development and optimization of constructed mangrove...

DEVELOPMENT AND OPTIMIZATION OF CONSTRUCTED MANGROVE WETLAND

SYSTEMS FOR TREATMENT OF MUNICIPAL WASTEWATER

WU YAN

MASTER OF PHILOSOPHY

CITY UNIVERSITY OF HONG KONG

JANUARY 2008

CITY UNIVERSITY OF HONG KONG

香港城市大学

Development and optimization of constructed

mangrove wetland systems for treatment of

municipal wastewater

开发并优化红树林人工湿地作为生活污水的处

理系统

Submitted to

Department of Biology and Chemistry 生物及化学系

In Partial Fulfillment of the Requirements for the Degree of Master of Philosophy

哲学硕士学位

by

Wu Yan 伍彦

January 2008 二零零八年一月

Abstract i

Development and optimization of constructed mangrove wetland

systems for treatment of municipal wastewater

Submitted by Wu Yan

For the Degree of Master of Philosophy at City University of Hong Kong

(January, 2008)

Abstract

The discharge of untreated or partially treated municipal wastewater deteriorates

coastal and marine ecosystems. Conventional wastewater treatment methods are often

too complicated and too expensive for developing countries and small communities in

rural areas of developed countries. The constructed wetland treatment system with

annual plants has been employed as an alternative treatment method but it needs

frequent harvesting. The aim of this MPhil research is to develop and optimize a

subsurface flow constructed mangrove wetland system as a secondary municipal

wastewater process. A series of greenhouse studies using constructed mangrove

microcosms without tidal flushing were conducted under different hydraulic retention

times (HRT), mangrove plant species, salinities and the introduction of an idle period.

The study also evaluates the comparability between artificial wastewater and real

primary-settled municipal wastewater collected from a sewage treatment work in Hong

Kong SAR in treatment performance and outcome for wastewater-borne pollutants.

The results demonstrate that constructed mangrove tanks planted with Kandelia

Abstract ii

candel had significantly higher treatment efficiency than the unplanted tanks. The

removal percentages of dissolved organic carbon (DOC), ammonia-nitrogen (N),

inorganic-N, total Kjeldahl N and ortho-phosphate in the planted systems were

70.43-76.38%, 76.16-91.83%, 47.89-63.37%, 75.15-79.06% and 86.65-91.83%,

respectively. Plant growth as well as tissue N and phosphorus (P) concentrations and

uptake were enhanced by the addition of wastewater. The mass balance showed that

active nitrification and denitrification processes occurred in the mangrove system, with

25-30% N lost to atmosphere, while P was mainly accumulated in sediment. The

removal efficiency under 10-day HRT was better than that of 5-day but more land area

is needed for longer the HRT. The introduction of an idle period significantly enhanced

removal percentages of DOC and N as microbial activities in the soil were stimulated

after the idle period. The denitrification potential at the end of the second treatment

period was approximately 50-fold higher than that at the end of the first treatment

period.

Although the planted systems had better treatment performance than the unplanted

ones, no significant difference in removal efficiency was found among the three

mangrove species, namely Aegiceras corniculatum, Acanthus ilicifolius and Bruguiera

gymnorrhiza during the four-month wastewater treatment. All planted systems

effectively removed pollutants with 90% of DOC, 99% of ammonia-N, 78% of

inorganic N removal, and > 97% of TKN and inorganic P removed under 5-day HRT.

Abstract iii

The total amounts of N and P accumulated in the tissues of A. ilicifolius were

comparable to that of A. corniculatum and B. gymnorrhiza. However, the fate of

wastewater-borne pollutants and their distribution in different components of the

constructed mangrove wetland varied among the three mangrove species, indicating that

the root structure and oxygen released from roots of each mangrove species might be

different, which then altered the nutrient and transformation in the soil. The treatment

performance of mangrove microcosms planted with A. corniculatum was affected by

wastewater salinity, with a poorer rate of removal of DOC and N under high salinities

(15 and 30ppt, parts per thousands). Saline wastewater reduced the denitrification

potential. However, growth of A. corniculatum and tissue nutrient uptake was the

highest at 15ppt.

