Flint River- final report- environmental engineering
Transcript of Flint River- final report- environmental engineering
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Figure 8 Simulation model used for zinc in Model Maker 4 ........................................................ 23 Figure 9 Model Maker 4 simulation ............................................................................................. 24
Figure 10 Total concentration of heavy metal in the water column ............................................. 25 Figure 12 Total concentration of Cadmium in the water column ................................................. 26
Figure 13 Weight fraction of heavy metals in the sediment column ............................................ 26
Figure 14 Cadmium weight fraction in the sediment column....................................................... 27 Figure 15 Suspended solid concentration in the water column .................................................... 27 Figure 16 Weight of zinc and Copper in the sediment column ................................................... 28
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1 Introduction
1.1 Location and features of Flint river
Flint River is located in the state of Michigan in United states of America, with 126.0km long,
Flint River is the main water resource for the city Flint and it flow through the countries if
Lapeer, Genesee, and Saginaw. There are three dams along the Flint River. The first one is
located in Richfield Township following is Utah Dam then the last one is Hamilton Dam. The
Richfield Township Dam form the Holloway Reservoir which is a water supply for Flint.1
In the city of Flint, the river flows past the sites of several former General Motors factories, most
notably Chevrolet's first assembly plant, which was bisected by the river, and downtown through
the campus of the University of Michigan–Flint and Riverbank Park.
Figure 1 Flint river in Michigan
1.2 Study segment for Flint River
In our case, in order to study the pollutant in the water body. We choose the segment below city
flint because the downstream after Flint it has two Waste water treatment plant, which is the
major pollutant for Flint River. Finally, we choose from Mill Road to Silver Creek as our study
segment and the whole length is 60.2km.
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August
Source Discharge(m3/s)
Discharge Concentration
Suspended Solids
(mg/l) (kg/d)
Total Zinc
(ug/L)
Total
Cadium
(ug/L)
Total
Copper
(ug/L) Upstream
Boundary 2.66 13.5 7.7 0.067 2.9
Flint WWTP 1.68 4.1 55 0.16 8.3
Flint Fly Ash 0.04 39.5 63 1.32 80
Brent Run 0.15 5.9 3.8 0.11 3.8
Ragnone WWTP 0.69 58.7 84 0.54 28.5
Pine Run 0.06 7 5 0.04 3.8
Silver Creek 0.085 5.8 5 0.04 3.8
December
Source Discharge(m3/s)
Discharge Concentration
Suspended Solids
(mg/l) (kg/d)
Total Zinc
(ug/L)
Total
Cadium
(ug/L)
Total
Copper
(ug/L)
Upstream
Boundary 26.35 7.4 4 0.05 2
Flint WWTP 2.19 7.8 54.3 0.18 16
Flint Fly Ash 0.1 23.5 220 2.89 127
Brent Run 0.57 7.7 7.67 0.097 2.93
Ragnone WWTP 1.14 40.7 75 0.21 18.5
Pine Run 0.67 5.5 3.33 0.013 2.1
Silver Creek 0.62 3.5 3.67 0.01 1.8
March
Source Discharge(m3/s)
Discharge Concentration
Suspended Solids
(mg/l) (kg/d)
Total Zinc
(ug/L)
Total
Cadium
(ug/L)
Total
Copper
(ug/L)
Upstream
Boundary 93.4 15.5 7.24 0.025 2.48
Flint WWTP 2.66 5.35 71 0.11 18.2
Flint Fly Ash 0.18 5.84 120 0.93 71.4
Brent Run 1.51 13.4 10.6 0.032 5.14
Ragnone WWTP 1.12 50.9 59.7 0.257 27.8
Pine Run 2 14 7 0.03 2 Silver Creek 2 14 7 0.03 2
Table 1 Data of the effluent from different station [2]
1.3 Preparation for building model
1.3.1 Model of discharge
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During the August the flow rate form upper stream is 2.66m3/s and except the Flint WWTP
others flow rate are much lower. In our case, to make our model simpler. We decided to combine
Brent Run, Pine Run and Silver Creek together to the Ragnone WWTP as one-point source
discharge because they have similar environmental condition like the lower pollutant and flow
rate.
So we divided it into 3 parts. Settingthe Flint WWTP as our point source discharge1 and
Ragnone WWTP as our point source discharge2. In our model, it’s 1.2km from the Mill Road to
discharge1. The distance between discharge1 and discharge2 is 29km then 29.80km below
discharge2 is Silver Creek.
