Assessment of UASB–DHS technology for sewage treatment: a comparative study from a sustainability perspective

Abstract

This paper assesses the technical and economic sustainability of a combined system of an up-flow anaerobic sludge blanket (UASB)-down-flow hanging sponge (DHS) for sewage treatment. Additionally, this study compares UASB-DHS with current technologies in India like trickling filters (TF), sequencing batch reactor (SBR), moving bed biofilm reactor (MBBR), and other combinations of UASB with post-treatment systems such as final polishing ponds (FPU) and extended aeration sludge process (EASP). The sustainability of the sewage treatment plants (STPs) was evaluated using a composite indicator, which incorporated environmental, societal, and economic dimensions. In case of the individual sustainability indicator study, the results showed that UASB-FPU was the most economically sustainable system with a score of 0.512 and aeration systems such as MBBR, EASP, and SBR were environmentally sustainable, whereas UASB-DHS system was socially sustainable. However, the overall comparative analysis indicated that the UASB-DHS system scored the highest value of 2.619 on the global sustainability indicator followed by EASP and MBBR with scores of 2.322 and 2.279, respectively. The highlight of this study was that the most environmentally sustainable treatment plants were not economically and socially sustainable. Moreover, sensitivity analysis showed that five out of the seven scenarios tested, the UASB-DHS system showed good results amongst the treatment system.

Up-Flow Anaerobic Sludge Blanket (UASB) Technology for Energy Recovery: A Review on State-of-the-Art and Recent Technological Advances

“…Consequently, a careful monitoring and a proper treatment unit of odor emissions from anaerobic reactors is recommended to avoid negative consequences also from a public perception perspective [ 16 ]. Different indicators (environmental, social and economic parameters) were proposed to assess the technical and economic suitability of a UASB reactor integrated with a down-flow hanging sponge (DHS) for sewage treatment, comparing this solution to other full-scale wastewater treatment schemes commonly found in India [ 144 ]. It was proved that UASB-DHS process had the highest value of the global sustainability indicator.…”

“…It was proved that UASB-DHS process had the highest value of the global sustainability indicator. In addition, a trade-off between an environmental-friendly wastewater treatment and the socio-economic aspects was highlighted [ 144 ].…”

Downflow Hanging Sponge System: A Self-Sustaining Option for Wastewater Treatment

“…TF is a well-known technology since ages and comparing DHS system with TF would assist in its proof of concept, scalability and deployment for its validation in the field of the sustainability science. So far, there is only one study which has addressed the sustainability of the full-scale DHS system [43]. However, self-sustainability of DHS system has not been explored yet.…”

“…Operational expenditure included number of mechanical equipment, skilled workers, power consumption, labor, chemicals, and consumables. The data were taken from the state-of-art literatures [43,74,75] for calculating the construction and operating costs for economic evaluation for both the systems. For the comparison in the same scale few considerations were made:…”

“…This does not impair our comparison as it's combinations with other systems is a disadvantage identified at the global level in developing countries [79]. Hence, assessment of the chosen indicators is based on TF studied [43]. Caution should be exercised that all the data for social assessment do not represent any generic weighting.…”