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Wastewater Collection

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End users
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Wastewater Treatment

Wastewater collection entails collecting wastewater from end users and transporting it to a final discharge point, usually a wastewater treatment facility. Depending on the type of system, energy and/or GHG emissions from wastewater collection will be related to the following:

  • Pumping efficiency and operation.
  • The amount of infiltration or rain water entering the collection system and being pumped.
  • Energy source (renewable, fossil fuels, grid energy mix) for pumping.
  • Combined Sewer Overflow (CSO) events leading to direct GHG emissions from receiving waters.
  • Direct discharges to receiving waters where there is no wastewater treatment coverage.
  • Fuel consumption from truck pickup/deliveries.
  • Methane emissions from methane produced in sewers under anaerobic conditions (from sediment buildup and/or long detention times).
  • Recovering Energy (Heat and topographical).
Impacted by: Impacts:
Wastewater Treatment

The distance and elevation of the wastewater treatment facilities dictates whether wastewater needs to be pumped (as opposed to gravity flow).

Wastewater Treatment

The wastewater treatment energy depends on the volume and concentration of the water collected. Collection systems with high infiltration and rain water collection lead to less efficient treatment. Collection systems with long detention times allowing for anaerobic organic matter decay, may lead to the use of chemicals in the treatment to ensure nitrogen removal.

Wastewater Discharge

When there is no wastewater treatment, the distance and elevation of the final discharge point dictates whether wastewater needs to be pumped.

End users

The type of collection system affects the amount of water used in the homes (dry or flush toilets, greywater separated from blackwater).

End users

The less water entering the collection system from end users, the less pumping energy is required (in pumped systems). However, reduced flows in the collection system network can lead to greater detention times, which can possibly result in greater methane emissions from the collection system.

What can you do?

Find out more about how you can improve specific areas of your system:

Expand All
  • Avoid anaerobic conditions in Sewers
    • N/A

      Description

      N/A

      Points to Consider

      N/A

      Impact Factors

      • GHG Emissions
      • Energy Footprint
      • Water Footprint
      • Cost Benefit

      Benefits

      N/A

  • Energy recovery in wastewater collection
    • Heat recovery from wastewater

      Description

      Temperature of water in sewers often varies between 15 and 25 degrees C. It represents a major pathway of heat loss from modern buildings. Through the installation of heat exchangers in large sewers or at the treatment plant, a small portion of this thermal energy can be recovered and used by heat pumps for local heating of buildings.

      Points to Consider

      By reducing the wastewater temperature, the treatment process may be affected (slower degradation). The minimum design temperature of the treatment plant should be considered when designing the heat exchanger.

      Impact Factors

      • GHG Emissions
      • Energy Footprint
      • Water Footprint
      • Cost Benefit

      Benefits

      Savings in building heating

  • Global management solutions, guidelines or general information of interest for urban water cycle
    • Global management solutions, guidelines or general information of interest -Solution-

      Description

      Global management solutions, guidelines or general information of interest.

      Points to Consider

      Global management solutions, guidelines or general information of interest.

      Impact Factors

      • GHG Emissions
      • Energy Footprint
      • Water Footprint
      • Cost Benefit

      Benefits

      Global management solutions, guidelines or general information of interest.

      GuidelinesLiteratureOpen source

      Water and wastewater energy best practice guidebook

      DOWNLOAD
      Case studiesLiteraturePaid

      Energy Efficiency in the Water Industry: A Compendium of Best Practices and Case Studies – Global...

      M J Brandt, R A Middleton and S Wang 2012
      DOWNLOAD
      LiteraturePaid

      Calibration and optimization of the pumping and disinfection of a real water supply system

      Matthew S. Gibbs; Graeme C. Dandy, M.ASCE; and Holger R. Maier 2010
      DOWNLOAD
      Assessment toolGuidelines

      Effective Utility Management – A Primer for Water and Wastewater Utilities

      THE EUM UTILITY LEADERSHIP GROUP 2017
      DOWNLOAD
    • Proactive Infrastructure Asset Management

      Description

      The timely rehabilitation/substitution replacement of pipes and service connections enables the reduction of minimizes the number of unplanned repairs and water loss in the water abstraction system; hence, its energy and GHG emissions. An Proactive Infrastructure Asset Management aims at this.

