterprise at the farm-gate level without considering downstream implications of biomass quality, i.e., ash content. Second, the effects of higher ash content as a percentage of the feedstock on biorefinery output are analyzed. Results show farm-gate profit is maximized when N fertilizer is applied at 111 kg/ha, while as a result of increased production levels and decreased percentage ash content, biorefinery profit is maximized when N is applied at 157 kg/ha. Lower ash could lead to premium prices paid to switchgrass producers if higher quality feedstock were to be demanded as part of an integrated biofuel industry.

Neutralization with liquid digestate and CO2 was compared herein to adjust the pH of lime-treated corn stover. The effects on the thermophilic (55 °C) anaerobic digestion were also analyzed. Liquid digestate neutralization (LDN) caused a decrease in pH from 10.5 to 7.5 in 60 h and accumulation of acetic/isobutyric acids. The CO2 neutralization (CN) under solid-state conditions reduced the pH from 10.5 to 8.5 in 30 min, which is faster than that of LDN and did not affect the subsequent anaerobic digestion. Biomethane production rate indicates that LDN contributed to the performance of anaerobic digestion, but this was not sufficient to compensate for the loss of total biomethane yield, resulting in a negative net profit (i.e., revenue from increased energy production minus reagent cost). For CN under solid-state conditions, the biomethane production was highest in both liquid- and solid-state anaerobic digestion, and also obtained a net profit of 98.74–100.89 RMB/tonne dry biomass. Therefore, the solid-state condition CN is a more efficient and economic method for adjusting initial pH of lime-treated corn stover.

Wood bark is one of the main residues in the forest industry worldwide. Currently, the bark is used to produce process heat and energy. A major amount of this is mainly used in power and heating plants. Due to the fact that the demand for heating energy is seasonal, the storage of bark is necessary. The storage process of bark and therefore related problems (like biomass loss, increase of ash content etc.) were discussed in previous studies. Different approaches to increase the economic and ecologic value of wood bark through gaining extractives from the bark were investigated in order to revalue this by-product as well. This study shows the change in calorific value and ash content of birch bark based on results of ultrasound-assisted extraction (UAE). Regarding the energy content (gross calorific value), a comparison was made that showed that due to the extraction process, the energy content of the birch bark is decreased. The extraction yield of the methanol extracts results as 17.74%. The total phenolic content (TPC) of this extract was 447.75 mg GAE/g of oven-dried bark extracts. The amount of ash increased by 23.74% after the extraction. The gross calorific value of the birch bark decreased by 6.98%. The calculated energy content decreased from 2.48 MWh/m3 before extraction to 1.61 MWh/m3 after extraction, which is a loss of 35.08%. The obtained results show that through the extraction of birch bark via ultrasound-assisted extraction, valuable substances can be produced. At the same time, the ash content of extracted birch bark increased whereas the energy content decreased.

A bacterial strain, identified as Lysinibacillus sp. LC 556247 POME, was isolated from palm oil mill effluent (POME). The present article highlights the potential utilization of POME as a sole fermentation medium by Lysinibacillus sp. LC 556247 to produce biomass fuel via aerobic fermentation. The fermentation was performed in a shake flask with a working volume of 300 mL, agitated at 180 rpm, incubated at 35 ± 2 °C for various fermentation hours, ranging from 1, 2, 3, 4, 24, 48, 72, 96, and 120 h, and was followed by a drying process. Elucidation of the POME characteristics, calorific energy values (CEV), moisture content (MC), oil and grease content, chemical oxygen demand (COD), biochemical oxygen demand (BOD), dissolved oxygen (DO), total suspended solids (TSS), pH, total nitrogen, and the colony-forming unit (CFU) were performed. The results demonstrate that the highest CEV, of 21.25 ± 0.19 MJ/kg, was obtained at 48 h fermentation. High amounts of extractable oil and nitrogen content were retrieved at the highest CEV reading of the fermented and dried POME samples, which were 17.95 ± 0.02% and 12.80 ± 0.08%, respectively. The maximum removal efficiencies for the COD (50.83%), the BOD (71.73%), and the TSS (42.99%) were achieved at 120 h of fermentation, with an operating pH ranging from 4.49–4.54. The XRF analysis reveals that the fermented and dried products consisted of elements that had a high amount of carbon and potassium, and a significantly low amount of silica, which is sufficient for the effective burning of biomass fuel in the boiler.

The study investigated the effects of the addition of starch on the properties of oil palm biomass particleboard bonded with citric acid. Three kinds of oil palm biomasses were used in this study for the fabrication of particleboard, namely, oil palm frond (OPF), oil palm trunk (OPT), and empty fruit bunch (EFB) particles. Citric acid and tapioca starch at the mixing ratios of 100:0, 87.5:12.5, and 75:25 were prepared at a 60% solid content. A 30% resin content based on the oven-dried weight of the oil palm biomass particles was used. The sprayed particles were pre-dried at 80 °C for 12 h before being hot-pressed at 180 °C and 4 MPa pressure for 10 min. The physical and mechanical properties of the particleboard were evaluated. The mixtures of citric acid and tapioca starch were characterized by FTIR and thermogravimetric analysis (TGA). Changes in peak intensity could be observed, and the thermal stability of citric acid was reduced after the addition of tapioca starch. The addition of 12.5% tapioca starch improved the bending strength of the particleboard but increased the thickness swelling slightly. All UF-bonded particleboard exhibited significantly inferior performance than that of citric-acid-bonded particleboard. Citric-acid-bonded particleboard maintained its original shape after being subjected to a cyclic-aging treatment, while the UF-bonded particleboard disintegrated half way through the treatment. The performance of EFB particleboard was significantly inferior to its OPT and OPF counterparts.

Recycling residual industrial gases and residual biomass as substrates to biofuel production by fermentation is an important alternative to reduce organic wastes and greenhouse gases emission. Clostridium carboxidivorans can metabolize gaseous substrates as CO and CO2 to produce ethanol and higher alcohols through the Wood-Ljungdahl pathway. However, the syngas fermentation is limited by low mass transfer rates. In this work, a syngas fermentation was carried out in serum glass bottles adding different concentrations of Tween® 80 in ATCC® 2713 culture medium to improve gas-liquid mass transfer. We observed a 200% increase in ethanol production by adding 0.15% (v/v) of the surfactant in the culture medium and a 15% increase in biomass production by adding 0.3% (v/v) of the surfactant in the culture medium. The process was reproduced in stirred tank bioreactor with continuous syngas low flow, and a maximum ethanol productivity of 0.050 g/L.h was achieved.

