A comparative life-cycle assessment and cost analysis of biofilters amended with sludge-based activated carbon and commercial activated carbon for stormwater treatment.

Environmental and economic issues resulting from the unsustainable management of sewage sludge from wastewater have necessitated the development of eco-friendly sewage sludge disposal methods, whereas stormwater effluent contains tremendous amounts of pollutants. This study compares the feasibility and environmental impacts associated with incorporating biofilters with sludge-based activated carbon (SBAC) versus commercial activated carbon (CAC) for stormwater treatment. The results demonstrate that the construction and disposal life-cycle stages are the dominant contributors to several environmental impact categories, including resource scarcity, carcinogenic toxicity, terrestrial ecotoxicity, and ozone formation indicators. Across multiple impact categories, the incorporation of biofilters with SBAC can reduce the negative environmental impacts associated with biofilter construction and disposal by 40% over a 50-year analysis period. In contrast, the most significant improvement is on construction-dominant indicators, where the decreased need for biofilter reconstruction results in a higher reduction in environmental impacts. Economically, amending the biofilter with SBAC can increase profits by up to 66% due to extending its lifespan. This study shows that SBAC has similar performance as CAC for lowering the negative environmental impacts resulting from biofilter construction, while increasing the overall net profits of the system. However, converting sewage sludge to an effective sorbent (SBAC) and incorporating SBAC into a biofilter to capture pollutants from stormwater is an economically and environmentally sustainable solution available to practitioners to manage sewage sludge and stormwater effluent. This solution protects the environment in a cost efficient, sustainable manner.

Quantifying Location-Specific Impacts of Pavement Albedo on Radiative Forcing Using an Analytical Approach.

High-albedo materials reflect more solar radiation and, thereby, alter the earth's radiative balance. Increasing pavement albedo, therefore, has been considered as a technological strategy to mitigate global warming. Previous studies have evaluated this strategy using global average models. To factor this effect into life cycle assessments, location-specific models of the albedo effect for pavements are required. A parametric analytical model is developed to estimate the radiative forcing (RF) using a novel model form and an iterative solution approach. The new model is extended to estimate the corresponding global warming potential (GWP) over an analysis period of 50 years for an albedo change in a pavement surface. This was applied to quantify the GWP impacts of increasing pavement albedo in 14 cities across various climate zones in the US. For the United States, the GWP in kg CO2 equivalent per square meter of altered surface ranges from 0.8 to 1.6 per 0.01 change in albedo, a range of more than 40%. Analysis of a hypothetical albedo change to all darker pavements in the US would produce a negative RF of a magnitude equivalent to that associated with a reduction in CO2 emissions of more than 17 Mton per year.