The Chartered Institution of Water and Environment Management (CIWEM, United Kingdom) organised a workshop of industry, experts and regulators to input to the Institute’s Policy Position Statement on valorisation of sewage biosolids (currently being redefined), London, 3rd March 2018. ESPP was invited to give a presentation to summarise developments in Europe, and outlined the Germany and Switzerland regulations and Baltic HELCOM policies requiring phosphorus recycling from sewage, pressures on agricultural use of sewage biosolids (e.g. announced public enquiry in Sweden – ESPP eNews n°24, Global GAP food industry criteria excluding use of sewage biosolids on cropland …) and current proposals regarding sewage biosolids in the EU Fertilisers Regulation proposal (expected to be excluded from composts, digestates, biochars, but authorised for precipitated phosphate salts and ash-based recycling). Discussion in the group noted that concerns about non-biodegradable polymers used in sludge dewatering could prevent sewage biosolids application to land (e.g. new German regulations). The discussion noted that nearly half of sewage sludge biosolids in Europe are today recycled via use on lands, and similarly in the USA (60%), Australia (nearly 60%) and China (nearly 50%). The UK has one of the highest rates of use on farmland (80% of sewage biosolids), which poses operational risks (for the water industry) and cost risks (for the consumer) if this route were to be stopped. Sludge biosolids are estimated by David Tomkins (AquaEnviro) to represent around 17% of total phosphorus input to UK agriculture. Sludge biosolids recycling to land has changed considerably over recent decades, and today is mostly as stable, solid, storable composts or digestates. Participants considered that biosolids use on cropland is recognised as safe for the food chain, but that there are questions about possible impacts of organic contaminants (such as pharmaceuticals) or micro-plastics on soils and the environment, and these need to be addressed. The energy value of sewage sludge was emphasised, and the options today available for energy valorisation (high energy-efficiency incineration, hydrothermal gasification). Questions were asked about the return of carbon to agricultural soils in sludge biosolids: is this significant given the application rates (limited by crop nutrient requirements). Participants suggested that the positive values of sewage sludge as an energy, carbon and nutrient resource should be emphasised, underlining the need for appropriate valorisation routes and technologies, for different local contexts.
CIWEM Wastewater and Biosolids Panel www.ciwem.org/technical-panels/wastewater-management
ESPP presentation at CIWEM workshop www.slideshare.net/NutrientPlatform/biosolids-and-nutrient-recycling-in-europe-ciwem-biosolids-workshop-london-3-october-2018