Tailieu CW EPA1

8/14/2019 Tailieu CW EPA1

1/87

United StatesEnvironmental Protection

Office Of Water

(4204)

EPA 832-R-93-008Jul !993

A"enc

Su#surface $lo%

&onstructed Wetlands $or

WasteWater 'reatment

ATechnology Assessment

Printed on Recycled Pa


2/87

Acknowledgements

ACKNOWLEDGEENT!

"# !he"wood C# $eed% E#% o' En"onment*l Engnee"ng Cons+lt*nts w*s the

,"nc,*l *+tho" *nd edto" o' ths doc+ment# *ny othe"s *lso cont"-+ted to ts

deelo,ment# .nst"+ment*l n ,"odng n,+t nto ths doc+ment we"e the wo"ksho,

,*"tc,*nts who met n New O"le*ns n !e,tem-e"% /2% *nd ,"oded technc*l *ndedto"*l comments# !,ec*l th*nks to $o-e"t E# Lee% Che'% +nc,*l Technology

1"*nch% *nd $o-e"t 1*st*n% Wo"k Assgnment *n*ge" o' the 3#!# E&A O''ce o'

W*stew*te" En'o"cement *nd Com,l*nce% 'o" the" n,+t *nd s+,,o"t *nd to

Engnee"ng!cence% .nc# whch ,"oded m*n*gement *nd ,"od+cton s+,,o"t d+"ng

ths e''o"t#


3/87


4/87

Eec+te !+mm*"y

"el*-ly *cheed wth ths ,"ocess% lowe" leels m*y "e;+"e ,ost dsn'ecton#

.n *ddton to desgn g+delnes% the "e,o"t ,"odes *n *ssessment o' conce,t

*,,lc*-lty *nd the "ese*"ch needs 'o" * -ette" +nde"st*ndng o' the ,"ocess#

)))


5/87

&"e'*ce

PRE$A&E

Ths "e,o"t w*s s,onso"ed -y the 3#!# E&A O''ce o' W*stew*te" En'o"cement

*nd Com,l*nce +nde" the d"ecton o' "# $o-e"t K# 1*st*n% *nd "# $o-e"t E# Lee%

o' the +nc,*l Technology 1"*nch#

.t s the ntent o' ths "e,o"t to ,"esent c+""ent (/=) n'o"m*ton *nd g+d*nce

on desgn% const"+cton% ,e"'o"m*nce% o,e"*ton *nd m*nten*nce o' s+-s+"'*ce 'low

const"+cted wetl*nds +sed 'o" t"e*tment 8o' domestc *nd m+nc,*l w*stew*te"s#

!+-s+"'*ce 'low const"+cted wetl*nds *"e n "el*tely common +se n E+"o,e%

A+st"*l*% *nd n * n+m-e" o' st*tes n the 3nted !t*tes# 7owee"% the"e h*s -eenno *,,*"ent consens+s on desgn ,"oced+"es o" ,e"'o"m*nce e,ect*tons# A two

ste, ,"oced+"e w*s +sed 'o" the ,"e,*"*ton o' ths "e,o"t to deelo, * consens+s

*mong knowledge*-le e,e"ts#

The '"st ste, w*s to s+-mt * d"*'t "e,o"t ,"e,*"ed -y "# !he"wood $eed%

E#E#C#% to selected e,e"ts 'o" the" det*led "eew# These ndd+*ls ncl+ded9 "#

Don*ld 1"own% 3#!# E&A $$EL> D"# Denns Geo"ge% Tennessee Tech 3ne"sty> "#

ch*el Ogden% !o+thwest Wetl*nds G"o+,9 D"# $ch*"d Ge"s-e"g% !*n Dego !t*te

3ne"sty> "# $on*ld C"tes% Nolte ? Assoc*tes> D"# $o-e"t Knght% C727ll> D"#

Geo"ge Tcho-*noglo+s% 3ne"sty o' C*l'o"n*D*s> "# ch*el 7nes% Tennessee

@*lley A+tho"ty> D"# :"*nk !*+nde"s% cC+lley% :"ck ? Glm*n% .nc#> *nd D"# &ete"

enssen% o"d'o"sk% No"w*y#

The second ste, w*s *ccom,lshed *t * twod*y wo"ksho, held n New

O"le*ns%#LA on !e,tem-e" 24 *nd 2


6/87

&"e'*ce

"ese*"ch wll +ndo+-tedly m,"oe +nde"st*ndng o' the -*sc conce,ts noled *ndle*d to mo"e so,hstc*ted desgn models# The desgn ,"oced+"es *nd "el*ted

g+d*nce n ths "e,o"t *"e the"e'o"e consde"ed to -e *ld% -+t s+-Bect to '+"the"

m,"oement#


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T*-le o' Contents

TA1LE O: CONTENT!

ACKNOWLEDGEENT! ################################################################## ######################################

EEC3T.@E !3A$ # # # # # # # # # # # # # # # # # # # # # # # # # # # # # # # # # # # # # #

&$E:ACE # # # # # # # # # # # # # # # # # # # # # # # # # # # # # # # # # # # # # # # # # # # # # # # #

C7A&TE$ /

C7A&TE$ 2

.NT$OD3CT.ON

1ACKG$O3ND

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# # # # # # # # # # # # # # # # # # # # # # # # # # # # # # #

//

2/

C7A&TE$ = &E$:O$ANCE [email protected]! # # # # # # # # # # # # # # # # # # # # =/

1 O D


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T*-le o' Contents

C7A&TE$ F OT7E$ &OTENT.AL A&&L.CAT.ON! # # # # # # # # # # # # # # # # # F/

!to"mw*te" !ystems # # # # # # # # # # # # # # # # # # # # # # # # # # # # # # # # # # # # # F/

L*nd'll Le*ch*tes # # # # # # # # # # # # # # # # # # # # # # # # # # # # # # # # # # # # # # # # F2

ne D"*n*ge # # # # # # # # # # # # # # # # # # # # # # # # # # # # # # # # # # # # # # # # # # # F2

Ag"c+lt+"*l $+no'' # # # # # # # # # # # # # # # # # # # # # # # # # # # # # # # # # # # # # # # F2

C7A&TE$ 6 $E!EA$C7 NEED! # # # # # # # # # # # # # # # # # # # # # # # # # # # # # 6/

7gh &"o"ty $ese*"ch Needs # # # # # # # # # # # # # # # # # # # # # # # # # # # # # # # # # 6/

ed+m &"o"ty $ese*"ch Needs # # # # # # # # # # # # # # # # # # # # # # # #

Low &"o"ty $ese*"ch Needs # # # # # # # # # # # # # # # # # # # # # # # # # # #

#

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#

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62

62

C7A&TE$

C7A&TE$ /0

CONCL3!.ON! # # # # # # # # # # # # # # # # # # # # # # # # # # # # # # # # # /

$E:E$ENCE! # # # # # # # # # # # # # # # # # # # # # # # # # # # # # # # # # /0/

APPE.)(

A Lst o' ,*"tc,*nts n New O"le*ns wo"ksho,#

1 &"ocess det*ls 'o" systems lsted n T*-le 2#

vii


9/87

T*-le o' Contents

/)S' O$ 'A/ES

T*-le /# 7sto"c*l Desgn A,,"o*ches% E+"o,e*n *nd

3#!# !o+"ces # # # # # # # # # # # # # # # # # # # # # # # # # # # # # # # # # # 24

