Phytoremediation using species such as Packchong grass, Canna indica, and Phragmites is increasingly integrated into Anaerobic Baffle Reactor (ABR) systems to enhance microbial activity, filtration efficiency, and nutrient removal. Effective end of cycle biomass management is essential to ensure environmental safety and operational sustainability. This study assessed both the quantity and quality of harvested biomass, estimating annual yields of 72.8 tonnes of Packchong grass and 30.5 tonnes of Canna indica from a 0.54 hectare area. Primary and secondary data were analyzed to evaluate the feasibility of composting, cattle feed production (Packchong grass only), bioenergy generation, and biofertilizer use. Findings indicate that composting and bioenergy production are the most viable and environmentally sound options. The nitrogen content was 3.7%, Phosphorus and potassium were each 0.48%, indicating good nutrient value. Moisture content was 11.9%, also suitable for composting. Heavy metals were assessed against national standards: arsenic 1.87 mg/kg, cadmium 1.89 mg/kg, lead 17.86 mg/kg, chromium 8.16 mg/kg, nickel 23.42 mg/kg, zinc 275.13 mg/kg, and copper 93.42 mg/kg. All values were within the Ministry of Agriculture’s permissible limits. Properly treated sludge converted into compost enriches soil fertility, reduces dependence on chemical fertilizers, and recovers valuable nutrients such as nitrogen, phosphorus, and potassium. The gravity fed system minimizes energy demand and lowers greenhouse gas emissions, contributing to climate mitigation and potential carbon credit opportunities. The study demonstrates that phytoremediation combined with sustainable biomass management can enhance resource recovery, reduce climate risks, and create economic opportunities, positioning faecal sludge treatment plants as climate adaptive WASH solutions.