March 16, 1998
To: Works and Utilities Committee
From:Commissioner of Works and Emergency Services
Subject:Feasibility of 100 percent beneficial reuse of the Main Treatment Plant processed biosolids by January 1, 1999.
Purpose:
The purpose of this report is to provide the Works and Utilities Committee with information on the feasibility of initiating
100 percent beneficial reuse of biosolids processed at the Main Treatment Plant (MTP) by January 1, 1999, and outline the
related plan of action.
Funding Sources, Financial Implications and Impact Statement:
A decision to proceed with the January 1, 1999 start-up of 100 percent beneficial reuse of MTP processed biosolids would
result in an additional and presently unbudgeted capital cost of approximately $2,750,000.00 in 1998, as well as increased
operation costs ranging between $18,000,000.00 and $22,000,000.00 over a three-year period starting in 1999.
Recommendations:
It is recommended to continue with a staged biosolids beneficial reuse program presently being developed, which has as its
goal full beneficial implementation by the year 2005, as stated in the approved MTP Environmental Assessment (EA)
document.
Council Reference/Background/History:
At its meeting held on February 11, 1998, when dealing with Clause No. 1 of Report No. 2, Biosolids Demonstration
Facility - Harbour Remediation & Transfer Inc., the Works and Utilities Committee recommended that incineration at the
MTP be stopped no later than January 1, 1999, and that the Interim Functional Lead for Water/Wastewater Operations be
requested to report to the next meeting of the committee, scheduled to be held on March 25, 1998, on the feasibility of such
date. This report addresses the above issue.
Comments and/or Discussion and/or Justification:
The sewage sludge treatment process at the Main Treatment Plant (MTP) consists of:
1.stabilization by processing liquid sludge through heated anaerobic digesters to kill pathogens (disease causing
microorganism), reduce the odour from the sludge and, reduce the quantity of sludge by conversion of volatile solids
present in sludge into usable gas;
2.concentration of digested liquid sludge into sludge cake by dewatering (removing water and reducing the sludge
volume) through centrifugation; and
3.incineration of the sludge cake to further reduce the sludge volume and produce an inert, odour free ash which is
disposed in a sanitary landfill site.
Each of the above-mentioned sludge treatment processes are continuous 24 hours a day, 365 days a year operations. There
are multiple equipment units involved, including stand-by units in each process, so that when one unit is taken out of
service for maintenance or repair, another unit is started up to maintain process capacity. These process trains have been
selected, designed and constructed to work together as one reliable system. These processes are highly interrelated as
described below.
The digester gas, produced in the anaerobic digesters, composed mainly of methane, is used as fuel to sustain sludge
incineration. The use of digester gas minimizes the purchase of natural gas. Odourous air from the sludge dewatering and
other plant processes is used in the incinerator for combustion air, ensuring complete odour destruction. The sludge cake
from the centrifuges burned in the incinerator has a significant fuel value, which is converted into heat energy. The hot
gases from the incinerators are used in the waste heat boilers to produce steam. This steam, plus steam from other plant
boilers, is used to heat the digesters year round and plant buildings in winter. The system has been designed to fully utilize
the abilities and interdependencies of each process.
The need for a highly reliable system is paramount. Each day over 200 dry tonnes of solids enters the MTP as part of the
raw sewage. After these solids are collected and stabilized through digestion, approximately 140 dry tonnes of solid end
product remains to be removed from the plant on a daily basis. If the solids are not removed from the plant at the required
rate, disruption of the liquid sewage treatment process will take place resulting in the increased discharge of contaminants
into Lake Ontario with the plant=s final effluent. If this were to occur, in addition to the pollution of the lake, the MTP
would likely be in violation of its Ministry of Environment (MOE) Certificate of Approval criteria which is a chargeable
offense.
