Environmental Letters
ISSN: 0013-9300 (Print) (Online) Journal homepage: http://www.tandfonline.com/loi/lesa17
Metal Concentrations in the Sewage, Effluents, and Sludges of Some Southern Ontario Wastewater Treatment Plants B. G. Oliver & E. G. Cosgrove To cite this article: B. G. Oliver & E. G. Cosgrove (1975) Metal Concentrations in the Sewage, Effluents, and Sludges of Some Southern Ontario Wastewater Treatment Plants, Environmental Letters, 9:1, 75-90, DOI: 10.1080/00139307509437458 To link to this article: http://dx.doi.org/10.1080/00139307509437458
Published online: 02 Sep 2009.
Submit your article to this journal
Article views: 9
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Citing articles: 7 View citing articles
Full Terms & Conditions of access and use can be found at http://www.tandfonline.com/action/journalInformation?journalCode=2esa20 Download by: [NUS National University of Singapore]
Date: 06 November 2015, At: 21:14
ENVIRON?ENTAL LETTERS, 9(1),
75-90 (1975)
NETAL COSCENTRATIONS IN THE SENAGE, EFFLUENTS, AND SLUDGES OF SOSIE SOUTHERN ONTARIO WASTEII’ATER TREATNENT PLANTS
Downloaded by [NUS National University of Singapore] at 21:14 06 November 2015
KEY WORDS:
metals, sewage, effluents, sludges B. G. Oliver and E. G. Cosgrove
Water and Wastewater Treatment Research Section Canada Centre for Inland Waters P.O. Box 5050 Burlington, Ontario L7R 4A6 Canada ABSTRACT Aluminum, barium, beryllium, bismuth, cadmium, chromium, cobalt, copper, iron, lead., manganese, me.rcury, molybdenum, nickel, silver, strontium, vanadium and zinc concentrations in the sewage, effluents and sludges of ten southern Ontario wastewater treatment plants are reported.
The efficiency for
metal removal by a conventional activated sludge plant was determined.
The effect of metal concentrations in receiving
waters from residual metals in sewage effluents is discussed. The environmental hazards of disposing of sewage sludges with high metal content on agricultural land is considered. INTRODUCTION Significant quantities of a wide variety of metals are present in domestic sewage.
Some biological treatment systems
receiving only domestic sewage with little industrial input 75 Copyright 0 1975 by blarcel Dekker, Inc. All Rights Reserved. Neither this work nor any par1 may be reproduced or transmitted in any form O r by any means, electronic or mechanical, including photocopying, microfilming, and recording,or by any information storage and retrieval system.without permission in writing from the publisher.
OLIVER AND COSGROVE
76
are not adversely affected by the metals in the sewage.
On
the contrary, it seems that domestic sewage may contain essential metal micronutrients’ and thus the metals may have a beneficial effect on the treatment system.
However, metal
problems can occur when industrial wastewater containing high metal content is discharged into the sewer system for subse-
Downloaded by [NUS National University of Singapore] at 21:14 06 November 2015
quent biologica1,treatments
because, if the metal levels at
the plant become sufficiently high, toxicity effects may occur which can reduce the efficiency of biological aerobic sewage treatment2* 5
sludges
3 9
and the anaerobic digestion of
.
The metal concentrations in sewage effluents are of concern since some metals are toxic to fish, and are transported and concentrated in the food chain.
In addition, some metals
are hazardous to human being at elevated concentrations in water supplies. A
further problem arises in disposing of metal-contamin-
ated sludge from sewage treatment facilities.
Studies have
shown that repeated application of sewage sludge to agricultural land results in metal toxicity to crops.69 7 ,
It has
also been shown that the application of sewage sludge to land for fertilization can result in the enhancement of toxic metal levels in consumable crops. 9 , 10 In this article the concentrations of aluminum, barium, beryllium, bismuth, cadmium, chromium, cobalt, copper, iron, lead, manganese, mercury, molybdenum, nickel, silver, strontium, vanadium and zinc in raw sewage, effluents and sludges are reported and discussed in terms of removal efficiencies by
77
METALS I N WASTEh'ATER TREATMENT PLANTS
biological treatment and in terms of the effect of metal concentration on receiving waters and on agricultural lands. EXPERIMENTAL Samples of raw sewage, primary effluent and final effluent were collected hourly using ice cooled Instrumentation Specialties
Co.