Figure 3 Overview of study segment
*+,+-
./010234 5363 78/ 98026 :8;/
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Because the segment we study in Flint River only 60.2km long and Flint River also located in
plain country, so we assume that the elevation doesn’t change a lot form the Mill Road to Silver
Creek.
Parameter Upstream Flint
WWTP
Raganone
WWTP
Length(km) 1.2 29 29.8
X_distance (km) 0-1.2 30.2 60
Cross section area
(m2)
19 19 19
Slope(°) 0.02 0.02 0.02
Average elevation(m) 230 230 230
U_Velocity (m/s) 0.14 0.22 0.28
W_Width (m) 36 36 36
H1_Deepth(m) 0.52 0.52 0.52
T_Temperature(℃) 20 20 20
pH 7.3 7.3 7.3
Table 3 Hydraulic parameters on Flint river
1.5 Contaminant in the Flint River
For our projects we chose biochemical oxygen demand (BOD) as our non conservative pollutant
and three major heavy metals as our conservative pollutants
*+?+*
@08=A0
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measure organic in water. Higher BOD concentration means high concentration of
microorganism which will lead to low DO concentration and others life like fish and plants
cannot survive.
In terms of BOD, it contains carbonate BOD and nitrogen BOD, but in our case we just consider
the carbonate BOD although nitrogen BOD is also an important factor in consumption in water
body.
*+?+- G;:9=25=5 :8405
Suspended solid in the river due to the erosion and others types of particulate form materials
discharge to water body. Although it is not toxicant it will affect the turbidity odor color in the
river. In addition, due to the fact that some of the metals are not fully dissolved in the water,
some of them are subject to sedimentation and settling which is highly affected by the suspended
solid. As a result, it’s very important to study the suspended solid concentration when we
building the model.
*+?+, H=3IC J=634:
!"##$%
Metallic Copper is insoluble in water, but many copper salts are soluble as cupric or cuprous
ions. Copper ions are not likely to be found in natural surface or ground waters. This is because
they are introducing into natural waters of Ph7 or above, these ions quickly precipitate and are
thereby removed by adsorption and/or sedimentation6,5
Copper is not considered to be a cumulative systematic poison , like lead or mercury. In
humans, most of the copper ingested is excreted by the body and little is retained. In lower
organisms and marine animals such as sponges there are some record of accumulation. In
concentrations high enough to be dangerous to humans, copper renders a disagreeable taste to the
water. Threshold concentrations for taste has been reported in the range of 1.0-2.0- mg/L while
5.0-7.0mg/L makes the water completely undrinkable.7,5
Coppe acts synergistically with the sulfates of other metals such as Zinc and Cadmium to
produce potent toxic effects on Fish 8,9. Synergism also exists between copper and mercury but in
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our studies Zinc and Cadmium are only considered. Copper standards for aquatic systems in the
state of Michigan is 1.0 mg/L which is the same as USPHS water standards.5
!'()*+)
The elemental form of Cadmium is insoluble in water although the chloride, nitrate and sulfate of
this metal are highly soluble. Cadmium salts may be found in wastes from electroplating plants,
pigment works, textile printing, lead mines and certain chemical industries. Cadmium is
moderately toxic to all organisms and it is a cumulative poison to mamals. It tends to concentrate
in liver, Kidney, pancreas and thyroids of humans and other mamals.
Cadmium acts synergistically with zinc to increase toxicity. Several studies found that the
cadmium concentration of 0.03 mg/l with combination with 0.15 mg/l of zinc from galvanized
screens caused mortality of salmon fry. The standards for aquatic systems for state of Michigan
is 0.01 mg/l.
,*-.
Some Zinc salts (eg. Zinc chloride and zinc sulfate) are highly soluble in water. These salts are
often found in industrial wastewater from galvanizing industries, and manufacturers of paint
pigments, cosmetics pharmaceuticals, dyes, insecticides and other products. High concentrations
of zinc in domestic water are undesirable from aesthetic standpoint as well as from a health
hazard standpoint. At high concentrations, zinc gives water a milky appearance. Concentrations
as low as 5 mg/l cause a greasy film on boiling of the water.
