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Source Segregation (SS) is a novel strategy in dairy housing that can reduce emissions and separate organic matter and nutrients more efficiently than traditional slurry solid-liquid separation. The anaerobic digestion (AD) methane yield of the SS fractions, however, is unknown. We aimed at unveiling the biomethane yield of these fractions by conducting AD experiments under different configurations: batch, continuous feeding, and fed-batch. In the batch test, the solid (SF) and liquid fraction (LF) from the SS system, a slurry collected from the pit (CS), and a self-made slurry (MF) were used as substrates. The results showed that the specific CH4 yields of the SF and MF were in same range and both higher than the CS. We concluded that SS can increase the CH4 yield of dairy excreta mainly by reducing losses in the animal house. The SF and MF were then compared in a continuously-fed thermophilic test, where SF had a higher specific (174 compared to 105 NL kg−1 VS) and volumetric (12.2 compared to 9.9 NL CH4 kg−1 excreta) yields. We concluded that the SF can effectively substitute slurry in AD without compromising the yield, possibly increasing economic viability by reducing transport costs and reactor size. Further, SF produced 356 NL CH4 kg−1 VS and a digestate with 1.8% lower dry matter in the fed-batch as compared to continuous feeding. Continuously stirred fed-batch can thus increase the CH4 yield of the SF and reduce the DM of its digestate potentially contributing to lower emissions in storage and field application.

Micropollutant influent and effluent concentration data belonging to the following publication: Micropollutants removal during high rate thermophilic and hyper-thermophilic anaerobic digestion of concentrated black water, https://doi.org/10.1016/j.jece.2022.107340, Micropollutant influent and effluent concentration data belonging to the following publication: Micropollutants removal during high rate thermophilic and hyper-thermophilic anaerobic digestion of concentrated black water, https://doi.org/10.1016/j.jece.2022.107340

Data belonging to results published in: Increased (Antibiotic-Resistant) Pathogen Indicator Organism Removal during (Hyper-)Thermophilic Anaerobic Digestion of Concentrated Black Water for Safe Nutrient Recovery, Sustainability 2020, 12(22), 9336, https://doi.org/10.3390/su12229336, Data belonging to results published in: Increased (Antibiotic-Resistant) Pathogen Indicator Organism Removal during (Hyper-)Thermophilic Anaerobic Digestion of Concentrated Black Water for Safe Nutrient Recovery, Sustainability 2020, 12(22), 9336, https://doi.org/10.3390/su12229336

Dataset containing continuous reactor data belonging to the following publication: Thermophilic (55 °C) and hyper-thermophilic (70 °C) anaerobic digestion as novel treatment technologies for concentrated black water, Bioresource Technology, 2021, 340, 125705, https://doi.org/10.1016/j.biortech.2021.125705, Dataset containing continuous reactor data belonging to the following publication: Thermophilic (55 °C) and hyper-thermophilic (70 °C) anaerobic digestion as novel treatment technologies for concentrated black water, Bioresource Technology, 2021, 340, 125705, https://doi.org/10.1016/j.biortech.2021.125705

Experimental batch data belonging to the following publication: Advanced modelling to determine free ammonia concentrations during (hyper-)thermophilic anaerobic digestion in high strength wastewaters, Journal of Environmental Chemical Engineering, 2021, 9(6), 106724, https://doi.org/10.1016/j.jece.2021.106724, Experimental batch data belonging to the following publication: Advanced modelling to determine free ammonia concentrations during (hyper-)thermophilic anaerobic digestion in high strength wastewaters, Journal of Environmental Chemical Engineering, 2021, 9(6), 106724, https://doi.org/10.1016/j.jece.2021.106724

Dataset for paper "Practical Performance and User Experience of Novel DUAL-Flush Vacuum Toilets" https://doi.org/10.3390/w13162228 Water 2021, 13(16), 2228

This study aimed to assess the effect of carbohydrates on protein hydrolysis and potential implications for the design of anaerobic reactors for treatment of protein-rich wastewaters. Batch experiments were carried out with dissolved starch (Sta) and gelatine (Gel) at different chemical oxygen demand (COD) ratios ranging from 0 to 5.5 under methanogenic conditions for methane production and up to 3.8 under non-methanogenic conditions for volatile fatty acids (VFA), both at 35 °C. The Sta/Gel did not have a direct effect on the gelatine hydrolysis rate constants under methanogenic (0.51 ± 0.05 L g VSS-1 day-1) and non-methanogenic conditions (0.48 ± 0.05 L g VSS-1 day-1). However, under non-methanogenic conditions, gelatine hydrolysis was inhibited by 64% when a spectrum of VFA was added at a VFA/Gel (COD) ratio of 5.9. This was not caused by the ionic strength exerted by VFA but by the VFA itself. These results imply that methanogenesis dictates the reactor design for methane production but hydrolysis does for VFA production from wastewater proteins

