Prepared for: Ontario Ministry of the Environment

Water Standards Section
Standards Development Branch
40 St. Clair Avenue West, 7th Floor
Toronto, Ontario
M4V 1M2

Prepared by: XCG Consultants Ltd.
2620 Bristol Circle, Suite 300
Oakville, Ontario
L6H 6Z7

Disclaimer

This guidance manual regarding water and energy conservation for sewage works ("Guidance Manual") was prepared by XCG Consultants Ltd. in collaboration with Her Majesty the Queen in right of Ontario as represented by the Minister of the Environment ("Ministry") and is intended to be a representative compilation and assessment of the current state of knowledge on water and energy conservation measures for municipal sewage works. The views and ideas expressed in this document are solely those of XCG Consultants Ltd.

The contents of the Guidance Manual were prepared in accordance with generally recognized engineering principles and practices existing at the time of its preparation and are for general information purposes only. In preparing the Guidance Manual, third party data and information has been provided and relied upon which has not been independently verified and which due to the nature or source of the data, is assumed to be accurate, complete, timely, non-infringing and fit for the intended purpose. The Guidance Manual is a technical document and is not a legal representation or interpretation of any environmental laws, rules, regulations, or policies of the Ministry or any governmental agencies. All findings stated in the Guidance Manual are based on facts and circumstances as they existed during the time period that the Guidance Manual was prepared. Any changes in fact or circumstances which may have occurred subsequent to the time of preparation of the Guidance Manual may change the findings in the Guidance Manual.

XCG Consultants Ltd. and the Ministry make no representation or warranty of any kind whatsoever with respect to the completeness or accuracy of the information contained in the Guidance Manual. Readers are advised to obtain competent advice prior to relying on or using any information contained in the Guidance Manual with respect to its suitability for general or specific application.

XCG Consultants Ltd. and the Ministry and their respective officers, employees, servants or agents expressly disclaim all liability for damages of any kind (including without limitation, damages for loss of profits, business interruption, loss of information, or direct, indirect, incidental, special, consequential or punitive damages) arising out of the use of, reference to, or reliance on the information contained herein whether under contract, in tort or under any other basis of liability.

Acknowledgements

The project consultant would like to thank the Ontario Ministry of the Environment (MOE) and their Technical Working Group for their support and advice on this project. The Project Team is grateful to all members of the Stakeholder Reviewers Group for their input to the Guidance Manual and to all of the case study providers for their time and effort in supplying the information provided for the document.

Guidance Manual Preparation

Principal Investigators (XCG Consultants Ltd.)

  • Lynne Maclennan
  • Stephen Nutt

Technical Working Group (MOE)

  • Brad Badelt, Land and Water Policy Branch
  • George Lai, Standards Development Branch
  • Mano Manoharan, Standards Development Branch
  • Sumi Naguleswaran, Standards Development Branch
  • Andre Schnell, Standards Development Branch (Project Manager)
  • Daisy Shen, Standards Development Branch
  • Mirek Tybinkowski, Land and Water Policy Branch

Stakeholder Reviewers Group

  • Jessie Cheng, City of Toronto
  • Mario Chiarelli, Ontario Power Authority
  • Pat Coleman, AECOM (on behalf of Water Environment Association of Ontario)
  • Conal Cosgrove, City of Brockville (on behalf of Municipal Engineers Association)
  • Bill De Angelis, Associated Engineering (on behalf of Consulting Engineers of Ontario)
  • Christine Dejan, Regional Municipality of Durham (on behalf of Water Environment Association of Ontario)
  • Richard Hanson, Optimize Consulting (on behalf of Canadian Water and Wastewater Association)
  • Wayne Harrison, Siemens (on behalf of the Ontario Pollution Control Equipment Association)
  • Youssouf Kalogo, MOE Environmental Assessment and Approvals Branch
  • Paul Leitch, Johnson Controls Inc.
  • Lucyna Mroczek, Ontario Clean Water Agency
  • Mike Newbigging, Wardrop Engineering (on behalf of Water Environment Association of Ontario)
  • Madhumita Ray, University of Western Ontario
  • Craig Reid, Association of Municipalities of Ontario
  • Peter Seto, Environment Canada
  • Robert Tmej, Ministry of Energy and Infrastructure
  • Cameron Walsh, City of Guelph

