Over 200 people attended the session on tighter sewage phosphorus removal requirements and phosphorus recycling at IFAT 2018, Munich, organised by DPP (the German Phosphorus Platform) and ESPP (European Sustainable Phosphorus Platform).
Monika Kratzer, Bavarian State Ministry of the Environment and Consumer Protection, noted that Bavaria depends strongly on imports of raw materials, including phosphorus for agriculture. Phosphorus recycling from sewage can contribute to reduce this dependency. The new German legislation sets objectives, and it is now important to identify which technologies are effective.
Pete Vale, Severn Trent Water UK, summarised key results of the UK national water industry trials of technologies to achieve very low phosphorus discharge limits, which will progressively come into force because of the EU Water Framework Directive (WFD). Limits of 0.2 mgP/l will be introduced in the next couple of years, with further tightening possible in the future. Considerable progress has been made in reducing phosphorus emissions from sewage works in the UK, with a 60% reduction 1990-2009, with over UK£ 2 billion investment, but phosphorus remains the most common cause of WFD quality objective failure in England. The industry national trials tested optimisation of existing technologies in place, new technologies already operational at sites elsewhere in the world and “novel” technologies. Conclusion is that optimisation can reduce discharge to 0.5 mgP/l, but not 0.1 mgP/l. Some of the new and novel technologies can achieve 0.1 mgP/l, but not always reliably without other installation and operational changes. Full results will be published shortly, including discharge performance data, whole life cost and carbon/energy costs. These will be used both to define the UK water industry’s investment cycle and to input to defining the Environment Agency discharge permitting regime.
Daniel Klein, Emscher Genossenschaft / Lippeverband, Germany, indicated that this water board is also preparing for 0.1 mgP/l discharge limits, and is looking at costs and performance, especially of “add-on” technologies (filtration/flocculation). Currently around 90% of the board’s total sewage inflow phosphorus goes to sludge (and 10% is lost in discharge), and nearly all sludge goes to mono-incineration. Important questions need to be addressed concerning the impact of tighter P-removal on P-recovery, possibly synergies and costs, with major investments expected in the coming ten years. The water board is testing different approaches for phosphorus recovery with the aim of identifying cost-effective solutions.
Christian Hubert & Christian Schaum, Munich Bundeswehr University, presented some general ideas on the theoretical value of resources in sewage (based on Westerhoff 2015), energy and interest of cooperation between sewage treatment organisations on sludge processing/incineration.
Bruno Barillon, Suez, indicated that the company’s objective is to improve economic sustainability of sewage treatment by recovery of resources, water reuse and energy production – but that sludge management will still represent a significant net cost. Suez’ Phosphogreen struvite recovery process, enables recovery of 15-45% of inflow phosphorus in biological P-removal sewage works, with 5-10 year RoI (return on investment) resulting from struvite sales (350€/t in Denmark) and 15-50% reduction in ferric consumption, as well as reducing the environmental footprint (-10% CO2). Suez has now five references: three plants in Denmark (Aarhus, Herning, Marselisborg ) and two in France (Villiers Saint Frédéric, Sausheim). See SCOPE Newsletter n°121.
Ralf Czarnecki, Remondis (Rethmann group), indicated that the company manages some 1.5 million ton/year of sewage sludge (wet weight of dewatered sludge), of which 1.2 mega ton is incinerated and 0.3 mega ton is used on land. He presented the company’s Tetraphos process, for phosphorus recovery from sewage sludge mono-incineration ash. A 20 000 ton ash/year Tetraphos P-recovery plant will be operational in Hamburg in 2020: see summary above and in SCOPE Newsletter n°126. Further pilot trials are planned with several water boards including Emscher/Lippeverband.
Mathias Staub, Veolia, considered that the new German phosphorus recovery legislation will oblige construction of some new sludge mono-incineration capacity, but that in some regions continuing use of co-incineration or cement works disposal will be economically and environmentally preferable, subject to recovering phosphorus upstream in the sewage works. Veolia’s PhosForce system, especially adapted for medium size works (50 – 500 000 p.e.), aims to achieve more than 50% P-recovery, by combining bio-acidification of sludge upstream of anaerobic digestion and struvite and/or brushite (calcium phosphate) recovery (StruviaTM system). A 3 m3/day pilot is operational at Schönebeck and a full scale plant is planned for 2019. The system is designed to operate with both chemical and biological P-removal sludges with limited use of chemicals, to enable low phosphorus discharge levels and to facilitate nitrogen recovery by stripping.
Discussion with speakers was led by Daniel Frank, German Phosphorus Platform, and summarised by Ludwig Hermann, ESPP, concluding that:
- Some new sludge mono-incineration capacity will be needed to meet the new German phosphorus recovery regulation obligations, especially in urban areas, but in other regions continuing use of existing co-incineration routes may be preferable;
- Costs of tighter phosphorus discharge consents and of P-recovery will be passed on to water consumers, but in time may be partly covered by resource recovery;
- New technologies for both phosphorus removal and recovery have been developed over recent years and now information is needed from operating trials in sewage works on costs and in-the-field reliability;
- Long-term contracts with sewage works operators and technology developers and supplies are needed to enable investment;
- Cooperation between water boards and WWTP-operators is crucial to identify and implement economic and operational solutions to meet the new phosphorus removal and recovery regulations.
“Phosphorus Special IFAT 2018. Phosphorus removal, phosphorus recycling and the circular economy: contradiction or opportunity?”, organised by DPP, ESPP with IFAT, the Bavarian State Ministry of the Environment and Consumer Protection and the German Federal Ministry for the Environment, Munich, 17th May 2018.
Meeting slides are available at www.deutsche-phosphor-plattform.de/information/dokumente under Präsentationen der IFAT-Veranstaltung „Phosphor-Special“