018530 - switch sustainable water management in the city of … · milstein et al., 2009),...

018530 - SWITCH

Sustainable Water Management in the City of the Future

Integrated Project Global Change and Ecosystems

Deliverable reference number and title

D3.3.8: Professional training workshop. Educational material on water reuse and benefit of the

CW-EF as an environmental friendly technology. The treatment sites may be open to the public

Due date of deliverable: M59 Actual submission date: M60

Start date of project: 1 February 2006 Duration: 60 months Organisation name of lead contractor for this deliverable Revision [draft]

Project co-funded by the European Commission within the Sixth Framework Programme (2002-2006) Dissemination Level

PU Public PU PP Restricted to other programme participants (including the Commission Services) RE Restricted to a group specified by the consortium (including the Commission Services) CO Confidential, only for members of the consortium (including the Commission Services)

1

ABSTRACT

This workshop was about a hybrid system of constructed wetland–electro-flocculation polishing

secondary effluent, based on the experiments in Shafdan municipal wastewater treatment plant, Israel.

The purpose of this workshop was to educate professionals about the hybrid process and its

constituents and to demonstrate how to apply it. The invitees to this workshop were engineers,

scientists and professionals from the Tel Aviv-Yafo water corporation, constructed wetland

companies, electro-treatment and wastewater treatment companies and scientists from HUJI and

TAU.

ACKNOWLEDGEMENT

This investigation was partially supported by the EU–SWITCH project and the Italian Ministry of

Environment through Tel-Aviv University. The presented material is part of MSc graduate works of

Barash and Ozer (HUJI), and PhD works of Harif and Ben-Sasson (HUJI) and Milstein (TAU).

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List of contents: page

ABSTRACT 1

ACKNOWLEDGEMENT 1

1. EF-CW WORKSHOP, SWITCH PROJECT, WP 3.3 3

2. PROFESSIONAL MATERIAL 4

2.1 INTRODUCTION 4

2.2 COMPONENTS OF WASTEWATER TREATMENT BY

WETLAND–ELECTROFLOCCULATION HYBRID SYSTEM 4 2.2.1 Constructed wetland 4

2.2.2 Electroflocculation (EF) 5

2.3 CONSTRUCTED WETLAND-ELECTROFLOCCULATION HYBRID 6

3. REFERENCES 6

APPENDIX A. WORKSHOP PRESENTATIONS 8

CONSTRUCTED WETLANDS, Prof. Avital Gasith 9

SECONDARY EFFLUENT TREATMENT BY CONSTRUCTED WETLANDS,

Dr. Dana Milshtein 42

CONSTRUCTION AND MAINTENANCE OF CONSTRUCTED WETLAND SYSTEMS,

Eli Cohen 65

ELECTROFLOCCULATION: PHYSICAL-CHEMICAL MECHANISMS AND

APPLICATION, Dr. Tali Harif 97

ELECTROFLOCCULATION AND MEMBRANE TREATMENT, Moshe Ben-Sasson 127

ELECTROFLOCCULATION-CONSTRUCTED WETLAND HYBRID SYSTEM,

Alon Barash 150

EF-CW MANUAL AND APPLICATIONS IN INTEGRATED CITY WATER MANAGEMENT,

Prof. Avner Adin 180

APPENDIX B. SCIENTIFIC PUBLICATIONS 186

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1. EF-CW WORKSHOP, SWITCH PROJECT, WP 3.3

Meetings Room, 6th floor, City Engineering Building,

5 Philon St.,Tel Aviv, 19.12.2010

Program

08:30 Registration

09:00 Opening – Prof. Avner Adin, Prof. Kala Vairavamoorthy (SWITCH)

09:10 Constructed Wetlands – Prof. Avital Gasith, Tel-Aviv University

09:40 Secondary Effluent Treatment by Constructed Wetlands – Dr. Dana Milshtein, Consultant

10:00 Electroflocculation: Physical-Chemical Mechanisms and Application – Dr. Tali Harif,

Atlantium Technologies

10:20 Electroflocculation and Membrane Treatment – Moshe Ben-Sasson, Water corp.

