Effects of greenhouse gas emission on decentralized wastewater treatment and reuse system

Abstract

There are growing concerns on greenhouse gas (GHG) emission from wastewater treatment. It is generally known that decentralized treatment of wastewater allows industrial sectors to increase wastewater reuse rate, meanwhile usually consume more energy resulted additional GHG emissions. Therefore the optimized wastewater reuse system can be largely differed when GHG emissions are considered. We optimized industrial wastewater reuse networks considering GHG emissions. We constructed a mathematical model of wastewater reuse network including intermediate treatment facilities and a final treatment plant. Amount of emission was calculated then converted to monetary terms via carbon price and cost minimization was performed. An industrial sector with four types of plants was selected as a case study. We figured out changes in the system when installation of intermediate facilities was allowed. If decentralized treatment and reuse were adopted the amount of freshwater consumption were decreased to 65% of the base case; when GHG emissions were considered as additional cost, the freshwater consumption increased to 87%, which is a drawback from the former case. Sensitivity analyses on the GHG expenses were performed which showed importance of pricing scheme on the network formation.