Wetland wastewater treatment systems : a New Zealand based review : a thesis presented in partial fulfilment of the requirements for the degree of Master of Technology at Massey University

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A NEW ZEALAND BASED REVIE"W

A thesis presented in partial fulfilment

of flit.: requirements for !he degre e or

Mastei of Technology at Massey University

- by -

Andrew Nicholas Shilton 1990

MASSEY UNIVERSITY

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1061113565

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ABSTRACT

Naturnl and constn.;ctcd wetlands have proven capable of prm'iding a high standard of renovation to wastewater :rnd their use as engineered treatment systems is rapidly dt>veloping in New Zealand and overseas. This thesis begins by examining the nature of the wetland environment and outlines the renovating proces~es it contains. The different types of wetland treatment systems are reviewed. Dis-:ussion continues into design and management principles which include physical and process design and hydrological and biotic considerations. Finally a review is made of the applicc:tior. of wetlands to the treatment of domestic sewage, non-point pollution, and indu:,trial wastewaters. The conclusion is reached that wetland treatment systems offers an innovative and appropriate solution to a wid~ range of New Zealand's waste treatment problems and are likely to become an increasingly common treatrr.ent option in this country.

PREFACE AND ACKNOWLEDGEMENTS

This thesis concludes approximately eighteen months of rcvib.ving literature, finding and interpreting data and interviewing prominent workers in this field. I sincerely thank all these people who sent me their reports and papers, and those who gave me their time and shared their knowledge and experiences.

My thanks to Dr Rao Bhamidimarri, my supervisor, for guiding me through my masterate

studies, and to both the Department of Biotechnology at Massey University and the Waste Tccynology Group at MAF Invennay for support and assistance. Also special thank:; to all these who helped typ~ and prepare this work.

Special acknowledgement must be given to the Returned Services Association of New Zealand who granted me financial assistance in the form of the Kippenburger Memorial Fellowship.

Finally I am most grateful for the unending help and support from my wife Jacqui.

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TABLE OF CONTENTS

ABSTRACT

PREFACE AND ACKNOWLED GEME NTS

INTRODUCTION

1.

2.

3.

THE PROFILE OF A 'WETLAND ENVIRONMENT

1.1 1.2 1.3

1.4

1.5 1.6 1.7

1.8

Defining a Wetland Types of Wetlands Importance of Wetlands Aquatic Environment

\Vetland Soils Wetland \'~gctation

Wetland Chemistry 1. 7 .1 Adsorption 1. 7 .2 Precipitation Wetland Microbiology

THE RENOVATING PROCESS

2.1

The Renovating Medium

2.2

Organic Dec0mposition

2.3

Oxygenation

2.4

Filtration and Scdiment~.ilion of Suspended Solids

2.5

Nitrogen Removal ami Stabi!i:)::ttion

2.6

Phosphorus Removal

2.7 Removal of Toxic Contaminants

2.7.1

Metals

2.7.2 Trace Organics 2.8 Pathogen Treatment

TYPES OF TREATMENT SYST€MS

3.1

Natural Wetbnds

3.2

Constructed Wetlands

3.2.1

Surface Flow Wetlands

3.2.2

Subsurface Flow Wetlands

3.2.3

Vertical Flow Wetlands

3.2.4

Surface Flow Versus Subsurface Flow Wetlands

3.3

Aquatic Plant Systems

3.3.1 Floating Plant Systems

3.3.2

^{Submerged Plan}t Systr-ms

Page

11

1 4 5 5 7 9

10

11

14 14

15 16

18

18 19 22

25

26 29

30

30 31 32

34

34

35

36

36 37

38

39

40

42

4.

5.

6.

PHYSICAL AND PROCESS DESIGN

4.1 Site Evaluntion

4.2 Design Equations and Evaluation 4.3 Design Parameters

4.3.l Flow Rate 4.3.2 Retention Time 4.3.3 Water Depth 4.3.4 Loading Rate 4.4 Sizing

4.5 Shape

4.6 Bed Configurations

4.7

Piping Configurations 4.8 bier Outlet Structures 4.9 Selection of Substrate

HYDRAULIC AND HY DROLOGIC AL DESIGN

S. 1

- '?

