A Decentralized Grey Water Treatment and Reuse System in a Residential Area for Landscaping and Environmental Purposes

Abstract

A case study was conducted in a residential area in Xi'an, China for grey water treatment and reuse for landscaping and environmental purposes. Through a dual-pipe system, grey water and black water were separately collected from 6 buildings at a flow rate about 100 m3/d. The collected grey water was treated by a hybrid physicochemical process using a fluidized pellet bed separator as the first stage and by ozone enhanced flotation as the second stage. In order to maintain good water quality in the artificial lake, part of the stored water was sent back to the second stage of the treatment facilities for water quality polishing. From the pond, water was also pumped for gardening and other non-potable uses. The average daily consumption (for gardening, surface evaporation and other losses) was about 60 m3/d. The project was proved technically feasible because the treatment system could provide water with good quality to meet the specification of for scenic environment reuse and sustain a beautiful water environment. It was also proved economically feasible because the cost for water reclamation could be well compensated by the cost saved for purchasing fresh water which would be consumed for the same purpose of landscaping and environmental water use. This case study provided a good example of decentralized wastewater treatment and reclamation for landscaping and environmental reuse.