Life cycle analysis and economic evaluation of adsorptive removal of arsenic from groundwater using GAC and GAC-Fe adsorbents

Abstract

The potential health effects associated with consumption of arsenic contaminated water have motivated chemical and energy intensive treatment processes. Granulated activated carbon (GAC) and iron impregnated granular activated carbon (GAC-Fe) are the two adsorbents which have shown significant removal of arsenic (As(V)). However, the synthesis of different adsorbents involves significant different materials and energy interactions which have different environmental and economic burdens. This study evaluates and compares the environmental impacts arising from treatment of arsenic containing water using GAC and GAC-Fe adsorbents, for the selection of more suitable one. The life cycle inventory pertaining to treatment through two adsorbents was prepared based on the data available in literature. The impacts were assessed utilizing ‘Sphera LCA for experts’ software with three midpoint methods i.e. CML 2001, TRACI 2.1 and ReCiPe 2016. Results show that chemically treated/impregnated adsorbents for arsenic contaminated water treatment not only have lesser environmental emissions but also reduces the treatment cost. The treatment with GAC-Fe has ∼30% lower impacts in GWP, AP, EP, MAETP, FAETP, ODP, ADP (E) and HTP categories than treatment with GAC, since increase in adsorbent's specific uptake in GAC-Fe reduces the amount of total adsorbent requirement. GAC-Fe based water treatment costs ∼23% less than with GAC. The main responsible parameters for emissions are synthesis of GAC from hard coal precursor, and electricity consumption in carbonization and drying operations. Apart from this, in case of GAC-Fe, additional impregnation and drying operation also contributes to emissions. The utilization of coke oven gas generated in adsorbent synthesis for energy credits has potentially reduced the emissions and operating cost. The less standard deviation (<10%) in Monte Carlo (MC) uncertainty analysis, indicated the reliability and robustness of LCA impacts. This study exemplified the environment friendliness of metal impregnated GAC based arsenic contaminated water treatment.