shock effects of copper ion on activated sludge unacclimated and its recovery technique
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This article was downloaded by: [Tulane University]On: 10 October 2014, At: 22:28Publisher: Taylor & FrancisInforma Ltd Registered in England and Wales Registered Number: 1072954 Registeredoffice: Mortimer House, 37-41 Mortimer Street, London W1T 3JH, UK
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Shock Effects of Copper Ion onActivated Sludge Unacclimated and ItsRecovery TechniqueBing Xie a & Eiko Nakamura ba Department of Environmental Science and Technology , EastChina Normal University , Shanghai, 200062, Chinab Department of Education and Human Science , YokohamaNational University , Yokohama, 240-8501, JapanPublished online: 29 Oct 2010.
To cite this article: Bing Xie & Eiko Nakamura (2002) Shock Effects of Copper Ion on ActivatedSludge Unacclimated and Its Recovery Technique, Toxicological & Environmental Chemistry,83:1-4, 55-67, DOI: 10.1080/716067230
To link to this article: http://dx.doi.org/10.1080/716067230
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Toxicological and Environmental Chemistry, Vol. 83, pp. 55–67 � 2001 OPA (Overseas Publishers Association) N.V.
Reprints available directly from the publisher Published by license under
Photocopying permitted by license only the Gordon and Breach Science
Publishers imprint,
a member of the Taylor & Francis Group.
SHOCK EFFECTS OF COPPER ION ON
ACTIVATED SLUDGE UNACCLIMATED
AND ITS RECOVERY TECHNIQUE
BING XIEa,* and EIKO NAKAMURAb
aDepartment of Environmental Science and Technology, East China NormalUniversity, Shanghai 200062, China; bDepartment of Education and Human Science,
Yokohama National University, Yokohama, 240-8501, Japan
(Received 5 February 2002; Revised 26 February 2002; In final form 3 December 2002)
To study the effects of heavy metals on the pilot-scale activated sludge process, the uptakeof heavy metals and the removal rate of CODMn by activated sludge were investigated in vari-ous conditions. When 20mg/L of copper ion was added to the sequence batch reactor (SBR) ofthe unacclimated activated sludge, copper ion was rapidly adsorbed by the activated sludgeflocs at first and then released from them after aeration. The copper ion concentrationof mixed liquor in the reactor increased until the removal rate of CODMn became constant.When three kinds of the additives including special nutrients (as CODMn 45mg/L),powdered activated carbon (PAC, 50mg/L) and condensed sludge (as MLSS less than300mg/L), which are possible candidates for the recovery techniques, were added to theactivated sludge, different bio-kinetic constants were obtained, indicating different inhibitionrates of treatment efficiency. In the case of special nutrients, the removal rate of CODMn wasthe highest among all three additives, showing that they stimulated microorganisms in theactivated sludge to absorb organic substances. Addition of PAC and condensed sludge alsoimproved the removal rates of CODMn and copper ion. Especially when the organic loadwas light, the addition of PAC could efficiently remove organic substances and copperion from the mixed liquor. However, the addition of the condensed sludge increased the turbid-ity of the mixed liquor. And some long time aeration was found leading to the deflocculationof activated sludge.
Keywords: Heavy metal; Copper ion; SBR; Unacclimated activated sludge; Wastewatertreatment; Recover technique
*Corresponding author. Fax: þ86-21-62233670. E-mail: wswz@public2.sta.net.cn
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INTRODUCTION
Heavy metals are toxic to microorganisms, although some trace amounts of
heavy metals are beneficial to microbes for their growth [1,2]. When heavy
metals are loaded in the acclimated activated sludge, there is little effect on
the treatment efficiency. Usually, the state of acclimation will maintain high
treatment efficiency of sludge if it has been exposed to high concentration
of heavy metals [3–5]. On the contrary, a load of heavy metals to the unac-
climated activated sludge causes serious problems on the process, the
treatment efficiency becomes unsteady, the structure and diversity of the
microorganism community of the activated sludge will be affected and
that will take a long time to recover [6]. The time period required for
recovery increased when the metal concentration went up [7]. Therefore, it
is important to study how to recover the activated sludge process that has
been damaged by heavy metals and to improve the treatment efficiency
quickly. The practical method of removing heavy metals from the mixed
liquor is one of the most important technology in wastewater treatment
[8]. Study on the recovery technique of the process is required not only to
reduce the effects of heavy metals in the activated sludge process, but also
to recover the treatment efficiency in a shorter term.