T*-le 2#

T*-le =#

D*t* !o+"ces 'o" &e"'o"m*nce E*l+*ton # # # # # # # # # # # # # # # # # #

Com,*"son o' :"st O"de" &l+g

=/

:low $*te Const*nts # # # # # # # # # # # # # # # # # # # # # # # # # # # # =6

T*-le 4# Ammon* $emo*l n !: Wetl*nds # # # # # # # # # # # # # # # # # # # # =/=

T*-le


10/87

Lst o' A--"e*tons

/)S' O$ ARE*)A')OS

C"osssecton*l *"e*

*c

*cHmgd

1 O D *n nento"y o' *ll const"+cted wetl*nds

+sed 'o" w*stew*te" t"e*tment n the 3#!# (s,onso"ed -y E&A $$EL)> ste sts wth

e*l+*tons *nd "e,o"ts *t selected o,e"*tng s+-s+"'*ce 'low wetl*nds n the 3#!#

(s,onso"ed -y E&A $$EL)> * -"e' ,e"'o"m*nce e*l+*ton *t th"ee s+-s+"'*ce 'low

systems n Lo+s*n* (s,onso"ed -y E&A 7e*d;+*"te"s)> det*led ,e"'o"m*nce

monto"ng *nd e*l+*ton *t two s+-s+"'*ce 'low systems% *lso n Lo+s*n*

(s,onso"ed -y E&A $$EL)> c"e*ton o' * det*led d*t* -*se coe"ng desgn% o,e"*tng

*nd ,e"'o"m*nce d*t* 'o" n*t+"*l *nd const"+cted wetl*nd systems t"e*tng m+nc,*l

*nd nd+st"*l w*stew*te" *nd sto"m w*te" "+no'' n the 3#!# (s,onso"ed -y E&A

Co"*lls)> *nd see"*l wo"ksho,s *nd semn*"s s,onso"ed -y E&A $egon @.#

All o' these so+"ces we"e +tl5ed n the ,"e,*"*ton o' ths "e,o"t *nd thedsc+sson *nd e*l+*tons whch *"e ncl+ded# The 'oc+s o' ths "e,o"t s the

s+-s+"'*ce 'low ty,e wetl*nd# .n'o"m*ton on othe" ty,es o' wetl*nd systems h*s

h*s -een ncl+ded 'o" com,*"*te ,+",oses#

l l


14/87

Ch*,te" 2

&AP'ER 2

A&1ROU.

Wetl*nds *"e de'ned *s l*nd whe"e the w*te" s+"'*ce s ne*" the g"o+nds+"'*ce l+ng eno+gh e*ch ye*" to m*nt*n s*t+"*ted sol condtons% *long wth the

"el*ted eget*ton#

occ+""ng wetl*nds#

*"shes% -ogs% *nd sw*m,s *"e *ll e*m,les o' n*t+"*lly

A Jconst"+cted wetl*nd s de'ned *s * wetl*nd s,ec'c*lly

const"+cted 'o" the ,+",ose o' ,oll+ton cont"ol *nd w*ste m*n*gement% *t * loc*ton

othe" th*n estng n*t+"*l wetl*nds# The"e *"e two -*sc ty,es o' const"+cted

wetl*nds% the '"ee w*te" s+"'*ce wetl*nd *nd the s+-s+"'*ce 'low wetl*nd# 1oth

ty,es +tl5e eme"gent *;+*tc eget*ton *nd *"e sml*" n *,,e*"*nce to * m*"sh#

The '"ee w*te" s+"'*ce (:W!) wetl*nd ty,c*lly conssts o' * -*sn o" ch*nnelswth some ty,e o' -*""e" to ,"eent see,*ge% sol to s+,,o"t the "oots o' the

eme"gent eget*ton% *nd w*te" *t * "el*tely sh*llow de,th 'lowng th"o+gh the

system# The w*te" s+"'*ce s e,osed to the *tmos,he"e% *nd the ntended 'low ,*th

th"o+gh the system s ho"5ont*l#

The s+-s+"'*ce 'low (!:) wetl*nd *lso conssts o' * -*sn o" ch*nnel wth *-*""e" to ,"eent see,*ge% -+t the -ed cont*ns * s+t*-le de,th o' ,o"o+s med*#

$ock o" g"*el *"e the most commonly +sed med* ty,es n the 3#!# The med* *lso

s+,,o"t the "oot st"+ct+"e o' the eme"gent eget*ton# The desgn o' these systems

*ss+mes th*t the w*te" leel n the -ed wll "em*n -elow the to, o' the "ock o" g"*elmed*# The 'low ,*th th"o+gh the o,e"*ton*l systems n the 3#!# s ho"5ont*l#

'4e S$ t5e of %etland is t4ou"4t to 4ave several advanta"es over t4e $WS

ty,e# .' the w*te" s+"'*ce s m*nt*ned -elow the med* s+"'*ce the"e s lttle "sk o'

odo"s% odo"s% e,os+"e% o" nsect ecto"s# .n *ddton% t s -eleed th*t the med*

,"odes g"e*te" **l*-le s+"'*ce *"e* 'o" t"e*tment th*n the :W! conce,t so the

t"e*tment "es,onses m*y -e '*ste" 'o" the !: ty,e% whch the"e'o"e c*n -e sm*lle" n

*"e* th*n * :W! system desgned 'o" the s*me w*stew*te" condtons# The

s+-s+"'*ce# ,oston o' the w*te" *nd the *cc+m+l*ted ,l*nt de-"s on the s+"'*ce o'

the !: -ed o''e" g"e*te" the"m*l ,"otecton n cold clm*tes th*n the :W! ty,e#

!+-s+"'*ce 'low const"+cted wetl*nds '"st eme"ged *s * w*stew*te" t"e*tmenttechnology n Weste"n E+"o,e -*sed on "ese*"ch -y !edel (/) commencng n the

/0s% *nd -y Kck+th (2) n the l*te /F0s *nd e*"ly /60s# E*"ly deelo,ment*lwo"k n the 3nted !t*tes commenced n the e*"ly /60s wth the "ese*"ch o'Wole"ton% et *l# (=) *nd Ge"s-e"g et *l# (4)#

2l


15/87

desgned (


16/87

'*mly +nts to l*"ge" m+nc,*l systems (=F6< m Hd% / mgd)#

Ch*,te" 2

these systems *lso h*d *n *dB+st*-le o+tlet whch ,e"mtted e*sy m*nten*nce o' the

des"ed w*te" leel n the -ed (/)#

Wole"tons wo"k n Lo+s*n* -eg*n wth e,e"ment*l -ench sc*le t"*ys n *g"eenho+se cont*nng "ock o" g"*el med* *nd s+,,o"tng * st*nd o' eme"gent

*;+*tc eget*ton (=)# The t"*ys we"e 'lled wth w*stew*te"% *nd then d"*ned *'te"

* ce"t*n n+m-e" o' ho+"s ("*nge /2 to 46 ho+"s)# .n essence the ,"oced+"e w*s *

'll *nd d"*w -*tch ty,e ,"ocess# Ecellent ,e"'o"m*nce w*s demonst"*ted 'o" 1OD th"ee*ddton*l systems% '"om othe" so+"ces% *"e *lso ncl+ded to etend the "*nge o' 7$T

shown#

'4e O.6removal values for t4ese data can #e reasona#l a55roimated # a

first order 5lu" flo% relations4i5 u5 to a#out 2 d:The 1OD


22/87

"el*tonsh, does est -etween these two ,*"*mete"s# The " *l+e 'o" the c+"e 't

Ch*,te" =

.n these c*ses the *s,ect "*to *"ed '"om less th*n 29/ to oe" /F9/# Asillustrated # t4e fi"ure7 t4ere does not a55ear to #e an relations4i5 #et%een as5ect

ratio and O.6removal ca5a#ilities: The e"y low "emo*l *ssoc*ted wth the

hghest L9W (/F9/) n the ,lot s d+e to the e"y low n,+t 1OD


23/87

Ch*,te" =

&aution is necessar %4en discussin" mass or"anic loadin"s on t4ese %etland

sstems:The *l+es shown on :g+"e 4% *nd sml*" *l+es whch c*n -e 'o+nd nothe" "e'e"ences% *"e not the *ct+*l *"e*l o"g*nc lo*dng on the system% -+t "*the" *"e

the J*,,*"ent o"g*nc lo*dngs o-t*ned -y ddng the d*ly o"g*nc lo*d -y the tot*l

s+"'*ce% *"e* o' the system# Th*t *,,"o*ch m,les th*t the o"g*nc lo*d s *,,led

+n'o"mly oe" the ent"e s+"'*ce *"e* o' the system# As dsc+ssed ,"eo+sly% m+ch

o' the n,+t solds *nd 1OD


24/87

tem,e"*t+"e de,endent "*te const*nt (d )

K20(/ #0)"*te const*nt *t 20o C% (d )/#/04 d

tem,e"*t+"e o' l;+d n the system ( C)

A "*te const*nt K20e; +*l to /#/04 d 'o" +se n e;+*ton (/) 'o" the desgn o'

*ssoc*ted J*,,*"ent "*te const*nt wo+ld -e *-o+t /#=6< d .n theo"y% t sho+ld

,oss-ly * sgn'c*nt nc"e*se n the /#/04 d "*te const*nt#

Ch*,te" =

A first order 5lu" flo% model for O. 6removal also 4as #een used # a num#erof en"ineers for desi"n of t4ese S$ %etland sstems - in t4e United States7 Euro5e7

and Australia 78797!07!27!37!?7!67!9720@: '4e "eneral form of t4e model is

5resented #elo%

Whe"e9 Ce

Co

KTt

KT

K20

T

M

M

M

MM

MM

M

E''l+ent 1OD


25/87

$*te Const*nt

(d)

