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Evaluation of wastewater treatment alternatives for different water reuse applications with modeling and cost analysis

Uyanık, Pınar
Wastewater reclamation can be a solution to water scarcity. Several wastewater treatment schemes exist for specific water reuse applications. This thesis aims to evaluate different wastewater treatment schemes for a range of water reuse applications through modeling and cost analysis. For this purpose, different secondary level treatment schemes as conventional activated sludge (TS_A), extended aeration (TS_B) and A2O (TS_C) were modeled using BioWin for three wastewater characteristics and three flowrates. Cost analysis for secondary treatment level, where BioWin modeling results were included, and tertiary, advanced treatment levels were done for 30 years period, including capital and operational costs. The total and unit costs of reclaimed water were calculated for different treatment schemes (TS_1 to TS_6) assigned to different water reuse applications such as groundwater recharge, urban, agricultural, industrial and environmental reuse. The unit reclaimed water costs were found to range in $ 0.029/m³ to $ 0.601/m³ for different treatment schemes. If the user has a lower budget for water reuse application, such as unrestricted area irrigation or agricultural reuse, TS_1 (A2O + Filtration + UV + Cl), TS_3 (CAS/EXT/A2O + Filtration + UV + Cl), TS_4 (A2O/CAS/EXT) and TS_5 (CAS/EXT/A2O + UV + Cl) could be used. Reclaimed water from TS_2 (CAS/EXT/A2O + Filtration + UV + Cl + SAT) and TS_6 (A2O + MF + RO + UV + Cl) could be used as potable usage with higher unit treatment costs because of the requirement of a higher level of water quality. This thesis study revealed that the decision-maker can make a cost-benefit decision considering partial reuse to involve a low-cost alternative and decide on which process to follow depending on the water reuse application.