Water Innovation & Research Centre, Department of Chemical Engineering, University of Bath, Claverton Down, Bath, BA2 7AY, United Kingdom.
Water Innovation & Research Centre, Department of Chemical Engineering, University of Bath, Claverton Down, Bath, BA2 7AY, United Kingdom.
J Environ Manage. 2021 Feb 15;280:111847. doi: 10.1016/j.jenvman.2020.111847. Epub 2020 Dec 23.
This study demonstrates a large roof (30,000 m) rainwater harvesting (RWH) system in an indoor arena by considering three water demand scenarios (toilet flushing, irrigation and combined demand) via hydraulic and economic assessments. The water saving efficiency (WSE) of the RWH system for each scenario was estimated by a simulation model using historical daily rainfall data (1968-2018). Depending on the water demand, the WSE was found to be independent of tank size when the tank size exceeded 1000 m. The results suggest that the WSE of the RWH system is highly influenced by water demand scenarios, and a storage capacity of 400-1000 m would be enough for the applications considered in this study. The economic analysis results further showed that depending on the water demand, the RWH system with a rainwater storage capacity of between 100 and 600 m was more economically beneficial due to its positive cost saving values. The results also showed that depending on the water scenarios, the unit water cost between 0.37 and 0.40 £/m was lower than the mains water cost (0.40 £/m). As a result, the use of the RWH system with a tank between 400 and 600 m can be the most favourable range under the conditions considered in this study. Given the variations in water price, rainfall patterns and discount rates, the sensitivity analysis showed that water tariffs and discount rates play a significant role in reducing the unit water cost of the system, maintaining it lower than the mains water cost. A payback period analysis of the RWH system with a 600 m tank revealed that a 5% discount rate and a water price of 3 £/m would be enough to make the RWH system cost effective and that the capital cost could be returned within 10-11 years. This study highlights the need for preliminary sizing of a rainwater tank and an economic analysis of a large rooftop RWH system to maximise the benefits.
本研究通过水力和经济评估，考虑三种用水需求情景（厕所冲洗、灌溉和综合需求），展示了一个 30000 平方米的大型屋顶雨水收集（RWH）系统。利用历史逐日降雨数据（1968-2018 年），通过模拟模型估算了每种情景下 RWH 系统的节水效率（WSE）。结果表明，当水箱尺寸超过 1000m 时，WSE 与水箱尺寸无关，而取决于用水需求。研究结果表明，RWH 系统的 WSE 高度依赖于用水需求情景，并且对于本研究中考虑的应用，400-1000m 的存储容量就足够了。经济分析结果进一步表明，取决于用水需求，雨水储存容量在 100-600m 之间的 RWH 系统由于具有积极的成本节约价值，在经济上更有利。结果还表明，取决于用水情景，单位水成本在 0.37-0.40 £/m 之间低于自来水成本（0.40 £/m）。因此，在本研究考虑的条件下，使用容量在 400-600m 之间的 RWH 系统可能是最有利的范围。考虑到水价、降雨模式和折扣率的变化，敏感性分析表明，水价和折扣率在降低系统单位水成本方面发挥着重要作用，使其保持低于自来水成本。对 600m 水箱的 RWH 系统进行投资回报期分析表明，5%的折扣率和 3£/m 的水价足以使 RWH 系统具有成本效益，并且资本成本可以在 10-11 年内收回。本研究强调了初步确定雨水水箱尺寸和经济分析大型屋顶 RWH 系统的必要性，以最大化效益。