List of Acronyms

AMO
Association of Municipalities of Ontario
AS
Activated Sludge
ASCE
American Society of Civil Engineers
ATAD
autothermal aerobic digestion
AWWA
American Water Works Association
BAF
biological aerated filter
BRN
biological nutrient removal
BOD5
five-day biochemical oxygen demand
CAS
conventional activated sludge
cBOD5
five-day carbonaceous biochemical oxygen demand
CCHP
combined cooling, heat and power
CCME
Canadian Council of Ministers of the Environment
CEPT
chemically-enhanced primary treatment
cfu
colony forming unit
CGBC
Canada Green Building Council
CHP
combined heat and power
CIP
clean-in-place
CofA
Certificate of Approval
CRD
Capital Regional District
DAF
dissolved air flotation
DBP
disinfection by-product
DO
dissolved oxygen
DOE
Department of Energy
EDD
Edmonton Diesel Desulphurisation
EPRI
Electric Power Research Institute
F/M
food-to-microorganism ratio
FOG
fats, oils and grease
GAC
granular activated carbon
GETF
Global Environment and Technology Foundation
GHG
greenhouse gas
H2S
hydrogen sulphide
HVAC
heating, ventilation and air conditioning
ICE
internal combustion engine
ICI
industrial, commercial and institutional
IFAS
integrated fixed-film activated sludge
LEED
Leadership in Energy and Environmental Design
LP
low pressure
LPHO
low pressure, high output
LPLO
low pressure, low output
LRWWU
Lowell Regional Wastewater Utility
MBBR
moving bed biofilm reactor
MBR
membrane bioreactor
MELP
Ministry of Environment, Lands and Parks
MF
microfiltration
MLSS
mixed liquor suspended solids
MOE
Ministry of the Environment
MP
medium pressure
MPN
most probable number
n/a
not available
N.D.
non-detectable
NF
nanofiltration
NO3-N
nitrate-nitrogen
NRCan
Natural Resources Canada
NTU
nephelometric turbidity unit
NYSERDA
New York State Energy Research and Development Authority
O&M
operation and maintenance
OEE
Office of Energy Efficiency
OTE
oxygen transfer efficiency
OWRA
Ontario Water Resources Act
pfu
plaque forming unit
RAS
return activated sludge
RBC
rotating biological contactor
RO
reverse osmosis
SBR
sequencing batch reactor
SCADA
supervisory control and data acquisition
SRT
solids retention time
STP
sewage treatment plant
TAN
total ammonia nitrogen
TDS
total dissolved solids
TOC
total organic carbon
TP
total phosphorus
TSS
total suspended solids
UF
ultrafiltration
U.S. EPA
United States Environmental Protection Agency
USGBC
United States Green Building Council
U.S. mgd
United States million gallons per day
UV
ultraviolet
VFD
variable frequency drive
VSS
volatile suspended solids
VWRC
Vernon Water Reclamation Centre
WAS
waste activated sludge
WCRWP
Western Corridor Recycling Water Project
WEF
Water Environment Federation
WHO
World Health Organization
WTP
water treatment plant
WWTP
wastewater treatment plant

Preamble

Since the Ontario Ministry of the Environment published the "Guide to Resource Conservation and Cost Savings Opportunities in the Water and Wastewater Sector" (MOE, 1998), it is likely that water and energy use at sewage works has increased as a result of the implementation of new technologies to meet more stringent requirements. At the same time, there has been a major development in the measures available to reduce water and energy use at sewage works, and also in the acceptance of water reuse applications. As a result, the Ministry has commissioned this Guidance Manual on water and energy conservation for sewage works that can be used as a resource by municipal sewage works managers, owners, operators and designers.

Energy is used in the extraction of raw water, its treatment and distribution, its reticulation from points of use, and for the conveyance to and the treatment and disposal of wastewater at sewage works. After labour, energy use is the highest cost item for most sewage works. There are opportunities to reduce water and energy use at sewage works in Ontario.