Microalgae cultivation in wastewater is an emerging approach to remove its contaminants and generate microalgal biomass. This study aimed to screen and isolate potential strains in a cassava biogas effluent wastewater (CBEW) treatment system and produce algal biomass. Chlorella sorokiniana strains P21 and WB1DG were isolated from CBEW and found to grow by utilizing various carbon sources. Experiments conducted in a batch reactor using an unsterilized substrate were done to evaluate the nutrient removal and growth of isolated strains from CBEW. The results showed that C. sorokiniana P21 and WB1DG could achieve biomass accumulation of more than 2564 and 1301 mg L−1, respectively. The removal efficiencies of chemical oxygen demand (COD), total phosphorous (TP), and total inorganic nitrogen (TIN) were found up to be 63.42, 91.68, and 70.66%, respectively, in a WB1DG culture and 73.78, 92.11, and 67.33%, respectively, in a P21 culture. Harvestability of the P21 strain was examined using several coagulant–flocculants. FeCl3 was found to remove more than 90% of the cells. Nutrient removal and growth rates resulting from these indigenous strains with application of untreated CBEW support the possibility of this strain being a promising candidate to couple a CBEW treatment and algal biomass generation with minimal process adjustment.

One of the anaerobic digestion process products in an agricultural biogas plant is digestate (digested pulp). Large quantities of digestate generated in the process of biogas production all over the world require proper management. Fertilization is the main management of this substrate, so it is essential to look for new alternatives. The work aims to determine and discuss the possibilities of using digestate solid fraction (DSF) for pellets as biofuel production. Pellets from DSF alone and pellets with sawdust, grain straw additives were analyzed. The lower heating value (LHV) based on the dry matter for all analyzed pellets ranged from 19,164 kJ∙kg−1 to 19,879 kJ∙kg−1. The ash content was similar for all four samples and ranged from 3.62% to 5.23%. This value is relatively high, which is related to the degree of fermentation in the anaerobic digestion process. The results showed that the DSF substrate after the anaerobic digestion process still has energy potential. Analyzing those results, it seems that DSF can be a highly valuable substrate for solid biofuels production.

The article discusses the findings related to the calorific value as well as the explosion and combustion parameters of dust from the raw biomass of fruit trees, i.e., apple, cherry, and pear branches, and from biochars produced using this type of biomass during pyrolysis processes conducted under various conditions. The plant biomass was thermally processed at 400, 450, or 500 °C for a duration of 5, 10, or 15 min. The study aimed to identify the calorific value of the biomass obtained from waste produced in orchards and to estimate the explosion hazard during the processing of such materials and during the storage of the resulting solid fuels. Tests were conducted to assess the total contents of carbon, ash, nitrogen, hydrogen, and volatile substances as well as the calorific value. The findings show a significant effect of the thermal transformation of fruit tree branches on the calorific value of the biochars that were produced. It was found that the mean calorific value of all of the biochars was increased by 62.24% compared to the non-processed biomass. More specifically, the mean calorific values of the biochars produced from apple, cherry, and pear branches amounted to 27.90, 28.75, and 26.84 MJ kg−1, respectively. The maximum explosion pressure Pmax measured for the dust from the biomass and for the biochars was in the range 7.56–7.8 and 7.95–11.72 bar, respectively. The maximum rate of pressure rose over time (dp/dt)max in the case of the dust from the biomass, which was in the range of 274.77–284.97 bar s−1, and the dust from biochar amounted to 282.05–353.41 bar s−1. The explosion index Kst max measured for non-processed biomass and biochars was found to range from 74.46 to 77.23 and from 76.447 to 95.77 bar s−1, respectively. It was also shown that a change in the temperature and duration of the pyrolysis process affected the quality of the biochars that were obtained. The findings show that pyrolysis, as a method of plant biomass processing, positively affects the calorific value of the products and does not lead to an increased risk of explosion during the treatment and storage of such materials. It is necessary, however, to continue research on biomass processing in order to develop practices that adequately ensure safety during the production of novel fuels.

The sugarcane industry has assumed an increasingly important role at a global level, with countries such as Brazil and India dominating the field. However, this causes environmental problems, since the industry produces large amounts of waste, such as sugarcane bagasse. This by-product, which is energetically partially recovered in sugar mills and in the pulp and paper industry, can make a significant contribution to the general use of biomass energy, if the usual disadvantages associated with products with low density and a high moisture content are overcome. From this perspective, thermochemical conversion technologies, especially torrefaction, are assumed to be capable of improving the fuel properties of this material, making it more appealing for potential export and use in far-off destinations. In this work, sugarcane samples were acquired, and the process of obtaining bagasse was simulated. Subsequently, the bagasse was dried and heat-treated at 200 and 300 &deg, C to simulate the over-drying and torrefaction process. Afterward, product characterization was performed, including thermogravimetric analysis, elemental analysis, calorimetry, and energy densification. The results showed significant improvements in the energy content, from 18.17 to 33.36 MJ&middot, kg&minus, 1 from dried bagasse to torrefied bagasse at 300 &deg, C, showing that despite high mass loss, there is potential for a future value added chain for this waste form, since the increment in energy density could enhance its transportation and use in locations far off the production site.

This paper provides a comprehensive description of the new approach to biomass torrefaction under high-pressure conditions. A new type of laboratory-scale high-pressure reactor was designed and built. The aim of the study was to compare the high-pressure torrefaction with conventional near atmospheric pressure torrefaction. Specifically, we investigated the torrefaction process influence on the fuel properties of wooden-pellet for two different pressure regimes up to 15 bar. All torrefaction processes were conducted at 300 °C, at 30 min of residence time. The initial analysis of the increased pressure impact on the torrefaction parameters: mass yields, energy densification ratio, energy yield, process energy consumption, the proximate analysis, high heating value, and energy needed to grind torrefied pellets was completed. The results show that high-pressure torrefaction needed up to six percent less energy, whereas energy densification in the pellet was ~12% higher compared to conventional torrefaction. The presence of pressure during torrefaction did not have an impact on the energy required for pellet grinding (p < 0.05).

