Rainwater harvesting systems reduce detergent use

Abstract

Purpose Due to population growth, urban water demand is expected to increase significantly, as well as the environmental and economic costs required to supply it. Rainwater harvesting (RWH) systems can play a key role in helping cities meet part of their water demand as an alternative to conventional water abstraction and treatment. This paper presents an environmental and economic analysis of RWH systems providing households with water for laundry purposes in a life cycle thinking perspective. Methods Eight urban RWH system scenarios are defined with varying population density and storage tank layout for existing buildings. Storage tank volume required is calculated using Plugrisost software, based on Barcelona rainfall and catchment area, as well as water demand for laundry, since laundry is a fairly constant demand of non-potable water. Life cycle assessment (LCA) and life cycle costing (LCC) methodologies are applied for this study. Environmental impacts are determined using the ReCiPe 2008 (hierarchical, midpoint) and the cumulative energy demand methods. Net present value (NPV), internal rate of return (IRR), and payback (PB) time were used in LCC. Savings from laundry additives due to the difference in water hardness was, for the first time, included in a RWH study. Results and discussion LCA results indicate that the best scenario consists of a 24-household building, with the tank spread on the roof providing up to 96% lower impacts than the rest of scenarios considered. These results are mainly due to the absence of pumping energy consumption and greater rainwater collection per cubic meter of built tank capacity. Furthermore, avoided environmental impacts from the reduction in detergent use are more than 20 times greater than the impacts generated by the RWH system. LCC indicates that RWH system in clusters of buildings or home apartments offer up to 16 times higher profits (higher NPV, higher IRR, and lower PB periods) than individual installations. Conclusions LCA and LCC present better results for high-density scenarios. Overall, avoided environmental and economic impacts from detergent reduction clearly surpass environmental impacts (in all categories except terrestrial acidification) and economic cost of the RWH system in most cases (except two scenarios). Another important finding is that 80% of the savings are achieved by minimizing detergent and fabric softener by using soft rainwater; and the remaining 20% comes from replacing the use of tap water.

Integrated Water Management in Mountain Communities: The Case of Feutap in the Municipality of Bangangté, Cameroon

“…In particular, individual cisterns enable water supply at the household level (St. Eustatius), while isolated tanks connected to ponds/tanks and reservoirs enable irrigated agriculture and livestock production (Sri Lanka). Technologies for RWH are part of collective memory in many cultures, but their large-scale productive exploitation is yet to be popularized [14,[103][104][105]. For example, Kattel and Nepal [14] acknowledged that "harvesting rainwater for animals is an old-age tradition in the hills of Nepal but rainwater harvesting for agriculture is relatively a new phenomenon".…”

Analysis of the polyester clothing value chain to identify key intervention points for sustainability

“…Similarly, the European Parliament has recently approved a law for the safe reuse of treated wastewater in agriculture [ 69 ]. Rainwater collection for laundry has also been proposed [ 70 ]. Furthermore, because rainwater is softer than tap water in Barcelona (where the study was carried out), the use of rainwater for laundry could also reduce the necessary dose of detergent by 62% with a positive knock-on impact on the environment.…”

The Intelligent Built-Environment as Cyber-Physical System

“…In this manner, a user need not spend potable water needlessly, nor worry about its waste in toilet functions. Rainwater-harvesting (RWH) systems can play an important role in providing limited alternatives to sources dependent on conventional water treatment to meet present water requirements [259]. Their versatile character enables them to be implemented in a variety of application domains including: cleaning services [260], farming and agriculture [261], [262], and-to a limited extent-healthcare [263], etc.…”