Towards better environmental performance of wastewater sludge treatment using endpoint approach in LCA methodology

Abstract

The aim of this study is to use the life cycle assessment method to measure the environmental performance of the sludge incineration process in a wastewater treatment plant and to propose an alternative that can reduce the environmental impact. To show the damages caused by the treatment processes, the study aimed to use an endpoint approach in evaluating impacts on human health, ecosystem quality, and resources due to the processes. A case study was taken at Bissell Point Wastewater Treatment Plant in Saint Louis, Missouri, U.S. The plant-specific data along with literature data from technical publications were used to build an inventory, and then analyzed the environmental burdens from sludge handling unit in the year 2011. The impact assessment method chosen was ReCipe 2008. The existing scenario (dewatering-multiple hearth incineration-ash to landfill) was evaluated and three alternative scenarios (fluid bed incineration and anaerobic digestion with and without land application) with energy recovery from heat or biogas were proposed and analyzed to find the one with the least environmental impact. The existing scenario shows that the most significant impacts are related to depletion in resources and damage to human health. These impacts mainly came from the operation phase (electricity and fuel consumption and emissions related to combustion). Alternatives showed better performance than the existing scenario. Using ReCipe endpoint methodology, and among the three alternatives tested, the anaerobic digestion had the best overall environmental performance. It is recommended to convert to fluid bed incineration if the concerns were more about human health or to anaerobic digestion if the concerns were more about depletion in resources. The endpoint approach may simplify the outcomes of this study as follows: if the plant is converted to fluid bed incineration, it could prevent an average of 43.2 DALYs in human life, save 0.059 species in the area from extinction, and make a 62% reduction in the plant’s current expenses needed by future generations to extract resources per year. At the same time it may prevent 36.1 DALYs in humans, save 0.157 species, and make a 101% reduction in current expenses on resources per year, if converting to anaerobic digestion.

Microbial community shifts in the oxic-settling-anoxic process in response to changes to sludge interchange ratio

“…Given the rising costs of and constraints associated with sludge treatment and disposal, the ideal approach to addressing problems associated with disposing or reusing excess sludge is to minimize sludge production in the first place. Additionally, there is a growing concern for the integration of sustainability issues in the new generations of wastewater treatment plants (Alyaseri and Zhou, 2017). To this end, various engineering strategies have been developed to reduce the yield coefficient and consequently sludge production in wastewater treatment plants, incorporating various microbial processes, such as lysis, cryptic growth, uncoupling metabolism, maintenance metabolism, and predation of bacteria (Liu and Tay, 2001; Low and Chase, 1999; Ratsak et al., 1996).…”

Mining Impacts Assessment Using the LCA Methodology: Case Study of Afema Gold Mine in Ivory Coast

“…A careful selection of the system boundaries has an important influence on an LCA (Alyaseri and Zhou 2017). The boundaries of the system include all of the phases of the mine: exploration, construction, operation, and rehabilitation (Figure 2).…”

Methodology for Optimizing Sewage Sludge Treatment, Valorization and Disposal Methods. Application to the Marrakech (Morocco) Wastewater Treatment Plant

“…A direct comparison of possibilities is sometimes possible, as it was done in [9], but the use of the Life Cycle Assessment (LCA) method is often found in the literature to evaluate different sludge management scenarios, as in the work [10], [11] and [12]. This methodology oriented towards environmental impact assessment can be used with an inventory of costs for decision-making, such as the work of [11].…”