Heavy metals have inhibitory or toxic effects on activated sludge
microorganisms and upset the operation of the activated sludge [9,10].
The removal rate of organic substances depends on the area of binding
sites for the substances of the activated sludge. The rate will decrease if
the binding sites are not sufficient since heavy metals compete with organic
substances for the binding sites [11,12].
Copper was selected for this study because of its high toxicity, ubiquitous
presence in wastewater and chemically well-known of its solution. The
effect of copper depends on its chemical species and concentration.
Copper has little effect on the viability of the microorganisms and removal
rate of BOD when its concentration is below 10 mg/L [3,7,12], and can
stimulate the biomass yield at 10 mg/L [13]. However, copper ion affects
the process seriously at a concentration above 30 mg/L [14]. The
copper ion concentration of influent was adjusted to 20 mg/L in this
experiment, since there are few researches about the effect of copper ion
at 10–30 mg/L.
However, addition of powdered activated carbon (PAC) will help the
adsorption of toxic substances and the stability against heavy metal shock
loads and toxic upset [15–17]. In this experiment PAC was tested as a
recovery agent. The adjustment of sludge age or a rapid increase of
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suspended solid concentration (MLSS) in the reactor is an easy approach
in activated sludge treatment plant [18,19]. Condensed activated sludge
was studied as another recovery method, because it would increase the
biomass and reduce the toxicity of heavy metals. Furthermore, addition
of special nutrients is helpful for the recovery of the process because some
nutrients can reduce the effects of heavy metals and stimulate the growth
of microorganisms. For example, peptone and cystine are useful in uptaking
the metals because they have an ability to form complexes with sludge
flocs [20]. Glycerophosphate (BGP) may meet the increasing demand
for Adenosine triphosphate (ATP) and enhance the culture viability of
microorganisms [21,22]. Addition of the mixture of these nutrients was
tested as the third possible recovery technique.
Other methods, including a longer aeration period, were also studied.
The treatment efficiency and economic evaluation of each method were
compared.
MATERIALS AND METHODS
Activated Sludge Simulation
The activated sludge process was simulated in a laboratory unit as shown in
Fig. 1. The unit was constructed with four plastic bottles (labeled 1,2,3,4) as
reaction tanks (reactors). A mixture composed of activated sludge (2 g/L),
synthetic wastewater and copper ion (20 mg/L) was added to each reactor.
Bottle 1 (control reactor) was used for control test. Bottle 2 (PAC reactor)
FIGURE 1 The experimental device: 1. Control reactor; 2. PAC reactor, supplied with pow-dered activated carbon; 3. Sludge reactor, supplied with condensed sludge; 4. Nutrients reactor,supplied with special nutrients (pepton, systine and BGP).
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was supplied with mixed solution and PAC at 50 mg/L. Condensed
sludge was added to Bottle 3 (sludge reactor) at 120 mg/L or 300 mg/L
in order to increase MLSS. Bottle 4 (nutrients reactor) was supplied
with mixed solution and special nutrients (Peptone 40 mg/L, BGP 50 mg/L
and cystine 20 mg/L; CODMn is 45 mg/L) [22]. The composition of the
synthetic wastewater is shown in Table I. The initial CODMn value of the
mixed liquor was adjusted to 180 mg/L (low organic load) or 328 mg/L
(high organic load) by adding aliquots of the synthetic wastewater.
The temperature of the unit was maintained at 20�C by a temperature
controller. The mixed liquor in the reactor was aerated for 30–40 h.
CODMn and the concentration of copper ion were measured at regular
time intervals.
The activated sludge was collected from the municipal wastewater
treatment plant (Yokohama central wastewater treatment center,
Yokohama, Japan). The sludge was washed five times with distilled water
to remove the original ions. The sludge was 10 days old and SVI was
100 mL/g prior to experiment. The concentration of the heavy metals in
the dry sludge of wastewater treatment plant is shown in Table II.
