Summit Day 3
Intro & Virtual Bulletin Board
9:20-9:30 am EST
Virtual and In-Person
We will share a virtual bulletin board where participants can add announcements, ideas, and opportunities for collaboration. This board will be shared with all attendees after the Summit.
PANEL: Urine Treatment and Processing Research
9:30-11:20 am EST
Virtual and In-Person
University of Cape Town, South Africa
Live Presentation via Zoom: Phosphorus recovery from source-separated human urine as vivianite
Urine contributes over 50% of the phosphorus load in domestic wastewater. Decentralized sanitation systems and source separation provide an opportunity to recover this phosphorus. The present study evaluated the viability of phosphorus recovery in the form of vivianite from human urine, leveraging a combination of thermodynamically modelled and empirically derived data. Our findings reveal that the type of iron(II) salt and reaction temperature exerted no discernible influence on the yield and purity of vivianite. However, the pH of the urine impacted the solubility of both vivianite and accompanying co-precipitates. The highest yield (93 ± 2%) and purity (79 ± 3%) of vivianite were attained at a pH of 6.0. Optimal vivianite yield and purity materialized when the Fe:P molar ratio was greater than 1.5:1, but less than 2.2:1. This specific molar ratio facilitated enough iron to react with all the available phosphorus, concurrently providing a competitive effect that prevented the formation of co-precipitates. Vivianite produced from real urine was less pure (63 ± 5%) than vivianite produced from synthetic urine (95 ± 2%) because of the presence of organics in real urine. These organics can form complexes with the iron and can also attach to the growth points of the vivianite crystal, thus limiting the purity of the vivianite. However, washing the solids with deionized water improved the purity by 15.5%, at a pH of 6.0. Overall, this novel work adds to the growing body of literature on resource recovery (phosphorus) from source-separated urine.
University of Technology Sydney, Australia
Microbial community analysis of a membrane bioreactor incorporated with biofilm carriers and activated carbon for urine nitrification
The integration of powdered activated carbon (PAC) and biofilm carriers within a membrane bioreactor (MBR) presents a promising and innovative approach to address the challenge of long hydraulic retention time (HRT) for nitrification of source-separated urine. This study investigated the effect of biofilm carriers and PAC incorporation on microbial dynamics, focusing on dominant nitrifying genera in both suspended and attached growth forms. Our findings indicate that the transition to urine feeding reduced in microbial diversity and richness, a trend further influenced by the addition of PAC and biofilm carriers, likely due to the selective enrichment of specific species. Furthermore, significant shifts in microbial compositions were observed in both MBRs and across different sludge growth forms. Remarkably, the NOB genus Nitrospira was highly enriched in the suspended sludge, while AOB genus Nitrosococcaceae thrived predominantly in the attached biomass, showing a significant 7-fold increase in relative abundance compared to its suspended counterpart. Consequently, the incorporated MBR displayed a 36% higher nitrification rate and 40% reduced HRT compared to the conventional MBR. These findings provide valuable insights for the development of compact and efficient MBR systems tailored for source-separated urine treatment, contributing to the achievements of a circular economy in nutrients.
Swedish University of Agricultural Sciences and Addis Ababa University Institute of Biotechnology,
Photoinactivation of jack bean (Canavalia ensiformis) urease in source-separated fresh human urine
In source-separating sanitation systems, inhibiting urease activity prevents enzymatic urea hydrolysis and volatilisation of ammonia when urine is concentrated by evaporation. This study tested UV-based photoinactivation as a novel alternative to existing methods of inactivating urease that require dosing urine with acid, base or oxidants. The enzymatic activity of jack bean (Canavalia ensiformis) urease in water, synthetic fresh urine and real fresh urine was investigated, with and without using a low-pressure UV lamp that emitted 185 nm and 254 nm radiation. In UV-free controls, urea was hydrolysed at a rate of 3.2 × 10 -3 mmol mg urease -1 min -1 , 3.3 × 10 -3 mmol mg urease -1 min -1 and 2.0 × 10 -3 mmol mg urease -1 min -1 in water, synthetic urine and real urine, respectively. In the presence of UV, no urease activity was detected in any matrix. A UV dose of 35 J m -2 and 85 J m -2 was needed for inactivating urease in water and synthetic urine, respectively, whereas a UV dose of 1935 J m -2 was needed for inactivating urease in real urine. Photolysis and photo-oxidation of amino acid residues at the active site of the enzyme were likely reasons for inactivation. Organic metabolites in real urine affected photoinactivation by (i) absorbing radiation between 190 nm and 400 nm, which reduced incident radiant flux; and (ii) scavenging hydroxyl radicals, which impeded oxidative damage to the enzyme. Overall, the findings demonstrate the feasibility of on-site treatment using a low-pressure UV lamp for inactivating urease in freshly excreted urine.
