Economic and Technical Investigation of Grey Water Reuse in High-Rise Buildings in Iran

Iran is located in an arid and semi-arid zone with limited water resources. In urban areas where water supplies are short, effluents from wastewater treatment plants can be considered as a reliable alternative source to supply water, especially for such urban uses as flushing and landscape irrigation. The effluents can be used to supply the water for textile, chemical, plastic, and construction industries in addition to agricultural irrigation. While these demands can be supplied from non-potable water resources such as treatment effluents, the water required for drinking and cooking that accounts for only a small portion of the total consumption must be supplied from those resources that conform to quality standards. The objective of the present study was to develop incentive plans and innovative designs that would assist builders and inhabitants of high-rise buildings to implement and employ grey water reuse systems. The study also investigated the effects of emoploying two-storage septic tanks to improve such water parameters as BOD, COD, N, P, and TSS. Given the fact that water connection charges in Iran are only a function of total land and building areas with volumetric parameters excluded, the current pricing system for water and sewage connections needs to be revisited and duly adjusted. The additional costs of systems required for segregating black water from grey water and recirculating treated water within the building may not be economically justifiable and, thus, the incentive plans are expected to provide the required justification for both the water industry and the builders.