(According to the data of Yokohama Wastewater Bureau.) All inorganic
salts were of analytical reagent grade. Water was double distilled. Plastic
ware and glassware were soaked in 1mol/L HNO3 and rinsed with distilled
water before use.
Analytical Procedures
Samples were centrifuged and filtrated with 0.45 membrane filter. Heavy
metals in the mixed liquor were determined using a Shimadzu AA-660
flame atomic absorption spectrophotometer. Samples were also filtered
with quantitative filters and dried to constant weight at 105�C, and the
final weights were measured to determine the biomass concentration
of MLSS. However, an hourly monitoring of MLSS was carried out
TABLE I Composition of the synthetic wastewater
Constituents Concentration (mg/L)
C6H12O6 320KH2PO4 14.1Na2HPO4 � 12H2O 44NH4Cl 108CaCl2 <0.3MgSO4 � 7H2O <5
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turbidimetrically with spectrophotometer. SVI and SS of the mixed liquor
were determined by standard methods [23] respectively, and CODMn was
determined by JIS methods [24].
Data Analysis
The treatment efficiencies (COD removal rate) were calculated from the
following equation (Eq. (1)).
E ¼ ðS � S0Þ100=S0 ð1Þ
Substance removal in biological treatment processes could be described
by Monod equation (Eq. (2)).
Vs ¼ �maxXSðKm þ SÞ ð2Þ
At low substrate concentration (Km�S), Eq. (2) will reduce to a first-order
formulation. For sequence batch reactor (SBR) process, a mass balance on
substrate in the reactor during the reaction period can be shown as:
�dS=dt ¼ �maxXS=Km ¼ KS ð3Þ
where in this experiment, S¼COD concentration of the mixed liquor
(mg/L); S0¼ initial COD concentration of the mixed liquor (mg/L);
Vs¼COD removal rate (mg COD/ l h); Km¼ half-velocity constants (mg
COD/L); X¼microorganism concentration (MLSS) in the mixed liquor at
steady state (mg COD/L); mmax¼maximum specific growth rate constant
(h�1); K¼ (mmaxX /Km) pseudo first order rate constant; the value of K
can be determined from a linear plot of ln S versus time.
TABLE II The concentration of the heavy metals in the drysludge of wastewater treatment plant (1999)
Heavy metals May (mg/kg) October (mg/kg)
Cu 190 140Zn 810 310Total Cr 43 21Ni 450 290Mn 25 9.8
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RESULTS AND DISCUSSION
Analyses on Bio-kinetics Constants
The CODMn concentration of the mixed liquor measured was plotted with
time as shown in Fig. 2(a) and (b), in which initial CODMn concentrations
were 180 mg L�1 and 328 mg L�1 respectively. Linear relationships between
lnCOD and time were obtained with a relatively good fit (R2 > 0.93) in
all cases. The linear relationships indicate that the first-order formulation
Eq. (3) can be applied in describing metal inhibition of COD removal.
FIGURE 2 Plots of lnCOD vs time for first-order kinetic constant determination for: (a) atlow strength organic load (initial COD concentration of the mixed liquor: 180mg/L); (b) at highstrength organic load (initial COD concentration of the mixed liquor: 328mg/L). � Nutrientsreactor, œ PAC reactor, 4 Sludge reactor, Control reactor.
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The values of K calculated from the slopes of these linear plots are
summarized in Table III. K values obtained at low strength organic load
were larger than those obtained at high strength organic load.
The lowest K value is obtained from the control reactor, while the K
values obtained from the nutrients and PAC reactors are higher than that
from the control reactor regardless of the initial CODMn. These results
indicate that copper ion has a serious impact on microorganisms in control
reactor than those in other reactors. The highest K value is obtained from
the nutrient reactor at high organic load. This shows that the addition of
nutrients is the best way to stimulate the growth of microorganisms. In
the case of adding PAC, its K value is the highest among the four reactors
at low organic load. Two processes are probably involved, namely adsorp-
tion and biodegradation in the removal of organic substances during
the course of aeration. The contribution of PAC is to adsorb copper ion,
thus minimize its effects on activated sludge [16,25].
