Phosphorus recovery from source-separated and anaerobically digested blackwater (BW) through struvite precipitation is becoming a promising strategy to recover P as value-added fertilizer that contribute to the reduction in dependence of commercial P and at the same time mitigate eutrophication risk due to excess P discharge into water bodies. Source-separated blackwater from vacuum toilet is concentrated and has a moderate orthophosphate (PO4-P) content, high ammonium nitrogen (NH4-N) content, strong buffering capacity because of high alkalinity, and a high pH close to 9. Anaerobic digestion process on BW increase the soluble P fraction in the effluent boosting the potential of BW as a good source for P recovery through struvite precipitation. A prototype struvite reactor with Mg-plate electrochemical method was developed. The feasibility of struvite precipitation using Mg electrolyte as Mg source for the recovery of P from concentrated BW digestate was examined. Characterization of the struvite produced from concentrated BW was performed using scanning electron microscopy (SEM) and energy dispersive spectroscopy Xray diffraction (EDS-XRD) techniques. The quality of struvite in terms of heavy metal content were examined by inductively coupled plasma mass spectrometry (ICP-MS). Phosphorus removal efficiency of 94% to 98% was achieved with 5 to 20 minutes reaction time. The N, Mg, and P content of the struvite is 4.6%, 11% and 12%, respectively. The heavy metal content in the recovered struvite is low except Zn, Cr and Ni. The high Zn, Cr, and Ni concentration observed, however, could be from appliances and materials used in the struvite reactor as their concentration in the anaerobically treated blackwater is very low.

With a constant, year-round and free supply human urine is an available nutrient resource for the urban farmer. Urine can be collected in urinals, urine flushing toilets (such as Laufen Save), and collection pots. Negative attitudes limit the use of urine as fertiliser in addition to bad smell of stored urine and possible content of pharmaceutical residues. In this project, we have considered 4 different types of urine fertilisers for use tomato production: 1) Fresh urine (< 3 d) used on a small scale (family), 2) Aged urine (6 months) that has been hygienized, 3) Processed urine (nitrified), where part of the ammonium content is converted to nitrate and 4) Processed urine for commercial sale (nitrified, UV-treated, filtration in activated carbon and condensed). The products are Aurin (manufactured by VunaNexus) and CROP. Results show that urine provides an excellent source of nitrogen, phosphorous, potassium (N-P-K ratio of 10:1:4) and trace elements for plants. Nitrification of liquids for use in urban agriculture reduce smell, make the liquid more stable in storage and make it a better plant nutrient. If the purpose is only to improve it as a plant nutrient, nitrification can be performed on diluted solutions, just before use for watering plants in a greenhouse. Successful nitrification has also achieved by using a moving bed bioreactor and by biological porous media multipass filter. The nitrification process is more challenging with higher nitrogen concentrations. However, since plants prefer both ammonium and nitrate a mixture is a good fertilizer. Further treatment using activated carbon filtration can remove pharmaceuticals and hormones if such compounds are of concern. Our results show that both fresh, stored, and nitrified urine has a high potential as recycling fertilizer in production of tomato and cucumber cultivation. Fast-acting fertilizers like urine is best utilized when spread in small portions in line with the growing conditions and plant size. We recommended mixing urine into the irrigation water (5-10%). Measurement of electrical conductivity will be of significant help for diluting to a suitable strength. Typically, we want a guide number of 1.5-2 for most crops (2000 μS/cm = 2 mS/cm).

Peat is a non-renewable resource that must be preserved as it is one of the most efficient carbon sinks on the planet. We have assessed alternative growth media for horticulture based on peat, as food waste compost, vermicompost and garden compost mixed with trees fibres. Composting can be done on different scales, from industrial to small gardens. It can easily be adapted to urban farming systems.