(ISCO) model 1391 automatic ~astewatersamplers
Downloaded by [NUS National University of Singapore] at 21:14 06 November 2015
from several wastewater treatment plants in Ontario.
Grab
samples of raw sludge and digested sludge were also periodically collected.
Immediately after return to the laboratory,
a portion of each sample was filtered through a 0.45 u membrane filter and the filtrate acidified, metal content could be determined.
so
that the dissolved
Dissolved metal levels
were not determined for samples which could not be processed within 2 4 hours of collection.
100 ml volumes of the samples
(10 mls of wet sludge) were acid digested in a mixture of HC1 and HN03 as previously described"
and the metal levels were
determined using standard atomic absorption techniques. RESULTS AND DISCUSSIOY Most of the treatment facilities studied employed the conventional activated sludge system:
screening and grit re-
moval; primary clarification; activated sludge aeration; final clarification and chlorination.
In most cases, the sludge
produced in the process was anaerobically digested before it was disposed of on land.
One extended aeration and one trick-
ling filter facility was also included in the study. Influent Metal Concentrations Table I shows the treatment plants studied as well as the type of treatment, design capacity, receiving water and dates
Downloaded by [NUS National University of Singapore] at 21:14 06 November 2015
TABLE
1
Scwagc Trcntmcnt Facilitics Studicd
Dcsignation
Trcatmcnt
Dcsign Capacity (million,gallons pcr'ldny)
Rccciving Waters
Oakvi 1l c
A
A.S.
6.5
L. Ontario
Clnrkson 0 s haw n Aurora Woods t0c k
B
A.S.
C D
T.F.
L. Ontario L. Ontario
A.S.
E
A.S.
3.2 12.5 1.8 4.5
Ingcrsoll
F
A.S.
1.5
Tliames R.
London (Vnuxhall) Dundas
G
A.S.
3.5
Thames R.
11
A.S.
2.0
Burlington (Elizabeth Gnrdcns) Burlington (Skyway)
I
A.S.
0.8
Desjardins Canal L. Ontario
J
E.A.
8
Plant
a
1 million gallons = 4546 m3
A u r o r a Cr. Thamcs R.
Ilamilton flarbour
Dotes Sample (1973
Flay 1 - 4 July 9 - A ~ blny 14-18 bl~y 22-24 )lay 29-31 April 17 a Junc 2 0 A p r i l 17 a Junc 20 April 1 7 a Junc 20 Fcb 2 0 and Fcb 23 A p r i l 17
Junc 26 an
IETALS
79
IN WASTEWATER TREARKENT PLANTS
of sampling.
blost of these facilities receive a mixture of
domestic and industrial wastewater varying from 5 0 % industrial 50% domestic for the Oakville plant to approximately 100%
domestic for Burlington's Elizabeth Gardens plant.
From this
study (Table I 1 a and b) it appears that the metal concentration in raw sewage are generally much higher in plants recei-
Downloaded by [NUS National University of Singapore] at 21:14 06 November 2015
ving industrial wastes (Oakville) than in plants receiving only domestic sewage (Burlington's Elizabeth Gardens).
Al-
though there is a general increase in all metal levels with industrial input, dramatic increases in certain metals are traceable to specific industrial sources.
For example the
high zinc levels in Oakville are apparently due to a radiator manufacturer's factory, while high aluminum and chromium levels at Aurora are due to aluminum processing and tannery discharges, respectively.
Many industrial effluents are dis-
charged from batch type processes s o that metal concentrations in the raw sewage are subject to large variations for short durations of time.
At Oakville, where hourly samples were
collected and analyzed for a three day period in Nay, 1973, the levels of zinc in the raw sewage ranged from 0.15 to 71 ppm and for nickel from cO.03 to 3.1 ppm.
High shock loads
of zinc at Oakville severely inhibited plant operations,
leading to an inferior effluent of high turbidity and a significant reduction in digestor efficiency as seen by reduced gas production and poor sludge settling.
The high aluminum
loading at Aurora was accompanied by poor settling o f biological sludges resulting in carryover o f organic matter into the effluent.