Effect of Different Additives on The Removal Rate of CODMn and Copper
The copper ion concentration of the mixed liquor measured was plotted
with time as shown in Fig. 3 (low strength organic load) and Fig. 5 (high
strength organic load). The CODMn removal rate of each reactor was
shown in Fig. 4 (low strength organic load) and Fig. 6 (high strength organic
load). The copper ion concentration in the mixed liquor was very low in
the beginning for several minutes, and then started to increase. The removal
rate of CODMn increased in about 10 h aeration at low strength organic load
and about 20 h aeration at high strength organic load (see Figs. 4 and 6).
Most of the uptake of copper ion was achieved within several minutes
after aeration [19,26]. The increase of copper ion in the mixed liquor
suggests that organic substances compete with copper ion at the binding
site of the activated sludge. After the removal rate of CODMn attained a
constant, the concentration of copper ion in mixture began to decrease.
These results were in agreement with previous studies [9,27]. A longer
time period was required for a constant removal rate of CODMn at high
TABLE III Comparisons of pseudo first order kinetic constants (h�1)
Group Controlreactor
PACreactor
Sludgereactor
Nutrientsreactor
COD 180mg/L 0.0451 0.0657 0.048 0.0616COD 328mg/L 0.0268 0.0378 0.0276 0.0399
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FIGURE 3 Change of copper ion concentration in the mixed liquor with time at low strengthorganic load.
FIGURE 5 Change of copper ion concentration in mixed liquor with time at high strengthorganic load.
FIGURE 4 CODMn removal rate with time at low strength organic load.
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strength organic load. This indicated that the reduction of the organic load
was helpful for a good quality of effluent when the activated sludge
was shocked with heavy metal.
The lowest concentration of copper ion in the mixed liquor was obtained
in PAC reactor at low organic load. Although the removal rate of CODMn
in PAC reactor was lower than that in the nutrients reactor within the
first 10 h of aeration, the removal rates of both reactors were getting
close after 20 h of aeration. PAC supplied great surface to adsorb copper
ions. The addition of PAC led to a low copper ion concentration in the
mixed liquor. It was good for the growth of microorganism and would
enhance the removal efficiency of CODMn. The result was consistent with
Sublette’s review [15]. However, at high strength organic load on the PAC
reactor is less than that on the nutrients one. It seems that the addition
of PAC (at 50 mg/L) is a good method to remove copper when organic
load is low. In case of nutrients reactor, no matter how low or high organic
load was, the removal rates of CODMn and copper ion in the mixed liquor
increase quickly in the first 10 h. This result indicated that the nutrients
could enhance the absorption of organic substance. These results were
different from Chang’s results [4]. Chang’s study showed that nutrients
could stimulate the uptake of heavy metals of acclimated activated sludge
for 25 h. The unacclimated activated sludge in our experiment had different
characters from the acclimated activated sludge on the uptake of heavy
metal. Our result showed that if in a sufficiently long period, the addition
of nutrients could enhance copper uptake of the activated sludge. Also,
the concentration of copper ion in the nutrient reactor was the lowest
among the reactors using different recovery techniques after 20 h at high
strength organic load.
FIGURE 6 CODMn removal rate with time at high strength organic load.
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The removal rates of CODMn and copper in the sludge reactor is shown in
Fig. 7. The removal rates of copper were calculated by Eq. (1). They
increased in line with the increasing amount of the condensed sludge
(with 6 and 15% MLSS up respectively), and at the same time, the turbidity
of the effluent increased. The addition of the condensed sludge increased the
biomass and undoubtedly enhanced efficiency of the treatment and uptake.
However, the formation of highly stable pinpoint flocs resulted from the
unacclimatised activated sludge shocked by heavy metals [28]. Of the
condensed sludge concentration studied, the removal rates of CODMn
and copper were lower than that of the other additives, and only slightly
better than that of the control. According to Lamb and Tollefson [18], 20
times MLSS could reduce metal toxicity from 80 to 3%. Perhaps more acti-
vated sludge should be added to make sure that the total MLSS contents is
high enough to increase the treatment efficiency significantly.
Above all, the conclusion could be drawn that the addition of nutrients
was the best method in this study for the removal rates of CODMn and
copper after 20 h of aeration. The nutrients used in this experiment were
expensive and could be replaced by less expensive ones such as starch.
