Araceli Gálvez

Organic and inorganic pollutants from cement kiln stack feeding alternative fuels

In this work, an analysis of the emission of different pollutants when replacing partially the fuel type used in a cement kiln is done. The wastes used to feed the kiln were tyres and two types of sewage sludge. The increasing mass flow of sludge is between 700 kg h(-1) and 5,500 kg h(-1)1, for a total production of clinker of 150th(-1), whereas the fed tyres were in the flow range of 500-1,500 kg h(-1). Dioxins and furans, polycyclic aromatic hydrocarbons (PAHs) and other hydrocarbons, heavy metals, HCl and HF, CO, CO(2), NO(x) and other parameters of the stack were analyzed, according to the standard methods of sampling and determination, through more than 1 year in six series: one blank (no sewage sludge) and five more with increasing amount of sludge and/or tyres. The emission of PAHs and dioxins seems to increase with the amount of tyres fed to the kiln, probably due to the fed point used for this waste.

Formation of polychlorinated compounds in the combustion of PVC with iron nanoparticles

The influence of iron nanoparticles in the fuel-rich combustion of PVC has been studied in this work. Dynamic runs for PVC and the mixture PVC and iron nanoparticles were firstly carried out by TGA-MS in order to study the influence of iron on the compounds evolved in the thermal degradation of PVC. To complete the study both PVC and a mixture of PVC and iron nanoparticles were burnt in a laboratory reactor under two different operating conditions: at 850 degrees C and in two stages, the first one at 375 degrees C and the resulting char cooled and subsequently burnt at 850 degrees C. Carbon oxides, light hydrocarbons, PAHs, chlorophenols, chlorobenzenes and PCDD/Fs were analyzed. It was observed that the mixture of PVC with iron nanoparticles at 375 degrees C greatly enhances the formation of light hydrocarbons and polychlorinated compounds, probably indicating that the presence of iron during the thermal decomposition of PVC causes the formation of iron chloride which may have a high catalytic effect.

Decomposition of paper wastes in presence of ceramics and cement raw material

Paper recycling is an environmental important activity that is carried out in all the countries, but during the recycling process a paper waste is produced. Generally these wastes are placed in landfill sites but it is possible to profit it as secondary fuel and raw material in manufacture furnaces. In this work the combustion of the waste papers with cement and ceramic raw material has been studied with the objective to analyse the interaction of these substances with the emitted pollutants like PAHs and PCDD/Fs. The results of the study show that the presence of inorganic material produces an increment in the lighter PAH emission but chlorinated compounds are not affected. The PCDD/F emission level found in the combustion of this waste is quite low compared with other wastes subjected to similar conditions.

Analysis of dioxin-like compounds formed in the combustion of tomato plant

In an initial effort to minimize some of the uncertainty regarding the open burning of biomass, emission factors of carbon oxides, light hydrocarbons, PAHs, PCDD/Fs and dioxin-like PCBs were determined in the combustion of tomato plant in a residential stove and in two runs at 500 degrees C and 850 degrees C in a laboratory scale reactor. In all the runs nearly the same PAHs were identified, being naphthalene the main obtained. Combustion of tomato plant at 500 degrees C in the laboratory scale reactor produced the highest emission factors for all compounds analyzed. Tomato plant was analyzed for PCDD/F and dioxin-like PCB content in order to establish the level of pollutants in the sample itself. Ash obtained in the combustion carried out in the residential stove was analyzed for the dioxin-like compound content and compared with a sample of ash collected from the open burning of tomato plant.

Dioxin Content in Compost Samples

Dioxin and furans (PCDD/Fs) are released into the environment from many possible sources, including incineration, industrial processes, and internal combustion engines. The PCDD/Fs have been identified as agents responsible for many toxic responses in exposed individuals, including cancer and developmental/reproductive dysfunctions. Because of their stable structure and lipophilic properties, PCDD/Fs have been the focus of many environmental and toxicological studies over the past several years, and these chemicals have been identified in diverse environmental samples from a range of countries. Although the composting of agricultural and urban residues such as winery and distillery residues (WDR) and sewage sludge is a useful method for producing a stable material that can be used for agricultural purposes, composting is a biological process that probably changes the dioxin and congener distribution, promoting the formation or destruction of some specific congeners. In this experiment, the presence and quantity of dioxins in a composting pile prepared with winery‐distillery residues (grape stalk and marc, GS and GM, respectively; exhausted grape marc, EG) and sewage sludge were determined at different stages of the composting process. The results showed that composting did not significantly increase the amount and distribution of dioxin and congeners, but the use of sewage sludge seemed to induce a significant increase of these hazardous components.