1 I 3 4
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A
I
1
C
3 4 1 2 3 4
1.6[
ISSN: 0013-9300 (Print) (Online) Journal homepage: http://www.tandfonline.com/loi/lesa17
Metal Concentrations in the Sewage, Effluents, and Sludges of Some Southern Ontario Wastewater Treatment Plants B. G. Oliver & E. G. Cosgrove To cite this article: B. G. Oliver & E. G. Cosgrove (1975) Metal Concentrations in the Sewage, Effluents, and Sludges of Some Southern Ontario Wastewater Treatment Plants, Environmental Letters, 9:1, 75-90, DOI: 10.1080/00139307509437458 To link to this article: http://dx.doi.org/10.1080/00139307509437458
Published online: 02 Sep 2009.
Submit your article to this journal
Article views: 9
View related articles
Citing articles: 7 View citing articles
Full Terms & Conditions of access and use can be found at http://www.tandfonline.com/action/journalInformation?journalCode=2esa20 Download by: [NUS National University of Singapore]
Date: 06 November 2015, At: 21:14
ENVIRON?ENTAL LETTERS, 9(1),
75-90 (1975)
NETAL COSCENTRATIONS IN THE SENAGE, EFFLUENTS, AND SLUDGES OF SOSIE SOUTHERN ONTARIO WASTEII’ATER TREATNENT PLANTS
Downloaded by [NUS National University of Singapore] at 21:14 06 November 2015
KEY WORDS:
metals, sewage, effluents, sludges B. G. Oliver and E. G. Cosgrove
Water and Wastewater Treatment Research Section Canada Centre for Inland Waters P.O. Box 5050 Burlington, Ontario L7R 4A6 Canada ABSTRACT Aluminum, barium, beryllium, bismuth, cadmium, chromium, cobalt, copper, iron, lead., manganese, me.rcury, molybdenum, nickel, silver, strontium, vanadium and zinc concentrations in the sewage, effluents and sludges of ten southern Ontario wastewater treatment plants are reported.
The efficiency for
metal removal by a conventional activated sludge plant was determined.
The effect of metal concentrations in receiving
waters from residual metals in sewage effluents is discussed. The environmental hazards of disposing of sewage sludges with high metal content on agricultural land is considered. INTRODUCTION Significant quantities of a wide variety of metals are present in domestic sewage.
Some biological treatment systems
receiving only domestic sewage with little industrial input 75 Copyright 0 1975 by blarcel Dekker, Inc. All Rights Reserved. Neither this work nor any par1 may be reproduced or transmitted in any form O r by any means, electronic or mechanical, including photocopying, microfilming, and recording,or by any information storage and retrieval system.without permission in writing from the publisher.
OLIVER AND COSGROVE
76
are not adversely affected by the metals in the sewage.
On
the contrary, it seems that domestic sewage may contain essential metal micronutrients’ and thus the metals may have a beneficial effect on the treatment system.
However, metal
problems can occur when industrial wastewater containing high metal content is discharged into the sewer system for subse-
Downloaded by [NUS National University of Singapore] at 21:14 06 November 2015
quent biologica1,treatments
because, if the metal levels at
the plant become sufficiently high, toxicity effects may occur which can reduce the efficiency of biological aerobic sewage treatment2* 5
sludges
3 9
and the anaerobic digestion of
.
The metal concentrations in sewage effluents are of concern since some metals are toxic to fish, and are transported and concentrated in the food chain.
In addition, some metals
are hazardous to human being at elevated concentrations in water supplies. A
further problem arises in disposing of metal-contamin-
ated sludge from sewage treatment facilities.
Studies have
shown that repeated application of sewage sludge to agricultural land results in metal toxicity to crops.69 7 ,
It has
also been shown that the application of sewage sludge to land for fertilization can result in the enhancement of toxic metal levels in consumable crops. 9 , 10 In this article the concentrations of aluminum, barium, beryllium, bismuth, cadmium, chromium, cobalt, copper, iron, lead, manganese, mercury, molybdenum, nickel, silver, strontium, vanadium and zinc in raw sewage, effluents and sludges are reported and discussed in terms of removal efficiencies by
77
METALS I N WASTEh'ATER TREATMENT PLANTS
biological treatment and in terms of the effect of metal concentration on receiving waters and on agricultural lands. EXPERIMENTAL Samples of raw sewage, primary effluent and final effluent were collected hourly using ice cooled Instrumentation Specialties
Co.