10:40 Coffee Break

11:10 Construction and Maintenance of Constructed Wetland Systems – Eli Cohen, Ayala Water &

Ecology

11:30 Electroflocculation-Constructed Wetland Hybrid System – Alon Barash, Sirkin-Buchner Water

Consulting

11:50 EF-CW Manual and Applications in Integrated City Water Management – Prof. Avner Adin,

Hebrew University

12:10 General Discussion – Prof. Avner Adin and Prof. Avital Gasith

12:30 End

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2. PROFESSIONAL MATERIAL

2.1 INTRODUCTION

Discharge of effluent into streams and rivers is a common practice worldwide. In arid lands

competition for the freshwater for human use diminishes stream flow and effluents often make much

of the base flow. In such situations stream health and rehabilitation highly depend on effluent quality.

Strict standards for effluent disposal call for economic and efficient treatment alternatives.

2.2 COMPONENTS OF WASTEWATER TREATMENT BY WETLAND-ELECTROFLOCCULATION HYBRID

SYSTEM

2.2.1 Constructed wetland

Constructed wetland (CW) is an environmental friendly technology for treating wastewater or

polishing effluent that is becoming increasingly popular in many parts of the world (Haberl, 2003). It

is designed and constructed based on natural marshes (Kadlec and Wallace, 2008). CWs are often

classified by the pattern of effluent flow in the system (e.g., Brix, 2003). In free-flow (surface flow -

SF) systems wastewater flows above the ground through emerged, submerged and floating aquatic

vegetation. In subsurface flow systems wastewater moves through a porous medium such as gravel or

aggregates, in which rooted hydrophytes grow (USEPA, 2000). Subsurface systems are further

classified into horizontal flow (HF), in which anaerobic conditions prevail, or vertical flow (VF)

which maintains aerobic conditions. Low flow velocities coupled with the presence of roots and solid

substrate, promote settling and filtration of particulate material. Biofilm of diverse microrganisms that

develops on the surface of the porous medium and the submerged vegetation is responsible for most

of the biotransformation and mineralization of pollutants. (e.g, Vymazal, 2003; Kadlec and Wallace,

2008). CWs usually remove organic matter efficiently

Vertical flow wetlands can oxidize organic and ammonia nitrogen (predominant forms of nitrogen in

municipal effluents) effectively. Oxidized nitrogen forms can be further transformed in downstream

HF or SF wetlands to nitrogenous gas (via denitrification), resulting in total nitrogen removal. Since

organic carbon is required for denitrification surface flow wetlands are favored for nitrate removal

under low organic matter conditions (e.g. polishing effluent). Under such conditions decomposed

plant litter can serve as a source for organic carbon.

Recent investigations indicate that VF CW remove efficiently micropollutants such as estrogens (e.g.,

Milstein et al., 2009), pharmaceuticals and personal care products (e.g., Matamoros et al., 2007) but

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are less efficient in removing phosphorous (P) compounds (Kadlec and Wallace, 2008). Retention of

P in CWs includes peat/soil accretion (mostly in natural and free flow systems), soil adsorption,

precipitation and plant uptake (Vymazal, 2003). In subsurface systems removal by plants is limited

and requires plant harvesting annually. The adsorption and chemical precipitation of phosphorus is

much more vigorous at the initial operation stage because the process has finite capacity (EPA, 2000).

As a result, CW capacity for phosphorous removal is quite limited. Complement process (e.g.

physiochemical process) should be used before or after CW to remove phosphorous efficiently.

2.2.2 Electroflocculation (EF)

Electroflocculation (electrocoagulation) presents an alternative method to conventional (chemical)

flocculation with several advantages: easy operation, lower quantities of produced sludge, avoidance

of chemical usage and, most importantly, no anions such as chloride or sulfate need to be added to the

solution (Mollah et al., 2001). Unlike conventional flocculation in which the coagulants are added to

the water as salts, in the EF process, the coagulants (iron or aluminum) are added to the solution by

dissolving the anode in an electrochemical cell. These coagulant ions ultimately lead to aggregation

of the original particles in the water, which are removed in a later sedimentation or filtration process.

Electroflocculation has been increasingly used in North America for the treatment of industrial

wastewater from pulp and paper industries, mining and metal processing industries, foodstuff wastes,

oil wastes, dyes, suspended particles, chemical and mechanical polishing waste, organic matter from

landfill leachates, deofluorination of water, synthetic detergent effluents, mine wastes and heavy

metal-containing solution (Mollah et al., 2001).

Other investigations indicate that the EFector may have additional abilities in removing pathogens;

heavy metals, and possibly endocrine disruptors. These capabilities can provide a considerable

improvement over conventional or modified CW systems.

If EF unit (EFector) is hybrid with constructed wetland, it may result to shorter residence time, better

water quality, reduced costs for land, construction and maintenance of the constructed wetlands as

well as water loss.