Zinc has no known adverse physiological effects at normal concentrations. It is an essential and
beneficial element in human nutrition. Zinc exhibits its greatest toxicity toward fish and aquatic
organisms. In soft water concentrations of zinc ranging from 0.1 to 1.0 mg/L reported to be
lethal5
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2 Biochemical oxygen demand and dissolved oxygen in Flint river
2.1 Determining parameters
As we can see in our case, the major pollutant is the sanitary waste from the city which contains
lots of organic materials. Organic materials are highly oxidizing to the dissolved oxygen in the
river. As the table shows below, the data for CBODU is obtained at each point source2. As to the
DO K1 K d Ka Kr we calculate them base on our velocity and depth in the Flint river. For
saturated DO concentration we were using to get three-point data3.
The formulas below we are using for the parameter calculation.
First for before we calculate the concentration of BOD, we have to know Kd, following formulas
we are using for our Kd calculation.
434.0
83.0
!
""#
$%%&
'=
H K
d
Because in our assumption we mentioned before, we assume the area of cross section is the same,
so the Kd in each part (upstream river1 river2) is the same which is equal to 4.8e-06/d
But then we have to consider the temperature effect on the biodegrade rate so we using the
formulas below to correct it. But due to the average temperature in this case is 20 degrees, so it’s
the same as we calculate.
( ) ( ) 20
20d )04.1( !
=
T
d T K K
In this case, Cs1 is search from the book[3] Principles of Surface Water Quality Modeling and
Control, So using the Cs at our this level, we finally calculate the Cs is 10.46mg/l. Because in
our case we have less change on elevation, therefore we assume that the Cs is the same in whole
segment.
Cs=Cs1*(100-0.0035H)/100
As to the reaeration rate base the equation below we calculate it. Although the cross-section aera
is the same in this case, flow rate is different. In addition, because the average depth of river is
less than 8feet, so we decided using this formulas:
85.1
67.06.21
H
U K
a = 0!H!8
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Also, we have to consider the temperature effect on the Ka ,but due to the same condition as Kd
mentioned .So Ka is the same as our result which
K a1=1.82e-05 k a2=2.42e-05 kaup=1.42e-05
( ) ( ) 2020a
)04.1( !=T
a T K K
On the initial values of DO concentration. Base the data we collect 2 from each station, then we
case on our decay rate K d and reaeration K a and initial concentration from the point source
discharge L0, then we using the formulas below to find out our initial values in our case.
Dc= ( ) t k t k t k d a
d a a d e D e e
k k
L k !!!
+!
!
0
0
Then after we calculate the deficit in each point we used the Cs in that point minus Dc and we
can get our DO concentration.
Parameter Meaning Upstream Flint
WWTP
Ragnone
WWTP
Q (m /s) Flow rate 2.66 1.68 1.025
C_BODU
(mg/L)
Concentration of BODU 5 16 30
C_DO (mg/L) Concentration of DO 5.4 4 3.5
K1_BOD5 (day-
1)
BOD5 decay rate 0.187 0.187 0.187
Kd (day-
) BOD5 decay rate 0.415 0.415 0.415
f (L0/y5) Ration of CBOD5 and
CBODu
1.4 1.4 1.4
Cs (mg/L) DO saturation 10.46 10.46 10.46
Kr (day- ) Overall loss rate 0.415 0.415 0.415
Ka (day-
) Volumetric reaerationcoefficient
3.272 4.180 4.648
Table 4 Parameters for BOD and DO [3]
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2.2 Simulation of the BOD with Model Maker 4
In this case because we have two-point source discharges in the whole system. Therefore, in the
model maker we setting the segment between discharge 1 and 2 as a compartment which the
quality of water is affect by the Up stream river and the point source discharge1. So in graph
below we can see clearly river1 is affected by both Flint WWTP and the concentration of Up
stream BOD.