) , _

5.3 5.4 5.5

\Vetland I3cd Hydraulics

5.1.1 Surface r:Iow Wetlands 5.1.2 Subsurface Flow Wctla11ds Water Hydrology

Hydrolo~ical Balance Staiing the Wetland Effluent Routing

DIOTIC CONSIDERATIONS

6.1 Plant Selection

6.2 \.Vetland Plant Species

6.2.1 Scirpus and similar species

6.2.2

Typlza spp.

6.2.3

Juncus spp.

6,?74

^{Glyceria spp.}

6.2.5

Phragmires spp.

6.2.6

Bawnea spp.

6.2.7

Other species

6.3 Establis;lment of \\'etland Plants 6.4 Harvesting

6.5

uesign

44 44 45 47 47

48 48

50 51

51 55 56 57

58

60 60

(,Q

60

64 66 67 69

70 71 72 72 73 73 74 74 74 75 75 79

80

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7. MANAGEMENT AND GENERAL CONSIDERATIONS

7. l Public Perceptions and Project Planning

7.2 At..:~.thctics

7.2.1

Plants

7.2.2

Odours

7.2.3 Organic Overloading 7 .3 Pest Control

7.3 1 Algae

7.3.2 Floating Plants 7.3.3 Sewage Fungus 7.3.4 Insects

7.3.5 Wildlife 7.4

!\1onitoring

8.

REVIEW OF

\ VETLAND TREATMENT

APPLICATIO~S 8.1

8.2

8.3

SUMMARY

Dumcstic Sewage

\). 1.1 Rawt:ne, l Io~ianga County - Surface flo\v Wetland 8.1.2

Coromanc.lel Township - Subsurface Flow Wetl;md

8. l .3

\tlatakana, Rodney County - Combined subsurface/

surface flow

wetland

Non

Point Pollution

8. 2.1 On Site Treatment of Domestic and Agricultural

Waste waters

8.2.2

Renovation of Polluted Runoff and Rece iving Waters

Industrial

and Toxic Wastewaters

8.3.1

Pulp and Paper Mill Effluent

8.3.2

Acid Mine Drainage

8.3.3 Landfill Leachate

REFERENCES

APPENDIX

81

81

84 84 84 85

86 86

87 87 87

~8

88

90

90

90

93

94

95

96 98

99 99 100

101

103

106

114

LIST OF FIGURES

1. Major Wetland Systems

2. Ill11stration of Redox Conditiom Around Roots of Wetland Plants

3. The Roots and Rhizomes of Phragmites rzustralis

4. Microbial Colonisation of the Submerged Section of

a

Typha Shoot

Page

6 11

13

20

5. The Three Variations of Organic Stabilisation by Bacterial Films in a Wetland 21 6. Algae Removal by a Wetland

7. Th~ Nitrogen Flow Through a Wetland Treatment System 8. Surfa~e Flow Wetland

9. Subsurface flow Wetland 10. Vertical Flow Wetland 11. Floating ?l::lnt System 12. Submerge(. Plant Sys¹~m

13. Serpentine Surface Flow Wetbnd 14. Inlet and Outlet Designs

15. Schematic Representation or a ..'lubsurface \Vctland Bed with Overflow Conditions

26 28 36 37

38

41 42 54

58 61

16. Schematic Rt:prl'.seiltation

or

thl Hydraulic Profile in a Subsurface Wetland 62

17. A Conceptual Model of Wetland Hydrology 65

18. Effect of Stagnation on Plant Growth 78

19. View of Dieback of Typha at Whangarei Trial Wetland 80

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LIST OF TABLES

Page

1.

Trace

Organic

Removal in

Pilot

Scale Water Hyacinth

32

Basins

2. Guideline

Values for Selection of Hydraulic Loading

50

Rate for Domestic Sewage

3.

Comparison of Treatment

Between

Vegetated and Unvegetated

70

Wetland Beds

4.

Monitoring Data from the Rawene Wetland

92

5.

Monitoring Data from

the

Corornandel Wetland

94

G.

Summary

of Monitoring

Data

from

the Matakana Wetlands

95

7.

Examples of On Site Treatment in New Zealand 97

8.

Polishing Efficiei:cics

of Pulp

Mill Effluent

99

9.

Tre<:tment Efficiencies of

Acid

Mine Drainage

100