There are a number of potential factors inhibiting the adoption of water and energy conservation measures at sewage works, including the costs of implementation, the conservative culture of the industry, and the relatively low cost of water and energy in Ontario. Over the longer term, however, pressures on municipalities to reduce water and energy consumption, and reduce emissions of greenhouse gases (GHGs) will increase. This fact, along with increasing energy costs, will facilitate the adoption of resource conservation measures by the wastewater industry in Ontario.

This Guidance Manual is a tool to inform decision makers and sewage works operators on the measures that can be taken to reduce water and energy use at their facilities. It provides information on potential water and energy conservation measures and how these measures can be implemented.

The Guidance Manual provides information on practical measures that can be implemented cost-effectively to reduce water use and energy consumption at sewage works. These measures include improvements in water use and energy efficiency through optimization of existing equipment and operations, as well as through the introduction of newer, more resource-efficient technologies. The document describes best practices to increase water and energy efficiency for collection systems, pumping stations and sewage treatment plants, with a focus on those activities and systems that are most energy intensive and use the largest amount of water. Also included is information on the approaches that can be used to reduce the hydraulic and contaminant loadings to a sewage treatment works from industrial, commercial and institutional (ICI) facilities, which can be used as a means to reduce energy and other operation and maintenance (O&M) costs at sewage works.

The Ministry recognizes that there is a need to consider alternative sources of water supply in Ontario. Water reuse is one strategy that could be used to respond to potential future water needs and to provide sustainable and reliable water supplies over the long-term. The fact that water reclamation and reuse is successfully practiced in many parts of the world is a powerful and positive endorsement for investigating this practice for potential application in Ontario. Jurisdictions that make use of reclaimed water use it mainly for irrigation, residential uses, urban and recreational uses, industrial cooling water, and drinking water production. The net amount of energy saved through water reuse is dependent on the end use of the reclaimed water, as the water quality required will impact the types of treatment processes needed. This Guidance Manual provides information on water reuse options and the quality of effluent typically required for each, based on information from other jurisdictions. It includes practical information on how to identify water reuse and/or reclamation options and how to determine the type of further sewage treatment required for reclamation projects.

1. Introduction

1.1 Background

Compared to many other jurisdictions, Ontario has a relative wealth of freshwater, which could lead to the assumption that water conservation is unnecessary in this province. However, population growth, the use of more water-intensive appliances, industrial uses, potential impacts of climate change, and water losses due to aging infrastructure could result in a water demand that may outstrip the available supply. There is a possibility that over-extraction of groundwater and surface water supplies will result in restrictions on Permits to Take Water and could impede growth and development in the province.

In addition to the issue of supply and demand, the impact of water use on the environment needs to be considered. Conveyance and treatment of water and wastewater uses a significant amount of energy and other resources. Energy conservation is a necessary measure to combat climate change. Water conservation reduces the volume of water and wastewater that needs to be conveyed and treated, which reduces the energy required to construct infrastructure and to convey and treat water and wastewater. Therefore, water conservation will help to reduce the carbon footprint of the water and wastewater sector. In addition, over-extraction of a water supply can result in adverse ecological impacts on a watershed as a result of lower flows and less assimilative capacity for discharges to a receiving waterbody. The use of water conservation measures by sewage treatment works and facilities that discharge to sewer will help to protect our water resources as well as reduce the environmental impact of the water and wastewater sector.

Water reclamation and reuse is another means of protecting the availability of future water supplies and is beneficial for communities with limited availability of potable water. The use of effluent from municipal sewage treatment works is practiced in many jurisdictions where suitable potable water sources are scarce. Australia, the Middle East, Japan and the southern United States have long used treated sewage effluent as a means of meeting water demand.

The beneficial use of treated sewage represents a practical option for supplying water for applications that do not require water of potable quality. In view of the fact that, for many jurisdictions, potable water demand represents a relatively small fraction of overall water demand – in the order of 10 percent in Canada (Environment Canada, 2010a) – using treated sewage can be economically and environmentally prudent, for the water supplier and the water user. In some cases, even the use of highly-treated effluent may be economically feasible where there is a significant issue(s) with water supply and/or wastewater discharge to a sensitive receiving waterbody.