In 1994, following the recommendations evolving from the MTP (EA) process, former Metro Works began work on
demonstrating beneficial end uses of biosolids (stabilized sewage sludge). This was the first phase in developing a new
long term solids management plan. A temporary biosolids loading facility was constructed to allow for haulage out of the
plant of some of the plant processed biosolids for beneficial end uses. Two contracts were signed for beneficial biosolids
reuse demonstrations; one with Terratec Environmental Inc. for direct application of biosolids on agricultural land at a cost
of $85.00 per dry tonne, and one with Harbour Remediation and Transfer Inc. (HR&T) for lime stabilization of biosolids
and use for mine tailing remediation at a cost of $238.00 per dry tonne. Each project would take 10,000 dry tonnes of
biosolids per year from the MTP=s current generation rate of some 53,000 dry tonnes per year for a period of five years.
From an approvals standpoint, the two demonstration projects were initiated as feasibility studies, which are allowed for
under the Environmental Assessment Act for a proponent undertaking an EA. Approvals were still needed for the
individual contractors, related to their operations. In addition, the MOE has guidelines regarding the hydraulic retention
time or length of time the sludge stays in an anaerobic digester. The guidelines require a minimum of 15 days to ensure
adequate stabilization and pathogen destruction in sludge prior to its land application. Since the MTP=s sludge was being
incinerated, the plant did not have to meet this requirement and there was an insufficient number of digesters to obtain this
level of sludge stabilization. However, to accommodate our demonstration projects, another sludge stabilization criteria
was applied by MOE, which limited certain pathogens present in a gram of stabilized sludge. The plant meets this new
criteria most of the time. Subsequently, in 1997, Council approved construction of new digesters and process changes to
achieve the required 15 days hydraulic retention time. However, this work will not be completed until the summer of 2000.
The two demonstration programs started in 1996. Demonstration of other biosolids reuse technologies, i.e. thermal drying
and composting as recommended in the MTP Environmental Assessment were to be undertaken as well, and completed
within a five-year period from the time of commissioning of the related process facilities.
Subject to successful completion of the demonstration program, and based on the theoretical and practical information
collected (both process and market type data), it is our intention to move to a full scale biosolids beneficial reuse program
using one or more of the demonstrated processes.
In order to successfully meet a suggested January 1, 1999 date for 100 percent beneficial reuse of the MTP processed
biosolids, there are several issues which must be addressed:
A.availability of beneficial biosolids reuse options;
B.sludge cake loading capacity;
C.sludge cake storage capacity;
D.heat generation capacity;
E.odour control ability;
F.MOE approvals;
G.implementation timing;
H.long term plan; and
I.reliability of service.
This report will address each of these issues and present available solutions. It is obvious that any solution which involves
significant design and construction work requiring more than nine months can not be implemented by January 1, 1999. Due
to the short time available for the related necessary changes, only temporary measures involving minimal construction
activities could be implemented by January 1, 1999. These temporary measures would have to be replaced by permanent
solutions as quickly as possible to ensure reliability of plant operations. Where possible the cost for the temporary measures
are provided. The possibilities presented are those which are considered to be fairly practical and the most cost effective
(liquid haulage of sludge is an exception which is included for illustration).
The recommended programs, presented after discussion, are made up of the best possible combination of solutions to all of
the significant issues. Full financial and implementation impact statements are presented only for the recommended
alternatives and not for all possible solutions . It is not possible to calculate a financial impact of any one contributing
solution to a problem in isolation and without considering the entire program chosen. Some combinations of solutions are
not possible for technical reasons.
Availability of Beneficial Biosolids Reuse Options
The two currently ongoing biosolids demonstration projects described earlier are for a total of 20,000 dry tonnes per year,
with an option for an additional 7,000 dry tonnes per year to be taken by Terratec , if required, for a premium of $40.50 per
dry tonne. The two projects are demonstrating direct land application of biosolids, and alkaline stabilization for mine tailing
remediation. The MTP EA recommends additional beneficial reuse demonstrations, i.e. thermal drying and composting.
New contracts would need to be negotiated to handle the remaining 26,000 dry tonnes per year of the MTP biosolids. The
distribution of biosolids between various options will be undertaken as part of a long term biosolids management plan to
provide maximum flexibility and reliability of operations, as well as its economy.
Six options are available to address the elimination of incineration:
a)award a new contract for demonstration of on-site thermal drying;
b)award new contract for demonstration of commercially available pelletization;
c)award a new contract for demonstration of composting;
d)award an additional contract for a demonstration of lime stabilization;
e)award an additional contract for demonstration of direct land application; and
f)combination of the above.
