This Week's Regeneration Research Digest

What the latest research reveals about regenerative practices

The research studies I came across this week offer empirical insight into the practical, policy, and equity dimensions of regenerative and sustainable systems.

From recycling’s unexpected air quality benefits across U.S. cities, to how rural wastewater plants are becoming unlikely hubs of solar innovation, to the emergence of five strategic patterns in circular business model design—these articles collectively reframe what it means to align environmental outcomes with organizational change and social justice.

Read on for more details. As always, I hope something here challenges how you think—or affirms the direction you're already heading. Please be in touch about any research on regeneration you come across.

• Recycle to breathe: Higher reuse cuts urban smog in U.S. cities.

• Solar flows: Rural wastewater plants power equity with the sun.

• Sound shapes sight: Forest study finds bird song and greenness align with perceived and real biodiversity.

• Loop logic: Firms shift to five circular business model innovation patterns.

Circular Economy on Air Quality

This Scientific Reports article presents one of the first large-scale empirical studies linking circular economy practices—particularly recycling—to improvements in urban air quality across 50 U.S. states from 2009 to 2022. Drawing on advanced econometric modeling (notably dynamic panel regression using GMM estimators), the authors find that higher recycling rates are significantly associated with reductions in key air pollutants, including PM₂.₅, PM₁₀, NOₓ, and CO₂.

Going beyond CO₂-centric climate research, the article demonstrates that circular economy practices—especially municipal solid waste recycling—can play a role in reducing urban smog and particulate pollution, thus offering measurable public health benefits. The study also confirms the Environmental Kuznets Curve (EKC) hypothesis: as income per capita rises, pollution initially worsens before falling, suggesting wealthier states have more capacity for regulatory and technological improvements. Population density, however, consistently correlates with higher pollution, underscoring the challenges faced by metropolitan areas.

By combining spatially differentiated data with robust causal inference techniques, the authors advance the policy case for embedding CE strategies into state-level sustainability planning. The article calls for stronger institutional frameworks—such as extended producer responsibility, recycling infrastructure investment, and compact urban design—to align waste reduction with cleaner air. It also emphasizes the need for collaborative governance, community engagement, and context-specific implementation to ensure effective and equitable CE transitions.

Read more: The impact of circular economy initiatives on urban air quality in the United States (Scientific Reports, July 2025)

Wastewater Systems

This Journal of Cleaner Production article investigates solar energy adoption in one of the most energy-intensive and often overlooked sectors: wastewater treatment. Drawing from a unique blend of technical, organizational, financial, and demographic data, the authors compare solar uptake at wastewater treatment plants (WWTPs) in California and New York to assess not only the drivers of adoption but also the distributive justice implications.

In California, solar adoption is more widespread—particularly among small, rural wastewater treatment plants—largely due to early state incentives targeting 1MW systems. These plants are more likely to serve communities with higher proportions of Hispanic residents and lower poverty rates, suggesting some positive alignment with energy justice goals. In contrast, New York, lacking such historic incentives, sees solar primarily at large, urban wastewater treatment plants—often in areas with Climate Action Plans—implying greater reliance on local government capacity than on statewide policy frameworks.

The study reframes energy transitions in wastewater treatment plants as both a technical and equity challenge. It finds that local fiscal capacity, demographic composition, and state policy histories all shape which communities benefit from renewable energy shifts. In doing so, it positions the wastewater sector as a valuable site for operationalizing energy justice—where infrastructure upgrades can intersect with climate action and social equity.

Read more: Exploring renewable energy transitions in energy intensive sectors: A comparative case study of solar adoption among wastewater systems in California and New York (Journal of Cleaner Production, July 2025)

Perceived biodiversity

This People and Nature article explores how people perceive biodiversity through sight and sound—and whether those perceptions match ecological measurements. Drawing on multisensory psychology, conservation biology, and environmental planning, the authors investigate how visual and acoustic cues from forest environments shape subjective experiences of biodiversity, which in turn relate to mental well-being.

Using a sorting experiment with forest photos and audio clips, they find that participants intuitively rely on cues like vegetation density, greenness, light, bird song complexity, and emotional tone when judging biodiversity. These subjective impressions were significantly correlated with objective indicators—especially for acoustic diversity. Notably, the "Greenness Index" and several soundscape indices (e.g., Acoustic Complexity) served as effective proxies for both perceived and actual biodiversity.

The study argues that understanding perceived biodiversity is crucial not just for psychological outcomes but also for designing health-promoting, biodiversity-rich green spaces. By bridging sensory experience with ecological measurement, it offers new tools for conservation planning that center human perception without abandoning scientific rigor.

Read more: Perceived biodiversity: Is what we measure also what we see and hear? (People and Nature, July 2025)

Circular Business Model Innovation

This Sustainable Production and Consumption article advances the field of circular economy by offering a structured, three-level analysis of how firms innovate their business models to retain the value of resources. Drawing on 63 case studies, the authors identify 46 distinct circular business model innovation (CBMI) practices across value proposition, value creation/delivery, and value capture. These are integrated with the 10R framework—ranging from "refuse" to "recover"—to assess how companies operationalize circularity.

The study finds that recycling, reducing, and rethinking are the most common resource retention options, but also surfaces 16 managerial practices not previously documented, such as on-demand production and the formation of CE-dedicated teams. Crucially, it proposes five circular business model innovation patterns—Circular Enablers, Dual Value Proposition, product-as-a-service (PAAS) Systems, End-of-Life Managers, and Process Optimizers—each suited to different firm types, sizes, and industries. These patterns illustrate how diverse configurations of practices and motivations shape the transition from linear to circular business models.

By combining circular economy and business model theory, the article offers a holistic framework for analyzing and implementing circular business model innovation. For practitioners, it provides a repertoire of actionable strategies; for policymakers, it informs the design of targeted interventions to encourage higher-value circular practices.

Read more: Circular business model innovation: Uncovering practices and patterns to retain the value of resources (Sustainable Production and Consumption, June 2025)

The regenerative business practices and sustainability innovations highlighted in this week's Regenerative Insights directly tackle the critical issues of corporate responsibility explored in my recent book explored in my recent book, The Profiteers: How Business Privatizes Profit and Socializes Cost.