Novel wastewater processing: Impact on our cities, infrastructure and society

We introduce a future vision of the urban environment in this Think Piece. A vision represented by a decentralised system, unlike the current centralised infrastructure. And one where the environment is characterised by a circular economy, with produced resources being re-introduced into the system and low levels of waste.

We use wastewater management as an example to assess this long-term vision of decentralised, circular-economy cities. Wastewater treatment is a vital service that currently uses a highly centralised infrastructure (pipes in the ground, centralised treatment facilities), and processes huge amounts of materials as wastes, which could alternatively be viewed as resources (nutrients, energy, water). The sustainability of the current paradigm is questionable, from the perspective of urban population growth and densification, coupled with issues of water scarcity and quality, loss of vital resources, energy demand, climate change impacts and overall system resilience.

We sought inputs to the Think Piece through a workshop, focussed on critiquing the opportunities and implications of the future vision, and a technical literature review.

The work has been distilled into four propositions around societal implications:

Social. A decentralised, circular urban economy which includes wastewater could help people reconnect with each other and their environment. However, acceptance of community level wastewater processing and reuse of resources from wastewater will need to be well managed, as will ensuring social equity for all.

Environmental. A decentralised, circular economy wastewater system will promote environmental sustainability. However, regulations and infrastructure may struggle to keep pace and, in fact, facilitate the move towards a more sustainable system.

Technical. Decentralised, circular economy wastewater systems are an exciting area of innovation and development, but they must take place alongside developments in the infrastructure and social integration of a circular economy.

Systemic. A substantive move towards decentralised, circular wastewater economy will not occur without a substantial buy-in from “the system”. Achieving even the slightest transitional movement will be one of the great challenges faced by those promoting this vision of the future.

Underpinning this, transitioning from the status-quo is raised as a significant challenge. A hybrid of decentralised infrastructure and centralised management may be required. New models of operation and ownership are likely to be needed and innovative community organisations could play a role. Health and quality must be continually monitored and ensured, the regulatory system will need maturing. Governance and policy will be needed to incentivise change and de-risk the transition.

Looking forward, we propose extending the scope of conversation around future urban infrastructure within the BBHTC National Science Challenge - beyond wastewater to include all water (potable, waste and storm), energy, transport, and communications, and to “model the future” by translating ideas from this vision into tangible urban examples.