Comments
a)The construction of a thermal drying facility at the MTP is attractive from a long term perspective, and it would
integrate well with the existing plant infrastructure. It requires a capital investment of $8,000,000.00 for a unit sized for
10,000 dry tonnes per year or $15,000,000.00 for a system to handle the full 26,000 dry tonnes per year. It would take 12 to
18 months to install after receiving all MOE approvals. Accordingly, it could not be constructed by January 1, 1999.
b)A process involving a specialized aerobic thermophilic digestion of sludge followed by drying, resulting in a pelletized
final product, will be commercially available in the Toronto area in the near future. By January 1, 1999, there may be
sufficient capacity available to handle most of the biosolids remaining after shut down of the MTP incinerators. However,
we would have to deliver biosolids in the form of cake, to their processing sites. We would have to pay for the cost of
delivery in addition to the cost of process. The costs of delivery is estimated at approximately $870,000.00 annually and the
cost for processing would range between $3,500,000.00 and $7,0000,000.00 annually, according to estimates provided by
the processing company.
c)The demonstration of composting would require significant capital investment and a facility could not be constructed
by January 1, 1999. In addition, current MOE regulations would prohibit the unregulated use of such a compost on public
and private lands. The additional cost of composting would not provide any new end uses of biosolids beyond those
available to direct land applicators. The technology itself has already been demonstrated and it is presently used by the City
of Guelph. The end product from the Guelph plant is used as landfill daily cover.
d)When HR&T, our present lime stabilization contractor, is able to demonstrate that they have rectified the current odour
problems related to the process, it is possible that the contract could be expanded up to its maximum biosolids processing
capacity of approximately 20,000 dry tonnes per year. A contract for lime stabilization could also be tendered to other
established sludge lime stabilization process operators.
e)Terratec and other biosolids land application operators have indicated that it may be possible to gear up to handle all of
the MTP biosolids by January 1, 1999. However, this would require construction, at the receiving end, of a large sludge
cake storage facility at a cost of approximately $750,000.00. The time for design, approvals, and construction of such a
facility would be a minimum of 12 months to a maximum of 36 months. In order to handle the biosolids during the
construction of the storage facilities, an option would be to truck the material to an approved landfill site. The cost of the
biosolids reuse service for the required additional 26,000 dry tonnes per year would range between $3,250,000.00 per year
to $3,900,000.00 depending on the hours of operation, excluding the landfilling cost.
A separate agreement would have to be negotiated to haul the biosolids to a landfill site during the winter months for a
period required to construct the storage facility. An additional cost of disposal would be approximately $2,000,000.00 per
year. This does not include the cost of haulage.
f)It is possible to embark at a number of various end use options at the same time. However, the cost of such an approach
(especially the capital cost) would be higher than for any one individual option.
Sludge Cake Delivery Capacity
The current temporary biosolids loading facility was designed and constructed to handle 22,000 dry tonnes per year. Its
maximum delivery capacity is 300 m3 per day of wet (approximately 30 per cent solids) sludge cake or approximately
29,600 dry tonnes per year. It is not possible to remove the full 53,000 dry tonnes of biosolids per year using the existing
loading facility.
Three options are available to address this problem:
(1)build a new loading facility ;
(2)remove a portion of sludge from MTP or Humber Treatment Plant (HTP) in a form of liquid; and
(3)retrofit the existing facility to increase it=s delivery capacity
Comments
(1)It is not possible to build a new loading facility by Jan 1, 1999. An expansion of the existing facility in the present
location is also not possible due to space constraints.
(2)Approximately 64 dry tonnes per day of solids would need to be removed in a form of 2.5 per cent solids
concentration liquid sludge. The volume of this sludge would be 2,600 m3 per day. This would require 70 tank truck loads
per day at a transportation cost of over $9.5 million a year. Storage and utilization costs of this material would be extra.