Future Water Institute, Chemical Engineering Department, University of Cape Town
Live Presentation via Zoom: Freezing your pee for maximum water removal
Urine is a more sustainable alternative to synthetic fertilizers, but, the nutrients need to be concentrated to make the transportation of the fertilizer to agricultural areas economically feasible. Reverse osmosis (RO) is a commercially scalable method that can concentrate urine. However, water removal is limited to 60-70% due to operating pressure limitations and membrane scaling. Freeze crystallization (FC) is also an effective concentration method but is more energy intensive (17 kWh/kg-N recovered, 70% water removal) than RO (2.8 kWh/kg-N recovered). A novel hybrid eutectic freeze crystallization (EFC) and RO system was investigated to improve water removal and energy use. EFC is an extension of FC where salts and ice crystallize simultaneously, the ice and salt can then be separated by gravity. This could be advantageous to crystallize the undesirable salts in urine and improve the fertilizer quality. However, urine is a complex solution, and it was unclear if salts would form simultaneously with ice crystals at the eutectic point. For the first time, it was shown experimentally that Na2SO4∙10H2O crystallizes simultaneously with ice in both real and synthetic urine, thus providing a new method to concentrate human urine for liquid fertilizer production. A theoretical mass balance showed that that 77% of the urea and 96% of the potassium could be recovered. In addition, 25% of the sodium and 87% of the sulfate ions would be remove at a total water removal of 95%. The final liquid fertilizer would have a weight composition of 11.5% N and 3.5% K. A hybrid RO-EFC process would require 10.8 kWh/kg-N recovered (95% water removal), which is substantially less than other concentration methods.
10:10 - 10:30 Q & A
Dr. Praveena Gangadharan
Indian Institute of Technology Palakkad, India
Magnesium air fuel cell for concurrent energy production and phosphorus recovery
A magnesium air fuel cell (MAFC) was fabricated and employed to produce energy and recover nutrients from source separated urine. The MAFCs are fabricated in three different configurations as: (i) single cell MAFC (250 ml), (ii) single cell MAFC (100 ML), and (iii) four chamber modular units. Each MAFCs comprise magnesium anode and a fabricated porous air cathode encompassing three layers (gas diffusion layer, current collecting layer and catalyst layer). The wettability of the air cathode revealed the presence of triple phase interface layer, ideal for oxygen reduction reaction. Each single MAFC cell exhibits a cell voltage of around 1.4 - 1.5 V. The MAFC was able to power LEDs with a power rating of 10 mW to 10 W consistently to power electronic gadgets ranging from LEDs to mobile phones. Along with harnessing energy, nutrient recovery experiments were also conducted in both batch and continuous mode. Optimum operational parameters such as pH, hydraulic retention time, chemical composition of source separated urine were determined. A nutrient recovery efficiency of 99% and 94% was achieved in batch and continuous mode respectively. The recovered precipitate was characterised by XRD, FT-IR, and FESEM-EDS. Thus, MAFC would contribute to the production of clean energy, sustainable waste systems, and circular bio-economy.
