Comparing conventional and natural wastewater treatment with life cycle assessment methodology. A case study in Nagpur, India
Tutor / director / evaluatorGarcía Serrano, Joan
Document typeMinor thesis
Rights accessRestricted access - author's decision
The aim of this study was to compare conventi onal and natural wastewater treatment systems appropriated for India considering the environmental and socio-economic dimensions. To this end, Life Cycle Assessment (LCA) of a conventional Wastewater treatment Plant (WWTP) (1,500 p.e) and 5 configurations of two stages co nstructed wetlands (CWs) (i.e Li ne 1: horizontal+horizontal flow; Line 2: horizontal+vertical flow; Line 3: vertical+horiz ontal flow; Line 4: vertical+vertical flow; Line 5: one aerated wetland) was carried out using SimaPro 8 software. The comparison was complemented by a Multi Criteria Analysis (M CA) which considered technical, socio-economic and environmental aspects. The results obtained from conventional WWTP LCA showed that for all impacts categories considered (i.e Abiotic Depletion, Acidification, Eutrophication and Global Warming) between 89 and 93 % of the contribution was due to system operat ion (i.e.: energy consumption, ferric chloride used for phosphorous precipitation and polyelectrolyte used for sludge treatment) while the construction phase (e.g: earth movings, excavation, materials an d manufacturing) accounts for 7-11 % of the total impacts. According to that for CWs LCA only system operation was taken into account. The results obtained from the LCA of the CWs sy stems showed that for all impacts categories considered (i.e Abiotic Depletion, Acidification, Eutrophication and Globla Warming) between 10 and 37 % of the contribution was due to energy consumption while sludge production and its transformation in compost (biowaste process) accounts for 62-90 % of the total impacts. In particular, Line 1 configuration has the smallest impact for all categories considered. Indeed, it had the lowest energy consumption compared to other configurati ons. On the other hand, Line 5 scenario presents the highest impact due to the high blower energy consumption in the aereted wetland. Comparing all scenarios, the impacts of WWTP operation was between 5 and 21 times higher than the impacts of CWs operat ion, for all lines and categories considered. It is mainly due to the high energy consumption in WWTP with res pect to CWs (1.26 and 0.0243-0.0738 kWh/m 3 , respectively). The MCA emphasized the high costs and energy consumption as well as the low land occupation and waste production of WWTP. The opposite was observed for CWs scenarios. Finally, MCA results showed that the most appropri ated alternatives for wa stewater treatment in India were Line 2 (horizontal+vertical flow CW), Line 3 (vertical+horizontal flow CW) and Line 4 (vertical+vertical flow CW), thanks to lowest energy consumption and costs.
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