Ch*,te" =

T*-le =# Com,*"son o' :"st O"de" &l+g :low $*te Const*nts (F%//%40)

T"e*tment &"ocess

!+-s+"'*ce :low Wetl*nd:*c+lt*te L*goon:"ee W*te" !+"'*ce Wetl*nd

/

/#/040#//F

0#


26/87

Ch*,te" =

:g+"e com,*"es the T!! "emo*l "*te to the 7$T 'o" the systems

e*mned# The "el*tonsh, s sml*" to th*t shown on :g+"e 2 'o" 1OD


27/87

Ch*,te" =

:g+"e F com,*"es the T!! "emo*l "*te to the *s,ect "*to o' the *"o+ssystems#'4ese results are similar to t4ose s4o%n in $i"ure 3 for O.6and indicateno relations4i5 #et%een t4e sstem as5ect ratio and 'SS removal:

A knetc desgn model s not **l*-le 'o" T!! "emo*l# 7owee"% -*sed onthe "el*tonsh,s ll+st"*ted n :g+"es / to F% t s *,,*"ent th*t T!! "emo*l 'ollows

the s*me ,*tte"n *s 1OD


28/87

Ch*,te" =

,"esently o,e"*ted (4%F%/0)# &l*nt tss+e *n*lyss *t see"*l loc*tons ndc*te th*t *

sngle *nn+*l h*"est o' the ,l*nt m*te"*l mght *cco+nt 'o" ten ,e"cent o" less o' thent"ogen "emoed -y the system (F%22%2=)# A mo"e '"e;+ent h*"estng ,"og"*m

mght nc"e*se ths ,otent*l% -+t t wo+ld *lso nc"e*se the costs 'o" o,e"*ton o' the

system##

:g+"e 6 ,"esents *mmon* n,+t e"s+s o+t,+t d*t* 'o" the systems ncl+dedn ths st+dy whch h*e * contn+o+s dsch*"ge *nd wtho+t "ecycle# The lne on the

g"*,h ndc*tes the condton when n,+t e;+*ls o+t,+t# One h*l' o' the systems *"e

*t o" *-oe th*t lne% ndc*tng th*t the"e s * net ,"od+cton o' *mmon* *s the

w*stew*te" ,*sses th"o+gh the -ed# The so+"ce o' ths Jet"* *mmon* s -eleed

to -e '"om the *n*e"o-c decom,oston o' the o"g*nc nt"ogen t"*,,ed n the -ed *s

,*"tc+l*te m*tte"# !nce the -ed s *n*e"o-c% the"e s then ns+''cent oygen

**l*-le n the -ed to od5e ths *mmon* to nt"*te# :g+"e ,"esents *mmon*

"emo*l 'o" some o' the systems e"s+s 7$T# The "es+lts 'o" see"*l systems

(Denh*m !,"ngs% LA 'o" e*m,le% N7% n M 0#F mgHL% N7% o+t M /0 mgHL% "emo*l

M /=F0) *"e -elow the lowe" lmt on the g"*,h *nd *"e the"e'o"e not shown# One

,ont (the o,en s;+*"e n the +,,e" "ght co"ne") "e,"esents d*t* '"om !*ntee% CA> the

"em*nde" *"e d*t* '"om the T*-le 2 systems#

:g+"e 6# Ammon* .n,+t @e"s+s O+t,+t#

=//


29/87

Ch*,te" =

:g+"e # Ammon* $emo*l @e"s+s 7$T

ost o' the systems shown on :g+"e ds,l*y * m*"gn*l o" * neg*te*mmon* "emo*l "*te "eg*"dless o' the detenton tme n the system# Two systems%

shown *s s;+*"es n the 'g+"e% ds,l*y e"y hgh "emo*l "*tes *t 7$T leels

com,*"*-le to the othe" systems#'4e difference is #elieved to #e t4e lacC of al"ae7t4e availa#ilit of o"en7 and sufficient R' in t4e latter t%o sstems7 so t4at 4i"4

levels of nitrification can occur in t4ese #eds:

The ,"m*"y oygen so+"ce n these two c*ses s -eleed to -e '"om the8"oots o' the eme"gent *;+*tc eget*ton# .n the '"st c*se% (1e*" C"eek% AL) the -ed

s only 0#= m (/ 't) dee, *nd s+,,o"ts * st*nd o'Typhawth the "oots o-se"ed

,enet"*tng to the -ottom o' the -ed> *mmon* "emo*l "e*ches 60 ,e"cent wth *n

7$T o' =# d# The second c*se s theScirpus-ed *t the !*ntee% CA ,lot system%

whe"e the "oots *lso ,enet"*ted to the -ottom o' the 0#F m (2#< 't) dee, -ed>*mmon* "emo*ls o' 4 ,e"cent we"e *cheed wth *n 7$T o' seen# d*ys (4)#

.t s *lso n'o"m*te to com,*"e the 1e*" C"eek "es+lts +sngTyphato the0#F mdee, -ed *t !*ntee% CA whch *lso s+,,o"ted * st*nd o'Typha.)n t4e latter

case7the ,l*nt "oots only ,enet"*ted to 0#= m (s*me de,th *s *t 1e*" C"eek) *nd the

*mmon* "emo*l w*s only 2 ,e"cent wth the F d 7$T# .n theTypha-ed *t

!*ntee% *-o+t 0 ,e"cent o' the 'low ,*ssed th"o+gh the -ed -elow the "oot 5onewhe"e oygen w*s not lkely to -e ,"esent *nd lmted *mmon* "emo*l w*s

=/2


30/87

Ch*,te" =

*cheed# At 1e*" C"eek% the ent"e 'low ,*ssed th"o+gh theTypha"oot 5one *nd 60,e"cent *mmon*% "emo*l w*s ,"od+ced n =# d# Ths st"ongly s+,,o"ts the

hy,othess th*t the ,l*nt "oots n these !: wetl*nd -eds *"e the ,"m*"y so+"ce o'oygen needed 'o" nt"'c*ton o' *mmon* *nd othe" -ochemc*l "es,onses% *nd th*t

t s the"e'o"e essent*l to -"ng the w*stew*te" nto d"ect cont*ct wth the "oot 5one#

T*-le 4 s+mm*"5es the ste condtons *nd the *mmon* "emo*l,e"'o"m*nce o' the /4 systems +sed n ths *n*lyss# .t s cle*" '"om *n e*mn*ton

o' these d*t* th*t systems wth no *lg*e% wth longe" detenton tmes% *nd wth dee,

"oot ,enet"*ton ,"od+ce the -est *mmon* "emo*l "es+lts# The two systems n the

lst (!*ntee *nd 1e*" C"eek) whch nco",o"*te *ll th"ee '*cto"s ,"od+ced the -est

"es+lts o' *ll#

T*-le 4# Ammon* $emo*l n !: Wetl*nds#

Loc*ton Ammon* Alg*e 7$T 1 e d $oot*

$emo*l

&"esent

d

De,th

m

De,th

Denh*m !,"ngs% LA7*+ghton% LA

C*"lle% LA

1enton% K

*ndelle% LAG"eenle*es% LA

7*"dn% K (-+l"+sh)7*"dn% K ("eeds)

3tc*% ! (no"th)

3tc*% ! (so+th)

Deg+ss* Co",#% AL

onte"ey% @A1e*" C"eek% AL

!*ntee% CA(Scitpus)