The removal percentages of DOC and P were different between artificial and real

municipal wastewater under the same treatment condition, probably due to the absence

of microorganisms, ions (particularly Fe3+ and Ca2+), trace elements and different forms

of organic matter and P in artificial wastewater, as these are difficult to simulate.

However, no significant difference in N removal was found between artificial and real

wastewater. This suggested that if the formula for preparing artificial wastewater is

further improved, it is possible to extrapolate data from artificial wastewater to real

wastewater situations.

Abstract iv

All effluent leaving the planted mangrove systems was able to meet the effluent

discharge standards of Water Control Zones set by the Environmental Protection

Department of Hong Kong SAR. The present research demonstrates the feasibility of

using constructed mangrove wetlands, without tidal flushing, as the secondary treatment

process for municipal wastewater, even for those with high salinity.

Table of Contents vii

Table of Contents

Abstract i

Acknowledgment v

Table of Contents vii

List of Tables xvii

List of Figures xxviii

Abbreviations xxxvi

Chapter 1 Introduction 1

1.1 General Introduction 1

1.2 Aims and objectives 3

1.3 Research plan 4

Chapter 2 Literature review 6

2.1 Problem of wastewater pollution 6

2.1.1 Sources and types of wastewater 6

2.1.2 Municipal wastewater 7

2.1.2.1 Quantities of municipal wastewater 7

2.1.2.2 Pollutants in municipal wastewater 9

2.1.2.3. Shortage of water and needs for water reuse 9

2.1.3 Nutrients and eutrophication problems 11

2.1.4 Toxic pollutant 11

2.2 Conventional technologies for municipal wastewater treatment 12

2.2.1 Physical methods 12

Table of Contents viii

2.2.2 Chemical methods 12

2.2.3 Biological methods 13

2.2.4 Wetland for wastewater treatment 15

2.3. Definition and distribution of wetland 15

2.3.1 Natural wetland ecosystems 15

2.3.2 Constructed wetlands 17

2.3.3 Significance of using wetlands for wastewater treatment 17

2.3.3.1 Wetland structure and function related to wastewater treatment 18

2.3.3.2 Examples of constructed wetlands for municipal wastewater

treatment

21

2.4 Mechanisms involved in wastewater treatment in constructed wetlands 21

2.4.1 Cycling of basic elements ( C, N, and P) in wetlands 21

2.4.1.1 Carbon 21

2.4.1.2 Nitrogen 24

2.4.1.3 Phosphorus 26

2.4.2 Removal of organic matter in wetlands 26

2.4.3 Removal of nutrients in wetland 27

2.4.3.1 Nitrogen removal 27

2.4.3.2 Phosphorus removal 29

2.4.3.3 Removal of bacteria and pathogens 30

2.4.3.4 Removal of suspended solids 30

2.4.3.5 Removal of toxic pollutants 31

2.5 Factors affecting wetland treatment efficiency 32

2.5.1 Flow patterns 32

2.5.2 Hydraulic retention time 35

2.5.3 Plant species and soil types 35

2.5.4 Salinity 36

2.5.5 Other factors 37

Table of Contents ix

2.6 Mangrove wetland for wastewater treatment 40

2.6.1 General features of mangrove wetland 40

2.6.2 Advantages of using mangrove wetland for wastewater treatment 41

2.6.3 Previous studies on mangrove wetland-wastewater treatment system 42

2.7 Limitation of using wetland for municipal wastewater treatment 44

2.7.1 Effects of wastewater on soils in wetland 44

2.7.2 Effects of wastewater on vegetations in wetland 45

2.7.3 Other limitations 46

Chapter 3 Effects of retention time on removal of nutrients and dissolved

organic carbon in primary settled municipal wastewater

48

3.1 Introduction 48

3.2 Materials and methods 49

3.2.1 Set-up of mangrove tide tanks 49

