A stand-alone Zero-Liquid-Discharge greenhouse model with rainwater harvesting capability

Abstract

Global warming is a prevalent topic throughout the world. The IPCC predicts that the maximum potential global temperature increase will be 4.8 oC by 2100. It has been concluded that a temperature rise of 1.4 oC or higher will have statistically significant impacts on global precipitation levels. Therefore, there is a need to investigate the future trends of precipitation and subsequent irrigation methods. This study will discuss a new multi-functional zero liquid discharge (ZLD) system for a greenhouse, incorporating a humidification dehumidification (HDH) mechanism, solar still desalination and rainwater harvesting. The focus of this paper is on analysing the water production of the system. Although previous literature discusses the inefficiency of solar still (SS) desalination, the fresh water produced during similar experiments has shown otherwise, desalinating 0.95 L/m²/hr of saline water. Using multiple panels could therefore give a substantial output of distilled water for certain usage such as agriculture. Implementing solar stills of large surface area would also allow the collection of rainwater thus increasing the total water productivity of the system. The ZLD system aims to produce no waste product and use the output brine water for aquaculture and salt cultivation.