Concerns about greenhouse gas (GHG) emissions and global climate change have led to a growing awareness of sustainability and the need to reduce the use of non- renewable energy sources. Energy is used extensively in the collection, treatment and disposal of wastewater. After labour, energy is the highest operating cost item for most sewage works. Typically, between 30 and 60 percent of a municipality’s energy consumption is by water treatment, distribution and sewage treatment (U.S. EPA and GETF, 2008). Of this energy use, typically 80-90 percent is a result of the pumping and blower operation (Monteith et al., 2007).

Increasing community expectations of high effluent quality, more stringent regulatory requirements and population growth will likely result in an increase in energy use by the wastewater sector, generally for pumping and the operation of energy-intensive treatment processes. At the same time, there is increasing scrutiny on energy use and pressure to reduce GHG emissions. The use of "cap and trade" is a potential means of reducing GHGs that may be implemented in the future, whereby an enforceable limit (or cap) is set on the amount of GHGs that a municipality is allowed to emit. Those municipalities that emit less than their allowance may be able to sell some of the unused allocation to municipalities or other organizations that are not as efficient. These facts, along with increasing energy costs, will likely be the driving forces for the adoption of energy conservation measures by the wastewater sector in Ontario.

The Ontario Ministry of the Environment (MOE) recognizes that managers and operators of sewage works could benefit from information and guidance on potential options for water conservation, water reuse and energy conservation. This Guidance Manual includes practical information on how to identify cost-effective water and energy conservation measures. It also provides information on water reuse and/or reclamation options for treated sewage and how to determine the type of further treatment required for reclamation projects.

1.2 Benefits of Water and Energy Conservation

1.2.1 Water Conservation

There are a number of potential benefits for municipalities through the implementation of water conservation measures, which include the following.

  • A reduction in energy use and associated cost by sewage works for conveyance and treatment of wastewater, with resulting lower GHG emissions by these facilities. Energy use at the sewage works can also be reduced by having the volume and/or strength of wastewater reduced at source by dischargers to the sewer system through water use reduction and pollution prevention measures.
  • A potential decrease in chemical usage and associated cost at sewage treatment works as a result of lower influent flows, e.g. chlorination.
  • A potential enhancement of wastewater treatment efficiency due to increased hydraulic retention time.
  • A decrease in energy and chemical use for water treatment as a result of lower demand for potable water.
  • Potential to free up available capacity of existing water treatment plants, wastewater treatment plants and associated infrastructure, which will delay the requirement for capacity upgrades in areas of population growth.
  • Cost savings as a result of lower water bills for industrial, commercial and institutional (ICI) facilities that implement water conservation and, in the case of some facilities, lower sewer use charges.
  • Protection of future water supplies since by lowering water use, over-extraction of an aquifer or surface waterbody can be avoided.
  • Maintenance of healthy aquatic ecosystems by preventing over-extraction and reducing wastewater discharges to a receiving waterbody.

1.2.2 Water Reclamation and Reuse

The main purpose of water reclamation and reuse is typically to conserve and extend available water supplies by substituting reuse or reclaimed water for applications that do not require potable water. It is also possible to use reclaimed water as an indirect or direct potable water source. Providing an alternative water source can assist in meeting present and future water demands, freeing up limited potable water resources, reducing the need for additional potable water treatment and distribution capacity, and providing water during drought situations.

Another significant benefit of using reclaimed water can be a reduction in energy use associated with the treatment and pumping of potable water supplies. However, if extensive treatment of sewage treatment plant (STP) effluent is required prior to being used and/or the use of reclaimed water requires pumping over significant distances, the energy and other cost savings resulting from lower potable water use may be negated by additional energy and other costs associated with the reuse/reclaimed water system.

For areas where there is a regular shortage of potable water supplies, using reclaimed water can help in growth and development of that area if it is practised by businesses and/or residences.