3.2.2 Collection of wastewater and soil sample 52

3.2.2.1 Sampling methods 52

3.2.2.2 Storage and preservation methods 52

3.2.3 Sample analyses 53

3.2.3.1 Analysis of soil sample 53

3.2.3.1.1 Soil porosity 53

3.2.3.1.2 Total organic carbon content 54

3.2.3.1.3 Inorganic nitrogen (ammonia-nitrogen and nitrate-nitrogen) 54

3.2.3.1.4 Inorganic phosphorus 55

3.2.3.1.5 Total P and total Kjeldahl N 55

3.2.3.1.6 Dehydrogenase activity 56

3.2.3.1.7 Denitrification potential 57

3.2.4 Measurement of water sample 58

Table of Contents x

3.2.4.1 Dissolved organic carbon, inorganic nitrogen and phosphorus 58

3.2.4.2 Total phosphorus and total Kjeldahl nitrogen 58

3.2.5 Plant determination 59

3.2.5.1 Plant growth 59

3.2.5.2 Nutrient concentrations (total phosphorus and total nitrogen) 59

3.2.6 Mass balance of nitrogen and phosphorous in mangrove tide tank

system

60

3.2.7 Determination of flow rate 61

3.2.8 Statistical analyses 61

3.3 Results 62

3.3.1 Wastewater treatment efficiencies 62

3.3.1.1 Removal of dissolved organic carbon 62

3.3.1.2 Removal of ammonia 63

3.3.1.3 Removal of nitrate 63

3.3.1.4 Removal of inorganic nitrogen 68

3.3.1.5 Removal of total Kjeldahl nitrogen 68

3.3.1.6 Removal of inorganic phosphorus 71

3.3.1.7 Removal of total phosphorus 71

3.3.2 Growth of mangrove plants 74

3.3.2.1 Initial properties of mangrove plants 74

3.3.2.2 Plant growth during wastewater treatment 74

3.3.2.3 Nutrient status of mangrove plants after wastewater irrigation 75

3.3.3 Characteristics of soils 79

3.3.3.1 Background properties of Sai Keng soils 79

3.3.3.2 Nutrients in the soil after wastewater treatment 79

3.3.3.2.1 Nitrogen 79

3.3.3.2.2 Phosphorus 84

3.3.3.3 Total organic matter 84

Table of Contents xi

3.3.3.4 Dehydrogenase activity 86

3.3.3.5 Denitrification potential 86

3.3.4 Mass balance of nutrients in constructed mangrove wetland

treatment systems

88

3.4 Discussion 94

3.4.1 Mangrove wetlands as a secondary wastewater treatment system 94

3.4.2 Mechanism of wastewater treatment in constructed mangrove

wetland

98

3.4.2.1 Role of mangrove plants 98

3.4.2.2 Roles of soil and microorganisms 100

3.4.3 Effects of HRT on treatment efficiencies 102

3.5 Conclusions 102

Chapter 4 Effects of using artificial wastewater on removal of nutrients

and dissolved organic carbon (DOC) in constructed mangrove

wetlands

104

4.1 Introduction 104

4.2 Materials and Methods 105

4.2.1 Experimental design and analyses 105

4.2.2 Preparation of artificial wastewater 106


4.3 Results 107


4.3.1.1 Removal of dissolved organic matter 107

4.3.1.2 Removal of nitrogen 108

Table of Contents xii

4.3.1.3 Removal of inorganic phosphorus (ortho-P) 116

4.3.2 Growth of mangrove plants under artificial and real wastewater

treatment

116


4.3.2.2 Nutrient status of mangrove plants after wastewater irrigation 118

4.3.3 Comparison of soil characteristic between discharge of artificial and

real municipal wastewater

122

4.3.3.1 Soil nutrient concentrations 122

4.3.3.2 Microbial activities in mangrove soil after wastewater treatment 127

4.3.4 Mass balance of nutrients in systems treated with artificial and real

wastewater

130

4.4 Discussion 135

4.5 Conclusions 136

Chapter 5 Effects of idle period on removal of nutrients and dissolved

organic carbon (DOC) in municipal wastewater

138





5.3 Results 140

5.3.1 Effects of idle period on wastewater treatment efficiencies 140

5.3.1.1 Removal of dissolved organic carbon 140



5.3.2 Effects of idle period on growth of mangrove plants 150


Table of Contents xiii