      Points to Consider

      Management has to be proactive and not focus on short-term strategies that lead to lower levels of service in the future and higher costs for the user. In addition to risk of pipe failure, the cost-benefit of rehabilitating/replacing pipe versus anticipated savings in energy and reduction in GHG emissions from water loss reduction should be considered.

      Impact Factors

      • GHG Emissions
      • Energy Footprint
      • Water Footprint
      • Cost Benefit

      Benefits

      Pipe rehabilitation/replacement reduces leakages resulting in energy and water savings, and GHG emissions reduction.

    • SCADA System to control pump operation

      Description

      Use of supervisory, control, and data acquisition (SCADA) system for monitoring, supervision and controlling of pumping systems can help minimize energy consumption of GHG emissions. It includes measurements in real time of water levels, pressures, flows, energy consumption and other operational parameters. It also helps to adjust and control the pump station operation, contributing to fight water losses or infiltrations, reduce pumping during energy peak hours and adjust pumping volumes to the needs of the system. The SCADA systems provide utility managers with access to real-time operating data and can help offset the higher operating costs by minimizing unplanned downtime and improving maintenance plans. The SCADA system can also be used to optimize pumping in real-time through advanced pump optimization software and control, or through either a model-based or knowledge-based optimization that is implemented via a rule-based system programmed into the SCADA system. This type of optimization entails the use of algorithms to determine the best pumping scheme for a given situation. This can incorporate the peak energy times previously referenced, but also a prioritization of which pumps or pumping stations are used to maximize efficiency whenever possible. For example, if only a certain volume is demanded, then the SCADA system will first operate the most efficient pumps or pumping stations to meet the demand until greater capacity or more pumps are needed.

      Points to Consider

      • The initial installation costs can be high • Operational benefits other than energy efficiency are high • Cost-benefit based upon listed benefits

      Impact Factors

      • GHG Emissions
      • Energy Footprint
      • Water Footprint
      • Cost Benefit

      Benefits

      • Lower energy consumption and costs • Greater operational reliability and flexibility • Facilitates assessing system performance and reporting • Improved asset management • Reduced GHG emissions • Reduced risks associated to sub-optimal operation

      Case studiesLiteraturePaid

      Detailed dynamic pumping energy models for optimization and control of wastewater applications

      W. De Keyser, Y. Amerlinck, G. Urchegui, T. Harding, T. Maere and I. Nopens 2014
      DOWNLOAD
    • Use of a supervisory control and data acquisition system (SCADA)

      Description

      A SCADA enables the remote monitoring and control of the whole system, or parts of it, and processes information to generate alarms, reports, graphs or other outputs essential to operation and maintenance. By enabling the remote control of valves and pumps, the SCADA systems allows faster responses in emergency situations, such as fires or pipe bursts. Remote control, gathered with the system’s monitoring, can also lead to a reduction of human resources and travelling needs, especially those related to the operation of electromechanical equipment.

      Points to Consider

      Proper training of staff to work and use this tool is essential

      Impact Factors

      • GHG Emissions
      • Energy Footprint
      • Water Footprint
      • Cost Benefit

      Benefits

      - Faster responses in emergency situations, such as fires or pipe bursts. - Reduction of human resources and travelling needs, especially those related to the operation of electromechanical equipment.

  • Pump efficiency
    • Evaluation of the pump impeller degradation

      Description

      An optimal control of the state of the mobile parts inside the pump as impeller can prevent some breakdowns in the pumps, and also a good maintenance of these parts keep the pumping efficiency in high levels.

      Points to Consider

      • Can help maintain best efficiency points and optimal pump performance. • Can help minimize energy consumption and costs.

      Impact Factors

      • GHG Emissions
      • Energy Footprint
      • Water Footprint
      • Cost Benefit

      Benefits

      N/A

      LiteratureOpen source

      Pump cavitation various npshr criteria, nphsa, margins, and impeller life expectancy

      Bruno Schiavello, Frank C. Visser 2009
      DOWNLOAD
    • Replace pumps for smaller, bigger, less or more pumps depending on the local conditions

      Description

      Adequate the pumps, and pump conditions to local in order to optimize resources and equipment.

      Points to Consider

      Could be initially expensive.

      Impact Factors

      • GHG Emissions
      • Energy Footprint
      • Water Footprint
      • Cost Benefit

      Benefits

      More energy efficience.

