This study analyses reference and innovative POWERSTEP schemes for municipal WWTP in their environmental and economic impacts using life-cycle tools of Life Cycle Assessment and Life Cycle Costing. Based on hypothetical scenarios at defined boundary conditions for WWTP size, influent quality, and effluent discharge limits, multiple process schemes have been modelled in a mass and energy flow model with a benchmarking software for WWTPs. This process data forms the basis to calculate operational efforts, and it is amended by infrastructure data for material demand and related investment costs. In addition, specific data has been added based on results of the POWERSTEP project (e.g. for N2O emissions) or information from literature. The results show that innovative schemes with advanced primary treatment operate with a superior electricity balance compared to current state-of-the-art schemes for municipal wastewater treatment as a reference, increasing electrical self-sufficiency from 27-82% to 80-170%. The POWERSTEP schemes reach this goal without compromising effluent quality targets of the schemes, i.e. reaching the same effluent quality than before. Concentrated influent with high COD levels supports the POWERSTEP approach and enables highly energy efficient schemes. However, nitrogen removal has to be realized with mainstream anammox after enhanced carbon extraction from concentrated influent. This process is still under development, and its performance and stability should be further validated in full-scale references. Sidestream N removal, advanced control of COD extraction and partial bypass of primary treatment are other options to guarantee nitrogen removal after enhanced carbon extraction with conventional denitrification. In the life-cycle perspective, POWERSTEP schemes significantly decrease primary energy demand of WWTP operation by 29-134% compared to the reference. In favourable conditions, their superior electricity balance can fully compensate life-cycle energy demand for chemical production, sludge disposal and infrastructure, resulting in real energy-positive WWTP schemes. Greenhouse gas emissions can also be substantially reduced with POWERSTEP (- 6 to 43%) due to savings in grid electricity production. GHG benefits of POWERSTEP are smaller than energy benefits on a relative scale, because direct emissions such as N2O from biological N removal and mono-incineration also deliver a major contribution to overall GHG emission profiles, and they are not reduced with POWERSTEP. In contrast, POWERSTEP schemes with mainstream anammox will most likely increase N2O emissions, compensating a large part of the electricity-related benefits in GHG emissions. Total annual costs are in a comparable range for both reference and POWERSTEP schemes. While the latter decrease operational costs by 3-16% due to lower purchase of grid electricity, they require higher investment for primary treatment, increasing capital costs by 4-17%. Overall, effects of POWERSTEP on operational and capital costs off-set each other and result in a net increase of total annual costs of 2-7%, which is within the uncertainty range of this cost calculation. Higher electricity prices (> 0.12 €/kWh) will increase the positive impact of POWERSTEP on operating costs, resulting in fully costcompetitive eco-efficient WWTP schemes at power prices of 0.25 €/kWh. Final recommendations are derived on the way to develop eco-efficient WWTP schemes of the future.

The ETV programme is designed to provide an independent validation of the performance claims of technology suppliers by a qualified third party called “ETV verification body”. The "Statement of Verification" delivered at the end of the ETV process can be used as evidence that the claims made about the innovation are both credible and scientifically sound. With proof of performance credibly assured, innovations can expect an easier market access and/or a larger market share and the technological risk is reduced for technology purchasers. In the POWERSTEP project, 2 technologies were finally chosen after a section process (“quick scan”), Drum filters for primary treatment of raw wastewater (supplied by the company “Veolia Water Technologies Sweden – Hydrotech”) and the Biomethanation process for conversion of biogas or CO2 into biomethane, using a proprietary biocatalyst and reactor configuration (supplied by the company “Electrochaea”). The report summarizes the how the quick scan was carried out to select the above mentioned technologies, feedback from the two companies of the overall ETV process and their experiences as well as general feedback and recommendation to improve the ETV process in general from the POWERSTEP project point of view. It has to be mentioned that until the end of the POWERSTEP project (30th of June) the ETV verification process is not finished in both cases, so no results or feedback on the outcomes can be presented in this report.

This report analyses the legal framework for marketing of renewable energy produced at a wastewater treatment plant for three different countries (Germany, France, Denmark). Looking at the energy types of electricity (for self-supply or grid supply), heat and biomethane, the report describes taxes, fees, levies, and subsidy schemes which directly affect the potential revenues of the WWTP operator. The analysis shows that there are large differences between the countries that have a decisive impact on the economic attractiveness of the different options. While electricity use for self-supply is favored in case of high purchase costs for grid electricity (e.g. Germany), subsidy schemes for grid supply can also make this option economically relevant. In all countries, the grid injection of biomethane is a viable option which will be increasingly attractive for WWTP operators in the future. Reliable legal frameworks are required to offer stability for longterm investment at WWTP level, which is today often not the case due to the dynamic nature of the energy markets and policies.

