Determination of Heavy Metals Levels in the Effluent Treatment Plant of Paint and Coating Industry in Nairobi County

ABSTRACT

Industrialization and urbanization has increased tremendously in the last few years, especially in underdeveloped countries, such as Kenya. This has resulted in rising demand for certain aesthetic goods such as paints and coatings. Paint and coating industries use extensive raw materials in their manufacturing processes that consist of heavy metals, various solvents, and organic compounds. The wastewater released from these industries contains residual chemicals that are highly toxic to human health and the environment, thus requiring treatment before disposal. The wastewater, therefore, requires constant observation of the contaminants before releasing them into the environment. This research project was aimed at identifying concentration levels of heavy metals such as Lead (Pb), Cadmium (Cd), Manganese(Mn) and physiochemical properties, such as pH from the effluent emanating from the paint and coating industry. Wastewater samples from the industry were collected consecutively using pretreated 500 mL plastic bottles at three different sampling points: at the entry of the treatment plant for untreated effluents, discharge from the treatment plant for treated effluents, and Clarifier located within the waste treatment plant. The samples were collected once a week for one month. They were stored in a cooler box and transported to the Analytical Chemistry Laboratory in the Department of Chemistry at the University of Nairobi. Later, the samples were kept in a refrigerator at a temperature of 25°C. Digestion was done to the wastewater samples in triplicates, using an aqua regia (a mixture of concentrated nitric (V) acid and hydrochloric acid in the ratio of 1:3). The standard solutions and digested samples were subsequently analyzed for heavy metal levels in mg/L using the Atomic Absorption Spectrometer. The pH was also analyzed using the standard methods The results revealed that the pH values ranged from 4.55-5.75, 7.08-8.48, and 8.15-9.05 for the samples collected Before Treatment of Effluent (BTE), Clarifier and the samples collected After Treatment of Effluent (ATE), respectively. The heavy metals mean±standard deviation (SD) concentrations BTE were as follows, Below Detection Limit (BDL), 1.9513±0.371439 and 0.11±0.042955 mg/L, for Cadmium, Manganese, and Lead, respectively. The corresponding Mean ± SD values for the metals ATE were as follows, BDL, 1.1803±0.7822 and 0.0357±0.002 6mg/L for Cadmium, Manganese, and Lead. Finally, the mean ± SD concentration of the metals at the Clarifier was as follows, BDL, 1.5146±0.5804 mg/L, and BDL for Cadmium, Manganese, and Lead, respectively. Both the mean concentrations for Cadmium and Lead metals were below the set regulatory limit by the National Environmental Management Authority (NEMA). The mean concentrations for pH were also within the range of NEMA ‘s values of 6.0 – 9.0. However, the mean values for Cadmium metal were BDL in all the samples. The slightly high level of manganese can nevertheless pose a threat when released into the municipal sewer.The study also recommends a comprehensive analysis of other physio-chemical parameters such as COD, TOD, and TDS.

Keywords: Heavy Metals, Industrial Effluents, Atomic Absorption Spectrometer.

TABLE OF CONTENTS 

DECLARATION

DEDICATION

ACKNOWLEDGEMENT

ABSTRACT

LIST OF TABLES.

LIST OF FIGURES 

LIST ABBREVIATIONS AND SYMBOLS 

CHAPTER ONE

1.0 INTRODUCTION 

1.1 Background Information 

1.2 Statement of the Problem 

1.3 General Objective

1.3.1 Specific Objectives 

1.4 Justification of the Study

CHAPTER TWO 

2.0 LITERATURE REVIEW

2.1 Industrial Effluent in Paints and Coating 

2. 2 Physio-chemical Parameters

2.3  Heavy Metals in Paints and Coating Industry

2.4.1 Principles of Atomic Absorption Spectrophotometer

2.5.0 Wastewater Treatment 

3.0 RESEARCH METHODOLOGY 

3.1 Study Area 

3.2 Sample Collection.

3.3 Equipment, Apparatus, and Chemical Reagents  

3.4 Digestion of Sample 

3.5 Procedure of Sample Digestion 

3.6 Atomic Absorption Spectrometry Sample Analysis 

3.7 Preparation of Standard Solutions  

4.0 RESULTS AND DISCUSSIONS

Introduction

4.3 Heavy Metals 

4.3.2 Manganese  

4.3.3 Cadmium  

4.4 Efficiency of the Wastewater Treatment Plant 

5.0 CONCLUSIONS AND RECOMMENDATIONS 

5.1 Conclusion  

5.2 Recommendations  

REFERENCES  

APPENDICES