The key drivers of per capita cost and GHG emissions were identified by characterizing the contributions from each unit (Figure ). For both energy source configurations, the per capita cost was driven by the replacement costs (captured within O&M) of components with shorter lifetimes than the system lifetime (e.g., 2-10 year pump lifetimes, 2-year electrochlorinator lifetime), labor costs associated with O&M, capital costs of the key components (e.g., pumps, reactors), and consumables used in treatment (e.g., zeolite, GAC, NaCl, and NaOH in NCS, LPG in sludge pasteurization). For all units except the NCS and Pretreatment, the O&M and capital were the first and second largest contributors, respectively, to per capita cost. The second largest cost for the NCS and Pretreatment was labor, which stemmed from the labor requirements for zeolite regeneration and screen cleaning, respectively, and pump replacements for both units. The relative costs across unit operations for the photovoltaic/grid-tied configurations were similar, with median percent contributions to per capita system cost highest for the Sludge Pasteurization (31%/34%), NCS (12%/13%), EC (13%/16%), and AnMBR (12%/13%) treatment units, followed by power unit (10%/1%), and controls (9%/9%; Figure ). The cost contribution of grid-tied power consumption was minimal to the overall cost (8%), and the grid-tied unit had lower capital and O&M costs than the photovoltaic unit, the latter of which included photovoltaic panels and a battery.