2.3 CONSTRUCTED WETLAND-ELECTROFLOCCULATION HYBRID

The scientific work concentrated on the coupling of Electroflocculation (EF) with constructed

wetland (CW) for improved contaminants removal, phosphorous in particular, from secondary

effluents. The work consisted of three phases: electro-jar testing, continuous-flow EF-filtration (GF)–

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CW bench scale experimentation and field, half-industrial piloting. P, turbidity, TSS and TOC were

particularly monitored. Laboratory experiments showed that EF-GF effectively removed phosphate

(96%), while CW effectively removed organic matter (85%). Therefore, it seemed that the coupling

of both unit processes would combine their treating abilities. Field pilot results show that EF–GF

removed up to 97% of total phosphorus, resulting in P concentrations of <0.4 mg/L, which are

extraordinary results by any comparison. In addition to phosphorus removal, from the ecological

point of view ammonia removal is as important as phosphorus. One of the advantages of the CW is

efficient ammonia removal (over 90% in the first vertical cell with very low HRT). This is also

important as the CW-EF hybrid consist of a vertical subsurface flow wetland which is the best for

ammonia as well as low-medium concentrations of BOD and TSS.

The system is capable of meaningfully reducing some of the TOC (53%) and most of the TSS. The

EF–CW hybrid action is explained by combining flocculation and adsorption mechanisms produced

by the EF with filtration, sedimentation, sorption, and biodegradation processes in the CW beds.

3 REFERENCES

Brix, H. Plant use in constructed wetland and their function. In Dias, V. and J. Vymazal (Eds.). The

1st international seminar on the use of aquatic macrophytes for wastewater treatment in

constructed wetland, (2003) Portugal pp. 81-109

EPA, Constructed wetlands treatment of municipal wastewater. (2000) EPA/625/R/99/010.

Haberl, R., History of the use of constructed wetland. In Dias, V. and J. Vymazal (Eds.). The 1st

international seminar on the use of aquatic macrophytes for wastewater treatment in constructed

wetland, Portugal (2003) pp. 12.1-12.1

Kadlec, R.H., Wallace, S.D., Treatment wetland, Second edition. CRC Press. (2008) INC, U.S.A.

Matamoros , V., Arias, C, Brix, H. and Bayon, M. Removal of pharmaceuticals and personal care

products (PPCPs) from urban wastewater in a pilot vertical flow constructed wetland and a sand

filter (2007). Environmental Science and Technology 41 pp: 8171-8177.

Milstein, D., Gasith, A. and Avisar, D. Estrogen removal in wetlands – review. International Water

Association (IWA) Newsletter (2009) 35: 17-23.

Mollah, M. Y. A., Schennach R., Parga J. R., Cocke D. L., Electrocoagulation (EC)-science and

applications, Journal of Hazardous Materials B84 (2001) 29-41.

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Vymazal, J. Removal mechanisms in constructed wetland. In Dias, V. and J. Vymazal (Eds). The 1st

international seminar on the use of aquatic macrophytes for wastewater treatment in constructed

wetland, (2003).Portugal. pp: 219-263.

8

APPENDIX A

WORKSHOP PRESENTATIONS

Constructed Wetlands – a modified natural system in the service of man

modification

Natural Wetland (NW)

Constructed Wetland (CW)

Prof. Avital Gasith, Faculty of Life Sciences, Tel-Aviv University (SWITCH-ISR-19.12.10)

Gasith Ecology Consulting

Photo: Internet Photo: Gasith

9

CWs are wastewater treatment systems

Why do we need CW when WWTP can do a good job?


Photo: Gasith

10

WWTPs take care of cities’ sewage

Photo: Internet

Gasith Ecology Consulting 11

The unwanted sewage was recognized as a resource

High quality effluent

Effluent Reservoir irrigation

Gasith Ecology ConsultingPhoto: Internet

12

Construction and maintenance cost of high tech. WWTP are relatively high

Usually aimed for large‐scale operations

Membrane Biological Reactor

There is a need for environmental friendly, low‐tech, cheap WWT system that is useful for small‐scale operations

Photo: Internet


What do we expect to achieve by treating wastewater?

