Material and monetary flows of construction and demolition waste and assessment on physical and environmental properties of illegally dumped construction and demolition waste in Hanoi.

The main aim of this study is to investigate the material and monetary flows of CDW management and to characterize the distribution of illegally dumped CDW in Hanoi. Construction and demolition waste management has become a source of much concern to the urban authorities and citizens of big cities in Vietnam. It is estimated that 3000 t of CDW were generated per day from construction and demolition activities in Hanoi, but only 45% of the CDW was received at official landfills, while 55% of the CDW was disposed of elsewhere. The consequences of improper waste management are potentially alarming. The study conducted interviews to identify the material and cash flow associated with licensed and unlicensed contractors in CDW classification, transportation, treatment, and disposal, to characterize the distribution of illegally dumped CDW in two districts in Hanoi (urban and suburban districts), and to assess the composition of dumped CDW and environmental assessment of illegally dumped CDW by chemical analyses such as leaching and content tests. The study concluded that illegal dumping was performed mostly by unlicensed private companies. The illegally dumped CDW was mostly composed of mixed materials such as concrete, bricks, stones, and some hazardous materials such as asbestos and gypsum were found. The environmental concern of illegally dumped CDW was mostly dust, blockage of water ways, and inundation of increased suspended solids, whereas the heavy metal leaching concentration of all samples was below the environmental standards in Vietnam.

Financial and economic evaluation of construction and demolition waste recycling in Hanoi, Vietnam.

Increasing waste generation and the absence of a formal recycling industry are exacerbating the inadequacy of Construction and Demolition Waste (CDW) management in Hanoi, Vietnam. This study assesses potential CDW recycling in Hanoi by estimating the prospective supply of and demand for CDW recycling plants and evaluating their likely costs and benefits. Supply of concrete waste was calculated based on the weight-per-construction-area method whilst demand for recycled concrete aggregates (RCA) was determined by estimating the amount of aggregates for road construction in Hanoi from 2013 to 2017. Two potential models of CDW recycling plants were considered: a stationary plant and a mobile plant, with capacities of 1,000 and 360 tons/day, respectively. Our findings reveal that demand for RCA exceeds waste concrete supply, suggesting a promising market for RCA. Positive Net Present Value and Internal Rate of Return values of the stationary plant indicate its feasibility as an investment option. Meanwhile, the introduction of mobile recycling plants might require governmental intervention to internalize recycling positive externalities. Supporting policies might include a combination of a virgin material tax, green public procurement, and quality standard development.

Waste generation, composition, and handling in building-related construction and demolition in Hanoi, Vietnam.

This study conducted a survey at 15 building construction and demolition sites in Hanoi, Vietnam in order to identify waste generation rates (WGR), composition, and current handling practices of construction and demolition waste (CDW). Waste quantification based on CDW layout, image analysis to identify CDW components, and face-to-face interviews with construction and demolition contractors to reveal CDW flows were performed. WGRs of 79.3 kg/m2 and 1,030 kg/m2 were determined in small- and large-scale construction sites, respectively, whilst WGRs at small and large demolition sites were 610 kg/m2 and 318 kg/m2. The composition analysis identified soil, concrete, and brick as the major CDW components, consistent with building structures in Vietnam. The interviews discovered that merely 10% of total CDW flows was from recycled and reused CDW. Reuse and recycling rates were most significant for metal and were lower (in descending order) for brick, concrete, and soil. These findings raise a need for aggressive and integrated strategies to promote more sustainable CDW management in the country, including the development of recycled CDW product standards, policies that facilitate recycling, and more importantly, a sustainable business model for CDW recycling, for which future evaluations of economic feasibility are of great importance.