/=26


31/87

Ch*,te" =

de,th o' the -ed# A ,"oced+"e *doc*ted -y Kck+th (


32/87

The "eg"esson c+"e o' -est 't s *lso shown% -+t the low " *l+e

Ch*,te" =

The"e s no *,,*"ent "el*tonsh, -etween m*ss lo*dng o' TKN *nd "emo*l 'o" thes !: systems whe"e d*t* we"e **l*-le# All -+t one o' these d*t* ,onts *"e

sgn'c*ntly -elow the :W! lne% ndc*tng th*t these !: systems *"e less e''cent

*t TKN (o" TN) "emo*l th*n :W! systems# The d''e"ence s *g*n -eleed to -e the

**l*-lty o' oygen# .n :W! systems% the w*te" s+"'*ce s e,osed to the

*tmos,he"e *nd some d"ect oygen t"*ns'e" s ,oss-le# The only d*t* ,ont on

:g+"e /0 whch s close to the lne s the 1e*" C"eek% AL system% whe"e (*s dsc+ssed

,"eo+sly) oygen '"om the ,l*nt "oots s *,,*"ently **l*-le n ths sh*llow -ed

(0#=m) to s+,,o"t nt"'c*ton#

.t h*s -een s+ggested th*t the e''l+ent *mmon* '"om these wetl*nd systemss "el*ted to the m*ss lo*dng o' TKN o" TN on the system (4/)# :g+"e // ,"esents

ths com,*"son 'o" s o' the T*-le 2 !: systems whe"e s+''cent d*t* we"e

**l*-le# 2

ndc*tes th*t the co""el*ton s not e"y sgn'c*nt# A mssng element n ths

*,,"o*ch s the "esd+e '"om decom,oston o' ,l*nt m*tte" n the system snce the

TKN lo*dng s only * me*s+"e o' nt"ogen n the ente"ng w*stew*te"# :g+"e //

s+ggests th*t * TKN m*ss lo*dng o' less th*n 2 kgHh*Hd (/#6 .-H*cHd) wo+ld -e

necess*"y to consstently *chee *n e''l+ent *mmon* o' 2 to = mgHL n !: wetl*nds

*s they *"e c+""ently o,e"*ted wth *n oygen de'cency#

TKN A!! LOAD.NG (k gHh*Hd)

:g+"e //# E''l+ent Ammon* @e"s+s TKN *ss Lo*dng

=/


33/87

Ch*,te" =

*ny o' the olde" systems n the G+l' !t*tes +sed so't tss+e 'lowe"ng ,l*nts'o" *esthetc "e*sons# The" decom,oston s e"y "*,d n the '*ll *nd *'te" * '"ost%

*nd me*s+"*-le nc"e*ses n e''l+ent 1OD

s+"'*ce 'low wll "es+lt n * m+ch mo"e "*,d -"e*kdown o' ,l*nt det"t+s *nd "ele*se

o' *mmon* to the w*te"# .' the s+"'*ce o' the -ed s m*nt*ned n * d"y condton

(ece,t d+"ng "*n'*ll eents)% ,l*nt det"t+s wll decom,ose m+ch mo"e slowly#

&7O!&7O$3! $EO@AL

:g+"e /2 ,"esents ,hos,ho"+s n,+t e"s+s o+t,+t d*t* 'o" the systems whe"ed*t* we"e **l*-le# The slo,ng lne on the 'g+"e "e,"esents the condton whe"e

n,+t e;+*ls o+t,+t# Two o' the systems '*ll on th*t lne *nd see"*l othe"s show

m*"gn*l "emo*l c*,*-ltes# Only one d*t* ,ont shows ecellent "emo*l the

1e*" C"eek% AL system# The med* n ths c*se *"e 'ne "e" g"*el% *nd the ,"esence

o' odes o' "on *nd *l+mn+m *ssoc*ted wth ths med* m*y -e "es,ons-le 'o" the

< ,e"cent "emo*l o' ,hos,ho"+s o-se"ed d+"ng the '"st ye*" o' system o,e"*ton#

:g+"e /2# &hos,ho"+s .n,+t @e"s+s O+t,+t

=/


34/87

'"om 6 /0 H/00 ml to /0Hl00 ml o" less on *n *e"*ge -*ss#

C h * , t e " =

&hos,ho"+s "emo*l n most const"+cted wetl*nd systems s not e"y e''ecte

-ec*+se o' the lmted cont*ct o,,o"t+ntes -etween the w*stew*te" *nd the sol#!ome e,e"ment*l *nd deelo,ment*l wo"k h*s -een +nde"t*ken +sng e,*nded cl*y

*gg"eg*tes *nd the *ddton o' "on *nd *l+mn+m odes> some o' these t"e*tments

m*y h*e ,"omse -+t the longte"m e,ect*tons h*e not -een de'ned# !ome

systems n E+"o,e +se s*nd nste*d o' g"*el to nc"e*se the ,hos,ho"+s "etenton

c*,*cty% -+t selectng ths med* "es+lts n * l*"ge" system -ec*+se o' the "ed+ced

hyd"*+lc cond+ctty o' s*nd com,*"ed to g"*el#)f si"nificant 54os54orus removal

is a 5roDect re;uirement7 t4en ver lar"e land areas or alternative treatment met4ods

%ill 5ro#a#l #e re;uired:

$E&A/ &O/)$OR+ RE+O*A/

'4ese S$ %etland sstems are7 in t4e "eneral case7 ca5a#le of a one- to t%o-

lo" reduction in fecal coliforms7 %4ic4 in man cases is not enou"4 to routinel satisf

disc4ar"e re;uirements %4ic4 often s5ecif 200F!00 ml:&e*k 'lows n "es,onse

to ntense "*n'*ll eents *lso ds"+,t "emo*l e''cences 'o" 'ec*l col'o"ms# As *

"es+lt% most o' the systems lsted n T*-le 2 +tl5e some 'o"m o' 'n*l dsn'ecton#

One ece,ton s the lghtly lo*ded system n 1e*" C"eek% AL% whch +ses * sm*lls5ed"e" g"*el *s the -ed med*# At 1e*" C"eek the 'ec*l col'o"ms *"e "ed+ced

4

=/F


35/87

Ch*,te" 4

C7A&TE$ 4

.ES)1 &OS).ERA')OS

The m*Bo" conce"ns n the desgn o' !: const"+cted wetl*nds ncl+de9

7yd"*+lc *nd hyd"ologc*l condtons%

1OD


36/87

1 O D n thewo"st c*se the solds ,"esent occ+,ed *-o+t s ,e"cent o' the **l*-le od s,*ces

*t * loc*ton close to the nlet ,,e# .n *ll c*ses% these solds we"e *t le*st 60 ,e"centno"g*nc m*te"*l# &l*nt "oots *nd "el*ted det"t+s we"e not enco+nte"ed -elow

de,ths o' *-o+t 0#= m (/ 't) n *ny o' these systems (2F%26/# As * "es+lt% *t these'e stes t does not *,,e*" th*t *cc+m+l*ton o' T!! o" ,l*nt det"t+s we"e"es,ons-le 'o" cloggng o" 'o" *ny s+"'*ce 'low whch m*y h*e occ+""ed#

At *ll s o' the stes nestg*ted% the "ock med* we"e dele"ed -y t"+ck oe"+n,*ed "o*ds% n *ll knds o' we*the"% *nd% *s desc"-ed -y the o,e"*to"s% the t"+cks

tended to 'ollow the s*me ,*thw*y ente"ng *nd le*ng the wetl*nd -ed# .t s ;+te

42


37/87

('t )#

M tot*l c"osssecton*l *"e*% ,e",endc+l*" to 'low% m

('t H't Hd)% o" (g*lHd)% etc#

,e",endc+l*" to the 'low d"ecton% m H m H d

M 'low ,e" +nt tme% m Hd ('t Hd)% o" (g*lHd)% etc#

Ch*,te" 4

,oss-le th*t * l*"ge ,o"ton o' the no"g*nc solds o-se"ed n the od s,*ces o' the

med* w*s d+e to sol '"om the t"+ck t"es% *nd sol% "ock d+st *nd 'nes '"om the "ockmed* t"*ns,o"ted n the t"+ck# At the 'o"me"ly ,*"t*lly clogged Kent+cky ste% these

no"g*nc m*te"*ls m*y h*e then t"*,,ed *lg*l solds ente"ng the -ed% "es+ltng n

'o"m*ton o' the gel*tno+s m*te"*l c"e*tng the cloggng# The '*ct th*t the clogged

5one nee" e,*nded -eyond the '"st 2< ,e"cent o' the -ed% *nd th*t the gel*tno+s

m*te"*l h*s now ds*,,e*"ed% s+ggests th*t const"+cton *ctty m*y h*e -een the

,"m*"y c*+se o' the cloggng nste*d o' * contn+ng -ochemc*l "e*cton#

,.RAU/)& .ES)1

When s+-s+"'*ce 'low condtons *"e e,ected n the !: wetl*nd -ed t scommon ,"*ctce to +se D*"cys L*w% whch desc"-es the 'low "egme n * ,o"o+s

med*# D*"cys L*w s ty,c*lly de'ned wth e;+*ton (2)#

I M k!A ! (2)

Whe"e9 I

ks

A

!

