Biomass Solid Waste Research Articles

Emissions of Polychlorinated Dibenzo-p-dioxins and Dibenzofurans from Biomass Combustion and Solid Waste Incineration

Dioxins (PCDDs) and furans (PCDFs) in which consist of carbon, oxygen, and chlorine are very toxic and hazardous substances. Dioxins emission from industrial biomass combustion can be a problem in the very near future. An increase of the dioxins emissions from a power boiler fuelled with biomass has provided insights on potential control technologies. The exposure of the population to chlorinated PCDDs and PCDFs in highly industrialized countries has reached an extent which requires the authorities in charge to seek a drastic reduction of the entry of these substances into the environment. Results from different furnaces were discussed and measures for dioxin reduction were proposed. Emissions from non-contaminated wood were usually less than 0.1 ng I-TEQ/N m 3 at 11% O 2 .

Predicting the heating value of sewage sludges in Thailand from proximate and ultimate analyses

There have been various methods used for determining a heating value of solid fuel such as coal, biomass and municipal solid waste (MSW) either by experiment using a bomb calorimeter or by modeling based on its compositions. This work proposes another aspect in developing models to predict the heating value of sewage sludge from its proximate and ultimate analyses data. The extensive number of samples was collected from different wastewater treatment plants in Bangkok and in the vicinity and was then analyzed for their heating values, proximate and ultimate analyses. Based upon proximate and ultimate analyses, the models were proposed. The best results show coefficients of determination ( R 2) of 0.899 and 0.905 for the models based on the proximate and ultimate analyses, respectively. The heating values obtained from the models were in good agreement with that attained by experiment. The application of the selected models was appreciable for the sewage sludge with ash content up to 50% (db).

05/00413 Effect of air flow rate and fuel moisture on the burning behaviours of biomass and simulated municipal solid wastes in packed beds: Yang, Y. B. et al. Fuel, 2004, 83, (11–12), 1553–1562

05/00413 Effect of air flow rate and fuel moisture on the burning behaviours of biomass and simulated municipal solid wastes in packed beds: Yang, Y. B. et al. Fuel, 2004, 83, (11–12), 1553–1562

Effect of air flow rate and fuel moisture on the burning behaviours of biomass and simulated municipal solid wastes in packed beds

Combustion of biomass and municipal solid wastes is one of the key areas in the global cleaner energy strategy. But there is still a lack of detailed and systematically theoretical study on the packed bed burning of biomass and municipal solid wastes. The advantage of theoretical study lies in its ability to reveal features of the detailed structure of the burning process inside a solid bed, such as reaction zone thickness, combustion staging, rates of individual sub-processes, gas emission and char burning characteristics. These characteristics are hard to measure by conventional experimental techniques. In this paper, mathematical simulations as well as experiments have been carried out for the combustion of wood chips and the incineration of simulated municipal solid wastes in a bench-top stationary bed and the effects of primary air flow rate and moisture level in the fuel have been assessed over wide ranges. It is found that volatile release as well as char burning intensifies with an increase in the primary air flow until a critical point is reached where a further increase in the primary air results in slowing down of the combustion process; a higher primary airflow also reduces the char fraction burned in the final char-burning-only stage, shifts combustion in the bed to a more fuel-lean environment and reduces CO emission at the bed top; an increase in the moisture level in the fuel produces a higher flame front temperature in the bed at low primary air flow rates.

Operation of magnetically assisted fluidized beds in microgravity and variable gravity: experiment and theory

The conversion of solid waste into useful resources in support of long duration manned missions in space presents serious technological challenges. Several technologies, including supercritical water oxidation, microwave powered combustion and fluidized bed incineration, have been tested for the conversion of solid waste. However, none of these technologies are compatible with microgravity or hypogravity operating conditions. In this paper, we present the gradient magnetically assisted fluidized bed (G-MAFB) as a promising operating platform for fluidized bed operations in the space environment. Our experimental and theoretical work has resulted in both the development of a theoretical model based on fundamental principles for the design of the G-MAFB, and also the practical implementation of the G-MAFB in the filtration and destruction of solid biomass waste particles from liquid streams.

Anaerobic digestion of lignocellulosic biomass and wastes

Anaerobic digestion represents one of several commercially viable processes to convert woody biomass, agricultural wastes, and municipal solid wastes to methane gas, a useful energy source. This process occurs in the absence of oxygen, and is substantially less energy intensive than aerobic biological processes designed for disposal purposes. The anaerobic conversion process is a result of the synergistic effects of various microorganisms, which serve as a consortium. The rate-limiting step of this conversion process has been identified as the hydrolysis of cellulose, the major polymeric component of most biomass and waste feedstocks. Improvements in process economics therefore rely on improving the kinetic and physicochemical characteristics of cellulose degrading enzymes. The most thoroughly studied cellulase enzymes are produced by aerobic fungi, namely Trichoderma reesei. However, the pH and temperature optima of fungal cellulases make them incompatible for use in anaerobic digestion systems, and the major populations of microorganisms involved in cellulase enzyme production under anaerobic digestion conditions are various bacterial producers. The current state of understanding of the major groups of bacterial cellulase producers is reviewed in this paper. Also addressed in this review are recently developed methods for the assessment of actual cellulase activity levels, reflective of the digester "hydrolytic potential," using a series of detergent extractive procedures.