We conducted a study to document effects on growth, yield, and fruit quality of tomato plants when cultivated in a sewage digestate-based compost in a subirrigation container system. This compost was compared with peat in different mixtures. Growing medium containing sludge can make Mn unavailable to plant roots and inhibit growth. Too much bark as a structure in compost can cause Mn poisoning to plants. We have grown tomato, cucumber, and lettuce in self-watering container systems, comparing fertilized and limed peat with alternatives to reduce peat consumption for the garden centre market. Overall, the compost was well suited for crops as tomato, cucumber, and lettuce and could compete with peat media, especially for tomatoes when used in combination with self-watering systems. Alternatives can replace peat, but it is important to dilute food waste compost with other compost as it is often rich in nutrients and other salts. Compost will often have more weeds than peat soil which requires regular weeding. We recommend using Bokashi containers for temporary storage and pre-treatment of the kitchen waste before using insulated tumbler composters. A mixture of food waste and other waste products (e.g., garden waste, wood chips) assisted improving the aeration of the mixture and resulted in a better composting process. These techniques are appropriate to small scale food waste in cities, as they are easy to operate, low cost and reduces typical problems such as flies, bad odours, and runoff.

The paper-based microgreen production technology invented by Beijing Green Valley Sprout (BGVS) LtD in China was successfully introduced to Europe (Norway) through SiEuGreen project knowledge transfer between EU and China. Microgreens are young leafy greens with appealing colours, textures and tastes. The technology is rather simple, and equipment needed consists of microgreen growing tray, kitchen paper and watering can. The vegetable seeds were soaked first and then laid on paper after germination with regular watering daily to keep moisture. Kitchen paper is safe and environmentally friendly with numerous advantages over the soil based microgreen production because of soil contamination and/or soil-borne pathogens.

Through a close collaboration between BGVS and NIBIO as well as knowledge sharing between China and Europe, NIBIO partner has carefully validated and optimized the microgreen production protocol developed by BGVS through our work during SiEuGreen project period. The microgreen production protocol has been translated from Chinese into English, Norwegian and Turkish for the implementation of this paper-based microgreen production in all showcases. The protocol in 4 differ-ent languages are available to public. BGVS partner has been very open and supportive by providing NIBIO’s team all necessary seeds, equipment etc contributing to the implementation of paper-based microgreen production in Norway, and the comparative study of outcomes from Chinese and European showcases. This paper-based microgreen production is a good case study and example demonstrating the fruitful China-EU collaboration and knowledge sharing under the IPR agreement. This paper-based microgreen produciton has been widely used to produce green leafy vegetables during the pandemic lockeddowns. It helped families to do something together and enjoyed consuming the microgreens at their lunch and dinner tables.

Machine learning techniques have been used for estimating biomass and fruit redness. During SiEuGreen project period, we evaluated the performance of one of the state of the art deep learning method being able to reconstruct hyperspectral image from single RGB image in high quality with two loss functions and three evaluation metrics. Secondly, selected a better model through evaluating these criteria with five-fold cross validation and reconstructed hyperspectral images from RGB images by selecting one of the best models for further processing. Thirdly, we evaluated the performance of the reconstructed redness of three tomato varieties in 12 grades which were graded subjectively; searched optimal cluster number that can be applied practically based on overall individual redness reconstructed from different RGB image sources: rendered from hyperspectral image, smartphones from different companies. An efficient pipeline to automatic segment, quantify and regrade (cluster) single tomato of different varieties into different clusters was be developed. The methodology and potential applications were reported to EU in our 2nd periodic report and Deliverable 2.2 as well as a peer-reviewed publication by Zhao et al. (Remote Sens. 2020, 12, 3258; doi:10.3390/rs12193258). To estimate vegetable biomass, we have used Crispy’ lettuce growing healthily in a simple nutrient film technique (NFT) setup to evaluate the methodology. Lettuce fresh biomass were very well predicted based on the head projected area using machine learning techniques. Results and recommendations are presented in our Deliverables 2.2. This machine learning-based biomass and redness estimation tools is most likely be developed further by NIBIO partner after the SiEuGreen period by applying funding from the Research Council of Norway or EU Horizon Europe because of the potentials.

