6BT Word count 7,090Key messages• Waste prevention and management can reduce material throughput.• Claims of the waste hierarchy are not proven or fully achieved through policy.• Absolute reductions require stricter specification of options and targets.• Classification of waste, and collection practices, must consider waste value.• Dematerialization needs an overarching strategy inclusive of waste. AbstractDematerialization can serve as a measurable and straightforward strategy for sustainability and requires changes in management of material inputs and waste outputs of the economy. Currently,waste management is strongly inspired by the waste hierarchy, an influential philosophy in waste and resource management that prioritizes practices ranging from waste prevention to landfill.Despite the inclusion and prioritization of prevention in the hierarchy, the positive contribution of the application of the waste hierarchy to dematerializing the economy is not inevitable, nor has it been conclusively studied. In this paper, the waste hierarchy is analyzed on a conceptual level by studying its original aims, its potential to fulfil those aims, and its actual policy implementation.Issues with the hierarchy include limited specification and implementation of prevention, a lack of guidance for choosing amongst the levels of the hierarchy and the absence of a distinction between open-loop and closed-loop recycling. Also, the hierarchy only communicates relative priorities and therefore does not support decisions that affect other sectors as well as waste management. The article concludes that the waste hierarchy in its current form is an insufficient foundation for waste and resource policy to achieve absolute reductions in material throughput. Suggested improvements are the adoption of a value-based conception of waste and related collection practices, more stringent and targeted policies on least desirable options like landfill, the specification of waste management targets based on dematerialization ambitions, and the use of the waste hierarchy within a resource productivity-oriented framework.

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Biomass densification processes increase fuel energy density for more efficient transport.This study presents new data to show that blending different types of biomass improves the properties of densified biomass briquettes. The specific objectives were to investigate the effects of sample batch (biomass source), material ratio (rice husks to corn cobs), addition of binder (starch and water mixture) and compaction pressure, on briquette properties, using a factorial experiment.Briquettes had a unit density of up to 1.9 times the loose biomass bulk density, and were stronger than briquettes from the individual materials. Considering average values from two biomass sources, an unconfined compressive strength of 176 kPa was achieved at a compaction pressure of 31 MPa for a 3:7 blend of rice husks to corn cobs with 10% binder.These briquettes were durable, with only 4% mass loss during abrasion and 10% mass loss during shattering tests. They absorbed 36% less water than loose corn cobs. Statistical analysis of the results showed that starch and water addition was required for adequate briquette strength, but significantly reduced green and relaxed densities. The source of the biomass had a significant effect on densification, which emphasises the need to understand factors underlying biomass variability.

Abstract:The construction industry uses more resources and produces more waste than any other industrial sector; sustainable development depends on the reduction of both, while providing for a growing global population. The reuse of existing building components could support this goal. However, it is difficult to reclaim components from demolition, and materials remain cheap compared with labour, so new approaches are needed for reuse to be implemented beyond niche projects. This study therefore reviews waste interventions. Multiple case studies, spanning new builds and refurbishment, were undertaken to examine systemic mechanisms that lead to components being discarded. Evidence from fieldwork observations, waste documentation, and interviews indicates that the generators of unwanted components effectively decide their fate, and a failure to identify components in advance, uncertainty over usefulness, the perception of cost and programme risk in reclamation, and the preferential order of the waste hierarchy mean that the decision to discard to waste management goes unchallenged. A triage process is proposed to capture timely information about existing building components to be discarded, make this information visible to a wide community, and determine usefulness by focusing creativity already present in the industry on an exhaustive examination of component reusability and upcyclability.