The study has been carried out under the COST Action CA17133 Circular City (implementing nature-based solutions for creating a resourceful circular city, http://www.circular-city.eu, duration 22 October 2018–21 October 2022). COST Actions are funded within the EU Horizon 2020 Programme., Cities are producers of high quantities of secondary liquid and solid streams that are still poorly utilized within urban systems. In order to tackle this issue, there has been an ever-growing push for more efficient resource management and waste prevention in urban areas, following the concept of a circular economy. This review paper provides a characterization of urban solid and liquid resource flows (including water, nutrients, metals, potential energy, and organics), which pass through selected nature-based solutions (NBS) and supporting units (SU), expanding on that characterization through the study of existing cases. In particular, this paper presents the currently implemented NBS units for resource recovery, the applicable solid and liquid urban waste streams and the SU dedicated to increasing the quality and minimizing hazards of specific streams at the source level (e.g., concentrated fertilizers, disinfected recovered products). The recovery efficiency of systems, where NBS and SU are combined, operated at a micro- or meso-scale and applied at technology readiness levels higher than 5, is reviewed. The importance of collection and transport infrastructure, treatment and recovery technology, and (urban) agricultural or urban green reuse on the quantity and quality of input and output materials are discussed, also regarding the current main circularity and application challenges.

Thermophilic and hyper-thermophilic anaerobic digestion (AD) are promising techniques for the treatment of concentrated black water (toilet fraction of domestic wastewater collected by low flush volume toilets; BW) and recovery of nutrients. High temperatures are applied in this study to ensure pathogen removal and thus safe reuse of recovered nutrients. This technique is applicable when ultra-low flush-volume collection (e.g. vacuum toilets) is used to obtain a highly concentrated waste stream (15-20 g COD/L) suitable for high rate anaerobic treatment and efficient nutrient recovery. This study showed that thermophilic AD (55 °C) of concentrated BW could achieve the same methanisation and COD removal as mesophilic anaerobic treatment of BW (collected with conventional vacuum toilets) and kitchen waste (KW) while applying a higher loading rate (2.5-4.0 kgCOD/m3⋅day). With a retention time of 8.7 days, and loading rates exceeding 3 kgCOD/m3⋅day a COD removal of 70% and a methanisation of 62% (based on CODt) was achieved during thermophilic anaerobic treatment, despite the high temperature (55 °C) and possible increased ammonia toxicity. Hyper-thermophilic (70 °C) reached lower levels of methanisation (38%). A UASB treating (highly) concentrated BW can be started-up in 12 days. Furthermore, microbiological analysis showed that the high temperature combined with high ammonia concentrations resulted in increased abundance of species closely related to Thermacetogenium phaeum and Syntrophaceticus schinkii, two syntrophic acetate oxidizers, along with an increased abundance of hydrogenotrophic methanogens (eg. species closely related to Methanothermobacter tenebrarum). This indicates that a shift from acetoclastic methanogenesis to hydrogenotrophic methanogenesis combined with syntrophic acetate oxidation can be observed as a consequence of the thermophilic conditions and possibly the related increased ammonia toxicity.

Vacuum toilets have gained increasing attention in circular urban development projects, because of their marked water saving qualities compared to conventional flush toilets and the increased resource recovery potential for energy in the form of biogas and phosphorous as, e.g., struvite from the resulting concentrated wastewater. A further reduction of the flushing volume of vacuum toilets would also bring nitrogen recovery options in reach. In the framework of the EU Horizon 2020 project Run4Life, a novel dual-flush vacuum toilet was developed and tested at two sites and combined with an analysis of the flushing patterns and a qualitative user survey. The results show that a 25–50% lower flushing water consumption and accordingly 1.5–2 times higher nutrient concentrations are achievable with this novel type of vacuum toilet. The usage frequency of the dual flush feature was higher in residential homes than in an office building, which also had urinals installed at the men toilets. A notable fraction of toilet visits in which the toilet was flushed twice as well as user feedback on dissatisfactory cleaning effects suggest that the applied reduction in water use is most likely the upper limit of what can be achieved in this type of toilet.