(ISCO) model 1391 automatic ~astewatersamplers
Downloaded by [NUS National University of Singapore] at 21:14 06 November 2015
from several wastewater treatment plants in Ontario.
Grab
samples of raw sludge and digested sludge were also periodically collected.
Immediately after return to the laboratory,
a portion of each sample was filtered through a 0.45 u membrane filter and the filtrate acidified, metal content could be determined.
so
that the dissolved
Dissolved metal levels
were not determined for samples which could not be processed within 2 4 hours of collection.
100 ml volumes of the samples
(10 mls of wet sludge) were acid digested in a mixture of HC1 and HN03 as previously described"
and the metal levels were
determined using standard atomic absorption techniques. RESULTS AND DISCUSSIOY Most of the treatment facilities studied employed the conventional activated sludge system:
screening and grit re-
moval; primary clarification; activated sludge aeration; final clarification and chlorination.
In most cases, the sludge
produced in the process was anaerobically digested before it was disposed of on land.
One extended aeration and one trick-
ling filter facility was also included in the study. Influent Metal Concentrations Table I shows the treatment plants studied as well as the type of treatment, design capacity, receiving water and dates
Downloaded by [NUS National University of Singapore] at 21:14 06 November 2015
TABLE
1
Scwagc Trcntmcnt Facilitics Studicd
Dcsignation
Trcatmcnt
Dcsign Capacity (million,gallons pcr'ldny)
Rccciving Waters
Oakvi 1l c
A
A.S.
6.5
L. Ontario
Clnrkson 0 s haw n Aurora Woods t0c k
B
A.S.
C D
T.F.
L. Ontario L. Ontario
A.S.
E
A.S.
3.2 12.5 1.8 4.5
Ingcrsoll
F
A.S.
1.5
Tliames R.
London (Vnuxhall) Dundas
G
A.S.
3.5
Thames R.
11
A.S.
2.0
Burlington (Elizabeth Gnrdcns) Burlington (Skyway)
I
A.S.
0.8
Desjardins Canal L. Ontario
J
E.A.
8
Plant
a
1 million gallons = 4546 m3
A u r o r a Cr. Thamcs R.
Ilamilton flarbour
Dotes Sample (1973
Flay 1 - 4 July 9 - A ~ blny 14-18 bl~y 22-24 )lay 29-31 April 17 a Junc 2 0 A p r i l 17 a Junc 20 April 1 7 a Junc 20 Fcb 2 0 and Fcb 23 A p r i l 17
Junc 26 an
IETALS
79
IN WASTEWATER TREARKENT PLANTS
of sampling.
blost of these facilities receive a mixture of
domestic and industrial wastewater varying from 5 0 % industrial 50% domestic for the Oakville plant to approximately 100%
domestic for Burlington's Elizabeth Gardens plant.
From this
study (Table I 1 a and b) it appears that the metal concentration in raw sewage are generally much higher in plants recei-
Downloaded by [NUS National University of Singapore] at 21:14 06 November 2015
ving industrial wastes (Oakville) than in plants receiving only domestic sewage (Burlington's Elizabeth Gardens).
Al-
though there is a general increase in all metal levels with industrial input, dramatic increases in certain metals are traceable to specific industrial sources.
For example the
high zinc levels in Oakville are apparently due to a radiator manufacturer's factory, while high aluminum and chromium levels at Aurora are due to aluminum processing and tannery discharges, respectively.
Many industrial effluents are dis-
charged from batch type processes s o that metal concentrations in the raw sewage are subject to large variations for short durations of time.
At Oakville, where hourly samples were
collected and analyzed for a three day period in Nay, 1973, the levels of zinc in the raw sewage ranged from 0.15 to 71 ppm and for nickel from cO.03 to 3.1 ppm.
High shock loads
of zinc at Oakville severely inhibited plant operations,
leading to an inferior effluent of high turbidity and a significant reduction in digestor efficiency as seen by reduced gas production and poor sludge settling.
The high aluminum
loading at Aurora was accompanied by poor settling o f biological sludges resulting in carryover o f organic matter into the effluent.
1 I 3 4
Downloaded by [NUS National University of Singapore] at 21:14 06 November 2015
A
I
1
C
3 4 1 2 3 4
1.6[