Mass balance we are using in BOD concentration:
L K dx
dL U
d!=
Figure 4 BOD simulation in Model maker
Compartment Equation Initial value (mg/l)
Upstream_BODU When t>1.2, dUpstream_BODU/dt=0Default, dUpstream_BODU/d=
-Kd*Upstream_BODU/U_Upstream
7
Flint_WWTP Qd1Cd1
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River1_BODU When t
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Upstream_D
O
When t>1.2, dUpstream_BODDO/dt=0
Default,((Kd*C01*exp(Kr*t/(U_Upstream))+(Ka_Upstream*(C
s_Upstream-Upstream_DO)))/(U_Upstream))
7
Flint_WWTP Qd1C01
River1_DO When t 30.2, dUpstream_BODDO/dt=0
Default,((-Kd*(6.72*Q01+Ce1*Qe1)/(Q01+Qe1)*exp(-Kr*(t-
1.2)/(U_River1))+Ka_River1*(Cs_River1-River1_DO))/(U_River1))
(QupC0up+Qd1C01)/(Qup+Qd1)
=4.85
Ragnone_WWTP
Qd2C02
River2_DO When t
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Figure 6 Concentration of BOD and DO
In the graph we can see before the point source discharge1, it shows a slightly decrease in this
1.2 km long distance. Obviously the concentration of BOD in this segment are decreasing. On
the contrary, the concentration of dissolved oxygen in this part make a upward trend which
means the oxidation materials in this part was reducing.
Then, when it reach to the point source discharge1 , due to point source discharge1 is the Flint
waste waster treatment plant. The municipal waste usually contains high concentration of
organic materials which will consume the oxygen in water. Therefore, the graph for
concentration of BOD shows us a dramatically increase which up to 12.79mg/l. And in this
period we assume that the mix of BOD is instances. At the same time DO concentration drop
down to 5mg/l in this case and it is not enough for some of the fish living in this segment. Then
as biodegradable function in the river (it shows in Ka reaeration rate in this case), because
velocity in this segment is high so the BOD increase very fast which is the reason why in this
section it didn’t show us sag curve.
Later on, when it to the 30.2km far from the beginning of up stream. The BOD concentrationdrop to 7mg/l and DO concentration reaerated back to 7.9mg/l respectively. This point is also the
Raganone WWTP facility which discharge municipal waste into water. Therefore it shows the
same result just like the Flint WWTP. Due to the velocity in this part is lower than river1 so the
Ka reaeration rate is lower and we can see the sag curve which take place at 45km downstream
form the beginning and DO concentration reach to 6.9mg/l .
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2.5 Impact and Suggestion
High organic concentration has highly impact on the water body especially it will consume DO
in water and lead to lower concentration which fish cannot survive in this critical situation. On
the figure7 most of the fish have to survive in water body which DO concentration higher than
6.5mg/l. As the figure 6 we saw in the 1.2km point source discharge, the DO concentration is
5mg/l which means in this segment fish cannot survive. So in order keep the DO concentration
higher than 6.5mg/l in this part, we have to add extra facilities on the down stream of Flint
WWTP. Air striping is a good way to increase the initial concentration of dissolved oxygen.
Figure 7 Demand of oxygen for different Biomass in river[4]
3
Modeling the sediment and heavy metal transport in flint river
3.1 Determining parameters
In order to model the heavy metal transport, the data required are river and waste water flow
rates and associated metal concentrations. The two waste water treatment systems are the largest
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source of metals in the study reach. Together with upstream contributions from the river, these
three sources ate assumed to comprise the total metal input to the system. Three priority
contaminants are Zinc, Copper and Cadmium.
In order to approach the model, several assumptions were made.
1) The river is at steady-state with respect to flow and loads;
2) Concentration of the modeled substance is uniform over the cross-section of the river (i.e., one
dimensional system); thus, any point discharge instantaneously mixes with the river flow at the
point of discharge;
3) Dispersion is negligible in the longitudinal direction; that is only advection is considered
significant in the direction of flow; thus, E = 0 in equation A4;
4) Flow, cross-sectional area, and mean depth are constant over the reach in question. 2
The model is chosen based on the two assumptions where, Kd2=Kd1=0, that is there is no
degradation or decay of metals in the sediment or water column. This assumption is quite
reasonable since most metals do not decay or otherwise degrade in exception of mercury which
can volatize. And the second one is that the partition coefficient of the metal in the water column
is not the same as the partition coefficient in the sediment column. Although the range of the
uncertainty on the partition coefficient is relatively high, the partition coefficient for suspended
and bedded sediments can differ since the characteristics of solids in the bed differ from the
water and generally lower. For these reasons and experimental data, the partition coefficient of
150,000 kg-1
was chosen. Based on the above assumptions, Level 2 interaction level was chosen
to model the flint river.
In addition to the flow rated and metal concentrations additional data and parameters have to be
either calculated by empirical equations or estimated. The typical river bottom will have a water
content between 60% to 95% by weight; therefore, if the solids have a specific gravity of 2.5, the
solid concentrations in the bed will vary from approximately 50,000-500,00 mg/L of bulk
sediment. Based on some sampling done by the study a value of m2=200,000 mg/L was chosen.