(3)By increasing the capacity of the existing sludge cake pipes and screw conveyors feeding sludge cake into the existing
loading facility, it is possible to increase its delivery capacity to 59,000 dry tonnes per year This would just meet the
requirement of the plant but would not allow for any spare capacity for maintenance or repair on the system, putting its
reliability in great jeopardy. This loading facility would be the only means of removing biosolids from the plant and any
major breakdown in this system could result in the plant=s final effluent quality violations. The cost for this option would
be approximately $2,000,000.00 with a design and construction time of a minimum of 9 months. The current biosolids
demonstration projects would need to be shut down for several months while the feed pipes and screws are replaced, and
the full amount of sludge generated by the plant during this period incinerated.
Sludge Cake Storage Capacity
The current temporary biosolids loading facility is sized to provide 400 m3 of biosolids storage, or a maximum of 2 days
storage at its design capacity of 22,000 dry tonnes per year. This storage capacity is required to handle brief interruptions in
biosolids haulage, and to balance out haulage rates from day to day. It also allows for haulage during the day time only
rather than 24 hours per day. The plant currently has an option to redirect biosolids to incineration in the event of a longer
term interruption. The existing biosolids loading facility retrofitted to meet the required material delivery capacity will have
no storage capability. With shutdown of incinerators, this back up disposal option would be eliminated. Any biosolids
haulage interruptions would result in the complete shutdown of the entire solids handling process and possible plant
effluent quality violations.
Two options are available to address this problem:
1)Construct additional storage capacity
2)Contract for 24 hour a day 365 days a year haulage to minimize need for storage
Comments
1)It is not possible to build a new storage facility by January 1, 1999, and there is no space to add an additional storage
capacity to the existing facility in its present location.
2)It is possible to negotiate a new contract, and/or renegotiate existing contracts, to provide for the continuous biosolids
haulage. The cost premium for such service would be approximately $1,500,000.00 per year. This would only partially
address the problem of storage capacity and is only a temporary measure. A proper storage facility would need to be built as
quickly as possible based on a long term biosolids management plan, at a cost of approximately $16,500,000.00.
Heat Generation Capacity
The waste heat boilers on the incinerators currently produce 30 percent to 70 percent of the plant=s steam requirements
(depending on the season). If the incinerators are not fired, the remaining plant steam boilers would not have sufficient
capacity to heat the plant processes and buildings. In addition, the loss of the biosolids as a fuel source would increase the
purchase of natural gas for heat generation purposes by approximately $500,000/year.
Three options are available to address the problem:
1)design and install additional boilers;
2)rent and temporarily install portable package boilers; and
3)fire incinerators with gas, without feeding them with sludge, to produce steam using the existing waste heat boilers.
Comments
1)It is not possible to install new boilers by January 1, 1999.
2)Package boilers of sufficient capacity are available at a rental cost of approximately $500,000 per year, excluding their
operation cost. This would only be a temporary solution and a new boiler facility would need to be installed quickly based
on a long term biosolids management plan.
3)The incinerators with their heat recovery boilers could be fired without sludge feed to act as boilers only. This would be
less efficient than normal boilers as the system was not designed to operate in this manner. The loss of efficiency would
require purchasing an additional amount of natural gas worth approximately $500,000/year. This would only be a
temporary solution and a new boiler facility would need to be installed quickly based on a long term biosolids management
plan.
Odour Control Ability
The incinerators currently provide the plant with ability to process foul air generated during the sludge dewatering and
loading. If the incinerators are not fired, the odourous air would have to be directed to a new odour control system .
Two options are available to address this problem:
1)install new odour control system; and
2)fire incinerators without sludge feed to continue acting as thermal odour destruction units.
Comments
1.It is not possible to install new odour control systems by Jan 1, 1999. Several proposals were recently received from
consultants for the design and installation of additional odour control systems for the biosolids loading facilities. These
proposals indicate that if contracts were awarded now, the system could be designed, installed and commissioned by the
summer of 2000. This design would only be sufficient for the current facilities.
2.The incinerators could be fired without sludge feed to continue acting as thermal odour destruction units. The cost, if
combined with the option of using the incinerator as a boiler, would remain $500,00.00 per year for additional purchase of
gas. However, this would only be a temporary solution and new odour control facilities would need to be installed based on
a long term biosolids management plan.