The PAC and condensed sludge can also reduce the toxicity of heavy
metals and increase the treatment efficiency. Higher efficiency might
be achieved if sufficient amount of additive would be provided. Mostly,
the increment of the sludge concentration is the easiest operation for the
sewage treatment plant.
The Effect of The Aeration Period on The Removal
Rate of CODMn and Copper
In heavy metal shock load system, a long aeration period can increase the
removal rate of CODMn and the absorption of copper by the activated
FIGURE 7 The removal rate of CODMn and copper ion and effluent turbidity (MLSS) atdifferent sludge adding amount. H: 0.4 g/L MLSS adding; L: 0.14 g/L MLSS adding.
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sludge after CODMn removal rate becomes constant. Also, it led to the
deflocculation of activated sludge and deterioration of the effluent quality
(as shown in Fig. 8), the variation of sludge volume in 30 min (SV30), and
SS in the effluent with time. Although PAC and nutrients bring forth
better effluent, both SV30 and effluent turbidity were on the increase from
a long aeration period. It indicates that prolonged aeration in the activated
sludge shocked by metals will damage the structure of activated sludge and
bring about the biomass loss.
CONCLUSIONS
. The load of copper ion to the non-acclimated activated sludge system
affected the bio-kinetics constant K. The addition of PAC, nutrients
and condensed sludge could reduce the inhibitory effect of copper ion
on microorganisms in the activated sludge and accelerate the recovery
of the system. The addition of nutrients and PAC showed the highest K
values at low and high strength organic load respectively.
. The addition of nutrients could stimulate the removal rate of CODMn and
enhance metal-complexing capacity of copper ion when the removal rate
of CODMn reached a certain level. Therefore, it may be a good recovery
method for the process shocked with heavy metals in sufficient time
period. However, the cost is high. Less expensive nutrients are suggested.
. The addition of PAC (50 mg/L) has a result of better removal rates of
CODMn and copper than adding of condensed sludge. At relatively low
strength organic load, the addition of PAC and continuing aeration
could enhance the removal rate of copper and CODMn. It is a good
FIGURE 8 Change of SV30 and effluent turbidity (MLSS) with time — SV30 (%);line - - - - effluent turbidity (mg/L).
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way to recover the process shocked by heavy metals if the organic load is
light.
. The addition of unacclimated condensed sludge could be effective to
increase the removal rates of CODMn and copper. However, the effluent
quality will be poor. It may be the easiest and most inexpensive recovery
method when sufficient amount of activated sludge is provided.
. The absorption of copper ion in SBR unacclimated activated sludge
process is characterized as follows:
The copper ion was rapidly adsorbed by the activated sludge flocs at
first and then released from it during the aeration period. The concentra-
tion of copper ion in the mixed liquor increased till the removal rate of
CODMn reached a constant. It is suggested that the copper ion has
more affinity for binding sites on the activated sludge flocs at first, but
the organic substance becomes a stronger competitor with long time
aeration; lower organic load was good for the effluent.
. A long aeration period could increase the removal rate of CODMn and
reduce the concentration of copper ion in the mixed liquor. However, it
would result in deflocculation of activated sludge and higher turbidity
of effluent.
References
[1] G. Ji and S. Silver (1995). Bacterial resistance mechanism for heavy metal of environmentalconcern. J. Ind. Microbiol., 14, 61.
[2] P.L. McCarty (1964). Anaerobic waste treatment fundamentals, Part III. Toxic materialsand their control. Publ. Works, 95(11), 91.
[3] G.N. McDermott, W.A. Moore and M.B. Ettinger (1963). Effects of copper on aerobicbiological sewage treatment. J. Wat. Pollut. Control Fed., 35, 163.
[4] D. Chang, F. Kensuke and S. Ghosh (1995). Stimulation of activated sludge culturesfor enhanced heavy metal removal. Wat. Environ. Res., 67, 822.
[5] E.Q. Moulton and K.S. Shumate (1963). The physical and biological effects of copperon aerobic biological waste treatment processes. In: Proceeding, 18th Industrial WasteConference, Purdue University, 112, 602.
[6] S.Y. Chang, J.C. Huang and Y.C. Liu (1986). Effects of Cd and Cu on a biofilm system.J. Environ. Eng. 112, 94.
