Optimal energy-water management in urban residential buildings through grey water recycling

Abstract

Energy and water are inseparable resources whose management in urban residential buildings is important. Continuing urbanization in developing nations is increasing the demand yet the supply is inadequate or non-existent. To relieve the demand on public utilities, decentralized water recycling systems provide alternative and affordable source of water. However, there are social, economic, environmental and technological factors that affect the uptake of these systems. Although advanced water treatment technologies for decentralized systems have been developed, there are challenges in their optimal operation. This paper introduces the open loop optimal control and closed-loop model predictive control (MPC) strategies aimed at ensuring safe and reliable operation of a grey water recycling system at building level. Both controllers have shown their ability in efficiently operate the system leading to water conservation and energy cost savings. Each of these controllers has its strengths in terms of cost, ease of implementation and robustness and they should be adopted according to specific application. Their adoption can greatly improve energy and water security in urban households, reduce their demand and waste water. Technology alone cannot solve resource insecurity, and therefore, appropriate policies, regulations, incentives and public awareness should be implemented to support such novel technologies.

Indicator rating methodology for Rapid Sustainability Assessment Method (RSAM) for existing residential buildings using opinions of residents

“…In terms of sustainability, there is a great potential in the reuse of greywater, because it might be utilized for many applications such as toilet flushing and other non-sanitary uses. Recycling and reusing greywater will reduce the demand for potable water as well as the amount of wastewater requiring treatment [34] . Regardless of the technique used to recycle/recover grey water, 1 point is given for every 10% of water recycled or reused of the amount of water consumed.…”

Ecological Assessment of Clay Brick Manufacturing in China Using Emergy Analysis

“…In this study, if electricity consumption was reduced by 5%, the factory's sustainability indicators may be improved by 1.1%. The residual energy reutilization of advanced systems should be deemed as the optimal sustainable approach and be adopted to realize the reduction of imported energy [61][62][63]. Other new energy-saving systems can be given priority for application and promotion, which consist of waste water recovery systems, waste heat recovery systems, cooling recovery systems, kiln top heat exchange and reuse systems, etc.…”

An assessment of the potential for shower water heat recovery

“…Besides providing a valuable source of water for non-potable purposes [22], greywater drained from sanitary facilities may also be used as a non-conventional source of energy, e.g. for water heating [23].…”