5.3.2.2 Plant growth after wastewater treatment 150

5.3.2.3 Nutrient status of mangrove plants after wastewater treatment 158

5.3.3 Effects of idle period on mangrove soil properties 161

5.3.3.1 Background properties 161

5.3.3.2 Chemical properties of soils after wastewater treatment 161

5.3.3.3 Microbial activities in mangrove soil after wastewater treatment 166

5.3.4 Mass balance of nutrients in systems during the first and second

wastewater treatment periods

170

5.4 Discussion 175

5.5 Conclusions 178

Chapter 6 Effects of three different mangrove species on constructed

mangrove wetlands for the treatment of artificial municipal

sewage

180





6.3 Results 183


6.3.1.1 Removal of DOC 183


6.3.1.3 Removal of phosphorus 187

6.3.2 Plant growth 189



6.3.2.3 Nutrient content of the three mangrove species after wastewater 195

Table of Contents xiv

treatment

6.3.3. Effects of different mangrove species on retention of

wastewater-borne pollutants in mangrove soil

197

6.3.3.1 Soil nutrients and total organic matter content before and after

wastewater treatment

197

6.3.3.1.1 Nitrogen 197

6.3.3.1.2 Phosphorus 200

6.3.3.1.3 Total organic matter 200

6.3.3.2 Microbial activities before and after wastewater treatment 203



6.3.4 Mass balance before and after wastewater treatment 205

6.4 Discussion 210

6.4.1 Comparison of treatment efficiencies among different plant species 210

6.4.2 Fate of pollutants in wetlands planted with different mangrove

plants

211

6.4.3 Selection of mangrove plants 214

6.5 Conclusions 215

Chapter 7 Effects of salinity on treatment efficiencies of nutrients and

DOC by constructed mangrove wetland systems

216


7.2 Materials and methods 218

7.2.1 Set-up of mangrove tanks 218

7.2.2 Statistical analysis 218

7.3 Results 219

Table of Contents xv


7.3.1.1 Removal of dissolved organic matter 219



7.3.2 Plant growth 225



7.3.2.3 Nutrient status of A. corniculatum before and after the

four-month wastewater discharge

230

7.3.3 Effects of wastewater spiked with different salinities on nutrient

content of mangrove soil

230

7.3.3.1 Nitrogen 230


7.3.3.3 Total organic matter (TOM) 234

7.3.3.4 Microbial activities 237



7.3.4 Mass balance of nitrogen and phosphorus before and after


239

7.3.4.1 Nitrogen 239


7.4 Discussions 244

7.4.1 Feasibility of using constructed mangrove wetlands for treating

wastewater with high salinity

244

7.4.2 Effects of salinity on treatment efficiency of mangrove wetland

systems

245

7.4.2.1 Effect on microbial activities in mangrove soil 245

7.4.2.2 Effects of salinity on the growth of A. corniculatum 247

Table of Contents xvi

7.5 Conclusions 248

Chapter 8 General discussion

250

8.1 Feasibility of using constructed mangrove wetland in treating primary

settled municipal wastewater

250

8.2 Optimization of mangrove constructed wetland treatment systems 253

8.3 Fate of wastewater-borne pollutants in constructed wetland treatment

systems

256

8.4 Contributions to original knowledge 257

8.5 Limitations of the present study and future research 259

8.6 Conclusions 262

References 265

Conferences and Publications 319

List of Tables xvii

List of Tables

Table 2-1 Examples of sources of wastewater in different places

8

Table 2-2 Composition of municipal wastewater (Units in mg L-1

except for pH)

10

Table 2-3 The major roles of macrophytes in constructed wetland

treatment systems

20

Table 2-4 Examples of using constructed wetlands for municipal


22

Table 2-5 Effects of recirculation on removal of total nitrogen (TN)

and ammonia (NH4+-N)