MOE Approvals
The current MTP biosolids reuse projects are permitted by MOE to operate on the basis that they are demonstrations. If
contracts are put in place for 100 per cent beneficial biosolids reuse, it would no longer be a demonstration program and the
current approvals would no longer be valid. However, the present guidelines are undergoing changes which would allow
the application of biosolids for agricultural purposes using the criteria given to us for our demonstration. It is anticipated
that the changes to this regulation will be in place by January 1, 1999. The newly constructed digesters, which are expected
to come into service in the summer of 2000, should give us sludge hydraulic retention time, as required by the present
regulations.
Implementation Timing
Many of the options presented above require a minimum nine month implementation timeline from the time contracts are
awarded. In order to meet a January 1, 1999 start-up date, numerous design, construction and biosolids management
contracts would need to be awarded immediately. This would eliminate the possibility of following the normal consultant
selection and contract tendering process and would not allow time for committee and council review and authorization of
the negotiated agreements.
Long Term Plan
The current program for developing a long term biosolids management plan is to first demonstrate the various end use
options available and then, based on the results of the demonstrations, formulate a plan that deals with the needs of the
plant, the compatibility of processes within the plant, the reliability of each process, the contingency requirements needed,
and the economics of each possibility including long term capital and operating costs. This work will need to be done
whether the January 1, 1999 target is adopted or not. It is extremely important to demonstrate that the biosolids can be
beneficially used by the agricultural or the mining industry on a continuous basis before committing to a long term solution.
In order to achieve the January 1, 1999 elimination of sludge incineration at the MTP, it would be necessary to sign
biosolids management contracts that would lock up 100 per cent of the biosolids. These contracts would need to be at least
five years in length to allow for capital amortization. Shorter contracts would incur a significant cost penalty. If these
contracts do not include all of the different end uses that we have to demonstrate, as per the MTP EA requirements, then it
would not be possible to demonstrate them before the five-year period, which would contravene the EA outlined program.
In addition, capital expenditures made to achieve the January 1, 1999 deadline would most likely be forfeited within a few
years as the long term facilities are put in place.
It should be noted, however, that using the proposed demonstration approach, it is possible to have all the MTP generated
biosolids beneficially reused prior to completion of the long term program, but the decision to completely eliminate sludge
incineration would be undertaken at the end of 2005.
Reliability of Services
During the current biosolids reuse operations, the ability to send biosolids to one or the other demonstration project has
been limited at certain times for various reasons. HR&T have experienced odour problems and have had to shut down
operations temporarily. The biosolids generated by the plant were occasionally, for short periods of time, not suitable for
direct land application due to pathogen counts in excess of the MOE criteria. Terratec has had occasional difficulty getting
onto fields during their application window and have had to limit the amount hauled from the plant. During these periods,
the plant has had the availability to divert the biosolids to incineration. Under 100 percent beneficial reuse scheme, there
must be a plan in place to ensure that there is no disruption in biosolids removal under any condition. This is especially
critical given the lack of sufficient biosolids storage capacity.
Two options are available to address this issue:
1)Maintain incineration capacity to burn biosolids on an emergency basis, as required; and
2)Enter into an agreement to haul biosolids to landfill, as required.
Comments:
1)A five day warm-up period is required to bring an incinerator up to operating temperature. The MTP could not
survive a five day disruption to biosolids haulage without violation of the final effluent quality criteria. The incinerators
would need to be continuously kept in hot standby mode. This would be automatically provided if they are used as boilers,
and/or odour control facilities.
2)There are landfills within haulage distance of Toronto which are permitted to receive biosolids. A contract could be
negotiated to haul the biosolids to such a landfill site. We estimate that the cost of this option would be approximately
$45,000.00 per day. This estimate is based on using the land application contractor=s fleet and paying a tipping fee at a
U.S. based landfill site.
Discussion and Justification:
In case of adoption of the January 1, 1999 start-up of the 100 percent beneficial biosolids reuse program, the following
solutions to the various issues would have to be implemented.