The recognition of the effects of fossil fuel consumption resulted in several agreements, legislation, and projects focusing on the minimization of impacts caused. Biomass is a versatile energy source. Eucalyptus is a fast-growing crop, mainly used by the pulp and paper industry. Torrefaction is a thermochemical conversion process that can improve biomass fuel properties, enabling its use in the energy sector. However, correct management of biomass is crucial for the sustainability of this process. Torrefaction can also be used to eliminate some elements that can hinder subsequent conversion processes. One example is chlorine, which, during combustion or gasification processes, can form hydrochloric acid that leads to corrosion of metal surfaces. In this context, this research aimed to determine the temperature at which chlorine is eliminated during torrefaction process. For this purpose, several tests were performed at different temperatures and residence times. All samples were analyzed before and after the process, and were characterized by proximate and elemental analysis, calorimetry, and chlorine titration. The analysis showed that, even for the lowest torrefaction temperature used, chlorine content was already below the detection value, showing that, even at lower temperatures, thermal treatment is an efficient technique for the elimination of chlorine from biomass.

While filtration, chlorination, and UV drinking water treatments are commonplace, globally an estimated 1.2 billion people continue to boil their drinking water over inefficient biomass fires instead because it allows them to use available resources paired with a time-tested and trusted method. Although boiling water is culturally well-established, there is vast potential to improve human health, environmental impact, and efficiency by leveraging the fact that a significant reduction in pathogenic microorganisms occurs at temperatures well below boiling through a process known as pasteurization. This paper presents the evaluation of a community-scale, biomass-powered, flow-through water pasteurization system that was designed to heat water to the temperature required for pasteurization to occur before recuperating heat while cooling treated water down to a safe-to-handle temperature. The system is then compared to other common thermal treatment methods including batch-boiling over open fires and improved cookstoves. Results from computational modeling and empirical analysis show that the water pasteurizer significantly increases the overall water treatment capacity (from 7.9 to 411 L/h, adjusted for one hour of treatment via household boiling and operation of the water pasteurizer at steady-state, respectively) and uses far less biomass fuel (from 22 to 5.5 g/L, adjusted for treatment of 1 L of water via household boiling and operation of the water pasteurizer at steady-state, respectively). Notable comparisons to the batch-boiling of water over institutional-sized traditional and improved cookstoves are also demonstrated. Further, the results of fecal indicator reduction through the system (8 log and 6 log reduction of E. coli and bacteriophage MS2, respectively) suggest compliance with US-EPA (6 log and 4 log reduction of E. coli and bacteriophage MS2, respectively) and WHO requirements (effluent concentrations below the detection limit, specified as E. coli CFU/100 mL and E. coli and bacteriophage for water treatment processes. It is recommended that engineers continue to explore the use of heat transfer and microorganism reduction theory to design technologies that increase the capacity and efficiency for thermal water purification that uses locally-available biomass resources.

This paper describes the laboratory-scale simulation of the behaviour of rejects from a biological-mechanical treatment (BMT) plant in Castell&oacute, n (Spain). For this purpose, four lysimeters were built, with different densities. Simulations were carried out for 7 weeks and leachate recirculation was applied to two of them. The experimental results allowed us to determine: (i) dirt in fractions, which was relatively high (up to 15% in some fractions) due to biological processes, (ii) the field capacity for this waste with similar values to other works, which varied depending on the experiment, (iii) variation in the biomass percentage which lowered after experiments in all cases (59.5% lower on average), and the rejects&rsquo, calorific value was higher after experiments (28.2% on average), (iv) the evolution of leachate properties with or without recirculation, where percolation, in addition to the dragging of soluble materials, stabilised waste, which diminished its biological activity. Rejects&rsquo, increased calorific value will allow combustible material to be recovered in the future as a way to exploit the energy potential stored in landfills.

Pyrolysis of anaerobically digested sludge can serve as an efficient biomass for biofuel production. Pyrolysis produces products like char, bio-oil, and combustible gases by thermochemical conversion process. It can be used for sludge treatment that decreases sludge disposal problems. Sludge produced from anaerobic co-digestion (microalgae, cow dung, and paper) waste has high carbon and hydrogen content. We investigated the candidacy of the anaerobic sludge having high heating value (HHV) of 20.53 MJ/kg as a reliable biomass for biofuels production. The process of pyrolysis was optimized with different temperatures (400, 500, and 600 °C) to produce high quantity and improved quality of the products, mainly bio-oil, char, and gas. The results revealed that with the increase in pyrolysis temperature the quantity of char decreased (81% to 55%), bio-oil increased (3% to 7%), and gas increased (2% to 5%). The HHV of char (19.2 MJ/kg), bio-oil (28.1 MJ/kg), and gas (18.1 MJ/kg) were predominantly affected by the amount of fixed carbon, hydrocarbons, and volatile substance, respectively. The study confirmed that the anaerobic sludge is a promising biomass for biofuel production and pyrolysis is an efficient method for its safe disposal.

This paper presents the results of the evaluation of the energy potential of waste from the process of drying corn grain in the form of corn cobs, damaged grains, corn grain husks, and mixtures of starting materials. A technical and elementary analysis was performed for the biomass under investigation. The elemental composition of ash and the tendencies for slagging and boiler slagging were determined, and the emission factors were estimated based on the elemental analysis performed. The tests showed the highest calorific value among the starting materials for corn cobs (CCs) (14.94 MJ·kg−1) and for the mixture of corn cobs with corn husk (CC−CH) (13.70 MJ·kg−1). The estimated emission factors were within ranges of 38.26−63.26 kg·Mg−1 for CO, 936−1549 kg·Mg−1 for CO2, 0.85−4.32 kg·Mg−1 for NOx, 0.91−1.03 kg·Mg−1 for SO2, and 3.88−54.31 kg·Mg−1 for dust. The research showed that the creation of mixtures from starting materials leads to materials with lower potential for negative environmental impact as well as a reduced risk of slagging and fouling of biomass boilers. However, taking into account all the parameters determined for the biomass under study, the highest energy potential was characteristic for corn cobs and the mixture of corn cobs with corn husk.