If treated sewage is used for agricultural irrigation, the additional source of nutrients from the effluent can lessen or eliminate the need for supplementary fertilizer application for some crops (European Commission, 2006). The wastewater sector spends a considerable amount of money to remove nitrogen and phosphorus from the wastewater before it is discharged to the environment, while the agricultural sector spends considerable amounts of money purchasing commercial fertilizers to provide these nutrients to crops. Therefore, both the wastewater and agricultural sectors can benefit from the use of STP effluent for irrigation if most of the nitrogen and phosphorus is not removed during the wastewater treatment process, and effluent is used to provide nutrients that would otherwise come from energy-intensive commercial fertilizers (Juby et al., 2009).

The use of treated sewage may be cost-effective if the water reuse/reclamation system eliminates or delays the need to obtain an additional water supply from a distant source. It may also make economic sense if the available raw water supply for potable water use is of a poor quality, or if the discharge of effluent from a municipal sewage treatment works requires extensive treatment to meet strict surface water discharge requirements (U.S. EPA, 2004).

Communities that practise water reuse or use reclaimed water to satisfy some or all of their water demand are recognized as good environmental stewards and can enjoy an enhanced reputation as a result. Other benefits include decreasing the diversion and consumption of freshwater and reducing the quantity of wastewater disposal, consequently protecting aquatic ecosystems by reducing the amount of nutrients and other potentially harmful constituents from entering the water system, reducing the need for stream flow control structures, and complying with environmental regulations by better managing water consumption and discharge (Metcalf & Eddy and AECOM, 2007).

Table 1.1 provides a summary of benefits that can result from water reuse.

1.2.3 Energy Conservation

Energy conservation has two main benefits, namely a reduction in GHG emissions and cost savings as a result of using less energy.

Information on energy savings at sewage works resulting from the implementation of practical design and energy optimization measures provided in guidance manuals in Europe indicates that there are significant benefits to this approach (WERF, 2010a). In Switzerland, the Swiss Federal Ministry for Environment, Forest & Landscape has prepared a guidance manual that has been used to assist with conducting an energy analysis of at least two-thirds of sewage treatment works, resulting in an average reduction in energy costs of 38 percent (Müller et al., 2006). A guidance manual developed by the Ministry for Environment, Nature Protection, and Agriculture & Consumer Protection in the German State of North Rhine Westphalia has assisted at least 344 sewage treatment works to reduce energy costs by an average of 50 percent (Müller and Kobel, 2004).

For municipalities that promote energy conservation at residential and/or ICI facilities, implementing energy reduction schemes at municipal facilities, including sewage works, provides a clear message that energy conservation is an important issue. Energy efficiency can, in some cases, result in additional benefits, such as performance gains, improvements in operation of processes and reduction in maintenance costs.

Table 1.1 Summary of Water Reuse Benefits (Adapted from European Commission, 2006)
Type Benefits
Economic and Financial Additional water supply that would otherwise be lost

Often the least cost option when overall urban water cycle is considered

Revenue from the sale of reclaimed water

Reduced water and/or energy charges by substituting with reclaimed water when non- potable supply is adequate to meet demand

Source of nutrients when used for irrigation

Legal Eliminate potential non-compliance issues related to discharge of wastewater effluent to sensitive ecosystems

Can be used to achieve demand management targets for water conservation programs

Environmental Reduce withdrawal of water from sensitive sources

Reduce wastewater discharge to sensitive receivers

Potentially lower greenhouse gas emission

Best scenario for nutrient recycling in agriculture

Smaller local or decentralized systems can relieve combined sewers, recharge local rivers and/or enable aquifer recharge

Social Improved level of service

Creates employment

Promotes sustainability

Can lead to improvements in public health by protecting downstream water supplies from contamination through the reduction or elimination of effluent discharges

1.3 Who Should Implement Water and Energy Conservation Measures

Water conservation and energy conservation have many potential benefits, as discussed in Section 1.2. Therefore, every sewage treatment works should consider implementing water and energy conservation measures.

The Water Opportunities and Water Conservation Act was passed in 2010. The Act provides regulation-making authority to require municipalities (as well as other prescribed public agencies) to prepare water conservation plans. This includes authority to require public agencies to achieve water conservation targets and consider technologies and services that promote the efficient use of water when making capital investments or purchasing goods and services.

