Control strategies to improve the low water quality of Souk-Ahras city

Dhaouadi Mellahi,Ridha Zerdoumi,Assia Chaib

doi:10.1016/j.heliyon.2021.e07606

Abstract

This work reports control strategies of the water quality in the city of Souk-Ahras (east Algeria). With the recent development, rapid population growth, and the consequences of climate change, the capacity of water supply reserves becomes more unpredictable in the long term. This has drastically affected the distributed water quantity. A correlation between bacteriological water analysis and the analysis of pollution indicative physicochemical parameters is developed to replace the slow bacteriological analysis, which takes more than two days, by directly accessible physicochemical analysis to anticipate the case-onset of waterborne diseases. A good correlation is found between different combinations of physicochemical pollution parameters: (Turbidity, Nitrates); (Turbidity, Active chlorine) (nitrates, active chlorine); (Ammonium, Chlorine) and (Turbidity, Ammonium) with Spearman rank coefficients of 0.8657, -0.8602 and -0.8531 -0.8227 et 0.7957 respectively. Besides, long term analysis (over several years) revealed a high correlation of more than 0.92 between the analysis of pollution indicative physicochemical parameters and bacteriological analysis. The EPANET software is used to simulate the hydraulic behaviour of the network system over an extended period within pressurized and pressure-deficient conditions. The simulation results of several supply scenarios of daily drinking water pressure in the city center area show that 62% of drinking water distribution system is supplied with a steep slope (80 m), 10% with unsatisfactory pressure and only 23% with acceptable pressure (1–80 m).Therefore, the high working pressure at the mesh, and the interruptions of the water supply are factors that can lead to the occurrence of cross-connection cases. This diagnosis of the defects in the water supply system is combined with a statistical data analysis of physicochemical parameters to set up an effective sampling strategy that takes into account the frequency of analysis and the areas at risk to prevent the risk of waterborne diseases.

Highlights

According to the World Health Organization (WHO, 2017), each year, diarrhoea kills around 525,000 children under five
In the majority of positive cases of bacteriological analysis, we identified mainly total coliforms, thermotolerant coliforms, Escherichia coli and streptococci responsible for the outbreak
The diagnosis of the drinking water distribution network of the city of Souk-Ahras has been studied to reduce the cases of waterborne diseases

Summary

Introduction

According to the World Health Organization (WHO, 2017), each year, diarrhoea kills around 525,000 children under five. The class of bacteria Bacilli and Clostridia spore-forming endows them an excellent resistance against desiccation and lack of nutrients (Laue et al, 2018; McKenney et al, 2013) In this regard, bacteria can reproduce in the distribution network under suitable conditions, such as: increased water temperature, presence of nutrients, decrease in the residual chlorine level, ...etc (Setlow et al, 2017). Bacteria can reproduce in the distribution network under suitable conditions, such as: increased water temperature, presence of nutrients, decrease in the residual chlorine level, ...etc (Setlow et al, 2017) This problem of water quality degradation is more or less specific to underdeveloped and developing countries and to countries with water resource deficiencies. Climate change can impact both the quantity and quality of water, and the integrated management of dams, watersheds as well as domestic, industrial and irrigation water (Salami et al, 2015)

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