Clemson University, South Carolina, USA
Live Presentation via Zoom: Electrochemical ammonia stripping from source-separated urine: cathode-fed operation vs. anode-fed operation
Electrochemical ammonia stripping from source-separated urine represents an approach through which renewable electricity can power the production of a base at the cathode of an electrochemical cell to result in the volatilization of ammonium in hydrolyzed urine and subsequent recovery of N as ammonia. Typically, such electrochemical systems for N removal/recovery have been designed to operate via anode-fed operation in which a cation exchange membrane selectively transfers ammonium in hydrolyzed urine to the cathode, where it is volatilized and collected as ammonia using gas-permeable membranes. We investigated whether anode-fed operation results in significant chlorine production in urine and if this subsequently leads to the formation of disinfection by-products (DBPs). While such systems leverage the anodic oxidation of water, chloride in urine can also be oxidized to chlorine on most typical anode electrodes. We also investigated if hydrolyzed urine is fed to the cathode of electrochemical cells, then issues related to chlorine production and the formation of DBPs can be avoided. We will present our results comparing anode-fed vs. cathode-fed operation and discuss performance both with respect to rates and efficiency of N removal/recovery.
University of Technology Sydney, Australia
Live Presentation via Zoom: Potential nutrient recovery from source-separated urine through hybrid membrane bioreactor and membrane capacitive deionisation
Human urine is rich in nutrients and an important source of fertilisers, especially when source-separated urine is available. Due to the increasing focus on the need for nutrient removal and recovery, various technologies and processes are being investigated. This study investigated a hybrid membrane bioreactor (MBR) and membrane capacitive deionisation (MCDI) where the source-separated urine was treated in MBR, and the subsequent MBR permeate was used as a feed for the MCDI for further nutrient removal and recovery. Overall, nitrate, phosphate and ammonium removal were 66%, 49% and 58%, respectively, in the treated urine using MCDI. Additionally, the recovery rate of nitrate, phosphate and ammonium were 80%, 64% and 76% in the concentrated brine. The energy demand for recovery of NH4+ was between 3.03-11.25 kWh/kg of NH4+-N and between 3.87-14.75 kWh/kg of NO3--N for the three different voltages used in the study. The study further demonstrates the viability of MCDI application for nutrient recovery and concentration, effectively using both the adsorption and desorption phases of MCDI operation without using any chemicals.
11:00 - 11:20 Q & A
PANEL: Urine Fertilizer in Agriculture
11:30 -12:20 pm EST
Virtual and In-Person
University of Michigan, USA
Live Presentation via Zoom: Application of Urine-Derived Fertilizers for Ecological Nutrient Management
Urine-derived fertilizers (UDFs) have chemical characteristics that more closely resemble those of inorganic fertilizers than of other waste-derived fertilizers. Similar to inorganic fertilizers, UDFs may lead to substantial nitrogen (N) losses through leachate and N 2 O emissions. To harness the full potential of UDFs for environmental benefits, an ecological nutrient management (ENM) approach is needed. ENM leverages ecological insights into soil nutrient cycling to achieve optimal plant growth while simultaneously preserving long-term soil functionality and mitigating nutrient losses. One key ENM strategy involves the synergistic use of soluble fertilizers, such as inorganic fertilizers and UDFs, alongside organic amendments. A better understanding of N loss magnitude and pathways from using UDFs alone and with organic amendments can inform improved uses of UDFs. We conducted a greenhouse experiment to compare the impacts of a UDF to an inorganic and organic fertilizer on soil health and N cycling. The experiment revealed that the UDF increased plant yield by a comparable amount to the inorganic fertilizer with no compromise to soil health. Due to their similarities in N availability, the effects on soil N cycling were more similar between UDF and inorganic fertilizer than to the organic fertilizer. When compost was applied with UDF, there were higher N 2 O emissions per gram of plant available N applied, but the ratio of N loss (as leachate and N 2 O emissions) to N harvested significantly decreased. The similar behavior of the UDF and inorganic fertilizer suggests that UDFs can substitute inorganic fertilizers, significantly reducing resource consumption in agriculture. Additionally, there is an opportunity for UDFs to contribute to ENM goals by combining their application with organic fertilizers.