Low-cost wood–plastic composites (WPCs) were developed from invasive trees and recycled low-density polyethylene. The aim was to produce affordable building materials for low-cost social housing in South Africa. Both raw materials are regarded as waste materials, and the subsequent product development adds value to the resources, while simultaneously reducing the waste stream. The production costs were minimised by utilising the entire biomass of Acacia saligna salvaged from clearing operations without any prior processing, and low-grade recycled low-density polyethylene to make WPCs without any additives. Different biomass/plastic ratios, particle sizes, and press settings were evaluated to determine the optimum processing parameters to obtain WPCs with adequate properties. The water absorption, dimensional stability, modulus of rupture, modulus of elasticity, tensile strength, and tensile moduli were improved at longer press times and higher temperatures for all blending ratios. This has been attributed to the crystallisation of the lignocellulose and thermally induced cross-linking in the polyethylene. An increased biomass ratio and particle size were positively correlated with water absorption and thickness swelling and inversely related with MOR, tensile strength, and density due to an incomplete encapsulation of the biomass by the plastic matrix. This study demonstrates the feasibility of utilising low-grade recycled polyethylene and the whole-tree biomass of A. saligna, without the need for pre-processing and the addition of expensive modifiers, to produce WPCs with properties that satisfy the minimum requirements for interior cladding or ceiling material.

This study shows the energy potential of pine wood waste for the production of solid biofuels, and was carried out in an indigenous community in the state of Michoacán. One of the main economic activities of this community is the production of handcrafted furniture, which generates a large amount of wood waste. The most relevant results obtained in this research show that the community generates approximately 2268 kg of sawdust and 5418 kg of shavings per week, and the estimated energy potential per year for both sawdust is 1.94 PJ and for shaving is 4.65 PJ. Based on the particle size observed, the wood residue can be used to generate pellets or briquettes. Other average results in sawdust and (shavings) are the following: initial moisture content 15.3% (16.8%), apparent density 169.23 kg/m3 (49.25 kg/m3), ash 0.43% (0.42%), volatile material 84.9% (83.60%), fixed carbon 14.65% (15.96%), hemicelluloses 12.89% (10.68%), cellulose 52.68% (52.82%), lignin 26.73% (25.98%), extractives 7.69% (10.51%), calorific value 17.6 MJ/kg (17.9 MJ/kg). The major chemical elements in the ash were Al, K. Fe, Ca, P, Na, and Mg. Finally, the results obtained indicate that this biomass can be used to generate pellets or briquettes in this indigenous community.

Future energy and environmental issues are the major driving force towards increased global utilization of biomass, especially in developing countries like Pakistan. Lignocellulosic residues are abundant in Pakistan. The present study investigated the best-mixed proportion of mechanically pretreated lignocellulosic residues i.e., wheat straw and rice straw (WSRS), bagasse and wheat straw (BAWS), bagasse, and rice straw (BARS), bagasse, wheat straw, and rice straw (BAWSRS) through anaerobic co-digestion. Anaerobic batch mode bioreactors comprising of lignocellulosic proportions and control bioreactors were run in parallel at mesophilic temperature (35 °C) for the substrate to inoculum (S/I) ratio of 1.5 and 2.5. Maximum and stable biomethane production was observed at the substrate to inoculum (S/I) ratio of 1.5, and the highest biomethane yield 339.0089123 NmLCH4/gVS was achieved by co-digestion of wheat straw and rice straw (WSRS) and lowest 15.74 NmLCH4/gVS from bagasse and rice straw (BARS) at 2.5 substrates to inoculum ratio. Furthermore, anaerobic reactor performance was determined by using bio-kinetic parameters i.e., production rate (Rm), lag phase (λ), and coefficient of determination (R2). The bio-kinetic parameters were evaluated by using kinetic models, first-order kinetics, Logistic function model, Modified Gompertz Model, and Transference function model. Among all kinetic models, the Logistic function model provided the best fit with experimental data followed by Modified Gompertz Model. The study suggests that a decrease in methane production was due to lower hydrolysis rate and higher lignin content of the co-digested substrates, and mechanical pretreatment leads to the breakage of complex lignocellulosic structure. The organic matter degradation evidence will be utilized by the biogas digesters developed in rural areas of Pakistan, where these agricultural residues are ample waste and need a technological solution to manage and produce renewable energy.

Open-pit mining causes soil damage and affects the health of the ecosystem. In the arid grassland mining areas, the soil is severely sanded, water-starved, and saline, thus making it difficult for plants and microorganisms to survive. Water-jet loom sludge can be used to improve the quality as it contains a lot of clay and is rich in organic matter, which provides a material basis for microorganism activity. To explore the effects of microbial agent-modified water-jet loom sludge on the restoration of degraded soil in grassland mining areas, four pot trials were set up, i.e., for untreated soil, the application of a microbial agent alone, the application of water-jet loom sludge alone, and the combined application of water-jet loom sludge and the microbial agent. The results show that (1) microbial agent-modified sludge can improve soil water-holding capacity and aggregate stability, (2) the nutrient content of the restored soil fraction increased significantly, and the pH of the original saline soil decreased from 9.06 to 7.84, (3) this method significantly increased plant biomass and microbial biomass carbon and enhanced the abundance and diversity of fungi and bacteria. The three treatments had different results in different soil properties, and the effect of the combined water-jet loom sludge and microbial agent treatment on soil remediation was significantly better than the individual application of either.

