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AbstractBiosolids are applied to agricultural land as a soil conditioner and source of crop nutrients. However, there is concern that bacteria from biosolids may become established in soils, particularly if that soil becomes water-logged. This study examined the microbial community of arable soils cultivated with barley under different applications of biosolids (0, 24t/ha, 48t/ha) in laboratory mesocosms which simulated a 10-day flood. Nutrients (P and N) and organic matter in the soil increased with application rate, but plant growth was not affected by biosolid application. The biosolids contained 10× more genetic material than the soil, with much lower bacterial diversity, yet application did not significantly change the taxonomy of the soil microbiome, with minor changes related to increased nutrients and SOM. Anaerobic conditions developed rapidly during flooding, causing shifts in the native soil microbiome. Some bacterial taxa that were highly abundant in biosolids had slightly increased relative abundance in amended soils during the flood. After flooding, soil bacterial populations returned to their pre-flood profiles, implying that the native microbial community is resilient to transient changes. The short-term changes in the microbiome of biosolid-amended soils during flooding do not appear to increase the environmental risk posed by biosolid application.

ABSTRACTThe decay of Escherichia coli in a sandy loam soil, amended with enhanced and conventionally treated biosolids, was investigated in a field experiment following spring and autumn applications of sewage sludge. Control soils, without the application of biosolids, were also examined to determine the background indigenous populations of E. coli which are present in the environment. The survival of indigenous E coli and populations of E coli applied to soil in biosolids, is assessed in relation to environmental factors influencing pathogen‐decay processes in soil.

The aim of this study was to evaluate the potential of agricultural land in the coastal Adriatic Karst region (Šibenik region, Croatia) for biosolids application by integrating spatial data from different sources: digital maps and remote sensing, parcel identification system, GIS field observations and measurements focusing on specific land and soil properties. Due to the rapid development of the wastewater treatment industry, excessive accumulation of sewage sludge (SS) in wastewater treatment plants is a growing problem worldwide. Management options for land application of biosolids require a comprehensive characterization of both SS and SS-amended soils. The assessment of agricultural land in the study area for SS disposal was based on EU and national legislation. The evaluation revealed that agricultural land in the study area accounts for only 10% of the total area (25,736 ha), but only a quarter of the existing land (6065 ha) is suitable for biosolids application. Furthermore, the data indicate that the sewage sludge can be safely applied to the soil in terms of soil metals according to the Croatian legislation. The short-term potential of the soil to sustain this ecosystem service, namely soil improvement with biosolids, should be used to determine the inherent long-term potential based on resistance to soil degradation and resilience. However, caution is needed and the long-term effects should be investigated before biosolids are continuously used for soil application.

AbstractIn 1996, Thames Water launched a range of peat‐free compost products based on biosolids. In order to keep up with demand and to maintain the high standards of product quality, the company has investigated higher‐rate composting processes and optimisation of the maturation stage. Agitated‐bay composting systems are the preferred in‐vessel technology for large sludge treatment centres using woodchip as a bulking agent. These automated systems (i) accelerate the composting process, (ii) maximise throughput on a smaller footprint, and (iii) achieve better control of odour emissions.A maturation trial with composted material from the US Filter agitated‐bay system confirmed that a horticultural‐grade product could be attained. Small‐scale maturation trials showed that seeding with mature green waste compost can accelerate nitrification to such a rate that near zero levels of ammonia can be achieved after one month of maturation.

The study objectives were to identify the best practice components of a biosolids composting utilization program; to determine current and emerging provincial and federal regulatory frameworks applicable to biosolids composting facilities in Manitoba; and to produce an annotated process map for planning, initiating and operating a biosolids composting facility. Recommendations from this study are to develop a stand-alone regulation that addresses composting requirements for probable feedstocks in provincial legislation, to clearly set out the requirements for such facilities; to update the Environmental Regulation for Treatment and Disposal of Biosolids in Manitoba policy document to acknowledge and provide guidance for biosolids composting as a potential management method; and to update and finalize the Manitoba Draft Compost Facility Guidelines to reflect current requirements for compost facilities and to include biosolids as a potential feedstock. The adoption of a categorization scheme for biosolids is also recommended to support determining appropriate management options based on biosolids quality. ; February 2014

The presence of trace organic chemicals (TOrCs) in municipal biosolids in the U.S. has received considerable attention by the public and scientific community over the last several years. Of particular concern is whether the presence of TOrCs in biosolids results in significant risks to public health and the environment upon land application of the biosolids. While the U.S. Environmental Protection Agency has evaluated the risks associated with dioxins present in biosolids-amended soils, to date, no other TOrCs, particularly those of emerging concern, have been subjected to complete risk assessments with respect to the land application of municipal biosolids. This study identified the scientific data gaps that should be filled if appropriate risk assessments are to be conducted. The focus of this effort was to compile data from published peer-reviewed literature that addresses the occurrence, mobility, persistence, bioaccumulation, toxicity, and microbial impacts of biosolids-borne TOrCs in soils. In addition, an evaluation of the current modeling approaches employed to evaluate the risks of biosolids-borne TOrCs was conducted

Between April to November of 2017, microplastics (MPs) were analysed in biosolids from two separate suppliers, and in the soils of three agricultural fields to which they were applied, in Ontario, Canada. Soils of a control site with no history of biosolid application were also examined. High MP concentrations of between 8.7 × 103 MP kg−1 and 1.4 × 104 MP kg−1 were found in biosolids samples. Lower MP concentrations observed in Provider 2 biosolids may be due to storage, settling and supernatant removal prior to applications. Annual MP additions to agricultural soils across Ontario were estimated at between 4.1 × 1011 and 1.3 × 1012 particles. All fields receiving biosolids had higher soil pre-treatment MP concentrations than the control. The field with the greatest number of previous biosolid treatments had the highest pre-treatment soil MP concentrations; suggesting some MP retention in soils between applications. Immediately following biosolids applications, two fields demonstrated significant increases in soil MP concentrations, with preferential retention of MP fibers over fragments observed, while a reduction in soil MP concentrations were observed in the third. Surprisingly, only one field demonstrated a net gain in soil MPs over the course of the study. At all three fields, >99% of MPs applied in biosolids in 2017 were unaccounted for. The study suggests that despite adhering to applicable legislation, biosolids applications at all sites likely result in high rates of MP export. This study is the first to track MP transport through soils following their application in biosolids, and contributes to filling current knowledge gaps regarding export of MPs to aquatic systems from the terrestrial environment. ; publishedVersion