Cornell University, USA and 2 Poverty and Health Integrated Solutions, Kenya
Live Presentation via Zoom: Grow-as-You-Go: Container-based sanitation meets container-based gardening
Urban and peri-urban soils are often contaminated with heavy metals and other pollutants that render them unsafe for food production. To develop safe, cost-effective, and sustainable options for raised bed gardening in these contexts, we are exploring an idea we call "Grow as You Go" or YouGo gardening -- the proposition that crops can be grown on soilless media based on organic underutilized resources (OURs, such as high-carbon agricultural residues), conditioned and fertilized with urine. In initial exploratory gardens conducted over three seasons, we were able to produce a range of vegetables on straw bales and in sacks of cereal residues and various amendments using urine as a conditioner and fertilizer. In 2023, we conducted a series of experiments in the US and Kenya using various carbon sources (wheat straw, corn stover and rice husks) and amendments (compost and biochar to favor a beneficial microbial community; FeSO4 and wood vinegar to reduce pH). Specific experiments were conducted to investigate issues related to substrate composition, decomposition and particle size distribution; water retention; salt accumulation; and the effects of biochar on plant production. Urine fertilization of kale grown on maize stover (with or without biochar) produced yields that were not statistically different from the corresponding yields obtained using synthetic fertilizer. In contrast, the yields obtained with urine fertilization were lower than with synthetic fertilizer on both soil (in sacks) and wheat straw substrates (in bales). In an experiment aimed at understanding salt buildup across substrates under urine fertigation, two-fold differences in water application did not influence yield across substrates; further analysis is being conducted with greater differences in flush rates. The effect of biochar varied across experiments. Yields of tomato and kale were not influenced by the presence of biochar in the medium in two experiments. In another experiment, however, okra plants did not survive on maize stover fertilized with urine, did poorly on maize stover irrigated with water, and grew well with urine + biochar. We found that okra growth was not substantially influenced by the size distribution of maize stover substrate, indicating that shredding the stover may not be necessary subsequent to coarse chopping.
Universidad Mayor de San Simon, Bolivia
Simulating reverse blending of dehydrated human urine fertilisers with organic wastes to meet macronutrient demand of 15 major food crops
This study evaluated the suitability of blending different organic wastes with dehydrated alkalized human urine to produce urine-based fertilizer blends that meet macronutrient requirements of major food crops. Using a modelling approach known as reverse blending, we developed blends comprising of dehydrated urine and organic waste(s), estimated their elemental composition, and simulated their potential to meet nitrogen, phosphorus and potassium (macronutrients) demand of 15 crops. The modelling was done using data on concentration of macronutrients in organic wastes and dehydrated urine, as well as macronutrients requirements of crops that was systematically sourced from peer-reviewed literature. Overall, we identified 388 organic wastes and simulated them with dehydrated urine to identify 38 blends that fulfilled the nutrient requirements of the 15 major crops. We found most of the identified blends contained ash and biochar, as the low N content and high P or K content of these organic wastes were found to balance the high N but low P and K content of dehydrated urine. We also identified four blends that met the nutrient demand of at least three crops. The simulated blends contained 5-17% N, 1.8-10% P and 2.5-20% K, and are therefore similar in composition to commercial mineral fertilizers. Overall, we conclude that organic wastes with high content of one of the macronutrients (N, P or K) are most suitable for blending with dehydrated urine and that it is possible to tailor urine-based fertiliser blends that better match nutrient requirements of different crops.
12:20 - 1:00 pm EST
In-Person Only, included in In-Person ticket
PANEL: Urine Fertilizer in Agriculture
1:00 - 1:50 pm EST
Virtual and In-Person
Waste Transformation Closed Loop Farming
Plants and animals do not appear separately within the natural world. Did you ever see an ecosystem consisting only of plants? or an ecosystem consisting only of animals? In the natural world we see multiple animal systems closely coupled to multiple plant systems. So simple and so obvious. That’s the way nature works. Such interdependency and mutualism at the local level must also be extended to the raising of domesticated plants and animals. The large-scale mono-cropping of domesticated plants and the large-scale mono-raising of domesticated animals stand out starkly as gross aberrations within the natural world. Both are highly inefficient in producing food, and together they constitute one of the most destructive forces on our planet. We must return to the concept of a multi-functional small-scale farm where multiple plant systems and multiple animal systems are closely integrated on the one farm. When this happens, small farmers are able produce all the feed and fertilizer they need without any external input of commercial feeds and chemical fertilizers typically brought in from thousands of kilometers away. When small farmers are able to produce feed and fertilizer in abundance, they can make money as never before, since many levels of parasitic buying and selling are eliminated. Since the production of food is localized, small farmers can sell food directly to nearby households and restaurants without a single trader, middleman, market, supermarket or farmers market involved. In the end, there is an abundance of safe food at affordable prices at the local level, and the pollution and disease associated with biodegradable waste are eliminated. As odd as this might sound, it’s all about waste. It’s all about transforming waste at the highest possible levels. It’s all about shuffling transformed waste back and forth between multiple plant and multiple animal systems on the one farm. It’s all about creating food cascades and loops that are infinitely self-renewing. Here not a gram of waste is wasted, and biodegradable waste, in all of its many forms becomes the most valuable resource that small farmers could ever possess.