The European research project CLARA (chemical looping gasification for sustainable production of biofuels, G.A. 817841) investigated chemical looping gasification of wheat straw pellets. This work focuses on pretreatments for this residual biomass, i.e., torrefaction and torrefaction-washing. Devolatilizations of individual pellets were performed in a laboratory-scale fluidized bed made of sand, at 700, 800, and 900 °C, to quantify and analyze the syngas released from differently pretreated biomasses, experimental data were assessed by integral-average parameters: gas yield, H2/CO molar ratio, and carbon conversion. A new analysis of devolatilization data was performed, based on information from instantaneous peaks of released syngas, by simple regressions with straight lines. For all biomasses, the increase of devolatilization temperature between 700 and 900 °C enhanced the thermochemical conversion in terms of gas yield, carbon conversion, and H2/CO ratio in the syngas. Regarding pretreatments, the main evidence is the general improvement of syngas quality (i.e., composition) and quantity, compared to those of untreated pellets, only slighter differentiations were observed concerning different pretreatments, mainly thanks to peak quantities, which highlighted an improvement of the H2/CO molar ratio in correlation with increased torrefaction temperature from 250 to 270 °C. The proposed methods emerged as suitable straightforward tools to investigate the behavior of biomasses and the effects of process parameters and biomass nature.

The large-scale cultivation of microalgae provides a wide spectrum of marketable bioproducts, profitably used in many fields, from the preparation of functional health products and feed supplement in aquaculture and animal husbandry to biofuels and green chemistry agents. The commercially successful algal biomass production requires effective strategies to maintain the process at desired productivity and stability levels. Hence, the development of effective early warning methods to timely indicate remedial actions and to undertake countermeasures is extremely important to avoid culture collapse and consequent economic losses. With the aim to develop an early warning method of algal contamination, the potentiometric E-tongue was applied to record the variations in the culture environments, over the whole growth process, of two unialgal cultures, Phaeodactylum tricornutum and a microalgal contaminant, along with those of their mixed culture. The E-tongue system ability to distinguish the cultures and to predict their growth stage, through the application of multivariate data analysis, was shown. A PLS regression method applied to the E-tongue output data allowed a good prediction of culture growth time, expressed as growth days, with R2 values in a range from 0.913 to 0.960 and RMSEP of 1.97–2.38 days. Moreover, the SIMCA and PLS-DA techniques were useful for cultures contamination monitoring. The constructed PLS-DA model properly discriminated 67% of cultures through the analysis of their growth media, i.e., environments, thus proving the potential of the E-tongue system for a real time monitoring of contamination in microalgal intensive cultivation.

There is wide consensus that Spirulina can serve as a tool for wastewater management and simultaneously provide feedstock for biorefining. However, the economic aspects associated with its use remain a significant challenge. Spirulina cultivated in wastewater decreased the concentrations of both ammonia and nitrate and also served as a biodiesel source. The oil obtained in the feedstock was subjected to transesterification and turned into biodiesel. The biodiesel was subsequently analyzed in a test motor (water-cooled, four-stroke, single-cylinder compression ignition with injection). The tests were conducted at a constant 1500 rpm, and the output power was 3.7 kW. Mixtures of diesel and biodiesel were also enriched with carbon nanotubes (CNTs). The amount of CNTs added to the diesel was 30 mg L−1. The algae and de-oiled biomass were characterized using XRD analysis, and an ultrasonicator was used to mix the CNTs with diesel and spirulina blends. A series of tests were conducted at different load conditions (25%, 50%, 75%, and 100%) for all fuel blends. Test results were compared with a neat diesel engine with a CR of 17.5:1. Among the fuel blends, the B25 reported improved brake thermal efficiency and reduced emissions. The outcomes are a reduction in thermal efficiency of 0.98% and exhaust gas temperature of 1.7%. The addition of Spirulina biodiesel blends had a positive impact on the reduction of greenhouse gas emissions, including reductions of 16.3%, 3.6%, 6.8%, and 12.35% of CO, NOx, and smoke, respectively. The specific fuel consumption and CO2 emissions were reduced by 5.2% and 2.8%, respectively, for B25 fuel blends compared to plain diesel and B50. Concerning cost competitiveness, vigorous research on microalgae for the production of biodiesel can cut production costs in the future.

Olive trees constitute one of the largest agroindustries in the Mediterranean area, and their cultivation generates a diverse pool of biomass by-products such as olive tree pruning (OTP), olive leaves (OL), olive stone (OS), and extracted olive pomace (EOP). These lignocellulosic materials have varying compositions and potential utilization strategies within a biorefinery context. The aim of this work was to carry out an integral analysis of the aqueous extractives fraction of these biomasses. Several analytical methods were applied in order to fully characterize this fraction to varying extents: a mass closure of &gt, 80% was reached for EOP, &gt, 76% for OTP, &gt, 65% for OS, and &gt, 52% for OL. Among the compounds detected, xylooligosaccharides, mannitol, 3,4-dihydroxyphenylglycol, and hydroxytyrosol were noted as potential enhancers of the valorization of said by-products. The extraction of these compounds is expected to be more favorable for OTP, OL, and EOP, given their high extractives content, and is compatible with other utilization strategies such as the bioconversion of the lignocellulosic fraction into biofuels and bioproducts.

The MixAlco process is a patented biomass conversion technology used to produce valuable chemicals. The basis of this design relies on the use of fermentation, where acidophiles utilize their own enzymatic pathways to convert a variety of biomass, such as organic wastes, into carboxylic acid salts. Unlike previous MixAlco designs in which carboxylate salts are processed further into hydrocarbon fuels, this proposed design simulates the optimization and commercialization of mixed carboxylic acid salts as the final product. Sensitivity analyses identified four critical input factors of the base case process—biomass feed rate, selling price, distribution cost, and biomass composition. Increasing the biomass feed rate or population size has the most pronounced effect on process economics. Overall, the sensitivity analyses of all four critical input factors support that the new design is flexible in its ability to support populations of varying sizes, as well as different biomass feed rates and compositions.

Sewage sludge hydrochars (SSHs), which are produced by hydrothermal carbonization (HTC), offer a high calorific value to be applied as a biofuel. However, HTC is a complex processand the properties of the resulting product depend heavily on the process conditions and feedstock composition. In this work, we have applied artificial neural networks (ANNs) to contribute to the production of tailored SSHs for a specific application and with optimum properties. We collected data from the published literature covering the years 2014–2021, which was then fed into different ANN models where the input data (HTC temperature, process time, and the elemental content of hydrochars) were used to predict output parameters (higher heating value, (HHV) and solid yield (%)). The proposed ANN models were successful in accurately predicting both HHV and contents of C and H. While the model NN1 (based on C, H, O content) exhibited HHV predicting performance with R2 = 0.974, another model, NN2, was also able to predict HHV with R2 = 0.936 using only C and H as input. Moreover, the inverse model of NN3 (based on H, O content, and HHV) could predict C content with an R2 of 0.939.

