Opportunities for Building-Scale Urine Diversion and Challenges for Implementation

Abstract

Conspectus Urine diversion (i.e., urine source separation) has been proposed as a more sustainable solution for water conversation, nutrient removal and recovery, and pharmaceutical sequestration. As wastewater regulations become more stringent, wastewater treatment plants reach capacity, and water resources become more strained, the benefits of urine diversion become more appealing. By using nonwater urinals and urine-diverting toilets, urine diversion systems seek to collect undiluted human urine for nutrient recovery and pharmaceutical sequestration. Urine is a unique, nutrient-rich waste stream that constitutes an overall low volume of waste entering a wastewater treatment plant. If urine is separated at the building-scale, various technologies can be used to recover nutrients and sequester pharmaceuticals at their most concentrated location. However, the implementation of urine diversion requires a paradigm shift from conventional comingling of wastewater and centralized treatment to source separation and decentralized treatment. This Account proposes a vision for building-scale implementation of urine diversion with the goal of clarifying the opportunities and challenges in this context. The main components of urine, i.e., nitrogen, phosphorus, potassium, and pharmaceuticals, are major drivers for technology development and system implementation. Stepping back, the benefits from water conservation and effects on wastewater treatment are an extension of the system boundary that can impact the sustainability of adjacent systems. However, major challenges have been identified in the literature as hurdles for widespread implementation of urine diversion. Challenges include the comparison of recovering nutrients at the wastewater plant versus at the source, the collection and storage of urine, the ability to recover nutrients and sequester pharmaceuticals, and the overall environmental and economic impacts of urine diversion systems. While these challenges exist, studies have been conducted to address some of the underlying research questions. As more research is conducted, the vision of a seamless urine diversion system with building-wide plumbing and storage comes closer to reality. As such, the application of urine diversion systems will benefit from technology development and research to fill gaps that have been identified. It is important to classify urine diversion systems as a process and not a product. This has implications for the way these systems are evaluated, as their impact on peripheral systems can be of benefit to different stakeholders. In the same light, new research areas, such as cyber-physical systems, reverse logistics, and sustainability transitions, can be applied to urine diversion as approaches for ensuring a robust process for widespread implementation. However, established technologies should be constantly reassessed and enhanced by newer techniques. For example, membrane distillation, eutectic freeze concentration, and solar evaporation should be considered for nutrient recovery and ...

The potential contribution of urine source separation to the SDG agenda – a review of the progress so far and future development options

“…2,70 The creation of two waste streams (instead of one) inside buildings, which need to be separately managed, challenges taken-for-granted core technologies, regulations and policies in the sanitation sector. This creates various frictions with incumbent actors, professional standards and user routines, 2,58,68,70,71 and implies that urine source-separating technologies cannot diffuse in a linear commercialization pattern. Instead, development depends on repeated experiments with social and technical elements before first 'configurations that work' emerge, which can fundamentally challenge the existing regime.…”

Nutrient control in water bodies: A systems approach

“…Urine diversion can be implemented in buildings to improve on-site nutrient management. This paper discusses several challenges in recovery of nutrients at the source and in buildings, issues associated with collection and storage, and their environmental and economic performance (Boyer & Saetta, 2019).…”

Water and Wastewater Building CPS: Creation of Cyber-Physical Wastewater Collection System Centered on Urine Diversion

“…However, past implementation has caused to unforeseen difficulties in management of nonwater urinals [21]- [23]. Solutions for increased functionality of nonwater urinals are needed to keep nonwater urinals as viable options for water conservation in commercial and institutional buildings and ultimately paper of a future urine diversion system [17].…”

“…This loss of nutrients in the collection system adversely affects the nutrients that can be recovered in subsequent technologies, which are seeking to recover the greatest amount of valuable product. Controlling urea hydrolysis has been an active research topic, with literature pointing to the addition of acid or base as a strategy for inhibiting the reaction [13]- [17]. As such, a cyber-physical system could be of great benefit for urine diversion systems as an automated, cyber-enable method for controlling the addition of inhibiting chemicals.…”