Assessment of Ecotoxicity of Incinerated Sewage Sludge Ash (ISSA)

Abstract

Combustion in fluidised bed boilers is one of the most commonly used methods of treatment of municipal sewage sludge. Fly ash (FA) and air pollution control (APC) residues are the solid by-products generated by flue gas treatment. There are significant differences in the chemical composition of these wastes. FA is composed of mainly SiO2, P2O5, CaO and metals such as Zn, Ti, Cu, Cr, Pb and Ni. APC residues mainly contain SO3 and Na2O. The leachability tests that were carried out indicate that these wastes display very low leachability of heavy metals (for example leachability of Pb was equal 0.0004 mg·dm−3 in both wastes, leachability of Cd was equal 0.0012 mg·dm−3 in FA an 0.00004 mg·dm−3 in APC). On the other hand, very high sulphate concentrations (49,375 mg·dm−3) were found in water extract for the APC residues. In order to determine the toxicity of these wastes for plants, pot experiments with different additions of waste to the soil were carried out (on Lepidium sativum and Sinapis alba). Tests based on seeds germinations (on Lepidium sativum) in water extracts from waste (in different concentrations) were also performed. The results obtained indicate the very high toxicity of APC residues. Complete inhibition of germination and growth of the test plants was found for all concentrations of the tested waste in water extract and for all additions of waste to the soil in pot experiments. Seed germination tests on water extracts from FA did not show any toxicity of this waste. Pot tests with FA showed their toxicity only with a high (30%) addition in soil.

Pierwiastki śladowe w pozostałościach z termicznego przekształcania odpadów komunalnych, osadów ściekowych i odpadów niebezpiecznych

“…There are many methods of managing this type of waste, they are used for the production of aggregates, glass-ceramics, cement, bricks, zeolites, in mining as backfill (Kępys et al 2014;Donatello and Cheeseman 2013;smol et al 2015;Cho et al 2020). In addition, they are subjected to processes limiting the leachability of impurities, chemical or changing their form from fine-grained to larger agglomerates (washing, stabilization, solidification, vitrification, sintering) and storage (Quina et al 2008).…”

Utilization of Carbon Dioxide and Fluidized Bed Fly Ash in Post-Industrial Land Remediation

“…Furthermore, although the use of untreated fly ash from conventional boilers in the handling of voids resulting from the mining of minerals and rocks is recognized in the literature, it is focused mainly on the flow properties of filling mixtures in pipeline transport and site-specific or modelled filling effects [37][38][39][40]. Some works involve more extensive studies of the chemical, hydraulic and mechanical properties of backfilling mixtures prepared with the addition of only a limited amount of conventional fly ash [40][41][42][43][44][45], or the use of unconventional materials or treated waste materials, like temperature-treated coal refuse as a component of blends with conventional fly ash in backfilling mixtures [43], limestone aggregate with conventional fly ash and low pozzolanic cement [46], or waste glass granulated blast furnace slag and fumed silica [47]. Most of the research is devoted to the cemented paste backfill composed usually of coal gangue, binders (e.g., Portland cement), slag and conventional fly ash [42].…”

The Impact of Fly Ashes from Thermal Conversion of Sewage Sludge on Properties of Natural Building Materials on the Example of Clay

“…Research is under way concerning the possibilities of the application of such wastes as a source of phosphorus (in the chemical (mainly fertilizers) industry) [19][20][21][22], in building construction [23][24][25][26], and in mining technologies [27,28].…”