• Remove suspended solids• Breakdown organic matter• Remove dissolved nutrients• Remove chemical pollutants

Improved water

quality


The following processes naturally occur in wetlands

• Suspended solids settle or are filtered out;• Organic matter is mineralized by microorganisms;• Nutrients are taken by plants and are transformed by bacteria;

• Inorganic pollutants are transformed chemically or biologically, taken by plants, or are removed from the water by adsorption to surfaces;


Why wasn’t CW technology adopted long ago?

• It was – about 50 years go!• However, it required large flooded areas – an inherent limitation.

• The wetland processes were intensified and became more efficient with the modification of the flow of wastewater through the systems, requiring much smaller area for operation


What is the structure of CWs and how do they function? (Dr. Avital Gasith)

What can CW do? (Dr. Dana Milstein)

How are CW built? (Mr. Eli Cohen)


The basic CW operation unit

Complex physical-chemical-biological

processes

Treatment cell/pond

wastewater effluent


The basic CW unit

The basin is either filled with water or granular bed (usually with hydrophytes)

The flow pattern through the cell varies respectively

wastewater effluent


CWs are categorized by flow pattern

Free Flow/Surface Flow (FF/SF)

Subsurface Flow (SSF)

Ofra Aqua Plants

Ofra Aqua Plants


Photo: Internet

Photo: Internet

20

Subsurface flow is divided into 2 flow

types:

Sub-surface horizontal flow

Photo: InternetGasith Ecology Consulting 21

Subsurface flow is divided into 2 flow

types:

Sub-surface horizontal flow


Sub-surface vertical flow

Photo: Internet22

Vertical subsurface flow is further divided into down or up flows

Vertical Down Flow

Vertical Up Flow


Flow pattern is divided into continuous and pulse flows


Flexibility in design makes modern CW system more efficient

a. Granular bed and plant roots provide greater surface area for microbial biofilm

b. Flexibility in structure and flow pattern determines residence time and enables regulation of aerobic‐anaerobic conditions

Microbial biofilmbed particle


Different flow patterns

Different aerobic-anaerobic conditions

Different microorganisms development and action

Different capacities to remove pollutants


bed particle

The microbial community of biofilmsis relatively long-lived giving chance for establishment fast as well as slow growing microorganisms


Operation under different oxic conditions

• Aerobic conditions: efficient degradation of OM and oxidation of Ammonia (nitrification);

• Anaerobic conditions: Efficient removal of nitrate by denitrification

oxidative and/or reducing conditions can be achieved under different designs:a. in different parts of a cell,

b. in time intervals of the same system

c. in separate systems operated serially (hybrid design)


HSSF - supports anaerobic conditions

VSSF - supports aerobic conditions


HSSF - supports anaerobic conditions

VSSF - supports aerobic conditions

Hybrid system operation


hybrid CW system

FF/HSSF

VSSF


Photo: Internet

31

VSSF HSSF

FF

3 stage hybrid operation

Photo: Internet

Photo: Internet

Photo: Internet


Green et al., 2006Passively Aerated Vertical Bed

Improvement of CW operation by passive aeration


A.A. Engineers (Israel) -Pilot system

Gasith Ecology ConsultingPhoto: Gasith

34

Improvement of CW technology reduced the area required per unit treatment

Activated sludge

Oxidation ponds

Free flow CW

Subsurface Flow

horizonthal

X 4.4X 16.7X 50X 801

Subsurface Flow vertical


CWs “explosion” of information


Yearly scientific meetings


In Israel the technology exists for quite a while but is not yet widely distributed


SHAFDAN CWsresearch system


CW as a go‐between polishing system for stream reahbilitation

Upgrading low quality effluents

Effluent quality control assurance

WWTP StreamCW

input

output

desired

pollu

tant

pollu

tant


Summary and Conclusions• CWs are low-tech, environmental friendly, low cost wastewater treatment/polishing systems;

• They can be useful for treating small communities and small agricultural andindustrial operations;

• Efficiency of treatment can be regulated by modifying structure and flow pattern;

• CWs can function as “dialysis” units for rehabilitation of streams;

• Israel’s first large-scale CW system is aimed to improve Yarqon’s stream water quality


Treatment of Secondary Effluent

by Constructed Wetlands

Dana Milstein

EF-CW Workshop, SWITCH Project, WP 3.3

42

Wastewater (Israel 2008: 460MCM)

Sewage System (>90%)

Effluent

Wastewater Treatment Plant (ca. 70% secondary or less)

Micro-pollutantsConventional pollutants

SoilSurface water

Sediment Soil interstitial water

Groundwater

(76%) Irrigation

(24%)streams

43

Naaman Stream. Photo: A.Gasith

44

גזית.א: צילום

45

“Don’t worry about Tom dear….It’s just chemicals in the water”

