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Given the high efficiency in phosphorus removal at municipal wastewater treatment plants (MMWWTP), sewage sludge constitutes a promising resource for phosphorus (P) recovery. Sewage sludge is, however, a complex matrix and its direct use as fertiliser is limited by its content of metals/metalloids and organic pollutants. In order to increase its usability as a potential resource of P, there is a need for increased knowledge on phosphorus speciation in these matrices. The sludge composition is highly influenced by local conditions (i.e. wastewater composition and treatment method), and it is therefore important to study sludge from several MMWWTPs. In this study, three different protocols for sequential extraction were utilised to investigate the chemical speciation of phosphorus in sludge from three different MMWWTP sludges in Sweden, as well as in corresponding ashes following incineration. The results showed that the total amounts of phosphorus ranged from 26 to 32 mg g−1 sludge (dry weight), of which 79–94% was inorganically bound (IP). In the sludge, 21–30% of the IP was associated with calcium (Ca-P), which is the preferred species for fertiliser production. Following incineration, this fraction increased to 54–56%, mainly due to transformation of iron-associated phosphorus (Fe-P), while aluminium-associated species of phosphorus (Al-P) remained unaltered. The results from this study confirm that incineration is a suitable treatment for sewage sludge in terms of potential phosphorus recovery.

Contamination of the environment due to mining and mineral processing is an urgent problem worldwide. It is often desirable to establish a grass cover on old mine waste since it significantly decreases the production of leachates. To obtain sustainable growth, it is often necessary to improve several properties of the waste such as water-holding capacity, nutrient status, and toxicity. This can be done by addition of organic materials such as wood residues, e.g., compost. In this study, we focus on the solution chemistry of the leachates when a substrate containing historic sulfidic mine waste mixed with 30 % (volume) bark compost is overgrown by Agrostis capillaris. The pot experiments also included other growth-promoting additives (alkaline material, mycorrhiza, and metabolizable carbon) to examine whether a more sustainable growth could be obtained. Significant changes in the plant growth and in the leachates composition were observed during 8 weeks of growth. It was concluded that in this time span, the growth of A. capillaris did not affect the composition of the leachates from the pots. Instead, the composition of the leachates was determined by interactions between the bark compost and the mine waste. Best growth of A. capillaris was obtained when alkaline material and mycorrhiza or metabolizable carbon was added to the substrate.

Uranium contamination of soils and water is a worldwide problem due to geology or anthropogenic release such as mining, or use of inorganic fertilizers. In situ remediation of low and moderately contaminated sites is a complicated procedure due to the complex chemistry of uranium. This study demonstrates that at pH 3.5, a fungal strain isolated from unprocessed uranium bearing shale creates hydrochemical conditions that immobilize 97% of a total of 10 mg L -1 dissolved uranium in a 0.20 μm pore system. The redistribution occurred within 10 minutes and remained for five weeks and just 12% of the inventory was retrieved in the biomass. Size exclusion chromatography of the dissolved phase identified organic substances in the range of more than 60 kD down to 100 D as a response to time of incubation. Geochemical modeling indicates formation of uranium-organic complexes where ligand size, coordination chemistry and their tendency to agglomerate determine the redistribution.

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