= =

M hyd"*+lc cond+ctty o' * +nt *"e* o' the med+m= 2

= 2

2

2

M hyd"*+lc g"*dent o' the w*te" s+"'*ce n the 'low

system dhHdL% mHm% ('tH't)#

(All +nts m+st -e consstent)

D*"cys L*w s not st"ctly *,,lc*-le to s+-s+"'*ce 'low wetl*nds -ec*+se o',hysc*l lmt*tons n the *ct+*l system# .t *ss+mes l*mn*" 'low condtons% whch

m*y not -e the c*se when l*"ge "ock o" e"y co*"se g"*el *"e +sed *s the med*#

T+"-+lent 'low wll occ+" n these co*"se med* when the hyd"*+lc desgn s -*sed

on * hgh hyd"*+lc g"*dent# D*"cys L*w *lso *ss+mes th*t the 'low (I) n the

system s const*nt *nd +n'o"m% -+t n the *ct+*l c*se n * !: wetl*nd the n,+t

e"s+s o+t,+t I m*y *"y d+e to ,"ec,t*ton% e*,o"*ton% *nd see,*ge> *nd sho"tc"c+tng o' 'low m*y occ+" d+e to +ne;+*l ,o"osty o" ,oo" const"+cton#Ail oft4ese factors limit t4e t4eoretical a55lica#ilit of .arcHs /a%7 #ut it remains as t4e

onl reasona#l accessi#le model for desi"n of t4ese S$ sstems: .' sm*ll to

mode"*te s5ed g"*el ( 4 cm) s +sed *s the med*% ' the system s ,"o,e"lyconst"+cted to mnm5e sho"t c"c+tng% ' the system s desgned to de,end on *

4=


38/87

0#2 m )# The nlet end o' the t"o+gh s c*,*-le o' -eng "*sed *-oe the d*t+m

Ch*,te" 4

mnm*l hyd"*+lc g"*dent% *ndif t4e I in e;uation


39/87

ag"*el med* wth * hyd"*+lc cond+ctty (ks) o' /0%000 m Hm Hd% the m*m+ms+-s+"'*ce 'low% -*sed on e;+*ton (2)% wo+ld -e 600 m Hd (0#2/ mgd)# 3sng the

c*se wo+ld -e /2 m Hd (0#04 mgd)% whch s 20 ,e"cent o' the 'low *llowed -y the.' the desgn 'low we"e *ct+*lly 600 m Hd n the second c*se% then

Ch*,te" 4

As5ect Ratio

The *s,ect "*to (L9W) o' the wetl*nd -ed s * e"y m,o"t*nt consde"*ton nthe hyd"*+lc desgn o' !: wetl*nd systems% snce the m*m+m ,otent*l hyd"*+lc

g"*dent s "el*ted to the **l*-le de,th o' the -ed dded -y the length o' the 'low

,*th# *ny o' the e*"ly systems desgned wth *n *s,ect "*to o' /09/ o" mo"e *nd

* tot*l de,th o' 0# m (2 't) h*e *n n*de;+*te hyd"*+lc g"*dent *nd s+"'*ce 'low

s net*-le# The hyd"*+lc g"*dent (! '*cto" n e;+*ton 2) de'nes the tot*l he*d

**l*-len the system to oe"come the "esst*nce to ho"5ont*l 'low n the ,o"o+s#

med*#

:o" e*m,le% n * !: -ed 200 m long *nd 0# m dee,% ' the w*te" leel s *tthe s+"'*ce o' the med* *t the n'l+ent end *nd ne*" the -ottom o' the -ed *t the

e''l+ent end (w*te" de,th M 0#2 m)% the **l*-le hyd"*+lc g"*dent wo+ld -e0#4mH200m o" 0#002# .' ths wetl*nd -ed we"e /00 m wde (L9W M 29/) *nd +sed

= 2

=

s*me ol+me o' g"*el n * -ed 4


40/87

m H m Hd

Ch*,te" 4

+edia '5es

T*-le 4 ,"esents * s+mm*"y o' ty,c*l ch*"*cte"stcs 'o" the ty,es o'med*whch h*e -een +sed n !: const"+cted wetl*nds# Essent*lly *ll o' the o,e"*ton*l

!: const"+cted wetl*nds n the 3#!# h*e +sed med* "*ngng '"om med+m g"*el to

co*"se "ock# The *l+es n T*-le 4 *"e ntended *s ,"elmn*"y n'o"m*ton only#

$ollo%in" selection of a media t5e and siBeN t4e 4draulic conductivit and 5orosit

of t4e material s4ould #e determined in t4e field or la#orator7 5rior to sstem desi"n7

The "ecent# t"end n the G+l' !t*tes tow*"d the +se o' l*"ge" s5es o' "ock s-eleed d+e to the m,"esson c"e*ted -y the s+"'*ce 'low condtons on m*ny o' the

e*"ly systems# .t w*s *,,*"ently tho+ght th*t the s+"'*ce 'low w*s c*+sed -y

cloggng *nd th*t the +se o' * co*"se" "ock wth l*"ge" od s,*ces *nd * hghe"hyd"*+lc cond+ctty wo+ld oe"come the ,"o-lem# .n most c*ses the ,"o-lem h*s

not -een oe"come snce the hyd"*+lc g"*dent ,"oded s too sm*ll# The +se o'

sm*lle" "ock s5es h*s * n+m-e" o' *d*nt*ges n th*t the"e s mo"e s+"'*ce *"e***l*-le on the med* 'o" t"e*tment% *nd the sm*lle" od s,*ces *"e mo"e com,*t-le

wth deelo,ment o' the "oots *nd "h5omes o' the eget*ton% *nd the 'low

condtons sho+ld -e close" to l*mn*"# When t+"-+lent 'low occ+"s n the co*"se"

med* lsted n T*-le


41/87

Ch*,te" 4

The hyd"*+lc cond+ctty (ks) *l+es n T*-le < *ss+me th*t the med* *nd thew*te" 'lowng th"o+gh t *"e cle*n so th*t cloggng s not * '*cto"# As dsc+ssed n

* ,"eo+s secton% some cloggng c*n occ+" n these systems% es,ec*lly ne*" the nlet

5one whe"e most o' the s+s,ended solds wll -e "emoed# As noted ,"eo+sly% the

o-se"ed cloggng "e,"esented less th*n ,e"cent o' the od s,*ces n the systems

nestg*ted# The m*Bo"ty o' the m*te"*l (60) w*s no"g*nc *nd -eleed to -e

the "esd+e '"om const"+cton *cttes% *nd sho+ld not% the"e'o"e% h*e * c+m+l*te

m,*ct on hyd"*+lc cond+ctty# .t s% howee"% necess*"y to ,"ode * l*"ge s*'ety

'*cto" *g*nst these contngences *nd *do,ton o' *n *,,"o*ch sml*" to th*t +sed

n the desgn o' l*nd t"e*tment systems (=0) s ,"o,osed# )t is t4erefore

recommended t4at a value !!3 of t4e effectiveK 4draulic conductivit 0 5ercent of t4e 5otential 4draulic "radient availa#le in t4e 5ro5osed #ed: '4eset%o limits7 com#ined %it4 an adDusta#le outlet for t4e #ed disc4ar"e s4ould ensure

a more t4an ade;uate safet factor in t4e 4draulic desi"n of t4e sstem:These two

lmts wll *lso h*e the ,"*ctc*l e''ect o' lmtng the *s,ect "*to o' the -ed to =9/'o" 0# m (2 't) dee, -eds *nd to *-o+t 0#F


