Extended Exergy Accounting (EEA) analysis of municipal wastewater treatment – Determination of environmental remediation cost for municipal wastewater

The goal of this study is determination of environmental remediation cost (EEENV) for municipal wastewater by means of Extended Exergy Accounting (EEA) method which is an exergy based resource use evaluation technique. EEENV represents the resource consumption equivalent of effluent treatment process (quantified in exergy) which is one of the indispensable constituents of EEA applications. To attain the goal, an anaerobic digestion based, commercially mature and widely known wastewater treatment technology is analyzed by means of EEA. This is a case study as well: presented results are obtained from application of the treatment system to municipal wastewater produced by Turkish Household Sector. This is the first study in the literature that EEENV of “municipal wastewater treatment” and “sludge abatement” is derived along the guidelines of original calculation procedure of EEA, i.e., without recurring to the conversion of monetary equivalent of the treatment process into its exergetic equivalent as it has been applied so far in the literature. Hence, presented EEENV results are possible to be used in future EEA analyses and have the corresponding importance. The results show the resource dissipation equivalent for the considered treatment processes and future analysis of other disposal routes may carry different EEENV results. As such, comparison of EEENV will indicate the less resource consuming way of wastewater and sludge handling and amendment. EEENV of raw municipal wastewater and sludge abatement are determined as 95.66 and 13.95MJ/m3, respectively. The considerable difference of the results arises from the high exergy consumption of wastewater collection which is not incorporated in sludge abatement processes.