Rainwater harvesting systems for low demanding applications

Area of Science:

• Environmental Engineering
• Water Resource Management
• Sustainable Infrastructure

Background:

• Rainwater harvesting systems (RHS) are crucial for sustainable water management in industrial settings.
• Optimizing RHS design is essential to balance water demand, storage capacity, and economic viability.
• Previous RHS designs often over-allocate storage volumes, leading to inefficiencies.

Purpose of the Study:

• To design and optimize a rainwater harvesting system for a waste treatment facility in northern Portugal.
• To determine optimal water tank volumes that balance system efficiency and economic feasibility.
• To assess the impact of optimized storage on system performance and investment return periods.

Main Methods:

• Utilized a 3-decade precipitation record for system design.
• Employed the Ripple method to calculate initial water tank volumes (Vr) for 100% efficiency under two consumption scenarios.
• Optimized Vr values based on observed drought scarcity and defined a demand fraction threshold (Cw/Vw=0.8) to differentiate system demands.

Main Results:

• Optimized storage volumes were approximately half of the initially calculated Vr values.
• The optimized RHS maintained high efficiency (around 90%) with a low probability of system failure (around 5%).
• Significant economic savings and reduced investment return periods were achieved with the optimized design.

Conclusions:

• Optimized rainwater harvesting systems offer a highly efficient and cost-effective solution for low-demand industrial applications.
• Reducing oversized storage capacities in RHS leads to notable economic benefits without compromising water availability.
• The study provides a validated approach for optimizing RHS design based on long-term data and demand analysis.