39

Table 2-6 Previous studies on wastewater treatment efficiencies by

mangrove

43

Table 3-1 Experimental design to examine effects of hydraulic

retention time (HRT) and mangrove plants

50

Table 3-2 Preservation methods of water samples

53

Table 3-3 Effects of plant and hydraulic retention time on wastewater

removal efficiency (in % except nitrate) during the 6-month

treatment of primary settled municipal sewage

65

Table 3-4 Two-way ANCOVA results (F-value) showing effects of 65

List of Tables xviii

hydraulic retention time (HRT) and plants on the

concentration of DOC, NH3-N, NO3--N, inorganic-N,

inorganic-P, TKN and TP in effluent

Table 3-5 Growth and biomass of K. candel before and after

wastewater irrigation

76

Table 3-6 Nutrient status of K. candel before and after wastewater

irrigation

77

Table 3-7 Background properties of Sai Keng mangrove soil

80

Table 3-8 Variations of initial background nutrient concentrations in

soil from different treatments

80

Table 3-9 Changes of concentration of nutrients and TOM in soil after


83

Table 3-10 Two-way ANOVA results showing effects of hydraulic

retention time (HRT) and plant on the percentages of

changes of nitrogen elements (NH4+, NO3

-, Inorganic N and

TKN) to the initial concentration in soil in tanks after

6-month wastewater treatment

83


retention time (HRT) and plant on the percentages of

changes of phosphorus elements (PO43-, TP) to initial

concentration in soil in mangrove tanks after 6-month

84

List of Tables xix



retention time (HRT) and plant on the percentage of changes

of TOM to initial concentration, denitrification potential and

dehydrogenase activity in soil in mangrove tanks after the


87

Table 3-13 Microbial activities (dehydrogenase activity and

denitrification potential) in mangrove soil at the end of


88

Table 3-14 Amount of input nitrogen from wastewater, soil and plant

over the 6-month wastewater treatment

90

Table 3-15 Amount of output nitrogen from wastewater, soil and plant


90

Table 3-16 Mass balance of nitrogen (mg) and percentages of individual

part of nitrogen to total nitrogen (in bold) in wastewater, soil

and plant over the 6-month wastewater treatment

91

Table 3-17 Amount of input phosphorus from wastewater, soil and plant


92

Table 3-18 Amount of output phosphorus from wastewater, soil and

plant over the 6-month wastewater treatment

92

Table 3-19 Mass balance of phosphorus (mg) and percentages of 93

List of Tables xx

individual part of phosphorus to total phosphorus (in bold) in

wastewater, soil and plant over the 6-month wastewater

treatment

Table 3-20 Removal efficiencies of different constructed wetlands for

sewage treatment

96

Table 3-21 Percentages of effluents complied with discharge standards

at different water bodies in Hong Kong set by the

Government

97

Table 4-1 Experimental design to examine effects of using artificial

wastewater on treatment efficiency of mangrove wetland

with 5-day HRT

105

Table 4-2 Characteristics of the artificial wastewater simulating real

municipal wastewater

107

Table 4-3 Compositions of stock solution used for preparing artificial

wastewater

107

Table 4-4 Effects of wastewater types (real and artificial wastewater)