IssueSolutions and Estimated Costs
availability of beneficial reuse optionsaward additional contracts for direct land application - additional operation cost
of $4,775,000.00 per year plus capital cost of $750,000.00.
sludge cake loading capacity retrofit pipes and screws in current facility - capital cost of$2,000,000.00.
sludge cake storage capacitycontract for 24 hour a day haulage - additional operation cost of $825,00.00 per year.
heat generation capacityfire incinerators only with gas to act as boilers - additional operation cost of $500,000.00 per
year.*
odour controlfire incinerators only with gas to act as odour control facility - additional operation cost of $500,000.00 per
year.*
MOEE approvalsstrive for speedy processing of the related applications
implementation timingprovide funding and authorization immediately
long term planningmust immediately follow the temporary measures
reliability of servicecontract for emergency backup haulage of biosolids to landfill - additional operation cost of
$1,950,000.00 per year.
* If both options are implemented at the same time, the total related additional cost will stay at $500,000.00 per year.
Given the above course of action it may be possible to obtain the January 1, 1999 start-up date. However, there are many
uncontrollable factors which could cause delays to various projects and delay full program implementation. It would also
leave the plant in a very precarious condition in which there would be a very real possibility of failure of the treatment
process and violation of the effluent discharge criteria. This is not recommended by staff. The above program would need
to be followed by a permanent set of facilities based on long term beneficial biosolids reuse planning as quickly as possible.
These new permanent facilities could be in place by 2005.
The cost to achieve the January 1, 1999 startup date would be the presently unbudgeted capital expenditure of some
$2,750, 000.00 this year and the operational cost increase of approximately $8,000,000.00 per year over the first three years
starting in 1999. The related cost savings at the MTP could reach only $700,000.00 per year (e.g. elimination of ash storage
and disposal etc.). The operation cost premium after this period should go down considerably as the permanent facilities
built in the first three years would start coming into service. The costs for permanent facilities can not be calculated at this
time as a long term biosolids management plan has not yet been fully developed, however, if permanent facilities were
designed and installed instead of the temporary facilities, it would allow for lower capital and operating cost as the cost of
the temporary facilities would be avoided.
Under the circumstances and taking into consideration difficulties related to the implementation of the 100 percent
beneficial biosolids reuse program by January 1, 1999, as well as the precarious situation the plant would be in for several
years if such a timing is imposed, the January 1, 1999 date for the program implementation is not recommended.
On September 24, 1997, the former Metro Council adopted, without amendment, Clause No. 8 of Report No. 12 of The
Works and Public Space Committee titled AMain Treatment Plant Environmental Assessment Implementation Plan@,
which recommended that Metro Council endorse the conclusions of the Main Treatment Plant Environmental Assessment
(MTP EA) and authorize its submission to the Ministry of the Environment for approval.
While referring to the proposed biosolids management program, based on demonstration projects, the Environmental
Assessment document concludes AIf demonstrations are successful, incineration may be phased out by about the year 2005.
It is anticipated that over the long term, Metro will want to implement a diverse biosolids management plan, using three or
more biosolids products. This diversity will help to ensure the reliability of the beneficial use strategy@.
Conclusions:
A start date of January 1, 1999 for 100 percent beneficial reuse of the MTP processed biosolids is possible but not
recommended. The total net cost to achieve this start date could reach up to $25,000,000.00 over a three year period. This is
in addition to the presently undetermined cost to design and install a permanent beneficial biosolids reuse management
system.
The 100 percent beneficial biosolids reuse program for the MTP should be implemented in stages based on the long term
plan. This plan was outlined in Clause No. 1 of Report No. 2 of the Works and Utilities Committee meeting of February 11,
1998. Briefly, the plan called for a workshop in the spring of 1998, followed by a draft strategy document in the summer of
1998. After finalization of the strategy document, the marketplace will investigate, through an initial Expression of Interest,
and finally through a Request for Proposals, for further demonstration projects. Confirmation of the terms of reference and
recommendations will be brought to Council for approval. The approval of the further demonstrations projects would be
before Council in early 1999.
Contact Name:
Mr. R. M. Pickett, Director, Water Pollution Control Division
Phone (416) 392-8230
Fax (416) 397-0908
e-mail address: bob_pickett@metrodesk.metrotor.on.ca.
M.G. Thorne, P. Eng.Barry H. Gutteridge
Interim Functional LeadCommissioner
Water and WastewaterWorks and Emergency Services
rmp:mmFile No. 1001.20-131
