Selection of Wastewater Treatment Plant Site for Bahir Dar Town, Ethiopia Using Multi-Criteria Analysis on GIS platform

Abinet Addis

doi:10.7176/cer/13-3-02

Abstract

The siting of wastewater treatment plant is an extremely complex task mainly due to the fact that the identification and selection process involves many factors and strict regulations. For proper identification and selection of appropriate sites for wastewater treatment plants careful and systematic procedures need to be adopted and followed. The main objective of this research was to find the environmentally and economically suitable location of wastewater treatment plant by using the GIS-based MCA approaches in Bahir Dar town. The present study had integrated road networks, rivers/streams, lake, geology, soil, slope, elevation, wind direction, groundwater wells, groundwater table, rural settlements, urban settlements and land use/ land cover for selecting a suitable wastewater treatment plant site within the study area. The relative weights of the factor were estimated using AHP and criteria maps were developed by using GIS spatial operations. Weighted linear combination was used to integrate weight with the factor maps. The final integration of weighted factor map and constraint map produced an overall wastewater treatment plant suitability map. The wastewater treatment plant site suitability map was presented in four suitability index such as highly suitable, moderately suitable, low suitable and unsuitable. The result shows that around 6.08% area is highly suitable for wastewater treatment plant site, 1.83% is moderately suitable, 0.61% of study area has low suitability and 91.48% area is unsuitable for wastewater treatment plant site. Among the highly suitable areas, five sites were selected and revaluated in terms of road network, river/streams, lake, geology, soil, slope, elevation, wind direction, groundwater wells, groundwater table, rural settlements, urban settlements and land use/land cover to select the optimal suitable site. Finally, site 4 was proposed as the most preferred option for the construction of the wastewater treatment plant site with the minimum effects on economic, environment risk and public health. Keywords: Bahir Dar, GIS, MCA, Site selection, Wastewater Treatment Plant DOI: 10.7176/CER/13-3-02 Publication date: May 31 st 2021

Highlights

Wastewater is a problem in developing countries due to the accelerated rate of increasing population
Potential suitable sites must be selected for wastewater treatment plant to minimize the contamination of surface and groundwater especially those used for drinking water
The purpose of this study is to identify a wastewater treatment plant site that integrates a multicriteria decision analysis method, which consists of the analytical hierarchy process (AHP) and weighted linear combination (WLC) methods, within a GIS environment in the case of Bahir Dar town

Summary

Introduction

Wastewater is a problem in developing countries due to the accelerated rate of increasing population. In the world especially in developing countries like Ethiopia almost 90% of wastewater remains untreated causing widespread water pollution [6] [4]. In Bair Dar town, there are problems of wastewater treatment plant sites. Two-thirds of all households in Bahir Dar discharge wastewater into rivers. They discharge wastewater into Lake Tana and Abbay (Blue Nile) river through pipes and open ditches. Such discharges pollute the environment and create offensive smell and aggravate the conditions for the spread of communicable diseases [5]

Objectives

Methods

Results