The aim of this study was the investigation of the effect of growth conditions of energy willow (Salix viminalis L.) on its physical and chemical parameters towards lignocellulosic biofuels. This work is linked to the global trend of replacing fossil fuels (coal, oil, natural gas) with energy and renewable fuels. This energy transition is dictated by the reduction of the human-induced greenhouse effect (to the greatest extent by industrial development). Changing from traditional to renewable energy sources results in industry becoming less dependent on fuels whose sources are beginning to run out, and in energy processing being broken down into smaller sectors with greater flexibility to change and less susceptibility to failure. The use of lignocellulosic raw materials such as wood, straw, food industry waste, wood, and post-consumer products such as old furniture for energy purposes allows the use of substances which bind the greenhouse gas carbon dioxide in their cellular structure during growth. In order to optimise the costs of producing such energy and minimise its impact on the environment, these plants should be located as close as possible to the source of raw materials. One of the most important characteristics for the profitability of energy production from woody biomass is a high biomass yield. For this purpose, the raw material used for this study was energy willow (Salix viminalis L.) seedlings, which are often used for energy crops. Due to the moisture-loving nature of the substrate, the effect of the addition of the active substance prednisonum as a catalyst for water adsorption from the substrate was investigated. In order to determine the substances formed during the thermal decomposition of energy willow (Salix viminalis L.) wood, a pyrolysis process was carried out at 450 °C using pyrolysis gas chromatography mass spectrometry (PY/GC-MS).

Abundant biomass is a potential energy source. However, it possesses several challenges when considered for energy applications. Torrefaction, a thermal pretreatment process can improve the properties of biomass as energy source. This study focused on comparing effect of torrefaction operating parameters on agricultural and wood wastes properties as fuel. The physiochemical properties, composition, moisture-biomass interaction and ash melting behavior were determined. The result show that higher torrefaction temperature and longer residence time increased lignin content, reduced hemicellulose and cellulose content. The moisture uptake of torrefied biomass was reduced in the range 2.47–9.94% compared with raw biomass depending on torrefaction temperature that indicate torrefied biomass was more hydrophobic than raw biomass. The moisture adsorption isotherm curve shows type II isotherm based on the Brunauer-Emmett-Teller’s (BET) classification and was best described by the Oswin model. In addition, torrefaction treatment showed significant influence on the melting behavior of the biomass ash. Especially for agricultural wastes, the fouling tendency shifted from serious range to low range with torrefaction treatment. Torrefaction showed promise for improving fuel characteristics of the studied biomass.

The influence of the briquetting process on SO2 and NO release characteristics, combustion properties and kinetic characteristics during biomass combustion was investigated. Two biomass (Wheat straw and Tree bulk) and two obtained briquettes were analysed. The briquetting process helps to prevent the release of SO2 and NO. The experimental results show that once the biomass is made into a briquette, when the reaction temperature is 900 ∘C, the sulphur release ratio for TB was reduced from 34.7% to 4.3% and for WS was reduced from 12.4% to 1.6%. When the reaction temperature increases to 1000 ∘C, the sulphur release ratio for TB was reduced from 73.4% to 30.4%, for WS it was reduced from 58.4% to 10.2%. SEM micrographs show that the compact structure of the TB-Briquette and WS-Briquette reduce the rate of SO2 and NO release during combustion. The thermogravimetry confirmed that the combustion performance of WS-Briquette is the best, while the TB-Briquette is the worst. According to the Coats-Redfern method, the fitting was performed at segments of 250 ∘C to 550 ∘C, and the correlation coefficient of the fitting degree was above 0.99. The effective collision rate of WS-Briquette is much higher than that of other briquettes. Compared to BR-1 and BR-2, trying to mix TB with WS to make a compound biomass briquette can enhance the combustion performance of TB-Briquette. The results may guide the upgrading of biomass briquettes technology and benefit the efficient application of biomass briquettes.

Biomass waste, as raw material for renewable energy, is an attractive alternative since it does not compete with human food supply. An emerging alternative for its treatment is supercritical water gasification (SCWG), due to the high moisture content of some types of biomass. On this regards, guava fruit (Psidium guajava L.) is one of the most wasted agro-food products in Mexico. This motivated us to evaluate gasification of guava waste on dry biomass base under supercritical water conditions for the first time, with the aim of analyzing the impact of moderate temperatures and feed ratios as reaction parameters on gas products. Temperature was varied in the range of 673.15–773.15 K and using a batch reactor loaded with biomass:water (B:W) mass ratios of 1:1, 1:4, and 1:6. Furthermore, the obtained solid, liquid, and gas phase products were characterized. Hydrogen (H2), carbon dioxide (CO2), carbon monoxide (CO), methane (CH4), ethane (C2H6), propane (C3H8), and butane (C4H10) were identified in gas phase and quantified by means of a gas chromatograph equipped with a TCD detector. Liquid and solid phase products were subjected to Fourier Transform Infrared spectroscopy analyses. This preliminary research indicated that high temperature operation and high biomass:water mass ratio enhanced gas yields (mol/kg) of about 4.137 for CH4, 6.705 for CO2, and 7.743 for H2; whereas the selectivity and gas efficiency for hydrogen was 65.26% and 58.94%, respectively.

While the production costs and logistical benefits of biomass pelleting have been widely discussed in the literature, the downstream economic and environmental benefits of processing pelleted biomass have been largely neglected. To investigate those benefits, we performed a comparative techno-economic analysis and life cycle assessment of producing ethanol using loose and pelleted forms of biomass. Analyses of a 2000 metric tons (dry)/d biorefinery showed that using pelleted biomass is more economical than using loose or baled biomass. The lowest minimum ethanol selling price (MESP) for pelleted biomass was USD 0.58/gal less than the lowest MESP for loose biomass. Among all processing conditions analyzed, MESP for ethanol produced with pelleted biomass was always lower than when produced with loose biomass. Shorter pretreatment and hydrolysis times, higher pretreatment solids loadings, lower ammonia requirements, and reduced enzyme loadings were the primary factors contributing to lower MESP with pelleted biomass. Similarly, pelleted biomass also demonstrated a 50% lower life cycle greenhouse gas emission compared to loose biomass. Emissions from higher pelleting energy were offset by downstream advantage in lower chemical needs.

