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Industrially, many solid wastes can be classified as biomass and their usage reduces disposal costs. In this work, seven wastes from textile and food industries were characterized chemically and physically and the gaseous emissions resulting from the combustion of three of them (textile residues 3, TR3; coffee grounds; and a mixture of meat processing industry wastewater sludge and saw dust (1:9) in weight, SS1) in a pilot scale cyclone type combustor were measured. Their potential for utilization as energy sources was assessed by comparing the emissions to current legislation. Chemical properties showed that the volatile matter values of all biomass were high, which indicate that the solids burn rapidly. Some biomass presented high levels of sulfur and consequently high levels of SO2 emission when burned. The lower heating values ranged from 6.44 MJ kg−1 (dry and ash free, daf) to 22.93 MJ kg−1 (daf) and thermogravimetric analysis of the biomasses showed ignition temperatures and maximum burning rates, which were compared with other papers’ data. Four combustion tests were carried out in a cyclone type combustor and CO, CO2, NOx, CxHy, and SO2 were measured. Moisture content and particulate matter were also measured during the combustion tests and showed effective combustion conditions. Volatile organic compounds were analyzed by gas chromatography-mass spectrometry and their content values were expressed as total organic carbon (TOC), being all TOC emissions below the limits imposed by the regulations taken as reference. Gaseous emissions were compared with limits imposed by Brazilian and international current legislations, what showed that the usage of these biomasses as energy sources is possible; however, gas treatment would be required, especially if the solid presents high levels of sulfur and chlorine.

The solid waste generated from the apple juice industry (apple bagasse (AB)) was characterized as a fuel, and the potential for its utilization as an alternative energy source was assessed through its combustion in a pilot scale cyclone combustor. A comparative evaluation of the AB and sawdust (SD) properties, as well as of the emissions during the combustion tests, was performed. The high energy content of AB (lower heating value (LHV) equal to 21.09 MJ kg−1), dry and ash-free (daf) basis, which is 26.9% higher than the LHV of SD (16.62 MJ kg−1, daf), and combined with the high volatile matter content (85.36 wt %, daf) improve the ignition and burning of the solids. The emissions of CO, SO2, and NOx and the total organic carbon (TOC) were compared with guideline limits established by Brazilian and international legislation. AB generated much lower CO than sawdust in spite of almost half of excess air levels (13% compared with 26%) and met even the stringent limit of the German regulation for waste incineration. The unburned carbon percentages found in the ash resulted from SD and AB combustion tests were 0.24% and 0.96% in weight, respectively. The absence of sulfur in AB composition represents an advantage with nondetectable SO2. The average level of NOx emission with SD combustion was 242 mg N m−3 and met all the regulation limits. The average NOx emission with AB combustion though was 642 mg N m−3 and met the U.S. EPA regulation but was marginally higher than the Brazilian norm by 15%. TOC concentrations remained below the limits considered even though the TOC level was higher in the AB combustion test. Polycyclic aromatic hydrocarbons (PAH) were not detected or were under the quantification limit of the equipment used in their analysis. Comparing the properties, the burning profiles of SD and AB, and the emissions from their combustion tests, it can be stated that the waste originating from the apple juice industry is suitable for direct combustion, constituting a renewable energy source for this industrial sector.

Flotation sludge from the meat processing industry can be applied as biofuel in already existing plant-scale boilers. This biosolid is rich in oil and grease and has higher energetic content on a dry ash-free basis (22.74 and 27.71 MJ kg −1 ) than the wood-based fuel (16.62 and 16.16 MJ kg −1 ). Co-combustion trials were performed at a pilot-scale cyclonic combustor (100 kg h −1 ) and at an industrial flamotubular rotatory grate-fired system (6000 kg h −1 ), co-firing pre-dried and centrifuged flotation sludges (respectively) and wood at a mass ratio of 1:3. At a moisture content of 60.13 wt%, the lower heating value of the centrifuged sludge was 10.24% lower compared to wood, thus reducing it to at least 40 wt% would be advisable to obtain energy gains in the industrial plant when operating the co-combustion. The emissions were evaluated and compared to emission standards, including the characterization of polycyclic aromatic hydrocarbons and polychlorinated dibenzo-p-dioxins and polychlorinated dibenzofurans (given as Toxicity Equivalent Factors at O 2ref = 7%), which have not yet been reported. The 16 target polycyclic aromatic hydrocarbons were identified at pilot and plant scales (0.582 ± 0.143 μg Nm −3 and 0.602 ± 0.506 μg Nm −3 , respectively) being lower than the Danish reference standard (5.0 μg Nm −3 ). The polychlorinated dibenzop-dioxins and polychlorinated dibenzofurans concentrations were 0.0004 ± 0.0001 ng Nm −3 at pilot scale and 0.3617 ± 0.1310 ng Nm −3 at plant scale, both below the Brazilian and American standards but differed greatly between the scales, requiring further investigation since their formation can occur due to combustion and postcombustion conditions.