Heavy metal content of Swedish municipal wastewater sludge – status and goals

Mattsson, Ann E.; Finnson, Anders; I'Ons, David

doi:10.2166/wst.2017.277

Cited by 17 publications

(11 citation statements)

References 4 publications

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“…Although much of the SS in Europe is subject to control, it may still contain unwanted compounds (Bloem et al 2017). Certification systems such as Revaq in Sweden (Mattsson et al 2017), aimed at systematic control of sources, have helped to ensure that the quality of SS has considerably improved over time (Kirchmann et al 2017). Field studies at Petersborg have also shown that soil microorganisms can rapidly degrade organic compounds, as shown by the following two examples:…”

Section: Other Contaminantsmentioning

confidence: 99%

“…European Union (EU) Directive 86/278/EEC, which sets limits for seven heavy metals, is currently being considered for revision (European Commission 2017). This is because many national authorities set lower limits for heavy metals than the EU directive, and also include organic contaminants (Inglezakis et al 2014;Mininni et al 2015;Mattsson et al 2017). Swedish regulations also limit phosphorus (P) and nitrogen (N) application rates with SS (Suppl.…”

Section: Introductionmentioning

confidence: 99%

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Soil fertility effects of repeated application of sewage sludge in two 30-year-old field experiments

Börjesson

Kätterer

2018

Nutr Cycl Agroecosyst

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Recirculation of plant nutrients from waste materials back to agriculture is necessary in a sustainable food production system. In this study we investigated the long-term effect of direct land application of sewage sludge (SS) on soil fertility on two Swedish farms, where field experiments were set up in 1981 with three rates of SS (0, 4 and 12 Mg dry matter ha-1 every 4 years) and three rates of mineral fertilisation, in a factorial design with four replicates. At one site, SS application tended to increase crop yield over time but, when plant nutrients were not limiting, the effect was only significant for spring barley. We deduced that improved soil structure was the main driver for this fertility enhancement after SS application, as indicated by lower soil bulk density and higher soil carbon concentration. After 30 years, soil organic carbon stocks to 0.40 m depth differed by up to 17 Mg ha-1 between treatments. According to carbon balance calculations, retention of carbon derived from SS ranged between 18 and 20% for the soil layers analysed at the two sites. Soluble phosphorus (P) increased with sludge application rate, but represented only around 2% of the expected residual P according to P-balance calculations. The fertiliser value of nitrogen was also low, with only 3-8% nitrogen use efficiency. Heavy metals such as copper, zinc and mercury showed moderate accumulation in the soil, but elevated levels of metals were not detected in crops, even at the highest dose of SS. These results show that SS represents a valuable resource for improving soil fertility in terms of soil organic matter and soil structure, but its efficiency for nutrient cycling is very low within the time frame considered in the study.

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Section: Other Contaminantsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Soil fertility effects of repeated application of sewage sludge in two 30-year-old field experiments

Börjesson

Kätterer

2018

Nutr Cycl Agroecosyst

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“…The Fertilizer Product Act [30] and Decree [31] imposes maximum limit values on eight heavy metals (As, Cd, Cr, Cu, Ni, Zn, Pb and Hg) in sewage sludge used as a fertilizer product, which are given in Table 2. In Finland, the maximum limit values for the heavy metals listed above are more stringent than the maximum limit values allowed in the European Union [32]. Except for Hg (1.4 mg/kg d.m.…”

Section: Total and Bcr Extractable Heavy Metal Concentrations In The Sewage Sludgementioning

confidence: 92%

Characterisation of Municipal Sewage Sludge as a Soil Improver and a Fertilizer Product

Pöykiö

Watkins

Dahl

2019

Ecological Chemistry and Engineering S

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In this study, we have determined the main important physical and chemical properties of municipal sewage sludge and compared them to the requirements of the Finnish Fertilizer Product Act and Fertilizer Product Decree in order to assess the potential utilization of this by-product as a fertilizer. Except for Hg (1.4 mg/kg d.m.), the total concentrations of Cd, Cu, Ni, Pb, Zn, Cr and As in our sewage sludge were lower that the Finnish maximum permissible heavy metal concentrations for sewage sludge used as a fertilizer products. However, the sewage sludge may be utilized as a soil improver, a growing media or as a fertilizer product in landfill sites (e.g. surface structures) or in other closed industrial areas, because the above mentioned Finnish limit values are not applied at these sites. If the sewage sludge is to be utilized in these kinds of areas, an environmental permit may be needed. According to BCR-extraction, the lowest release potential (solubility) from the sample matrix was observed for sulphur (58.4 %) and the highest for Cd (100 %).

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“…The species and concentrations of HMs in AD effluents are also highly depended on the feedstock (typically a mixture of animal manures and other organic wastes) and the specific ratio of the different WaW used. While stricter regulations are expected to minimize HM's in waste and wastewaters this is not always possible for every contaminant (Mattsson et al, 2017).…”

Section: 5mentioning

confidence: 99%

Using agro-industrial wastes for the cultivation of microalgae and duckweeds: Contamination risks and biomass safety concerns

Μάρκου

Wang

et al. 2018

Biotechnology Advances

141

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Aquatic organisms, such as microalgae (Chlorella, Arthrospira (Spirulina), Tetrasselmis, Dunalliela etc.) and duckweed (Lemna spp., Wolffia spp. etc.) are a potential source for the production of protein-rich biomass and for numerous other high-value compounds (fatty acids, pigments, vitamins etc.). Their cultivation using agro-industrial wastes and wastewater (WaW) is of particular interest in the context of a circular economy, not only for recycling valuable nutrients but also for reducing the requirements for fresh water for the production of biomass. Recovery and recycling of nutrients is an unavoidable long-term approach for securing future food and feed production. Agro-industrial WaW are rich in nutrients and have been widely considered as a potential nutrient source for the cultivation of microalgae/duckweed. However, they commonly contain various hazardous contaminants, which could potentially taint the produced biomass, raising various concerns about the safety of their consumption. Herein, an overview of the most important contaminants, including heavy metals and metalloids, pathogens (bacteria, viruses, parasites etc.), and xenobiotics (hormones, antibiotics, parasiticides etc.) is given. It is concluded that pretreatment and processing of WaW is a requisite step for the removal of several contaminants. Among the various technologies, anaerobic digestion (AD) is widely used in practice and offers a technologically mature approach for WaW treatment. During AD, various organic and biological contaminants are significantly removed. Further removal of contaminants could be achieved by post-treatment and processing of digestates (solid/liquid separation, dilution etc.) to further decrease the concentration of contaminants. Moreover, during cultivation an additional removal may occur through various mechanisms, such as precipitation, degradation, and biotransformation. Since many jurisdictions regulate the presence of various contaminants in feed or food setting strict safety monitoring processes, it would be of particular interest to initiate a multi-disciplinary discussion whether agro-industrial WaW ought to be used to cultivate microalgae/duckweed for feed or food production and identify most feasible options for doing this safely. Based on the current body of knowledge it is estimated that AD and post-treatment of WaW can lower significantly the risks associated with heavy metals and pathogens, but it is yet unclear to what extent this is the case for certain persistent xenobiotics.

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Heavy metal content of Swedish municipal wastewater sludge – status and goals

Cited by 17 publications

References 4 publications

Soil fertility effects of repeated application of sewage sludge in two 30-year-old field experiments

Soil fertility effects of repeated application of sewage sludge in two 30-year-old field experiments

Characterisation of Municipal Sewage Sludge as a Soil Improver and a Fertilizer Product

Using agro-industrial wastes for the cultivation of microalgae and duckweeds: Contamination risks and biomass safety concerns

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