Cellulosic biorefineries have attracted interest due to the growing energy security and environmental concerns related to fossil fuel-based energy and chemicals. Using pelleted biomass as a biorefinery feedstock can reduce their processing inputs while improving biomass handling and transportation. However, it is still questionable whether energy and emission savings from feedstock transportation and processing can justify pelletization. A life cycle assessment approach was used to compare energy consumption and greenhouse gas (GHG) emissions from pelleted and non-pelleted corn stover as a biorefinery feedstock. Operations considered were pelleting, transportation, and soaking in aqueous ammonia (SAA) pretreatment. Despite greater GHG emissions (up to 25 times higher than the transportation) generated from the pelleting process, the model showed a significant opportunity to offset and even reduce overall GHG emissions considering the pretreatment process benefits. Our process energy analysis showed that SAA pretreatment of pelleted biomass required significantly lower energy inputs (56%) due to the lower-severity pretreatment’s effectiveness. Higher pretreatment solid loadings are allowed when pelleted biomass is used and this reduces the process chemicals and water requirements by 56% and 49%, respectively. This study demonstrated that the SAA pretreatment of pelleted biomass might be a feasible option as the cellulosic biorefinery feedstock.

The use of residual biomass of forest and/or agricultural origin is an increasingly common issue regarding the incorporation of materials that, until recently, were out of the typical raw material supply chains for the production of biomass pellets, mainly due to the quality constraints that some of these materials present. The need to control the quality of biomass-derived fuels led to the development of standards, such as ENplus®, to define the permitted limits for a set of parameters, such as the ash or alkali metal content. In the present study, samples of vine pruning, and ENplus®-certified pellets were collected and characterized, and the results obtained were compared with the limits presented in the standard. The values presented from vine pruning approximated the values presented by Pinus pinaster wood, the main raw material used in the production of certified pellets in Portugal, except for the values of ash, copper (Cu), and nitrogen (N) contents, with vine pruning being out of the qualifying limits for certification. However, it was found that the incorporation of up to 10% of biomass from vine pruning allowed the fulfillment of the requirements presented in the ENplus® standard, indicating a path for the implementation of circular economy processes in the wine industry.

Five major operations for the conversion of lignocellulosic biomasses into bioethanol are pre-treatment, detoxification, hydrolysis, fermentation, and distillation. The fermentation process is a significant biological step to transform lignocellulose into biofuel. The interactions of biochemical networks and their uncertainty and nonlinearity that occur during fermentation processes are major problems for experts developing accurate bioprocess models. In this study, mechanical processing and pre-treatment on the palm trunk were done before fermentation. Analysis was performed on the fresh palm sap and the fermented sap to determine the composition. The analysis for total sugar content was done using high-performance liquid chromatography (HPLC) and the percentage of alcohols by volume was determined using gas chromatography (GC). A model was also developed for the fermentation process based on the Adaptive-Network-Fuzzy Inference System (ANFIS) combined with particle swarm optimization (PSO) to predict bioethanol production in biomass fermentation of oil palm trunk sap. The model was used to find the best experimental conditions to achieve the maximum bioethanol concentration. Graphical sensitivity analysis techniques were also used to identify the most effective parameters in the bioethanol process.

This research studies the incidence of the type of substrate, soluble or particulate, in the emergence, development, and inhibition of bulking in activated sludge systems. It was evaluated using the sludge volume index (SVI), mixing liquor-suspended solids (MLSS), microscopic analysis of biomass, and effluent suspended solids (ESS). In the first experiment, four sequencing batch reactors (SBRs) were fed with soluble substrate at a fixed mass, while the mass of the particulate substrate varied, as those (saccharose mass/flour mass) ratios were 3:1, 3:2, 3:3 and 3:4., with a deficit ranging from 20 to 30% compared to the ratio recommended. The four SBRs have similar MLSS, IVL, and ESS. From day 30, with a deficit from 80 to 90%, the influents have ratios 1/1 and 1/2 until 48 days. The SBRs present IVL between 600 and 730 mL/g and ESS from 370 to 440 mg/L, unlike influents with ratios 1/3 and 1/4, they present IVL between 170 and 185 mL/g, and ESS from 260 to 270 mg/L. The favorable effect of particulate matter is categorical. In the second set of experiments, two SBRs were studied: SBR 1 fed with saccharose, and SBR 2 with flour, there is a lack of nutrients causing bulking in SBRs. Once the nutrient deficiency condition is changed in day 11 to excess, after 22 days, the SVI was 190 mL/g, ESS was 360 mg/L, and MLSS was 2000 mg/L for influents with saccharose, the influent with flour, with an SVI of 80 mL/g, ESS of 100 mg/L, and MLSS of 4000 mg/L, shows faster and more consistent recovery with the particulate substrate. Therefore, the proposal is to add particulate substrate-like flour to active sludge plants facing bulking. It is a clean, innocuous and sustainable alternative to processes that use chemical reagents.

Gasification is considered a clean and effective way to convert low quality biomass to higher value gas and solve various waste utilization problems as well. However, only 80% of biomass is converted through thermal processes. The remaining part is char, which requires more time for conversion and in that case reduces the efficiency of gasifier. Seeking to optimize the process of gasification, this work focuses on the intensification of residual char gasification in a gasifier. For this purpose, three different types of char prepared from wood, sewage sludge and tire were examined under different conditions in a lab-scale gasification setup. Results showed that the air flux increase from 0.11 kg/(m2s) to 0.32 kg/(m2s) intensified the gasification process and the gasification rate increased from 0.8 to 2.61 g/min with the decrease of duration of wood char gasification by 72%. An additional introduction of pyrolysis gas into the char gasifier led to decreased bed temperatures, but the gasification rate increased from 0.8 to 1.25 g/min and from 2.61 g/min to 2.83 g/min, respectively, for the wood char and the sewage sludge char. Moreover, the use of pyrolysis gas coupled with air as the gasifying agent enhanced the composition of produced gas from char, and the CO2 concentration decreased by 1.68 vol% while the H2 concentration increased by 2.8 vol%.