      LiteratureOpen source

      MONTEIRO, M.A.G.; MONACHESI, M.G. Eficiência energética em sistemas de bombeamento. Rio de Janeiro, Eletrobras; Procel, 2005....

      2014
      DOWNLOAD
    • Replacement of Pumps

      Description

      Replacement of old pumps and motors helps to increase the overall efficiency of the pumping systems. New high efficiency electrical motors and pumps is available for any type of application: from chemical pumps to big water centrifugal pumps.

      Points to Consider

      • Can potentially represent high capital costs. • Financing • Payback period. • Cost-benefit based upon capital costs, increased energy efficiency, and energy savings. • Master planning. • Potential future changes to the system that can affect pumping requirements and performance.

      Impact Factors

      • GHG Emissions
      • Energy Footprint
      • Water Footprint
      • Cost Benefit

      Benefits

      • Increase the overall efficiency of the pumping systems. • Reduce energy consumption and costs. • Reduce GHG emissions.

      LiteratureOpen source

      MONTEIRO, M.A.G.; MONACHESI, M.G. Eficiência energética em sistemas de bombeamento. Rio de Janeiro, Eletrobras; Procel, 2005....

      2014
      DOWNLOAD
  • Pumping optimization
    • Automatic pump controller

      Description

      Automatic Pump Controllers make it possible to operate a rainwater system without a large pressure tank, pressure switch, and float switch. In the simplest design, the bottom inlet connects to the pump, the top outlet connects to the plumbing system, and the pump is plugged into the controller which is in turn plugged into to an electrical receptacle. When a faucet is opened, the controller senses the drop in line pressure and instantly turns on the pump to re-pressurize the line. If no water is available, the controller shuts down the pump to prevent dry-run damage.

      Points to Consider

      N/A

      Impact Factors

      • GHG Emissions
      • Energy Footprint
      • Water Footprint
      • Cost Benefit

      Benefits

      Simplest design. Save money and energy avoiding the necessity of more complex infrastructure.

    • Control pumping rate

      Description

      Based upon the system head conditions, pumps may be able to pump at higher rates than needed when operating at 100% motor speed. This flow rate can be controlled by one of two ways, throttling the pump with a valve if the pump is a constant speed pump, or changing the motor speed with a variable speed drive. The former is only energy efficient if the higher flow operating point of the pump without throttling is to the right of the best efficiency point on the pump performance curve, and the throttling results in reducing the flow to a point closer to the best efficiency point on the pump curve. Otherwise, throttling the pump can result in using more energy than at the higher flow, as well as wasting energy because you end up using more energy than is needed. When the demand on the system fluctuates significantly, the pumping rate can be controlled automatically by varying the speed of the motor with a variable frequency drive (VFD), such that the pump output matches only what is needed to meet demands or the intended pumping conditions. The pump’s flow rate then increases or decreases based upon the affinity laws and the controlled speed of the motor. This way lower pumping rates can be achieved, which may result in lower efficiency than those at full motor speed; however, the energy consumption is still lower because the energy requirements to pump lower flows at lower heads are lower.

      Points to Consider

      • Pump performance curves and best efficiency point in relation to controlled flow rate • Motor types for installing VFDs - only certain motors can be used as variable speed • Costs of VFDs and new motors if necessary can be high • Financing • Cost-benefit based upon capital costs, increased energy efficiency, and energy savings

      Impact Factors

      • GHG Emissions
      • Energy Footprint
      • Water Footprint
      • Cost Benefit

      Benefits

      • Less energy consumption • Lower energy costs • Reduced GHG emissions • Better control of pumping

    • SCADA System to control pump operation

      Description

      Use of supervisory, control, and data acquisition (SCADA) system for monitoring, supervision and controlling of pumping systems can help minimize energy consumption of GHG emissions. It includes measurements in real time of water levels, pressures, flows, energy consumption and other operational parameters. It also helps to adjust and control the pump station operation, contributing to fight water losses or infiltrations, reduce pumping during energy peak hours and adjust pumping volumes to the needs of the system. The SCADA systems provide utility managers with access to real-time operating data and can help offset the higher operating costs by minimizing unplanned downtime and improving maintenance plans. The SCADA system can also be used to optimize pumping in real-time through advanced pump optimization software and control, or through either a model-based or knowledge-based optimization that is implemented via a rule-based system programmed into the SCADA system. This type of optimization entails the use of algorithms to determine the best pumping scheme for a given situation. This can incorporate the peak energy times previously referenced, but also a prioritization of which pumps or pumping stations are used to maximize efficiency whenever possible. For example, if only a certain volume is demanded, then the SCADA system will first operate the most efficient pumps or pumping stations to meet the demand until greater capacity or more pumps are needed.