Since the August data is during a relatively low flow season, it is intuitive that the resuspension
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velocity is almost zero, however based one several studies it has been shown that this assumption
is true up to the Ragnone WWTP, however after km point 35 the resuspension could not be
ignored, therefore the value of 2.0 x 10-5 m/day was chosen as the resuspension velocity of the
whole section. 1,2
Partition coefficient of the metals were calculated based on the following formula:
"Kp(l/Kg)=K po . SSalpha
Where SS is the suspended solid concentration mg/l, and Kpo and Alpha are found from the
following table.
Table 7 Partition coefficient of priority pollutants
Metals Kpo in streams Alpha
Cadmium 4.00E+06 -1.13
Copper 1.04E+06 -0.74
Zinc 1.25E+06 -0.7
It is assumed that the partition coefficients remain constant through out the river.
The initial conditions for suspended solid concentration in the water column were calculated
using the formula shown below:
( ) !"
#
$%
&''+
(()
*
++,
-'= )exp(1exp
1
2
1
01 x
U H
V
V
m V x
U H
V m m
s
s
u s
Where Vs is the settling velocity, Vu is the resuspension velocity, H1 the depth of the river and
U is the velocity of the river at each segment. In this formula we used the assumption that the
dilution is almost instantaneous and there is no axial dispersion. The models were also based on
the above equation.
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All calculated parameters are shown in the table below.
Parameter Meaning Upstream Disch
arge1
Discharge2 Partition
Coefficient kgC_Zinc Concentration of Cr in
water column (ug/L)
7.70 55.00 60.15 2.00E
C-Cadmium Concentration of Cr in
water column (ug/L)
0.07 0.16 3.70 6.00E
C-Copper Concentration of Cr in
water column (ug/L)
2.90 8.30 34.80 2.10E
m1_SS Solid concentration in
water column (mg/L)
13.50 4.10 42.00
m2_SS Solid concentration in
sediment column (mg/L)
200,000 200,00
0
200,000
H2 Depth of sediment column
(m)
0.05
Kd2 Decay rate in sediment
column
0.0
Kp2 partition coefficient in bed 150,000
fd1 Fraction of dissolved xxx
in water column
0.91
Kp1 Partition coefficient in
water column (kg-1
)
200,000
!2 Sediment porosity 0.75
K f Sediment-water diffusive
transfer coefficient
(m/day)
0.027
Table 8 Concentration of heavy metals and parameters in each point discharge
Parameter Meaning Steady Conditions
fp2 Fraction of particle Cr in sediment column 0.0100000
Vs (m/day) Settling velocity 0.2500000
Vd (m/day) net sedimentation 0.0000114
Vu (m/day) Resuspension velocity 0.0000200
Vn (m/day)
Net loss of solids from the water column 0.0907643
" 0.7699018
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VTs (m/day) Loss due to sediment interaction 0.0010059
Table 9 parameters for level 2 analysis
3.2 Model Maker simulation
In order to simulate the transport of heavy metals, Model Maker has been used. The model
consists of two main components: The total concentration of heavy metal in the water column
and the suspended solid concentration in the water column. These two components can be
combined to predict the weight fraction of the heavy metal in the sediment.
The following equations were used in order to model the heavy metal and suspended solid
concentrations. And these two values can be combined to calculate r2 from the subsequent
formula.3
2
1
1
1
1m
H
V m
H
V
dx
dm U
u s +!=
24#$%
4+ & '
.$/
01 #$6
( )!!"
#
$$%
&''(
)**+
, -''(
)**+
,= x
U H
V
Q
W
m
f x r
T T p
11
1
2 exp.
where,
( ) ( )
( ) 222222
2
2
122
/
/
H f K f K f V V
f K f V V
d d d f p d u
d
f p d u
+++
++
=
!
! " "
#
Compartment Equation Initial value
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and Cadmium.
