Polycyclic aromatic hydrocarbons emission from cigar burner combustion system and comparison of their content in fly ashes

Agricultural biomass is considered a preferred RES in Serbia because of its availability and suitability to limit the use of fossil fuel resources and reduce GHG emissions. Therefore, constant work has been done to develop technologies that enable its utilization for energy purposes. As an example of these efforts, in the Agricultural Corporation PKB, the soybean straw cigarette-type combustion system has been applied for greenhouse heating for over a decade. However, many volatile and semivolatile organic compounds are emitted directly into the atmosphere or concentrated in ash particles during agricultural biomass combustion. Since some of the emitted compounds, such as polycyclic aromatic hydrocarbons (PAHs), are toxic, monitoring their concentrations in fly ash is recommended. Literature data regarding PAHs content in agricultural biomass ashes are insubstantial, especially in Serbia. For that purpose, PAHs contents in the cyclone and stack fly ashes of soybean straw were investigated and compared. In addition, the emission factors, toxicity, carcinogenicity and benzo[a]pyrene equivalence concentrations were determined and used to estimate the potential environmental impact of these ashes. As a result, stack ash has been shown to have a higher potential environmental risk than cyclone ash. Hence, an assessment of using soybean straw as a feed fuel in a real cigarette-type combustion plant regarding PAHs emission is given. These results provide important information for optimizing combustion conditions and assisting the local entities in managing air pollution and control policies in Serbia

Risk Evaluation of Pollutants Emission from Coal and Coal Waste Combustion Plants and Environmental Impact of Fly Ash Landfilling

Emission factors (EFs) of gaseous pollutants, particulate matter, certain harmful trace elements, and polycyclic aromatic hydrocarbons (PAHs) from three thermal power plants (TPPs) and semi-industrial fluidized bed boiler (FBB) were compared. EFs of particulate matter, trace elements (except Cd and Pb), benzo[a]pyrene, and benzo[b]fluoranthene exceed the upper limits specified in the EMEP inventory guidebook for all combustion facilities. The comparison of trace elements and PAHs content in fly ashes (FAs) from lignite and coal waste combustion in TPPs and FBB, respectively, as well as the potential environmental impact of FAs disposal, was performed by employing a set of ecological indicators such as crustal enrichment factor, risk assessment code, risk indices for trace elements, and benzo[a]pyrene equivalent concentration for PAHs. Sequential analysis shows that the trace elements portion is the lowest for water-soluble and exchangeable fractions. The highest enrichment levels in FAs are noticed for As and Hg. Based on toxic trace elements content, FAs from TPPs represent a very high ecological risk, whereas fly ash from FBB poses a moderate ecological risk but has the highest benzo[a]pyrene equivalent concentration, indicating its increased carcinogenic potential. Lead isotope ratios for Serbian coals and FAs can contribute to a lead pollution global database

Procena rizika za potencijalno opasne supstance iz letećih pepela dobijenih sagorevanjem uglja i otpadnog uglja

Lignite and coal waste used as feed fuels in thermal power plants (TPPs) and semi-industrial fluidized bed boiler (FBB), as well as their representative fly ashes (FAs), were examined. Fly ashes were compared employing anions and cations content in correspondent water extracts, trace elements and polycyclic aromatic hydrocarbon concentrations, as well as health risk assessments of substances known to be of concern for public health. Fluoride and sulfate contents in water extracted FAs are far below the legislation limits for waste, classifying all investigated FAs as non-hazardous. Among investigated trace elements, Cd content is the lowest, while Mn content is the highest. The highest enrichment ratios are noticed for As, Pb, Hg, Cu, V and Cr. The results indicate that total PAHs content is elevated in FA from the combustion of coal waste (AFB), with fluoranthene prevailing. The cancer risk of As and the non- -cancer risk of As and Ni in some FAs surpass their respective permissible limits. The incremental lifetime cancer risk of an adult population indicates a potential PAHs risk in AFB, whereas all other fly ashes are within safe limits.U ovom radu, ispitivana su goriva (lignit i otpadni ugalj) koja se koriste u termoelektranama i poluindustrijskom postrojenju sa fluidizovanim slojem, kao i leteći pepeli dobijeni njihovim sagorevanjem. Leteći pepeli su upoređeni na osnovu: sadržaja anjona i katjona u njihovim vodenim ekstraktima, koncentracije elemenata u tragovima i policikličnih aromatičnih ugljovodonika (PAH), kao i procene zdravstvenog rizika koji potiče od prethodno pomenutih potencijalno opasnih supstanci. Sadržaj fluorida i sulfata u vodenim ekstraktima letećih pepela daleko je ispod zakonski dozvoljenih granica za otpad, na osnovu čega se mogu svrstati u bezopasne. Od ispitivanih elemenata u tragovima, sadržaj Cd je najniži, dok je koncentracija Mn najviša. Najveće obogaćenje pepela u odnosu na odgovarajući ugalj, primećeno je za As, Pb, Hg, Cu, V i Cr. Na osnovu dobijenih rezultata pokazano je da je ukupni sadržaj PAH najveći za leteći pepeo dobijen sagorevanjem otpadnog uglja. Među ispitivanim PAH, najvišu koncentraciju ima fluoranten. Rizici koji potiču od arsena (među kancerogenim elementima), kao i arsena i nikla (među nekancerogenim elementima), premašuju dozvoljene granične vrednosti. Vrednost procenjenog rizika od raka kod odrasle populacije u slučaju PAH, pokazuje da za leteći pepeo dobijen sagorevanjem otpadnog uglja postoji potencijalni rizik, dok su vrednosti za ostale pepele unutar dozvoljenih granica