      Points to Consider

      • The initial installation costs can be high • Operational benefits other than energy efficiency are high • Cost-benefit based upon listed benefits

      Impact Factors

      • GHG Emissions
      • Energy Footprint
      • Water Footprint
      • Cost Benefit

      Benefits

      • Lower energy consumption and costs • Greater operational reliability and flexibility • Facilitates assessing system performance and reporting • Improved asset management • Reduced GHG emissions • Reduced risks associated to sub-optimal operation

    • Use of a supervisory control and data acquisition system (SCADA)

      Description

      A SCADA enables the remote monitoring and control of the whole system, or parts of it, and processes information to generate alarms, reports, graphs or other outputs essential to operation and maintenance. By enabling the remote control of valves and pumps, the SCADA systems allows faster responses in emergency situations, such as fires or pipe bursts. Remote control, gathered with the system’s monitoring, can also lead to a reduction of human resources and travelling needs, especially those related to the operation of electromechanical equipment.

      Points to Consider

      Proper training of staff to work and use this tool is essential.

      Impact Factors

      • GHG Emissions
      • Energy Footprint
      • Water Footprint
      • Cost Benefit

      Benefits

      - Faster responses in emergency situations, such as fires or pipe bursts. - Reduction of human resources and travelling needs, especially those related to the operation of electromechanical equipment.

    • Variable frequency drives (VFD)

      Description

      N/A

      Points to Consider

      N/A

      Impact Factors

      • GHG Emissions
      • Energy Footprint
      • Water Footprint
      • Cost Benefit

      Benefits

      N/A

    • Variable speed drives for pump speed control and adjustment of pumping head and flow

      Description

      Variable speed drives (frequency inverters) to control pumps/ electrical motors speed, allow adjusting the pumping flow and head to the demand treatment and/ or consumption. It makes it possible to adjust the flow depending on the demand hour/ day/ month/ season. Reducing pump/ electric motor speed to operate the pump at its maximum efficiency point results in reducing energy consumption per m3 pumped.

      Points to Consider

      An automation system is needed for operation. Cost is typically justified for motor powers above 10-15 KW"

      Impact Factors

      • GHG Emissions
      • Energy Footprint
      • Water Footprint
      • Cost Benefit

      Benefits

      Lower energy costs Higher operational flexibility

      Paid

      A visual tool to calculate optimal control strategy for non-identical pumps working in parallel, taking motor...

      Markus I. Sunela and Raido Puust 2015
      DOWNLOAD
      GuidelinesOpen source

      Energy efficiency: benefits of variable speed control in pumps, fans and compressors

      Schneider Electric Industries SAS 2008
      DOWNLOAD
      GuidelinesOpen source

      Variable speed pumping: A guide to successful applications.

      U.S. Department of Energy 2004
      DOWNLOAD
      GuidelinesOpen source

      Variable Speed Drive (VSD) for Irrigation Pumping

      United States Department of Agriculture 2010
      DOWNLOAD
  • Reducing Combined Sewer Overflow (CSO)
    • N/A

      Description

      N/A

      Points to Consider

      N/A

      Impact Factors

      • GHG Emissions
      • Energy Footprint
      • Water Footprint
      • Cost Benefit

      Benefits

      N/A

  • Reduction of inflow / Infiltration
    • N/A

      Description

      N/A

      Points to Consider

      N/A

      Impact Factors

      • GHG Emissions
      • Energy Footprint
      • Water Footprint
      • Cost Benefit

      Benefits

      N/A

  • Renewable energy
    • Solar and wind energy

      Description

      Use of solar panel and wind turbines to power pumps and other equipment.

      Points to Consider

      Technology details, sun direction / angle of panels, wind speeds and patterns, installation costs and financing models (i.e. loans, ESCO, power purchase agreements, etc.).

      Impact Factors

      • GHG Emissions
      • Energy Footprint
      • Water Footprint
      • Cost Benefit

      Benefits

      Can significantly reduce grid energy consumption and related GHG emissions.

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Wastewater Treatment

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