42/87

Ch*,te" 4

m*nten*nce# .n one c*se% * -+"ed m*n'old -ec*me clogged wth t+"tles (ente"ed the

,,ng system '"om the ,"elmn*"y t"e*tment l*goon) *nd h*d to -e "emoed#

A surface manifold7 %it4 adDusta#le outlets7 seems to 5rovide t4e maimum

flei#ilit for future adDustments and maintenance and is recommended:3se o' *

co*"se "ock (6 to /< cm P= Q) n ths ent"y 5one% co+,led wth *n *de;+*te

hyd"*+lc g"*dent 'o" the -ed% sho+ld ens+"e "*,d n'lt"*ton *nd ,"eent ,ondng *nd

*lg*e deelo,ment# .n contn+o+sly w*"m *nd s+nny clm*tes% sh*dng o' ths ent"y

5one wth ethe" eget*ton o" * st"+ct+"e m*y *lso -e necess*"y# .n cold wnte"

clm*tes% some the"m*l ,"otecton 'o" *n *-oes+"'*ce m*n'old wll ,"o-*-ly -e

necess*"y#

Outlet Structures

O+tlet st"+ct+"es n +se *t o,e"*ton*l !: wetl*nd systems ncl+de s+-s+"'*cem*n'olds% *nd we" -oes o" sml*" g*ted st"+ct+"es# The ,e"'o"*ted s+-s+"'*ce

m*n'old s the most commonly +sed dece> howee"% the loc*ton o' th*t m*n'old

n the -ed h*s *"ed consde"*-ly# .n * 'ew c*ses t h*s -een loc*ted n * sh*llow

t"ench% -elow the -ottom o' the -ed% ,e"mttng com,lete d"*n*ge o' the -ed *nd

deelo,ment o' the m*m+m hyd"*+lc g"*dent 'o" the system# .n m*ny c*ses% the

m*n'old *ndHo" the o+tlet ,o"ts h*e -een loc*ted *-oe the -ottom o' the -ed% *nd

n some c*ses the o+tlet ,o"ts h*e -een oc*ted ne*" the to, o' the -ed# As

ndc*ted ,"eo+sly% ths l*tte" ,"*ctce "es+lts n s+"'*ce 'low on the -ed#

.n most c*ses% the s+-s+"'*ce o+tlet m*n'old connects d"ectly to the 'n*ldsch*"ge ,,e% *ndHo" to * conc"ete ch*nnel +sed 'o" 'n*l dsn'ecton# !ome system

desgns n E+"o,e *nd those n the 3#!# de"ed '"om th*t ,"*ctce (=/%=2)% connect

the s+-s+"'*ce m*n'old to *n *dB+st*-le o+tlet 'o" w*te" leel cont"ol# :low then

,"oceeds to ethe" dsch*"ge o" dsn'ecton#

The +se o' *n *dB+st*-le o+tlet w*s ,"eo+sly "ecommended to m*nt*n *n*de;+*te hyd"*+lc g"*dent n the -ed# Ths dece c*n *lso h*e sgn'c*nt%

o,e"*ton*l *nd m*nten*nce -ene'ts# The s+"'*ce o' the -ed c*n -e 'looded to

enco+"*ge% deelo,ment o' newly ,l*nted eget*ton *nd to s+,,"ess +ndes"*-le

weeds% *nd the w*te" leel c*n -e lowe"ed n *ntc,*ton o' m*Bo" sto"m eents *nd

to ,"ode *ddton*l the"m*l ,"otecton *g*nst '"ee5ng d+"ng wnte" o,e"*tons ncold clm*tes#

'4e+seof a 5erforated su#surface manifold connected-to an adDusta#le outlet%ould seem to offer t4e maimum flei#ilit and relia#ilit as t4e outlet device for S$

wetl*nd systems# !nce the m*n'old s -+"ed *nd n*ccess-le 'ollowng

46


43/87

Ch*,te" 4

const"+cton% c*"e'+l g"*dng *nd s+--*se com,*cton wo+ld -e "e;+"ed d+"ngconst"+cton *nd cle*no+t "se"s sho+ld -e ,"oded n the lne#

O.6RE+O*A/

W4en 5rocess Cinetics %ere "iven an consideration7 most of t4e eistin"

sstems in t4e U:S: and: Euro5e %ere desi"ned as an attac4ed "ro%t4 #iolo"ical

reactor usin" a first order 5lu" flo% model7 s4o%n 5reviousl as e;uation

(/)

The e''l+ent 1ODfinal O.6 6 m"F/:

.t h*s -een *"g+ed th*t ,l+g 'low knetcs do not *,,ly to !: const"+ctedwetl*nd systems -ec*+se the dye *nd t"*ce" st+des whch h*e -een ,e"'o"med do

not eh-t the de*l ,l+g 'low "es,onse# :g+"e /= ,"esents the "es+lts o' * t"*ce"st+dy% +sng lth+m chlo"de (*n no"g*nc% conse"*te t"*ce")% cond+cted n /60

*t the o,e"*ton*l !: wetl*nd system *t C*"lle% LA (2F)# Essent*lly /00 ,e"cent o'

the t"*ce" w*s *cco+nted 'o" n the e''l+ent% so ths c*n -e consde"ed * *ld st+dy#

.t cle*"ly dd not eh-t de*l ,l+g 'low "es,onses% -+t the c+"e s m+ch close" to

,l+g 'low condtons th*n to the com,lete m *lte"n*te# The cent"od o' the c+"e

ndc*tes *n 7$T o' 46 ho+"s% whch s dentc*l to the theo"etc*l detenton tme

c*lc+l*ted wth the *ct+*l 'low% me*s+"ed ,o"osty% *nd wetl*nd cell dmensons#

The"e w*s no s+"'*ce 'low d+"ng ths test# D*t* '"om sml*" tests *t othe" stes

show *n een close" "esem-l*nce to ,l+g 'low#

The sh*,e o' the c+"e on :g+"e /= s sml*" to those o-se"ed wth'*c+lt*te ,onds *nd sml*" w*stew*te" t"e*tment conce,ts whe"e ,l+g 'low

condtons *"e *lso *ss+med *s the -*ss 'o" desgn (==)# odels *"e **l*-le 'o"

these systems whch *ttem,t to de'ne condtons -etween ,l+g 'low *nd com,lete

4


44/87

Ch*,te" 4

m% -+t the d''c+lty n de'nng the necess*"y ,*"*mete"s h*s "es+lted n mnm*l +seo' these *lte"n*tes#

:g+"e /=# Lth+m T"*ce" !t+dy% C*"lle> LA#

The ,l+g 'low model s ,"esently n gene"*l +se# *nd t seems to ,"ode *"e*son*-le *,,"om*ton o' ,e"'o"m*nce n these !: const"+cted wetl*nds#

7owee"% mo"e so,hstc*ted models h*e *lso -een ,"o,osed 'o" !: wetl*nds# One

model ncl+des * ,l+g 'low segment 'ollowed -y th"ee contn+o+sly st""ed (com,lete

m) "e*cto"s n se"es (4=)# When s+''cent d*t* *"e **l*-le to *ld*te these

*lte"n*te models% they m*y "e,l*ce the c+""ent *,,"o*ch#)n t4e interim7 t4e use of

t4e 5lu" flo% model is recommended for desi"n:

The Jt o" hyd"*+lc "esdence tme (7$T) '*cto" n e;+*ton (/) c*n -e de'ned

*s9


45/87

*e"*ge 'low th"o+gh the -ed% m Hd ('t Hd)

Ch*,te" 4

Whe"e9 n

L

W

d

M e''ecte ,o"osty o' med* (see T*-le


46/87

M -ed s+"'*ce *"e*% m ('t )

:n*l E''l+ent I+*lty% m;HL

Ch*,te" 4

!nce the te"m LW n e;+*ton (


47/87

Ch*,te" 4

C"eek% AL) +sngTyphan 'ne g"*el s o-t*nng ecellent ,e"'o"m*nce wth * de,th

o' 0#= m% whch m*tches the "oot ,enet"*ton lsted n T*-le 'o" th*t ,l*nt#

'4e final desi"n and siBin" of t4e S$ #ed for O.6removal is an

iterative 5rocess

!: .etermine t4e media t5e7 ve"etation7 and de5t4 of #ed to #e used:

2: .etermine # field or la#orator testin" t4e 5orosit


48/87

"*nged '"om 5e"o to 4< gm 02H m Hd o' wetl*nd s+"'*ce *"e* (4%F%=4)# Ths oygen

Ch*,te" 4

Sus5ended Solids Removal

A knetc model s not **l*-le 'o" s+s,ended solds "emo*l> -*sed on the d*t*,"esent*tons n :g+"es < *nd % t s +nlkely th*t s+ch * model wll -e deelo,ed#.t wo+ld *,,e*" th*t wth *n 7$T o' *-o+t / d the T!! wll -e "emoed to * leel o'

*-o+t!0mgHL#As a rule of t4um# it can #e assumed t4at if t4esystemisdesgned

for a certain level of O.6removal7 t4e 'SS removal %ill #e com5ara#le as lon" as

si"nificant lon"-term surface flo% does not occur:Longte"m s+"'*ce 'low c*n "es+ltn sho"t c"c+tng *nd the *ddton o' T!! to the s+"'*ce 'low st"e*m n the 'o"m o'

