URBAN WASTEWATER TREATMENT WITH MATURE CONSTRUCTED WETLANDS Design and operation of experimental vertical-flow constructed wetland applied for treatment of urban wastewater (with/without diesel spills contamination), and recycling of effluent for agriculture purposes RAWAA HUSSEIN KADHIM AL-ISAWI PhD Thesis 2016 URBAN WASTEWATER TREATMENT WITH MATURE CONSTRUCTED WETLANDS Design and operation of experimental vertical-flow constructed wetland applied for treatment of urban wastewater (with/without diesel spills contamination), and recycling of effluent for agriculture purposes RAWAA HUSSEIN KADHIM AL-ISAWI School of Computing, Science and Engineering University of Salford, Salford, UK Submitted in Partial Fulfilment of the Requirements of the Degree of Doctor of Philosophy in Civil Engineering December 2016 TABLE OF CONTENTS TABLE OF CONTENTS ................................................................................................ I LIST OF FIGURES ...................................................................................................... IV LIST OF TABLES ........................................................................................................ IX ACKNOWLEDGEMENTS ....................................................................................... XII DECLARATION: LIST OF ORIGINAL PAPERS AND CONFERENCES ..... XIV ACRONYMS AND ABBREVIATIONS .................................................................. XXI ABSTRACT .............................................................................................................. XXV CHAPTER ONE: INTRODUCTION .......................................................................... 1 1.1 OVERVIEW ........................................................................................................................... 1 1.2 BACKGROUND ..................................................................................................................... 1 1.3 PROBLEM STATEMENT ....................................................................................................... 12 1.4 AIM AND OBJECTIVES ........................................................................................................ 14 1.5 IMPORTANCE OF THE STUDY ............................................................................................. 18 1.6 THESIS STRUCTURE ........................................................................................................... 19 CHAPTER TWO: CRITICAL LITERATURE REVIEW ...................................... 21 2.1 OVERVIEW ......................................................................................................................... 21 2.2 DEVELOPMENT OF CONSTRUCTED WETLANDS TREATMENT ............................................. 22 2.3 CLASSIFICATION OF CONSTRUCTED WETLANDS ................................................................ 30 2.3.1 Overall classification ............................................................................................................... 30 2.3.2 Free water surface-flow constructed wetlands......................................................................... 31 2.3.3 Subsurface-flow constructed wetlands ..................................................................................... 34 2.3.3.1 Vertical-flow constructed wetlands .................................................................................. 35 2.3.3.2 Horizontal flow constructed wetlands .............................................................................. 38 2.3.3.3 Hybrid constructed wetlands............................................................................................. 40 2.3.3.4 Application of tidal vertical-flow constructed wetlands ................................................... 41 2.4 COMPOSITION OF WETLAND .............................................................................................. 42 2.4.1 Overview .................................................................................................................................. 42 2.4.2 Water ........................................................................................................................................ 43 2.4.3 Macrophytes ............................................................................................................................. 44 2.4.4 Substrate................................................................................................................................... 47 2.4.5 Micro-organisms ...................................................................................................................... 48 2.5 REMOVAL MECHANISMS OF A CONSTRUCTED WETLAND .................................................. 50 2.5.1 Overview .................................................................................................................................. 50 2.5.2 Particle removal ....................................................................................................................... 53 2.5.3 Organic compounds removal ................................................................................................... 54 2.5.4 Nutrient removal ...................................................................................................................... 56 2.5.5 Hydrocarbon removal .............................................................................................................. 62 2.5.6 Heavy metal removal ................................................................................................................ 77 2.6 CLOGGING WITHIN CONSTRUCTED WETLANDS ................................................................. 79 2.7 TREATMENT WETLAND MODELS ....................................................................................... 81 i 2.8 PERFORMANCE OF CONSTRUCTED WETLANDS BY COMPARISON WITH PONDS .................. 85 2.9 RECYCLING OF WASTEWATER FOR AGRICULTURAL PURPOSES ......................................... 89 2.9.1 Application of wastewater for irrigated edible crops ............................................................... 89 2.9.2 Plant selection and the growing environment .......................................................................... 92 2.9.3 Nutrients and minerals ............................................................................................................. 93 2.10 SUMMARY........................................................................................................................ 94 CHAPTER THREE: MATERIALS AND METHODS ........................................... 95 3.1 OVERVIEW ......................................................................................................................... 95 3.2 EXPERIMENTAL SET-UP AND BOUNDARY CONDITIONS OF WETLANDS SYSTEM ................ 96 3.3 OPERATION METHOD FOR VERTICAL-FLOW CONSTRUCTED WETLANDS ......................... 103 3.4 WATER QUALITY ANALYSIS ............................................................................................ 105 3.5 WETLAND PLANT GROWTH MONITORING ........................................................................ 108 3.6 PETROLEUM HYDROCARBON SELECTION ........................................................................ 108 3.7 PETROLEUM HYDROCARBON ANALYSIS .......................................................................... 109 3.8 CLOGGING TESTS AND MODELLING ................................................................................. 110 3.9 EXPERIMENTAL SET-UP FOR PERFORMANCE COMPARISON BETWEEN ARTIFICIAL PONDS AND CONSTRUCTED WETLANDS ............................................................................................ 115 3.9.1 Artificial pond set-ups ............................................................................................................ 115 3.9.2 Vertical-flow constructed wetland set-up ............................................................................... 116 3.9.3 Operation method for vertical-flow constructed wetlands and pond systems ........................ 118 3.10 EXPERIMENTAL SET-UP AND BOUNDARY CONDITIONS OF CHILLI PLANTS IN GREENHOUSE ENVIRONMENT ....................................................................................................................... 120 3.10.1 Selection of fruiting vegetables ............................................................................................ 120 3.10.2 Growing of chillies ............................................................................................................... 120 3.10.3 Irrigation water sources ....................................................................................................... 126 3.11 STATISTICAL ANALYSIS ................................................................................................. 130 3.12 EXPERIMENTAL RESEARCH LIMITATIONS ...................................................................... 131 3.13 SUMMARY...................................................................................................................... 133 CHAPTER FOUR: RESULTS AND DISCUSSION .............................................. 134 4.1 OVERVIEW ....................................................................................................................... 134 4.2 LONG-TERM TREATMENT EFFICIENCY PERFORMANCE OF WETLAND FILTERS ................ 135 4.2.1 Inflow water quality ..............................................................................................................