Experimental Investigation of Solar Powered Reverse Osmosis Desalination

Petros Gebray,Fana Filli,Ashenafi Kebedom

doi:10.4314/mejs.v7i2.2

Abstract

Pollution and over exploitation of groundwater aquifer and surface water have led to a decrease of quality and availability of natural water resource in many regions. This situation has led to elevated total dissolved solids (TDS) beyond standards and facilitates toxic metals accumulation and other problems like staining and/or precipitation. One of the treatment options for an elevated total dissolved solution is desalination using a solar driven reverse osmosis system. The northern part of Ethiopia has short rainy season and long dry weather with clear sky radiation. Solar radiation ranges from 5.46 kWh/m 2 /day in August to 6.82 kWh/m 2 /day in April, with an average of 6.09 kWh/m 2 /day. This paper deals with application of reverse osmosis, driven by desalination system using solar energy, to supply safe drinking water for the rural areas of northern Ethiopia. Reverse osmosis due to its low energy consumption is one of the best desalination alternatives. Solar powered reverse osmosis system was developed and installed at Mekelle University. The main components are photovoltaic panels, two DC powered pumps, carbon filters, and flow meters. The system made to operate in a variable power, flow, and pressure considering the naturally varying irradiance throughout the day. The entire process of irradiation potential measurements, the amount of energy generated using solar panel, and the amount of TDS is discussed. The feed water with nearly constant TDS around 2800 ppm from the study area has reduced to fairly constant TDS of about 100 ppm after desalination. The average desalination capacity of the system is 50 litres per hour. Keywords : Carbon filter; Desalination; Flow meter; Reverse osmosis; Photovoltaic cells, Ethiopia.

Highlights

Safe drinking water is a human birthright - as much a birthright as clean air
This paper deals with application of reverse osmosis, driven by desalination system using solar energy, to supply safe drinking water for the rural areas of northern Ethiopia
The experimental field is located at an altitude of 2150 meters above sea level, at the Ethiopian Institute of Technology-Mekelle- Department of Mechanical Engineering, Solar Demonstration Center of Mekelle University, on the out skirts of the city of Mekelle, the regional capital of Tigray. 2.2 Design Data At the beginning of the experiment, the reverse osmosis had a capacity of 250 gallons per day (GPD), and reached up to 7,000 GDP

Summary

Introduction

Safe drinking water is a human birthright - as much a birthright as clean air. As a matter of fact, in most of the African, Asian countries and even in the relatively developed countries such as India, safe drinking water is not available (TWAS, 2002). Water scarcity is one of the world’s leading problems affecting more than 1.2 billion people globally. This number is growing fast and by 2025, about 1.8 billion people will be living in regions or countries with absolute water scarcity (UN-Water, 2014). Exploitation of groundwater aquifers and surface water has led to a decrease of quantity and/or quality of available natural water resources in many regions (Fritzmann et al, 2007). About 2.5 billion do not have access to adequate sanitation services (Gebrekidan and Samuel, 2011)

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Results

Conclusion