Furthermore, for municipalities that promote water conservation at residential and/or ICI facilities through incentive programs or other means, implementing water reduction schemes at municipal facilities, including sewage treatment works, provides a clear message that water conservation is an important issue.

The appropriate on-site water conservation measures for sewage treatment works will vary, as they are dependent on a number of site-specific factors, including the types of treatment processes and cleaning equipment used at the sewage works, and size of landscaped area at the facility. The cost-benefit ratio and payback period for water conservation measures will likely be the determining factor for many sites. Costs will include capital and operation and maintenance (O&M) costs associated with the water conservation measures, and benefits can include those discussed in Section 1.2.1.

The promotion of water conservation measures to ICI facilities is an important tool for municipalities to potentially free up available capacity of municipal water and wastewater facilities, as well as for reducing the carbon footprint of treatment facilities. In addition to the potential for energy use reduction at a sewage works due to a lower hydraulic loading from ICI facilities, there is potential for lower energy use as a result of lower contaminant mass loadings through pollution prevention programs at ICI facilities. The cost of such schemes needs to be weighed against the benefits in each case.

Potential negative effects of lower flows on the operation of a sewage treatment works need to be considered on a case-by-case basis. Too low a flow to a sewage treatment works in certain cases can result in the operation of a plant that is hydraulically oversized, but treating a higher strength waste. Low flows can contribute to odour problems and solids deposition in sewers. There is also the potential for an impact on process performance and final effluent quality as a result of a higher strength waste. However, there are potentially significant benefits to be gained by sewage treatment works from upstream source control, and in most cases, the benefits will outweigh the costs.

Water reclamation and reuse is applicable for any sewage treatment works that has an issue with discharging to a receiving waterbody due to a limited assimilation capacity of the receiving water. It may also be an attractive option for end-users where there is a shortage of available potable water supplies.

The potential cost savings and reduction in GHG emissions means that every sewage works should consider options for energy conservation. There are energy conservation measures that will be appropriate for many sewage works and others that will be dependent on a number of site-specific factors, particularly the types of treatment processes and equipment that are used. Some of the potential conservation measures discussed herein may be impractical or infeasible for some facilities due to the cost of implementation or technical considerations, such as the impact on effluent quality or effect on other treatment processes.

Section 6 of the Green Energy Act (Government of Ontario, 2009) enables the province to develop and implement regulations requiring municipalities (as well as other public agencies) to develop a Conservation and Demand Management (CDM) plan. If these regulations are created, they would require the CDM plan to include information on energy consumption, measures to conserve energy, and a summary of achievements in energy conservation (Manning and Vince, 2010).

1.4 General Approaches to Water Conservation

In this Guidance Manual, two approaches to water conservation are considered, namely:

  • reduction in the amount of water used at the sewage treatment works
  • reduction in the incoming flow from upstream ICI sources.

The first approach involving reduced water consumption at the treatment plant will help to reduce the amount of potable water use at municipal facilities. It will typically have an insignificant effect on the operation of a sewage treatment works. The types of water conservation measures at sewage treatment works include equipment changes for processes using potable water, optimization of existing water-using processes, using plant effluent as an alternative to potable water, and changes in operational practices where potable water is used. An assessment of water use and potential options to conserve water should be the first step, which can be carried out by plant staff.

Conserving water at wastewater sources upstream of a sewage treatment works such as residences and ICI facilities has the potential to significantly affect sewage treatment plant operations by reducing the flow to be treated. Concomitant implementation of at-source pollution prevention measures can reduce the contaminant load to the sewage treatment works. There are three main approaches to reducing water use by dischargers to municipal sewers that are discussed in this document, which include education programs, incentive programs and sewer use bylaws.

With regard to upstream source control, the focus of this Guidance Manual is on ICI facilities, where a resultant reduction in the hydraulic and mass loadings can impact energy usage at downstream municipal sewage works.

1.5 General Approaches to Water Reclamation and Reuse

Effluent from municipal sewage treatment works can be used in a number of different ways, some of which will require further treatment (i.e., water reclamation). The general approach to implementing a water reclamation or reuse scheme is to first identify where effluent from a municipal sewage treatment works can be used, estimate the volume and quality of effluent required and then determine if it is feasible.