Feminization of male fish

46

Biological effects:

E2: 5 ng/l

EE2: <1 ng/l

Estrogens

47

PPCP:Pharmaceuticals (e.g. pain killers

antibiotics)and Personal

Care Products

48

Effluent

SoilSurface Water

Sediment Soil Interstitial water

Groundwater

Research Objectives

49

Shafdan Constructed Wetland

Shafdan secondary effluent

1 2 3 4 5 6 7Treatment efficiency

1. System maturation

(age)

2. Vegetation composition

3. Flow pattern

4. Contaminants load

50

Cumulative removal (%)Inflow

Stage1+2+3

Stage1+2

Stage1

Removal mechanisms

(mg/l)Parameter

556666Bioticdegradation

6.1±4.0BOD

557775Filtration andsedimentation

5.2±3.1TSS

899795Nitrification 2.2±1.1NH4-N

-5-110-235Denitrificationuptake

0.6±0.2NO3-N

52257Nitrification+Denitrification

4.8±1.1TN

-8-20-22-1.2±0.4PO4-P

Removal Efficiency (3rd year)

55

Shafdan constructed wetland

(mg/l)

Inbar criteria

(mg/l)

Effluent following

SSF+SSF+SF

Effluent

following

SSF+SSF

InflowDischarge

into

streams

IrrigationVariable

0.19±0.23

(0.98)

0.06±0.08

(0.41)

2.2±1.1

(4.0)

1.520NH4

2.7±1.0

(5.6)

2.1±1.0

(4.3)

6.1±4.0

(18.6)

1010BOD

2.3±1.9

(7.0)

1.2±1.2

(9.2)

5.2±3.1

(16.8)

1010TSS

0.7±0.6

(2.0)

2.1±1.2

(4.9)

0.6±0.2

(1.1)

--NO3

2.3±1.0

(4.6)

3.6±1.6

(6.2)

4.8±1.1

(6.3)

1025TN

1.3±1.3

(1.9)

1.5±0.5

(2.8)

1.2±0.4

(2.1)

15TP

Effluent Reuse

56

P-Problem?

The ProblemEutrofication in surface water

Solution

P removal in WWTPHybrid technologies

57

Micro-Pollutants“Emerging Contaminants”

58

N=22 Estradiol (E2) Estrone (E1)

Average (ng/l) 10.6 24.2

SD (ng/l) 8.4 14.5

SE (%) 79 60

Median (ng/l) 7.7 22.9

Min (ng/l) 3.7 4.9

Max (ng/l) 38.7 64.0

Estrogen in the Shafdan Secondary Effluents

Estriol (E3) < 5 ng/l

Ethynylestradiol (EE2) < 2ng/l

Mestranol (MeEE2) < 2ng/l

59

Estrogen Removal in CWEffect of vegetation composition

Shafdan secondary effluent

VSSF

60

20.5

2.2 2.0 2.0

7.7

2.53.7 3.0

0

5

10

15

20

25

30

inflow poly no veg mono

Estr

og

en

s (

ng

/l)

E1 E2

pondst1Following treatment in the E2 removal>70%E1 removal>90%a

a

b b bb b b

Estrogen Removal in CWEffect of vegetation composition

61

0

20

40

60

80

100

120

Re

mo

val (

%)

VSSF with plants VSSF no plants

Pharmaceuticals Personal Care Produces

Matamoros et al., 2007

• Treatment of municipal wastewater•Hydraulic residence Time: 3-6 Hr

PPCP Removal in CWEffect of vegetation composition

62

Conclusions

•CW represents an aesthetic environmental friendly technology

•CW can upgrade secondary effluent to “Inbar Criteria” (ammonia)

•CW are suitable as “quality control” systems for stream

rehabilitation (e.g.: BOD and TSS)

•CW have limited ability to remove phosphorus

•CW (VSSF) can remove organic micro-pollutants from municipal

secondary effluent

•CW design should be site-specific (omposition and concentration of

contaminants) 63

Acknowledgments

Shafdan WWTPMinistry for environmental quality, ItalyPorter school of environmental studies, Tel-Aviv UniversityMinistry for science, cloture and sport, Israel (Eshcol scholarship) Rigger Foundation, USA-Fellowship ProgramOfra Aqua Plants (system construction)Moran Consultant & Development (system upgrade)

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