Assessment Of Wastewater Quality in Nyabugogo Stream Kigali, Rwanda

ABSTRACT

The study assessed the characteristics of wastewater of Nyabugogo stream highlighting on their sources and the nature of contaminants they constitute as Chemical and Physio-chemical. It was anticipated that the water in the stream had high levels of both solid and liquid contaminants originating from domestic and industrial activities and wastewater discharges into the stream. The objectives of the study were to assess the nature of contaminants in the wastewater discharged into Nyabugogo stream and to identify the composition of contaminants by chemical and physio-chemical characteristics. The study employed both quantitative and qualitative experimental designs to arrive at the results. Water samples from four sites along Nyabugogo stream through Kigali city were collected in well illuminated containers and taken to Energy and Water Sanitation Authority (EWSA) laboratory for analyses. At the sites, many reactive were done directly on the stream waster using conductivimeter and thermometer to determine Electrical Conductivity, Temperature and pH respectively. The results of the study were analyzed using Stata version 8.0 and Pearson correlation coefficient was compulated to establish the relationship between metal concentration and physico chemical characteristics. The results showed that a lot of water contaminants such as Copper, Magnesium, Iron, Potassium, Calcium, Nickel, Chloride, Sulphate, and Zinc were contained in the wastewater and once they reach the stream, the characteristics of the stream water change. Thus the stream water constituted contaminants from both domestic and industrial/commercial origins. On average, the water pH of 7.94, vi temperature of 21.6°C, total dissolved solids 164mg/I, conductivity 3 18.9ps/cm/l, turbidity 67.93NTU/L and hardness 978mg/I/CaCO3. Ions present in the stream water varied in their average concentrations as Mn2~(O.27±0.0mg/l), Cu2~(0.09±O.0mg/l), Fe2~(0.6±0.2mg/I), K~(6.5± 1.6mg/I), Ca2~(46±26.8mg/l), Zn2~(0. 13±0.1mg/I), Ni2~(0.04±0.0mg/l), C1(63.64±7.6mg/I) and SO42~(19.9±7.5mg/I). A Pearson correlation test (r, at 0.05), was used to determine the relationships of interdependences amongst the ions present in the stream water. In dry/wet season, the interactions were Mn/Cu,r =0.94; Mn/K ,r=0.87; K/Ca r=0.96, and Fe/Ni, r=0.98. In conclusion, water in Nyabugogo stream is polluted by some elements such as potassium, calcium and chlorides due to the increasing discharges of wastewaters from Kigali city activities of both organic and inorganic contaminants. This makes the water unsafe for human consumption as it contains heavy metals. Therefore, proper water treatment before use is vital to reduce or avoid any harmful effects of this water to the Kigali inhabitants. Management of the wastewater at the generation sources can reduce the volumes received by Nyabugogo stream. Further studies are required to look at other sources and preventive innovations of water pollution on Nyabugogo stream.

 TABLE OF CONTENTS

DECLARATION A

DECLARATION B ii

APPROVAL SHEET iii

DEDICATION iv

ACKNOWLEDGEMENT v

ABSTRACT vi

One Introduction 1

Background 1

Problem statement 3

General objectives 4

Scope of the study 4

Significance otthe study 4

Two Review Of The Related Literature 7

Introduction 7

Concepts, opinions, ideas 7

Three Materials and Methods 26

Research design 26

Study area and sampling sites. 26

Sample selection 28

Sampling procedure 29

Four The Physio-Chemical Characteristics Of Stream Water 35

Abstract 35

Methods 35

Results and discussion 36

Conclusion 41

Five Chemical Concentration Characteristics of Wastewater 42

Abstract 42

Methods 42

Results and discussion 43

Conclusion 49

Six Conclusion and Recommendations 50

Introduction 50

Conclusion 50

Recommendations 50

REFERENCES 53

APPENDICES 56