PLUG FLOW CAN BE INDUCED IN MATURATION PONDS BY
INCREASING THE L/W RATIO.
REPÚBLICA BOLIVARIANA DE VENEZUELAUNIVERSIDAD DEL ZULIAFACULTAD DE INGENIERÍA
CENTRO DE INVESTIGACION DEL AGUA
By
Nibis Bracho
Barry Lloyd
Gerardo Aldana
OBJECTIVE
This research evaluates the influence ofhydraulic flow characteristics on mixingmaturation ponds into open and bafflelagoons, considering the critical informationneeded for engineering design.
REPÚBLICA BOLIVARIANA DE VENEZUELAUNIVERSIDAD DEL ZULIAFACULTAD DE INGENIERÍA
CENTRO DE INVESTIGACION DEL AGUA
INTRODUCTION
REPÚBLICA BOLIVARIANA DE VENEZUELAUNIVERSIDAD DEL ZULIAFACULTAD DE INGENIERÍA
CENTRO DE INVESTIGACION DEL AGUA
Typical dispersion curves for tanks.Source: Camp (1946)
BOD remaining as a percentageSource: Thirumurthi, 1969.
Dispersion number and faecal coliform concentration in the effluent of open ponds, a lagoon with 2, 3, 4, 6 & 9 baffles
N d tmdays
Faecal coliform
cfu/100 ml in
outlet
Type of system
Source of information
0369
0.1610.1260.1120.096
4.205.987.309.10
They did not include.
Pilot WSP with baffles
Kilani and Ogunrombi
(1984)
0246
0.15940.13350.11540.1028
4.704.755.4
5.79
4.1x105
8.0 x104
4.9 x104
2.5 x104
Pilot WSP with baffles
Muttamara and
Puetpaiboon (1997)
03
0.7900.656
1.061.26
9.62 x104
3.9 x104Full scale maturation pond with
baffles
Lloyd et al.(2002)
03
0.370.074
1.451.66
7.7x104
3.7x102Full scale maturation pond with
baffles
Bracho et al.(2006)
METHODOLOGY
REPÚBLICA BOLIVARIANA DE VENEZUELAUNIVERSIDAD DEL ZULIAFACULTAD DE INGENIERÍA
CENTRO DE INVESTIGACION DEL AGUA
REPÚBLICA BOLIVARIANA DE VENEZUELAUNIVERSIDAD DEL ZULIAFACULTAD DE INGENIERÍA
CENTRO DE INVESTIGACION DEL AGUA
N
REPÚBLICA BOLIVARIANA DE VENEZUELAUNIVERSIDAD DEL ZULIAFACULTAD DE INGENIERÍA
CENTRO DE INVESTIGACION DEL AGUA
122.4 m
14..0
0 m
14.5
0 m
13..5
0 m
1 2..0
0 m
12..9
0 m
12. 2
0 m
6.25 m
7.25 m
Influ
ent
Out
let
NORTH LAGOON
CENTRAL LAGOON
SOUTH LAGOON
2.40
m
Depth = 1.00 m
Depth = 0.95 m
Depth = 1.10 m
2.15 m
Outlet discharge to stream
Flow coming from treatment plantBypass
1.35 m
0.90
m
Dimensions of three maturation ponds in Lidsey sewage treatment plant.
4.65 m4.65 m 4.65 m
2”x 1”3”x 3”
1..8 m
Nails 2”1/2x 3mm
1.8 m
L/W = 9:1 to 79:1
FLOW = 7.9 L/SOPEN LAGOON
FLOW = 4.5 L/SBAFFLE LAGOON
FLOW = 4.5 L/SOPEN LAGOON
FLOW = 9.0 L/SOPEN LAGOON
FLOW = 6.0 L/SBAFFLE LAGOON
FLOW = 4.5 L/SBAFFLE LAGOON
FLOW = 4.5 L/SOPEN LAGOON
FLOW = 4.5 L/SBAFFLE LAGOON
FLOW = 6.0 L/SBAFFLE LAGOON
EFFECT OF THE FLOW
WITH SIMILAR CONFIGURATION
FLOW = 7.9 L/SOPEN LAGOON
FLOW = 4.5 L/SOPEN LAGOON
FLOW = 9.0 L/SOPEN LAGOON
FLOW = 4.5 L/SOPEN LAGOON
FLOW = 7.9 L/SOPEN LAGOON
FLOW = 9.0 L/SOPEN LAGOON
Rhodamine tracer studies in the lagoons.
Rhodamine WT
Fluorimeter
Online to record the Rhodamine concentration from the effluent
Rhodamine WT studies in the open and baffles lagoon
The tracer began to exit
2 hours 35 min after the injection
d= 0.37 and tm =2080 min = 34.66 hours
17.5 hours after the injection
d = 0.074 and tm = 2361 min = 39.35 hours
Q = 4.5 l/s
Rhodamine WT studies in the baffles lagoon
Q = 6.0 l/s
d= 0.042
Rhodamine WT studies in the open lagoon
Q = 7.9 l/s
d = ∞
Rhodamine WT studies in the open lagoon
Q = 9.0 l/s
d= ∞
Tracer studies
Date Lagoon Nominal retention time (day)
tm (day)
Flow(l/s)
d
26/06/01 South 4.76 1.66 4.5 0.074
20/07/01 Central 2.17 0.76 9.0 ∞
11/10/01 North 4.02 1.45 4.5 0.37
18/10/01 South 3.57 1.07 6.0 0.042
09/05/02 North 2.36 1.13 7.92 ∞
• The baffle intervention at the South lagoon may beconsidered to be the appropriate engineering solutionin order to produce plug flow in maturation pond,particurlary when the wind is opposite to the flow.
• The flow rate does not affect the dispersion number inbaffle lagoon, but it is affected by wind direction.
• The dispersion number increases In open lagoonwhen flow rate increases.
Baffles lagoon is a possibleengineering solution that enables therehabilitation of maturation ponds atlow cost, using the existinginstallations.