[7] E.F. Barth, M.G. Ettinger and B.V. Salotto (1965). Summary report on the effects ofheavy metals on the biological treatment processes. J. Wat. Pollut. Control Fed., 37, 86.
[8] A.I. Ferraz and J.A. Teixeira (1999). The use of flocculation brewer’s yeast for Cr (III)and Pb (II) removal from residual wastewaters. Bioprocess Engineering, 21, 431.
[9] M.H. Cheng, J.W. Patterson and R.A. Minera (1975). Heavy metals uptake by activatedsludge. J. Wat. Pollut. Control Fed., 47, 362.
[10] P. Battistoni, F. Gabriele and L.R. Maria (1993). Heavy metal shock load in activatedsludge uptake and toxic effect. Wat. Res., 27, 821.
[11] H. Chua (1998). Effects of trace chromium on organic adsorption capacity and organicremoval in activated sludge. Sci. Total Environ., 214, 239.
[12] S.K. Mittal and R.K. Ratra (2000). Toxic effect of metal ions on biochemical oxygendemand. Wat. Res., 34, 147.
66 B. XIE AND E. NAKAMURA
Dow
nloa
ded
by [
Tul
ane
Uni
vers
ity]
at 2
2:28
10
Oct
ober
201
4
[13] F. Dilek, C.F. Gokcay and U. Yetis (1991). Effects of Cu on a chemostat containingactivated sludge. Environ. Technol., 12, 1007.
[14] S. Ghosh and S. Bupp (1992). Stimulation of biological uptake of heavy metals. Wat. Sci.Tech., 26, 227.
[15] K.L. Sublette, E.H. Snider and N.D. Sylvester (1982). Review of mechanisms of powderedactivated carbon enhancement of activated sludge treatment. Wat. Res., 16, 1075.
[16] S.E. Lee, H.S. Shin and B.C. Paik (1989). Treatment of Cr(VI) containing wastewaterby addition of powdered activated carbon the activated sludge process. Wat. Res., 23, 67.
[17] M.A. Munoz, J. Codian, A.D. Vicente and J.M. Sanchez (1996). Effects of nickel and leadand a support material on the methanogenesis from sewage sludge. Letters in AppliedMicrobiology, 23, 339.
[18] A. Lamb and E.L. Tollefson (1973). Toxic effects of cupric, chromate and chromic ionson biological oxidation. Wat. Res., 7, 599.
[19] R.D. Neufeld and E.R. Hermann (1975). Heavy metal removal by acclimated activatedsludge. J. Wat. Pollut. Control Fed., 47, 310.
[20] D.P. Higham, P.J. Sadler and Scawen (1984). Cadmium-resistance pseudomonas putidasynthesizes novel cadmium proteins, Science, 225, 1043.
[21] J.T. Trevors and G.W. Stratton (1986). Cadmium transport, resistance, and toxicity inbacteria, algae, and fungi. Can. J. Microbiol., 32, 447.
[22] K. Fukushi, C. Duk and G. Sam (1996). Enchanced heavy metal uptake by activated sludgecultures grown in the presence of biopolymer stimulators. Wat.Sci.Tech., 34, 267.
[23] APHA (1980). Standard Methods for Examination of Water and Wastewater, 15th edn.APHA(American Public Health Association), AWWA(American Water WorksAssociation),WPCF(Water Pollution Control Federation), Washington DC.
[24] Japanese Industrial Standard (JIS) (1998). Testing methods for industrial water, P48-51,Japanese Standard Association.
[25] J.S. Lee and W.K. Johnson (1978). Powdered carbon activated sludge batch studies ofprocess kinetics. WWEMA 6th Annual Industrial Pollution Conference.
[26] B.V. Salotto, E.F. Barth and W.E. Tolliver (1964). Organic load and the toxicity of copperto the activated sludge process. In: Proceeding of the 19th Industrial Waste Conference.Purdue University, p.1025.
[27] H. Chua and F.L. Hua (1996). Effects of a heavy metal on organic adsorption capacityand organic removal in activated sludge. Apply Biochem. Biotechnol., 57, 845.
[28] R.D. Nuefeld (1976). Heavy metals-induced deflocculation of activated sludge. J. Wat.Pollut. Control Fed., 48, 1940.
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