POWERSTEP aims to demonstrate energy-positive wastewater treatment, which requires the utilization of the internal carbon in the wastewater to produce biogas. An increased carbon extraction for biogas production challenges conventional nitrogen removal, in which denitrifying bacteria depend on an easily accessible source of carbon. Hence, POWERSTEP focuses on novel concepts for nitrogen removal in the mainstream line, with a minimum requirement of carbon. Within work package (WP) 2 of POWERSTEP, Mainstream nitrogen removal, three different tasks have been performed that represents three different options for nitrogen removal after advanced carbon extraction. In task 2.1 Advanced control strategies, it was demonstrated in Case study Westewitz WWTP that, with an advanced control system where polymer addition in the primary treatment was based on minimum carbon source requirement for denitrification, a high degree of carbon extraction could be achieved while still meeting the effluent demands for nitrogen, utilizing the conventional nitrification-denitrification pathway. In task 2.2 Mainstream deammonification, the concept using a specific group of autotrophic bacteria, commonly referred to as anammox bacteria, for removal of ammonia to nitrogen gas was demonstrated in full scale prototype in Case study Sjölunda WWTP. Since anammox bacteria are not dependent on carbon for nitrogen removal, the full potential of carbon recovery for biogas production can be reached. In task 2.3 Mainstream duckweed reactor, the potential of using duckweed for high production of vegetal organic biomass for biogas production and simultaneously achieve nitrogen removal, was demonstrated in Case study Westewitz WWTP. This deliverable provides a guideline, where the different options to remove nitrogen within municipal wastewater after advanced carbon extraction are presented based on the performed tasks in WP2 of POWERSTEP, and in comparison with conventional processes. Special emphasis is made on resources (energy, footprint, chemicals) and performances (removal stability, flexibility, sludge production). The outcome from POWERSTEP (tasks 2.1.-2.3) and comparisons with conventional processes showed that in order to meet the full potential of carbon recovery and turning the wastewater treatment plant truly energy positive while still meeting high nitrogen removal requirements, there is a need to implement anammox removal technology. However, the full scale demonstration showed that even if the potential is clearly there, the technology is not yet mature enough to be commonly implemented during cold (<15°C), diluted (low NH4N concentrations) and unfavourable (high) COD to N conditions in the wastewater, why further full scale demonstrations are highly recommended. Under more favourable, and especially warmer wastewater conditions, the anammox technology is today ready for the early frontrunners. Finally, the power of an advanced control strategy for conventional nitrification and denitrification should not be underestimated. With an optimised extraction of primary organic carbon, a large increase of biogas and energy recovery can be obtained without jeopardizing the nitrogen limits. This strategy is ready for implementation and should be evaluated on all wastewater treatment plants.

Discussion on options and performances of advanced control sys-tems for biological nitrogen removal after advanced primary treatment. The process control options are described in details as well as process performance in the demo site was quantified in-cluding transition strategy from conventional scheme to process with the advanced carbon extraction.

Producing more biogas from sludge digestion is one of the main factors to reach energy-neutral or energy-positive WWTP operation. In the project POWERSTEP a primary goal is to remove as much energy rich primary sludge as possible from the system prior to the biological treatment without having negative effects on downstream processes and effluent quality in terms of nitrogen removal. Within the project Work Package 1 addresses enhanced carbon extraction in primary treatment with different filtration technologies (drum and disc filters from Veolia Technologie AB - Hydrotech) tested in Case Study 1 (Westewitz, Germany) and 2 (Sjölunda, Sweden). To give scientific proof of the results and benchmark the performance against other competing technologies, process performance data has to be compared with other technologies used for primary treatment. In this report the results of literature research and comparison with data of case studies of full scale enhanced primary treatment units are shown and compared to each other. Specific indicators for the comparison are defined followed by identification of available alternative technologies for primary treatment at municipal wastewater treatment plants (WWTPs). These technologies are described by functionality, efficiency and operational data. Finally an overview of the results is presented in form of a fact sheet for primary treatment processes.

This deliverable describes Guidelines for design and operation of advanced primary treatment with microscreen. Technical speci-fications including pre-treatment, mesh size, hydraulic velocity, chemicals (substances, doses, contact times), operational re-quirements (backwash, cleaning) and operational performanc-es (removal rates, backwash sludge quantity and quality) are presented with data gained from the two Case study site trials in Westewitz (Germany) and Sjölunda (Sweden)..

This study was done in connection with the EU-funded project POWERSTEP. Powerstep, with various research-work packages, is positioned to help conceptualise waste water treatment facilities as energy suppliers. The goal of the study is to evaluate if micro-filtration, as part of an expanded pre-treatment stage, can provide organic matter for digestion while allowing stable treatment conditions in sludge activation.

One aim of the EU-funded research Project POWERSTEP is to investigate the applicability of duckweed in wastewater treatment in removing nitrogen based on the principle of the APS duckweed plant system. The motivation for this investigation is the intended combination of the Hydrotech drum filter with the APS duckweed plant system at case study one of the POWERSTEP project. The goal is to demonstrate and market a new wastewater treatment concept heading towards energy positive wastewater treatment plants. The investigations were first carried out on a laboratory scale to identify suitable duckweed species, the optimal duckweed mat density, relative growth rate (RGR), doubling time and the ammonium removal under the given conditions at the case study. Subsequently, the results were used to test on a large scale on a sewage treatment plant. From the four tested duckweed species Lemna Minor, Lemna Minuta, Landoltia Punctata and Spirodela Polyrhiza, the species Lemna Minor and Landoltia Punctata adapted best to the given wastewater composition. In a mix population of Lemna Minor and Landoltia Punctata a mat density of 0.075 g· cm-2 was determined to be best in suppressing competitive submerged algae growth and enabling duckweed relative growth rates of 0.072 d-1 and doubling times of 9.93 days. Based on the APS duckweed plant system, mean daily ammonium removal of 0.56 g N· m-2d-1 and a daily ammonium degradation efficiency of 72.75% to a mean ammonium effluent of 12.26 m·l-1 was shown at a lab-scale for a retention time of 24 hours. Based on the results of this research, it can be concluded that the principle of the APS duckweed plant system under the use of Lemna Minor and Landoltia Punctata can be applied to remove ammonium from wastewater achieving high reduction rates. The experiment on the wastewater treatment plant shows that the effectiveness of the purification process is heavily dependent on climatic conditions. For example, in the summer the duckweed had a total nitrogen(TN) removal rate of 40-70%, while in winter it was only 17-40%. There were also great difficulties due to the occurrence of heavy storms. The plant switched off and was destroyed in many places which led to a dying of duckweed. There were also problems with the harvest of duckweed. Due to poor flow conditions, duckweed was not easy to clear off and could not be harvested.