The feasibility of a reclamation or reuse scheme will depend on its acceptance by the end users and the public, as well as the costs associated with the program (e.g. costs for enhanced effluent treatment, if required, distribution of the reclaimed water, and/or retrofitting the end-user water systems).

1.6 General Approaches to Energy Conservation

In this Guidance Manual, three approaches to energy conservation are considered, namely:

  • changes to operational practices resulting in more efficient energy use by existing systems, processes or equipment
  • installation of more energy-efficient systems, processes, equipment or controls
  • utilization of renewable energy sources.

The first approach involves changing the operation of a system or process or existing equipment. As a result, this approach will typically be the lower cost option for energy conservation at sewage works. In some cases, the cost-benefit of upgrading or replacing equipment may be sufficient to merit the second approach. In addition, the use of more energy efficient systems, processes or equipment should be considered when upgrading an existing sewage works or designing a new plant (MOE, 2008).

There are a number of options for renewable energy use at sewage works. Some of this energy is available as a result of the wastewater treatment process (e.g. biogas from digesters and heat recovery from incinerators). Other renewable energy sources may be feasible for sewage treatment works, and these should be considered.

The focus of this Guidance Manual is limited to the boundary of the sewage works, and does not include considerations such as energy consumption associated with production of chemicals used, the disposal or reuse of sludge/biosolids (excluding incineration), or fuel used by trucking of chemicals or sludge/biosolids.

2. Objectives of the Guidance Manual

2.1 Purpose

The main purpose of this Guidance Manual is to provide information on water conservation, water reclamation and reuse and energy conservation to municipal wastewater managers, operators and engineers. It is hoped that this information will be used to identify and implement feasible schemes, which will help to conserve and extend our available water and energy supplies and resources and reduce the emissions of GHGs by the wastewater sector. Not included in this document is information on stormwater inflow and infiltration control measures, which have a greater potential for reducing the influent flow to sewage treatment works than the water conservation measures presented.

This Guidance Manual is intended as a tool to aid decision makers when determining options for reducing water and energy use and for using reclaimed water. It is not intended as a step-by-step guide on how to implement specific measures or what specific treatment processes are required for reclaimed water, as this would need to be done on a case-by-case basis.

In the context of this Guidance Manual, a sewage works includes the municipal wastewater collection system and the sewage treatment plant.

2.2 Using the Guidance Manual

2.2.1 Water Conservation

The information in Section 3 of this document provides practical information on how to reduce the amount of water used at sewage treatment works, and what options are available for reducing the influent flow and contaminant load from ICI dischargers to the sanitary sewer. Information provided includes how to identify and prioritize water use reduction areas and measures. Examples are given of operational changes or technology changes that can be used to reduce water consumption at an STP. Information on residential water conservation measures is not provided in this document.

2.2.2 Water Reclamation and Reuse

The type of information provided on water reclamation and reuse in Section 4 includes factors to be considered when implementing a water reuse or reclamation scheme, a summary of reuse/reclamation options, guideline and regulatory information on reuse/reclamation schemes applied in other jurisdictions, and the types of treatment processes that could be used. It provides some information on cost and energy use for water reclamation and reuse, as well as some case history examples of existing water reuse and reclamation applications.

The information herein is a good starting point for any municipality considering a water reuse project and should help in determining the best option(s) for reuse and reclamation and what treatment systems need to be put in place, either at the sewage treatment plant and/or at the user’s facility.

This Guidance Manual focuses on water reclamation and beneficial uses of effluent from municipal sewage treatment works. Other sources of water for reclamation and reuse outside the framework of this document include wastewater from agricultural return flows, stormwater runoff and industrial discharges.

2.2.3 Energy Conservation

Section 5 of this Guidance Manual provides practical information on how to identify and prioritize energy use reduction areas and measures, and provides examples of operational changes or technologies that can be used to reduce the consumption of non-renewable energy at sewage works. A summary of alternative sources of energy that can be used at municipal sewage works is also provided. Quantifying GHG emissions associated with energy reductions at sewage works are outside the scope of this document. Information in Section 5 should be used when assessing treatment options for water conservation and water reclamation and reuse schemes.