Biomass can be envisaged as a potential solution to mitigate the problems that the extensive exploitation of fossil sources causes on the environment. Transforming biomass into added-value products with better calorific properties is highly desired. Thermochemical liquefaction can convert biomass into a bio-oil. The work herein presented concerns the study of direct liquefaction of Eucalyptus globulus sawdust. The main goal was to optimise the operating conditions of the process to achieve high bio-oil conversion rates. Studies were carried out to understand the impact of the process factors, such as the residence time, catalyst concentration, temperature, and the biomass-to-solvent ratio. The E. globulus sawdust conversion into bio-oil was achieved with a maximum conversion of 96.2%. A higher conversion was reached when the eucalyptus sawdust's thermochemical liquefaction was conducted over 180 minutes in the presence of a &gt, 2.44% catalyst concentration at 160 °C. A lower biomass-to-solvent ratio favours the process leading to a higher conversion of biomass into bio-oil. The afforded bio-oil presented a better higher heating value than that of E. globulus sawdust.

Activated carbon obtained from biomass wastes was presently studied in order to evaluate its applicability in an energy storage device. Biochar was obtained by the carbonization of spent malt rootlets and was further processed by mild treatment in NaOH. The final product had a specific surface of 362 m2 g−1 and carried Na, P and a few mineral sites. This material was first characterized by several techniques. Then it was used to make a supercapacitor electrode, which reached a specific capacitance of 156 F g−1. The supercapacitor electrode was combined with a photocatalytic fuel cell, making a simple three-electrode device functioning with a single alkaline electrolyte. This device allows solar energy conversion and storage at the same time, promoting the use of biomass wastes for energy applications.

Torrefaction is a thermal pretreatment technique usually adopted for improving biomass properties to be on par with that of coal for energy production. In this study, the torrefaction characteristics of blended fuel of sewage sludge (SS) and sugarcane bagasse (BG) biomass were investigated for the purpose of gasification. The thermal degradation behavior of the blended biomass sample was tested in an inert atmosphere from ambient temperature to 900 °C using thermogravimetric analysis (TGA). The obtained TGA data aided in the determination of thermochemical parameters that are of necessity in gasification. Morphological changes in the blended torrefied samples were examined through scanning electron microscopy. Further changes in the chemical structure of the samples were investigated through Fourier-transform infrared analysis. The blend ratio of 75% SS + 25% BG torrefied at 350 °C gave the highest energy value (HHV) of 23.62 MJ/kg, fixed carbon of 51.37 wt % and fuel ratio of 1.70. The obtained fuel ratio is comparable to that required for optimum combustion performance of coal. The morphological structure of the samples showed that there was an aggregation of the biomass particles into small lumps at higher torrefaction temperature for 50% SS + 50% BG and 75% SS + 25% BG blend indicating a better grind ability of the biomass material. Thus, it can be concluded that the blend and torrefaction enhanced the properties of the biomass materials.

The sustainable management of biomass is a key global challenge that demands compliance with fundamental requirements of social and environmental responsibility and economic effectiveness. Strategies for the valorization of waste biomass from agrifood industries must be in line with sustainable technological management and eco-industrial approaches. The efficient bioremoval of the pesticides imazalil and thiabendazole from aqueous effluents using waste biomass from typically Mediterranean agrifood industries (citrus waste, artichoke agrowaste and olive mill residue) revealed that these residues may be transformed into cost-effective biosorbents. Agrifood wastes present irregular surfaces, many different sized pores and active functional groups on their surface, and they are abundant in nature. The surface and adsorptive properties of olive mill residue, artichoke agrowaste and citrus waste were characterized with respect to elemental composition, microstructure, crystallinity, pore size, presence of active functional groups, thermal stability, and point of zero charge. Olive mill residue showed the highest values of surface area (Brunauer–Emmett–Teller method), porosity, crystallinity index, and pH of zero point of charge. Olive mill residue showed the highest efficiency with sorption capacities of 9 mg·g−1 for imazalil and 8.6 mg·g−1 for thiabendazole.

Massive use of wood biomass is usually associated with its long-term, large-scale storage in power plants and heating plants. Long-term storage of wood biomass (more than 3 months), in large volumes, brings risks from the point of view of human health or property treatment. This work aimed to verify how the long-term storage of wood chips from beech wood in small piles affects their energy properties and whether in this way it is possible to reduce the risk of fire by self-heating in piles and the volume of phytopathogenic spore production. Four experimental piles, each with a base of 4 × 4 m and a height of 2 m, were established. After 6 months, one of the piles was disassembled and samples from 0.5 m, 1.0 m, and 1.5 m height levels were taken for analysis. The results of the experiment confirmed that the energy properties of wood chips stored in small piles significantly deteriorate after more than half a year of storage. It has also been confirmed that the choice of this method of storing in smaller, spatially divided piles can lead to a significant minimization of the risk of spontaneous combustion and fire. The length of the storage period did not have a positive effect on the abundance of phytopathogen content in the stored piles. With the length of storage, only the number of identified harmful species of phytopathogens were changed and, at the same time, their number of colonies increased.

The objective of this work was to assess the use of biomass fly ash (BFA) as cement replacement material or as an alkalinity source in high volume fly ash mortar and concrete. Mortar formulations were prepared with different types of cement replacement: fly ash from thermal power plants, BFA, a blend of two pozzolans, and small amounts of BFA or/and hydrated lime (HL). Mortar formulations were tested both in the fresh and hardened state. The replacement of cement by the two fly ashes led to a decrease in the mechanical strength. The best strength values were obtained when higher HL content was introduced in mortars, however, mortars with the lower BFA content presented the best results for the majority of the tests. In general, BFA has a similar effect on cementitious mortars to coal fly ash, having good performance as cement replacement., Portuguese Foundation for Science and Technology (FCT)and the Eco-Construction and Rehabilitation Doctoral Program for supporting the PhD scholarship(reference PD/BD/52661/2014). This work was partly financed by FCT/MCTES through nationalfunds (PIDDAC) under the R&D Unit Institute for Sustainability and Innovation in StructuralEngineering (ISISE), under reference UIDB/04029/2020