on removal efficiency (in % except nitrate) during the

6-month treatment

111

Table 4-5 Two-way ANCOVA results (F-value) on concentrations of

DOC, NH3-N, NO3--N, inorganic-N, ortho-P, and TKN in

effluent from microcosm with different types of wastewater,

111

List of Tables xxi

and with and without plants

Table 4-6 Growth and biomass of K. candel before and after

wastewater irrigation

120

Table 4-7 Nutrients status of K. candel before and after wastewater

irrigation

121

Table 4-8 Changes of soil nutrients concentration of nutrients and total

organic matter in soil after wastewater treatment

125

Table 4-9 Two-way ANOVA results showing effects of types of

wastewater and plant on the percentages of changes of

nitrogen elements (NH4+, NO3

-, Inorganic N and TKN) to the

initial concentration in soil in systems after the 6-month


125


wastewater and plant on the percentages of changes of

phosphorus elements (PO43-, TP) to initial concentration in

soil in mangrove tanks after 6-month wastewater treatment

127


wastewater and plant on the changes of total organic matter,

denitrification potential and dehydrogenase activity in soil in

mangrove tanks after 6-month wastewater treatment

129

Table 4-12 Microbial activities (dehydrogenase activity and 129

List of Tables xxii

denitrification potential) in mangrove soil at the end of the


Table 4-13 Amount of input and output nitrogen from wastewater, soil


131




132

Table 4-15 Amount of input and output phosphorus from wastewater,

soil and plant over the 6-month wastewater treatment

133

Table 4-16 Mass balance of phosphorus (mg) and percentages of


wastewater, soil and plant over the 6-month wastewater

treatment

134

Table 5-1 Experimental design to examine effects of idle period on

treatment efficiencies of mangrove wetland with 5-day HRT

139

Table 5-2 Effects of idle period on wastewater removal percentage (in

% except nitrate) during the two periods of wastewater

treatment

143

Table 5-3 Two-way ANCOVA results (F-value) on concentrations of

DOC, NH3-N, NO3--N, inorganic-N, inorganic-P, and TKN

in effluent from microcosms during the two treatment

143

List of Tables xxiii

periods

Table 5-4 Growth of A. corniculatum before and after the first and

second periods of wastewater treatment

151

Table 5-5 Percentage increase of biomass of A. corniculatum during

the first and second treatments

151

Table 5-6 Percentage increase of nitrogen concentration and uptake of

A. corniculatum during the first and second treatments

159

Table 5-7 Percentage increase of phosphorus concentration and uptake

of A. corniculatum during the first and second treatments

160

Table 5-8 Background properties of mangrove soil used in the first and

second treatment periods

162

Table 5-9 Changes in nutrients concentration per wastewater loadings

in soil after the first and the second wastewater treatment

periods

164

Table 5-10 Two-way ANOVA results showing effects of a period of idle

and plant on the percentages of changes in concentrations of

nitrogen elements (NH4+, NO3

-, Inorganic N and TKN) per

wastewater loading after the 6-month wastewater treatment

164

Table 5-11 Two-way ANOVA results showing effects of an idle period

and plant on the percentages of changes in concentrations of

168

List of Tables xxiv

phosphorus elements (PO43-, TP) per wastewater loadings

after the first and second wastewater treatment periods

Table 5-12 Two-way ANOVA results showing effects of idle and plant

on the percentages changes in concentration of total organic

matter per wastewater loadings, denitrification potential and

dehydrogenase activity in systems after the first and the

second wastewater treatment periods

169

Table 5-13 Microbial activities (dehydrogenase activity and

denitrification potential) in mangrove soil at the end of the

first and second treatment periods

169

Table 5-14 Amount of input and output nitrogen from wastewater, soil

and plant during the first and second wastewater treatment

171



and plant during the first and second wastewater treatment

periods

172

Table 5-16 Amount of input and output phosphorus from wastewater,

soil and plant during first and second wastewater treatment

periods

173



wastewater, soil and plant during the first and second

174

List of Tables xxv

treatment periods

Table 5-18 Percentages of effluents fulfilling the different levels of

discharge standards in Hong Kong

177

Table 6-1 Average removal efficiencies (%) of dissolved organic

carbon (DOC) and nutrients from primary settled wastewater

184

Table 6-2 Nutrient content in three mangrove species at the beginning

191

Table 6-3 Nutrient content in three mangrove species in the end of the

experiment

196

Table 6-4 Changes of concentration of nutrients and total organic

matter in soil after wastewater treatment

199


over the four-month wastewater treatment

206



206

Table 6-7 Mass balance of nitrogen (mg) and percentages of nitrogen

in each component (wastewater, soil and plant) to total

nitrogen (in bold) over the four-month wastewater treatment

207



208

List of Tables xxvi


plant over the four-month wastewater treatment

208


phosphorus in each component (wastewater, soil and plant)