Figure 9 Model Maker 4 simulation
3.3 Results and Analysis
In general, for heavy metals the results can be somewhat predicted by finding out the value of
Kp.SS.10-6
. If Kp.SS.10-6
>>1 the metal is highly absorbed to the particulates in the water column
and the fate of the metals is directly proportional to the particulates and can be predicted by just
monitoring particulates, however when Kp.SS.10-6
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souring or settling period is higher for copper with higher partition coefficient and therefore
higher Kp.SS.10-6
value supporting our claim. Also Copper exists in more particulate form than
dissolved form comparing to zinc, therefore more subjected to settling and scouring. Overall, all
three priority pollutants are mostly in dissolved form with very minimal settling and scouring
showing that any metals entering the stream will exist in the dissolved form and dilution is the
governing factor in determining the concentration of these metals.
Since the concentration threshold of cadmium is much lower than copper and Zinc, Cadmium is
shown in different graphs.
Figure 10 Total concentration of heavy metal in the water column
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Figure 11 Total concentration of Cadmium in the water column
Figure 12 Weight fraction of heavy metals in the sediment column
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Figure 13 Cadmium weight fraction in the sediment column
Figure 14 Suspended solid concentration in the water column
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Figure 15 Weight of zinc and Copper in the sediment column
The maximum concentrations of metals are presented in the table below.
='44)%/$%2 L/H
D'$*1$%&/%+'$2P:9Q.R
7%/$(/&( 0'& 0+2E /$( /S)/%+*
4+01P:9Q.R
T+$* THTMP 6
D/(:+): THTTT7 THT7D'>>1& THTTO THTMTable 10 Maximum concentrations in the flint river vs standard
4 Conclusion and Mitigation strategies
As it can be seen from the previous sections, the river mostly meets the standards except from
dissolved oxygen which drops to around 5 mg/L shortly after the flint WWTP discharge.
However, as it can be seen from the initial conditions the DO upstream is low too, that is because
the the flint river above flint is in a polluted condition because of wastes from secondary
treatment plants of Lapeer and the Lapeer state home and training schools, and periodic
discharges of untreated wastes from the communities of North Branch and Columbiaville.
The severe oxygen depletion downstream from Flint was cause by the organic load to the river
although the secondary plant is operation at a high degree of efficiency.
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During the drought flow periods, the waste flow would equal to 90% of the river flow as can be
seen in the August survey. Under these conditions, even efficient secondary treatment results in
high concentrations of pollutants in the stream especially in conservative and semiconservative
wastes such as salts and nutrients which are little affected by present secondary treatment
methods. As a result, the flint river with 24% of the total Saginaw river flow, contributed 50% to
the total nutrient loading of the Saginaw river. The pollution load to the Flint river from this
highly developed area is in excess of the assimilative capacity of the stream with the present
degree of treatment. Moreover, the population of these areas are increasing therefore, the WWTP
has to take that into the account for preventive measures.
Although heavy metal concentrations meet the standards, Cadmium, Copper and Zinc tend to act
synergistically and when present at the same time will have lower thresholds as discussed in the
introduction. In order to mitigate the metal concentration and DO depletion in Flint river and
consequently in Saginaw river and the drainage area waste allocation program as to be done for
all industries and municipal discharges to the river. If higher population of these municipal areas
results in even higher DO depletion other methods such as aerators have to be installed in the
river in order to preserve the aquatic life of the river. A tertiary treatment system for flint and
Ragnone WWTPs can also be a good investment for preventive measures.
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References
[1] Federal Water Pollution Control Administration Great Lake Region “Lake Huron Basin.
Flint River –Michigan” 1965 Survey
[2] United States Environmental Protection Agency “Water Quality Assessment: A screeningProcedure for Toxic and Conventional Pollutants in Surface and Ground Water”
[3 ] Robert V. Thomann, John A. Mueller. Principles of Surface Water Quality Modeling and
Control[M]. Harper Collins Publishers, 1987: 1-637.
[4] United states Environmental Protection Agency “Ambient Water Quality Criteria forDissolved Oxygen”
[5] Flint river-Michigan-Water Quality Data- 1965 survey Clean water series DPO-13-C EPA
US department of the interior federal water pollution control administration.
[6] McKee J.E and H.W Wolf, 1963 “Water Quality Criteria”,2nd
ed. State water quality control
board of California.
[7] Schneider E. G. 1931 “Copper and Health” Jour NEWWA , Water pollustion Abs (sept 1931)
[8] Tarzwll C. M 1958 “Disposal of Toxic Wastes” Ind. Wastes 3:2 48
[9] Dourdoroff. P. M Kratz 1953, “Critical Review of Literature on the toxicity of industrial
wastes and thei components to Fish