*lg*e *nd ,l*nt det"t+s#

)'RO1E RE+O*A/

As ndc*ted n the dsc+sson "el*ted to :g+"es 6 *nd % the m*Bo" ,*thw*y 'o"nt"ogen "emo*l n !: wetl*nd systems s -ologc*l nt"'c*ton 'ollowed -y

dent"'c*ton (4%F%6)# 1*sed on the d*t* ,"esent*tons n :g+"es 6 *nd % t s cle*"

th*t *mmon* "emo*l s not e"y e''ecte n most o' the o,e"*ton*l !: systems

st+ded# The lmtng '*cto" n *mmon* "emo*l * nt"'c*ton s -eleed to -e the

**l*-lty o' oygen n the med* ,"o'le# Ths const"*nt s *,,*"ent "eg*"dless o'

the *ge o" o,e"*ton*l hsto"y o' the system# The only two systems demonst"*tng

ecellent *mmon* "emo*l n :g+"e h*e ,l*nt "oots (*nd the"e'o"e **l*-le

oygen) th"o+gho+t the ,"o'le% *nd s+''cent 7$T to com,lete the "e*ctons# The

m*Bo"ty o' the systems const"+cted n the G+l' !t*tes n "ecent ye*"s h*e too -"e'

*n 7$T ( 2d) *nd n*de;+*te "oot ,enet"*ton *nd deelo,ment to de,end on the

,l*nt "oots *s *n oygen so+"ce 'o" sgn'c*nt nt"'c*ton# .n these c*ses% othe"

oygen so+"ces wll -e necess*"y#

The"e s no consens+s on how m+ch oygen c*n -e '+"nshed -y the eget*tonn !: wetl*nds o" on the oygen t"*ns'e" e''cency o' *"o+s ,l*nt s,eces# The"e

s consens+s th*t these eme"gent *;+*tc ,l*nts t"*nsmt eno+gh oygen to the" "ootsto kee, *le# The ds*g"eement occ+"s oe" how m+ch ecess oygen s then

**l*-le to s+,,o"t -ologc*l *ctty n the "oot 5one# &+-lshed estm*tes h*e2

s not -eleed to -e d''+sed th"o+gho+t the s+-s+"'*ce ,"o'le% -+t s lkely to -e**l*-leonly on the s+"'*ces o' the sm*lle" "oots% wthn the "oot 5one% n the -ed#

These *e"o-c mc"ostes on the "oot h*"s ,"ode ,otent*l cont*ct s+"'*ces 'o" thent"'c*ton o' *mmon*# These mc"ostes ,"o-*-ly occ+" th"o+gho+t the length o'

the -ed% -+t the oygen dem*nd 'o" 1OD


49/87

*e"*ge *l+e o' F#< gm 02Hm Hd s *lso consstent wth% *nd ne*" the low end o'% the

gmHm Hd gmHm Hd

Ae"*ge **l*-le oygen F#< gmHm Hd ('"om T*-le )

Ch*,te" 4

An alternative o"en source7 ot4er t4an t4e 5lant roots7 is not a55arent in t4e

com5letel su#mer"ed7 #ut full rooted7 S$ #ed:!nce these systems% *s shown n

T*-le % do ,"ode sgn'c*nt *mmon* "emo*l (whch s co""el*ted to "oot de,th)%

t seems lkely th*t the"e s some oygen **l*-le on the s+"'*ces o' the ,l*nt "oots#

!nce t t*kes *-o+t < mg o' oygen to cone"t / mg o' *mmon* to nt"*te% t s

,oss-le to estm*te the oygen th*t w*s ,"oded n the !*ntee system to *chee

the "emo*ls shown n T*-le # These "es+lts *"e s+mm*"5ed n T*-le F#

The *l+es n T*-le F do not de'ne the *ct+*l oygen ,"od+cton o' the ,l*nts%-+t only ndc*te the *mo+nt o' oygen necess*"y to *cco+nt 'o" the known "emo*l

o' *mmon* *t the !*ntee ,"oBect# .t seems lkely th*t the ,l*nt "oots we"e the so+"ce

o' ths oygen snce no othe" so+"ce s *,,*"ent no" s *ny othe" *lte"n*te *mmon*"emo*l ,"ocess lkely# These *l+es '"om !*ntee *"e *lso consstent wth the

,e"'o"m*nce o' the 1e*" C"eek system (see :g+"e *nd "el*ted dsc+sson)# The=

"*nge "e,o"ted -y E+"o,e*n nestg*to"s (F%=4/#

T*-le F# &otent*l Oygen '"om @eget*ton *t !*ntee% CA

&l*nt Ty,e $oot De,th

m

A*l*-le Oygen= * 2 -

1+l"+sh "+sh(Scirpus)$eeds(Phragmites)

C*tt*ls(Typhal

Ae"*ge

0#F0#0

0#=0

F# the 7$T 'o" the s*me condtons% +sng e;+*tons % F%

*nd 6% "*nges '"om /= to / d*ys# Ths m*y -e -ec*+se *ll th"ee ,"oced+"es we"e

de"ed '"om ste condtons whe"e oygen m*y h*e -een slghtly to sgn'c*ntly

de'cent n the w*te" 'lowng th"o+gh the system# None o' these e;+*tons wll

,"ode *n *cc+"*te ,"edcton o' *mmon* "emo*l 'o" the !: systems shown on

:g+"es 6 *nd # Ths s -eleed to -e d+e to the *lmost com,lete l*ck o' oygen n

most o' the systems *nd% cone"sely% to the ,"esence o' **l*-le oygen n the two

systems whch demonst"*ted ecellent *mmon* "emo*l E;+*tons % F% *nd 6 m*y

,"ode * "e*son*-le o"de"o'm*gnt+de estm*te o' *mmon* "emo*l ,e"'o"m*nce

? - !8


53/87

Ch*,te" 4

o' m*ny o' the estng !: const"+cted wetl*nds whch do not h*e s+''cent oygen'"om the ,l*nts o" othe" so+"ces#

*E1E'A')O SE/E&')O A. +AA1E+E'

ost o' the const"+cted wetl*nds n the 3#! +tl5e one o" mo"e o' the ,l*nts,eces lsted n T*-les *nd F# A-o+t 40 ,e"cent o' the o,e"*ton*l !: systems +se

onlyScripus. Phragmitess the most wdely +sed s,eces n the E+"o,e*n systems#

A n+m-e" o' systems n the G+l' !t*tes *lso +sed * n+m-e" o' 'lowe"ng ,l*nts 'o"

*esthetc "e*sons# These so't tss+e ,l*nts decom,ose e"y "*,dly *nd c*n *''ect

w*te" ;+*lty n the e''l+ent# *ny loc*tons *do,ted * "o+tne '*ll h*"est to "emoe

these ,l*nts -e'o"e they ded o" s+''e"ed '"ost d*m*ge# The"e h*e -een some

*ttem,ts to c"e*te * ,l*nt de"sty sml*" to th*t ,"esent n * n*t+"*l m*"sh> ths*,,"o*ch s mo"e e,ense *nd the ntended de"sty c*n -e d''c+lt to m*nt*n#

An of t4e t4ree s5ecies listed in 'a#les = and > are suita#le for use in S$

sstems:.' the ,l*nt s e,ected to ,"ode * sgn'c*nt t"e*tment '+ncton% then the

de,th o' the -ed sho+ld not eceed the ,otent*l "oot ,enet"*ton de,th#' 4 e

Phragmitesused in man Euro5ean sstems offer several advanta"es for a lo%

m*nten*ncetreatment sstem:They wll g"ow *nd s,"e*d '*ste" th*n -+l"+sh> the"

"oots sho+ld go dee,e" th*n c*tt*ls> *nd they *"e not * 'ood so+"ce 'o" m+sk"*ts *nd

n+t"* whch h*e -een * ,"o-lem 'o" c*tt*l *nd -+l"+sh wetl*nds# 7owee"% the

h*-t*t *l+es 'o" *Phragmitessystem *"e ,"o-*-ly less th*n 'o" othe" ,l*nt s,eces#

A n+m-e" o' systems n the G+l' !t*tes +tl5e *n *nn+*l h*"est% "eg*"dless o'the ,l*nt s,eces +sed# .n cont"*st% "o+tne *nn+*l h*"estng s not ,"*ctced n

E+"o,e o" *t most othe" systems n the 3#!# .t m*y -e +se'+l to "emoe +ndes"*-leweeds d+"ng the e*"ly ,*"t o' the g"owng se*son 'o" the '"st 'ew ye*"s o' o,e"*ton#

:loodng o' the -ed s+"'*ce *'te" the nt*l ,l*ntng c*n hel, "ed+ce weed n'est*ton#