to total phosphorus (in bold) over the four-month wastewater

treatment

209

Table 6-11 Comparison of concentration of nitrogen and phosphorus

(mg g-1) in different plant tissues

213

Table 7-1 Removal efficiencies (%) using artificial saline municipal

wastewater

221

Table 7-2 Growth and biomass of A. corniculatum before and after


226

Table 7-3 Nutrient status in A. corniculatum before and after


229

Table 7-4 Changes of nutrients concentration in soil after wastewater

treatment

233

Table 7-5 Changes of concentration of TOM, denitrification potential

and dehydrogenase activity in soil after wastewater treatment

236



240

List of Tables xxvii



240



and plant over four-month wastewater treatment

241



242


plant over the four-month wastewater treatment

242


part of phosphorus to total phosphorus (in bold) in

wastewater, soil and plant over the four-month wastewater

treatment

243

Table 7-12 Percentages of effluents complied with discharge standards

at different water bodies in Hong Kong set by the

Government

246

List of Figures xxviii

List of Figures

Fig. 2-1 Free water surface flow system

34

Fig. 2-2 Subsurface flow system

34

Fig. 3-1

Schematic diagram of a constructed mangrove tank system

showing the inlet, treatment and outlet zones

51

Fig. 3-2 Concentrations of dissolved organic carbon (DOC) in

influent and effluent from different treatments during the

6-month wastewater application

64

Fig. 3-3 Concentrations of ammonia in influent and effluent from

different treatments during the 6-month wastewater

application

66

Fig. 3-4 Concentrations of nitrate in influent and effluent from


application

67

Fig. 3-5 Concentrations of inorganic nitrogen in influent and effluent

from different treatments during the 6-month wastewater

application

69

Fig. 3-6 Concentrations of TKN in influent and effluent from


application

70

List of Figures xxix

Fig. 3-7 Concentrations of inorganic phosphorus in influent and

effluent from different treatments during the 6-month

wastewater application

72

Fig. 3-8 Concentrations of TP in influent and effluent from different

treatments during the 6-month wastewater application

73

Fig. 3-9 Growth of mangrove plants during the 6-month wastewater

treatment (a) Stem height; (b) leaf number; (c) branch

number

78

Fig. 3-10 Nutrient concentrations in soil before (March) and after

(September) the 6-month experiment: (a)ammonium; (b)

nitrate; (c) inorganic nitrogen; (d) TKN

81

Fig. 3-11

Nutrient concentrations in soil before (March) and after

(September) experiments: (a) Inorganic P; (b) TP

85

Fig. 3-12

Two-way ANOVA results showing effects of hydraulic

retention time (HRT) and plant on the percentage of changes

of TOM to initial concentration, denitrification potential and

dehydrogenase activity in soil in mangrove tanks after the


87

Fig. 4-1

Mean concentrations of DOC in effluent from different

systems during the 6-month wastewater treatment

110

List of Figures xxx

Fig. 4-2 Mean concentrations of ammonia-N in effluent from

different systems during the 6-month wastewater treatment

112

Fig. 4-3 Mean concentrations of nitrate-N in effluent from different


113

Fig. 4-4 Mean concentrations of inorganic N in effluent from

different systems during the 6-month wastewater treatment

114

Fig. 4-5 Mean concentrations of TKN in effluent from different


115

Fig. 4-6 Mean concentrations of inorganic P in effluent from different


117

Fig. 4-7 Growth of mangrove plants during 6-month wastewater

treatment (a) stem height; (b) branch number; (c) leaf

number

119

Fig. 4-8 Nitrogen concentrations in soil before (march) and after

(September) experiments: (a) ammonium; (b) nitrate; (c)

inorganic nitrogen; (d) TKN

124

Fig. 4-9 Phosphorus concentrations (inorganic P and TP) in soil

before (March) and after (September) wastewater treatment

126

Fig. 4-10 Total organic matter in soil before (March) and after

(September) wastewater treatment

128

List of Figures xxxi

Fig. 5-1 Mean concentrations of DOC in effluent from different

systems during the two periods of wastewater treatment

142

Fig. 5-2 Mean concentrations of ammonia in effluent from different


144

Fig. 5-3 Mean concentrations of nitrate in effluent from different

treatments during the two periods of wastewater treatment

146


different systems during the two periods of wastewater

treatment

147



148



149

Fig. 5-7 Plant biomass in terms of roots, stems and leaf before and

after wastewater treatment during the first and second

treatment periods

152

Fig. 5-8 N concentrations in terms of roots, stems and leaf before and


treatment periods

153

Fig. 5-9 P concentrations in terms of roots, stems and leaf before and 154

List of Figures xxxii


treatment periods

Fig. 5-10 N amount in terms of roots, stems and leaf before and after

wastewater treatment during the first and second treatment

periods

155

Fig. 5-11 P amount in terms of roots, stems and leaf before and after

wastewater treatment during the first and second treatment

periods

156

Fig. 5-12 Growth of mangrove plants over the first and second periods

of wastewater treatment (a) stem height; (b) leaf number; (c)

branch number

157

Fig. 5-13 Nutrient concentrations in soil in the beginning and end of

the first and second periods: (a) ammonium; (b) nitrate; (c)

