3b anaerobic ponds
Post on 03-Apr-2018
216 Views
Preview:
TRANSCRIPT
-
7/29/2019 3b Anaerobic Ponds
1/21
ANAEROBICANAEROBICPONDSPONDS
ro essor ara
-
7/29/2019 3b Anaerobic Ponds
2/21
dissolved oxygen
depth range 15 m; depends on ground
con ons usua y m
importantimportant
-
7/29/2019 3b Anaerobic Ponds
3/21
ALGAE:ALGAE:
occasional surfaceoccasional surfacefilm of sulphidefilm of sulphide--
toleranttolerant
ChlamydomonasChlamydomonas
-
7/29/2019 3b Anaerobic Ponds
4/21
ALGAE:ALGAE:
occasional surfaceoccasional surfacefilm of sulphidefilm of sulphide--
toleranttolerant
ChlamydomonasChlamydomonas
OPERATION OF ANAEROBIC PONDSOPERATION OF ANAEROBIC PONDS
sedimentation of settleable solids and
intense anaerobic digestion (>15oC) and
copious biogas (CH & CO ) production
high BOD & SS removalhigh BOD & SS removal
functions much like an open septic tank
-
7/29/2019 3b Anaerobic Ponds
5/21
sludge layer
About 30% of influent BOD leaves as biogas
same groups of anaerobic bacteria
digesters require same environmentalrequire same environmental
con ons eg, p > .con ons eg, p > .
-
7/29/2019 3b Anaerobic Ponds
6/21
based on volumetric BODbased on volumetric BOD loadinloadin
VV = L= Lii Q/V g/mQ/V g/m33dd
= L= L // =
mg/l (= g/m3)
VQ
Q = flow, m3/d
= vo ume, m
1 ddV/Q =V/Q =
(retention time, days)
aa
1 d1 d
-
7/29/2019 3b Anaerobic Ponds
7/21
Design range for normal domesticDesign range for normal domestic
was ewa er:was ewa er:
100100 400 400
if 400, then risk ofodourodourrelease
-
7/29/2019 3b Anaerobic Ponds
8/21
caused mainly by hydrogen sulphide gashydrogen sulphide gas(H2S)
4 ponds by obligately anaerobic sulphate-
reducing bacteria (eg, Desulfovibrio spp) 2 , ,
depends on pH:depends on pH:
-
7/29/2019 3b Anaerobic Ponds
9/21
S=HS-
2
Effect of H on h dro en sul hide
bisulphidesulphide equilibrium
-
7/29/2019 3b Anaerobic Ponds
10/21
Odour, continued
odour not usually a problem if sulphateodour not usually a problem if sulphate
concentration
-
7/29/2019 3b Anaerobic Ponds
11/21
Anaerobic PondsAnaerobic Ponds
temperature, but insufficient reliable field
a a ava a e o eve op goo es gnequation
Design temperatureDesign temperature: mean air temp. inmean air temp. in
pond temp. some 2pond temp. some 233ooC warmer)C warmer)
Minimum retention time of 1 dayMinimum retention time of 1 day
-
7/29/2019 3b Anaerobic Ponds
12/21
BOD5 Percentage
Temp (oC) loading BOD
g m ay remova
10 100 40
1020 20T 100* 2T + 20*
2025 10T + 100* 2T + 20*
>>
* = o,
-
7/29/2019 3b Anaerobic Ponds
13/21
Raw wastewater 306 g/m306 g/m33dd
A2 A3A2
A4
129 g/m3d
Northeast Brazil, ~25Northeast Brazil, ~25 CC
-
7/29/2019 3b Anaerobic Ponds
14/21
Retention BOD SS FC
time (mg/l) (mg/l) (per
Raw ww 245245 310 4.7 107
** **** 6.. .
A3 0.4 45 64 5.0 106
A4 1.9 49 57 4.7 106
** ****
Not worth having (at least for domestic ww)
-
7/29/2019 3b Anaerobic Ponds
15/21
Northeast Brazil 25Northeast Brazil 25ooCC
Pond Retention Volumetric Percentage
Code time BOD load BOD(days) (g/m3 day) removal
.
A6 1.01.0 215 7676
A4/1 1.9 129 80
A1/3 2.0 116 75A1/2 4.0 72 68
.
-
7/29/2019 3b Anaerobic Ponds
16/21
very good removal of BOD & SSvery good removal of BOD & SS this has effect ofreducing land areareducing land area
requ remen or overa pon sys emrequ remen or overa pon sys em, soanaerobic onds should alwa salwa s be used
(except at small works serving only a few
thousand people)
-
7/29/2019 3b Anaerobic Ponds
17/21
Operation and maintenanceOperation and maintenance1. fl breedin in scum la er ma be a
problem: use a suitable larvicide
.
occurs every n years:
(Pond volume, m(Pond volume, m33))n =n =
Sludge accumulationSludge accumulation33 (Population)(Population),,
~ 3
~0.08 m3/cap.yr in Europe
-
7/29/2019 3b Anaerobic Ponds
18/21
en ra
CYPRUS
-
7/29/2019 3b Anaerobic Ponds
19/21
-
7/29/2019 3b Anaerobic Ponds
20/21
-
7/29/2019 3b Anaerobic Ponds
21/21
Anaerobic pond, Cyprus
top related