A "o+tne *nn+*l h*"est o' the ent"e system ,"odes mnm*l -ene'ts *nd s not

"ecommended# .t s *lso s+ggested th*t the +se o' so't tss+e 'lowe"ng ,l*nts -e*oded *nd the"e-y elmn*te the need 'o" the" *nn+*l h*"est *nd "el*ted

m*nten*nce#

W*te" leel m*n*gement n the !: -ed s not only hel,'+l 'o" weed cont"ol% -+tc*n *lso -e +sed to nd+ce dee,e" "oot ,enet"*ton# 1*sed on e,e"ence n E+"o,e%t s cl*med th*t ' the w*te" leel n the -ed s g"*d+*lly lowe"ed n the '*ll o' e*ch

ye*" the "oots wll ,enet"*te to g"e*te" de,ths# A th"ee ye*" ,e"od s consde"ednecess*"y 'o"Phragmites"oots to "e*ch the" 0# m ,otent*l de,th# Altho+gh ths

*,,"o*ch h*s not -een t"ed n the 3#!# t sho+ld -e s+ccess'+l% -+t t m*y h*e to -e

4/


54/87

Ch*,te" 4

"e,e*ted ee"y ye*" 'o" the o,e"*ton*l l'e o' the system# The *lte"n*te s * "oot5one whe"e the m*Bo" m*ss o' "oots *"e lmted to the to, S 0#2< m n the ,o"tons

o' the -ed whe"e n+t"ent concent"*tons *"e hgh#

TheTypha"oots ,enet"*ted to the '+ll de,th o' the sh*llow -ed ( 0#= m) *t theconst"+cted wetl*nd system n 1e*" C"eek# Ths system w*s lghtly .o*ded% *nd snce

t se"ed * ,+-lc hgh school t "eceed essent*lly no w*stew*te" 'low *t nght%

d+"ng the weekends% *nd d+"ng the s+mme" months# These do"m*nt ,e"ods when

the n+t"ent concent"*tons wo+ld -e *t low leels n the -ed *"e -eleed to -e *

cont"-+tng '*cto" to the "*,d ,enet"*ton o' the "oot system# .t mght -e ,oss-le

to "e,lc*te ths e,e"ence *t othe" loc*tons wth contn+o+s 'low ' the system we"e

dded nto two o" mo"e ,*"*llel cells *nd ' the nt*l 'low we"e less th*n the +ltm*te

desgn c*,*cty# .n ths c*se% the w*stew*te" 'low co+ld -e *lte"n*ted -etween the

cells d+"ng the s+mme" *nd '*ll months *nd "es+lt n enh*nced "oot ,enet"*ton n thetem,o"*"ly do"m*nt cell#

At the !*ntee ,lot system% the ,l*nt "oots ,enet"*ted to the de,ths shown nT*-le wtho+t *ny s,ec*l m*n,+l*ton o' w*te" leels o" othe" sml*" m*n*gement

*cttes# The sd*y 7$T com-ned wth the w*"m clm*te *nd contn+o+s g"owng

se*son *t ths ste ,"o-*-ly *l cont"-+ted to low n+t"ent condtons n the l*tte" ,*"t

o' the -ed% the"e-y nd+cng "oot g"owth *nd ,enet"*ton#

As "oot deelo,ment commences% nt"'c*ton sho+ld -e enh*nced> ths sho+ld-e "*,dly 'ollowed -y dent"'c*ton (*s long *s * c*"-on so+"ce s **l*-le)# The

"es+ltng loss o' nt"ogen to the *tmos,he"e '+"the" "ed+ces the **l*-lty o' n+t"entsn the -ed *nd m*y ,"omote '+"the" ,"og"esse "oot deelo,ment n the ,o"tons o'

the -ed whe"e the nt"'yng o"g*nsms c*n s+ccess'+lly com,ete 'o" the **l*-le

oygen# .t s lkely th*t "oot deelo,ment wo+ld stll -e lmted n the '"ont ,*"t o'

s+ch * -ed whe"e the oygen dem*nd 'o" 1OD


55/87

Ch*,te" 4

*nd dee,e" "oot ,enet"*ton# The dee,e" "oot ,enet"*ton n ths c*se wo+ld not "es+lt

n m,"oed t"e*tment snce the "oots *"e not n cont*ct wth the -+lk o' thew*stew*te"# 7yd"*+lc m,"oements *"e necess*"y 'o" s+ch systems to m*nt*n

'low th"o+gho+t the '+ll -ed ,"o'le% -+t the sho"t detenton tme wll stll -e * lmtng

'*cto"#

4 2/


56/87

Ch*,te" n these c*ses the m*t+"e stem sho+ld -e c+t -*ck to 0#= m# ( / 't) -e'o"e

,l*ntng#

The w*te" leel n the -ed sho+ld -e m*nt*ned slghtly *-oe the med*s+"'*ce d+"ng ,l*ntng *nd 'o" see"*l weeks the"e*'te" to s+,,"ess weed

deelo,ment *nd ,"omote g"owth o' the ,l*nted s,eces# An nt*l% mode"*te*,,lc*ton o' comme"c*l 'e"tl5e"s wll *lso enh*nce ,l*nt deelo,ment# W*stew*te"

*,,lc*tons c*n ,"o-*-ly commence s to eght weeks *'te" ,l*ntng ' go"o+s

g"owth s o-se"ed# An e*"ly s,"ng ,l*ntng s ,"e'e""ed whenee" ,oss-le# The

,l*nts% *nd the"e'o"e system ,e"'o"m*nce 'o" nt"ogen% m*y not -egn to "e*ch

m*t+"ty *nd e;+l-"+m +ntl l*te n the second g"owng se*son##

CO!T!

A "ecent s+"ey (/=) ndc*tes th*t the c*,t*l costs 'o" !: wetl*nd systems*e"*ged *"o+nd 200%000 ,e" hect*"e (6F%000H*c) *nd the :W! systems we"e

*-o+t


58/87

Ch*,te" L#W# Lon% (//)#/n /ssessment of the Root Zone&ethod of +aste#ater Treatment.o+"# W&C: =(=)%2=24F#

/


77/87

Ch*,te" /0

2/#

22#

Tcho-*noglo+s% G#% :#L# 1+"ton (//)#+aste#ater ngineering2 Treatment,Disposal and Reuse.Th"d edton% cG"*w 7ll .nc#% New o"k% N#

7e"skowt5% #% !# 1l*ck% W# Lew*ndowsk% (/6F)#'isto#el /rtificial &arshTreatment Pro@ect. n9 A;+*tc &l*nts 'o" W*te" T"e*tment *nd $eso+"ce

$ecoe"y% $eddy ? 1l*ck% ed#% 24F2


78/87

Ch*,te" /0

=2# !tene"% G#$#% $# # :"eem*n% (/6)# Configuration and Substrate !esignConsiderations for Constructed +etlands +aste#ater Treatment.n9 Const"+cted

Wetl*nds 'o" W*stew*te" T"e*tment9 +nc,*l% .nd+st"*l *nd Ag"c+lt+"*l% D#7*mme"% ed#% ===/% Lews &+-lshe"s% Chelse*% l#

==# 3#!# E&A% (/6=)#!esign &anual2&unicipal +aste#ater Stabili%ation PondsE&A 2


79/87

APPE.)( A

/istof Partici5ants in U:S: EPA WorCs4o57 Se5tem#er 2?F267 !992

"# $o-e"t E# Lee+nc,*l Technology 1"*nch

O''ce o' W*stew*te" En'o"cement

? Com,l*nce

3#!# E&A

W*shngton% DC 2040

"# Don*ld 1"own

3#!# E&A $$EL

Cncnn*t% O7 4


80/87

APPE.)(

Site .etails for t4e Sstems /isted in 'a#le 2


81/87

APPE.)(

P)//)PS )1 S&OO/(1e*" C"eek% AL)

:low9 0#0/


82/87

APPE.)(

E'O7 /A(1enton% LA)

:low9 M 0#/00 mgd% A"e*9 /#< *c% L M 00 't% W M


83/87

APPE.)(

+A.E*)//E7 /A(*ndelle% LA)

:low9 /#224 mgd% A"e*9 4#


84/87

APPE.)(

AR.)7 ,7phragmites side (7*"dn% K)

:low9 0#024 mgd% A"e* M 0#F *c% L M 4F< 't% W M F2 't% L9W M #9/%

-ed de,th9 2 't% 7$T M =#= d% &"elmn*"y t"e*tment9 cont*ct st*-l5*ton ,l*nt%W*stew*te" ty,e9 m+nc,*l% ,l*nts9 "eeds#

1 O D

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