inorganic nitrogen; (d) TKN

163

Fig. 5-14 Inorganic P and TP concentrations in soil in the beginning

and end of the first and second periods

167

Fig. 5-15 Total organic matter concentrations in soil in the beginning

and end of the first and second periods

168

Fig. 6-1 Mean concentrations of dissolved organic carbon (DOC) in

effluent from different systems during the four-month


183

List of Figures xxxiii

Fig. 6-2 Mean concentrations of ammonia in effluent from different

systems during the four-month wastewater treatment

185

Fig. 6-3 Mean concentrations of nitrate in effluent from different


185


different systems during the four-month wastewater

treatment

186



187



188

Fig. 6-7 Initial dried biomass in terms of root, stem and leaf in A.

corniculatum, B. gymnorrhiza and A. ilicifolius

190

Fig. 6-8 Growth in terms of stem height, leaf number and branch

number of the three mangrove species during the four-month


193

Fig. 6-9 Dried biomass in the end of the experiment (root, stem and

leaf of A. corniculatum, B. gymnorrhiza and A. ilicifolius)

194

Fig. 6-10 Nitrogen content in four systems before (March) and after 198

List of Figures xxxiv

(July) wastewater treatment

Fig. 6-11 Phosphorus content in four systems before (March) and after

(July) wastewater treatment

201

Fig. 6-12 Content of TOM in the four systems before (March) and

after (July) wastewater treatment

202

Fig. 6-13 Denitrification potential before and after wastewater

treatment

204

Fig. 6-14 Dehydrogenase activity before and after wastewater

treatment

204

Fig. 7-1 Mean concentration of DOC in effluent in systems planted

with A. corniculatum at different salinities

220

Fig. 7-2 Mean concentration of ammonia in effluent in systems

planted with A. corniculatum at different salinities

221

Fig. 7-3 Mean concentration of nitrate in effluent in systems planted


223

Fig. 7-4 Mean concentration of inorganic nitrogen in effluent in

systems planted with A. corniculatum at different salinities

223

Fig. 7-5 Mean concentration of TKN in effluent in systems planted


224

List of Figures xxxv

Fig. 7-6 Mean concentration of inorganic P in effluent in systems

planted with A. corniculatum at different salinities

224

Fig. 7-7 Growth of A. corniculatum after the four-month treatment of

wastewater at different salinities (a) 0 ppt; (b) 15 ppt; (c) 30

ppt

227

Fig. 7-8 Growth of A. corniculatum during the four-month

wastewater treatment in terms of stem height, leaf number

and branch number

228

Fig. 7-9 Concentration of nitrogen elements in the beginning (March)

and end of (July) wastewater treatment (a) ammonium, (b)

nitrate, (c) inorganic nitrogen and (d) TKN

232

Fig. 7-10 Concentration of phosphorus elements in the beginning

(March) and end (July) of wastewater discharge (a) inorganic

phosphorus, (b) total phosphorus

235

Fig. 7-11 Content of total organic matter in the beginning (March) and

end (July) of wastewater treatment

236

Fig. 7-12 Microbial activities in the beginning (March) and end (July)

of wastewater treatment (a) denitrification potential (b)

dehydrogenase activity

238

Abbreviations xxxvi

Abbreviations

Ac Aegiceras corniculatum

Ai Acanthus ilicifolius

ANCOVA analysis of co-variance

ANOVA analysis of variance

AnSBR anaerobic sequencing bath reactor

APs alkylphenols

APEs alkylphenol ethoxylates

AW artificial wastewater

Bg Bruguiera gymnorrhiza

BOD biological oxygen demand

COD chemical oxygen demand

FCs faecal coliforms

FIA flow injector analyser

GC-ECD gas chromatograph-electron capture detector

HRT hydraulic retention time

INT 2-p-iodophenyl-3-(p-nitrophenyl)-5-pheny tetrazolium chloride

Kc Kandelia candel

RW real wastewater

SC somatic coliphage

SPSS statistical package for social science

TKN total Kjeldahl nitrogen

TN total nitrogen

TOM total organic matter

TP total phosphorous

TSS total suspended solid

UASB upflow anaerobic sludge blanket

UAF upflow anaerobic filter

development and optimization of constructed mangrove...

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