In the new circular nutrient, energy and water economy, wastewater is considered as a valuable resource rather than a liability of waste streams. As a resource, domestic wastewater contains water, energy, & nutrients all in one place at a time that can be treated, recovered, & reused simultaneously. This, however, requires development of an integrated, appropriate, & effective circular wastewater solutions. The main challenge is to identify the optimum combinations of systems that would provide efficient, safe & cost-effective treatment and recovery schemes as a sustainable sanitation solution. In the Campus Ås Showcase, black water and organic household waste are collected from a dormitory, which is equipped with a vacuum toilet. The treatment system comprises an anaerobic digestion reactor (AD), with recovery of biogas, and post-treatment methods that aim at plant nutrient recovery. The post-treatments are liquid fertilizer production (LF), struvite precipitation (SP) and microalgae cultivation (PBR). The systems demonstrated high efficiency of treatment and recovery of nutrients. The potential recovery of N and P, per capita per year, from anaerobically treated blackwater at Ås Campus, is about 3.8 kg as total N from the 4.1 kg generated and 0.3 kg P from 0.4 kg P which is about 93% and 77% recovery in total N and P. But up to 107% in NH4 and 141% in PO4 form N and P, respectively.

We tested self-watering containers for tomato production for amateur gardeners in Norway over 5 summers (2018-2022) in the Oslo area. First, we tested the containers for a master thesis over 2 summers (2018-2019). Then, more than 100 individual households participated, some of them over 3 years (2020-2022). The containers were of the type described here: Pindstrup self-watering container (selvvanningskasse) on wheels.https://www.bauhaus.dk/catalogsearch/result/?q=selvvanningskasse+p%C3%A…. The containers hold 9L x 2 of growth medium and 18L nutrient water (if using a double unit). There is a flotteur which gives an indication of the water level and when to fill up with more nutrient solution. An alternative to the commercial product we tested, is to build your own, as described here: https://hageselskapet.no/hagestoff/praktisk/selvvanningskasse. The results were very good; everyone (except one participant) was very happy with the containers recommended. They found them especially useful when going on holiday and the plants would take 1-2 weeks (depending om growth stage) between filling them with water. The master thesis (Lacôtte, 2020) showed that the amount of tomato production was equal in these and the drip-irrigated alternative. The self-watering needed much less maintenance and spent significantly less water for the same yield. We also used these self-watering containers to test out alternatives to peat and have found many good alternatives. The main result from this work was that if the growth medium was mixed with wood chips, more fertilisers was needed to provide for both the plant and the microbes digesting the wood chips. Otherwise, the microbes would win the competition for nutrients and the plants would suffer from nutrient deficiency. O.therwise, the peat and the compost alternatives were as good as the peat, if enough nutrients for tomatoes was provided. Garden compost is not rich enough in itself and needs to be mixed with either vermicompost or some animal manure.

Greywater handling system includes treatment for the purposes of reuse for different water-demanding activities. The main objective of the application of greywater treatment using Biofilter/Filter bed and bio membrane treatment systems is the improvement of water quality before being returned to nature. As a result, treated greywater can be reused for inhouse activities reducing water consumption, irrigation purposes as well as use for groundwater recharge. In a source separating system where water saving toilets is used, the greywater accounts for over 90% of the water use in a household. The effluent from the planned Filter bed is expected to meet bathing water quality. Reuse of treated greywater and harvested rainwater for irrigation, groundwater recharge, car washing, or even as potable water can give up to 90% water saving. Hence, this effluent is of a better quality than many raw water sources, especially on a global scale. Reuse of greywater after bio. and membrane filtration facilitate a reduction of the household water footprint by up to 90%. If, in addition, harvested rainwater is utilized up to 100% local supply water for agriculture, household use and green areas is possible. Treated greywater can be used to irrigate both food and nonfood producing plants. Also, drinking water can be produced from greywater and harvested rainwater. A primary benefit of using a greywater system is lowered water usage, reducing your overall water consumption and your water bill. Additionally, using a greywater system will reduce the amount of wastewater entering sewers or on-site treatment systems. These can benefit the individual household, but also the broader community.