Renaud de Looze
Palmeraie des Alpes, France
Live Presentation via Zoom: Urino-fertilization of lettuces day after day
Living Web Farms, USA
Live Presentation via Zoom: Anthroponics: Closed Loop Hydroponics
Introducing 'Anthroponics' as a very efficient and truly circular method of hydroponic growing with urine as a primary nutrient source. I'll include my trials with nutrient balancing, biochar-based grow media and nitrification media, duckweed, and lettuce and Japanese indigo production in my 500 gallon experimental system.
Rich Earth Institute
In-Person Presentation: Reducing On-Farm Ammonia Loss From Manure through Fermentation Using Whey & Paper Fibers
Ammonia volatilization from manure is a major source of nitrogen pollution in the environment, and also reduces the fertilizer value of manure or source-separated urine on the farm. Conventional methods of acidification have shown promise in mitigating ammonia emissions but involve the use of concentrated inorganic acids, which can be hazardous and expensive to handle. The Rich Earth Institute researched an innovative approach to reducing ammonia emissions: Bio-Acidification via Fermentation. This method introduces carbon-rich waste materials into liquid manures, initiating a fermentation process that generates organic acids. This, in turn, lowers manure pH and mitigates ammonia loss. During this webinar, we will share our research findings fermenting liquid dairy manure, digestate, and pasteurized human urine, collected through our Urine Nutrient Reclamation Program.
PANEL: Resource Recovery Portable Toilets
2:00 - 3:00 pm EST
Virtual and In-Person
Live Presentation via Zoom: How to change the mobile toilet industry
In-Person & Streaming: Characterizing Portable Toilet Waste: Unlocking Nutrient, Energy, and Water Recovery Potential, Minimizing Emissions, and Exploring Water Circular Practices
Portable toilets, a common fixture in our daily lives, have long been overlooked in academic literature, particularly concerning decentralized waste management and the potential for circularity and resource recovery. This presentation shares insights from an extensive study characterizing portable toilet waste, revealing its unique composition and multifaceted environmental implications. In addition to exploring the chemical makeup of this waste, our research delves into the often untapped potential for nutrient, energy, and water recovery, aligning with principles of sustainable resource management and circular economy. Identifying valuable nutrients within the waste stream offers opportunities for recycling, repurposing, and mitigation, with the aim of reducing the environmental footprint. Furthermore, we investigate organic matter and methane emissions associated with portable toilet waste, recognizing their significance as potential greenhouse gases and renewable energy. A comprehensive understanding of these emissions informs both waste management practices and sustainability efforts. In conclusion, our research provides a holistic perspective on portable toilet waste, highlighting opportunities for sustainable resource utilization, considerations for circular practices, and the importance of minimizing emissions due to storage, transport and treatment. This presentation invites discussion on innovative waste management solutions and underscores the broader implications for sustainable practices across diverse settings.
Jamina Shupack & Arthur Davis
Rich Earth Institute, USA
In-Person & Streaming: Rich Earth Institute's Urine Collecting & Sawdust Composting Portable Toilets
Happy Hour at Hermit Thrush Brewery
5:00 - 6:30 pm EST, 29 High St, Brattleboro, VT 05301
In-person (not included in ticket)