Barrie Wastewater Treatment Facility

An Energy Recovery and Generation Study for the Barrie Wastewater Treatment Facility was aimed at identifying opportunities to reduce energy and operational costs at the 76 MLD plant. The primary focus of the study was on the operations and processes of the current facility that could yield immediate improvements, as well as options to be considered during the future upgrade design and implementation phase.


Location

  • Barrie, Ontario

Sector

  • Energy
  • Hydropower
  • Bio-Industrial and Thermal Energy
  • (View all)

Service

  • Energy Management and Efficiency
  • Power Generation
  • (View all)

Project Status

  • Study to be completed in March 2019


Located in the city of Barrie, Ontario, the Barrie Wastewater Treatment Facility (WWtF) has an average day rated capacity of 76 MLD, with a peak daily flow capacity of 156 MLD. Barrie WPCP treats wastewater using a High Purity Oxygen activated sludge process with aluminum sulfate addition for phosphorus removal. WSP was retained to produce an Energy Recovery and Generation study for the Barrie WWtF to identify technical solutions for potential energy savings.

Rated Flow
76 ML/d
Peak Flow
156 ML/d
Outfall
1,200 mm dia
Number of Opportunities Identified
21
Number of Opportunities Short-listed
6

Short-Listing

The initial exercise was a brainstorming workshop with operators and engineering staff from Barrie, along with engineers and technical staff from WSP. During the workshop over 20 opportunities were identified, which were then short-listed to 6, to be investigated in more detail in order to determine the cost-benefit potential.

The approach for evaluating the opportunities was based on a lifecycle costing analysis over a 20-year planning horizon, spanning from 2021 to 2041. The year 2021 was selected as the start year as it was assumed that the equipment would be installed by then. The assumptions used in the costing analysis were based on:

  • Annual inflation rate for equipment and labour
  • Annual inflation rate for energy
  • Discount rate to determine the net present value (NPV), as applicable
  • Replacement period of 20 years
  • Electricity Rate (2019) and inflated by 5% annually
  • Hauling Rates (2019) and inflated by 2% annually
  • An Operator labour rate that was increased by 5% annually
  • Capital costs that included a contingency allowance and an engineering allowance

The study did not consider the biogas facility, as it would be reviewed under a separate project.

Short-Listed Options

The main objective for the short-listed options was to determine if each option was viable and provided real savings to the city, either in the short or long term. The short-listed alternatives are outlined as follows:
 

Coagulation injection upstream of the primary clarifier for enhanced sedimentation

The chemically enhanced primary treatment (CEPT) was assessed using the GPS-X model with alum as the coagulant.

The effect of CEPT addition on the loading to the activated sludge process, the high purity oxygen requirements, biogas production, alkalinity, and sludge production were evaluated.

The evaluation of the financial merit of this alternative found that reducing the oxygen requirements would result in annual savings. However, the added costs incurred in providing additional alum outweighed the savings gained.
 

Optimization of filter backwash 

Energy savings could be obtained by reducing the backwash frequency in the filter system, based on diurnal flow and the installation of turbidity analyzers.

Reducing the backwash frequency would not incur any capital costs and could reduce energy costs by 25% to 75%, resulting in a saving of energy ranging from $46,758 to $106,630 annually.
 

Installation of heat recovery system for the plant effluent

The installation of a heat recovery pump system to extract energy from the effluent water to be converted to heating water was based on providing heat to a known nearby facility where electricity for heating was used.

From an effluent water temperature of 10oC, the heat pump can generate heating water at temperatures greater than 70oC. The annual energy savings were not sufficient to offset the estimated capital cost (Class D estimate) payback period.

This option was found to be a long-term option because it showed that there is potential if the scale of the project was increased and the cost of electricity reached a certain value.
 

Installation of micro-turbines on the outfall

The installation of a hydro-turbine at the outfall of the plant to harness energy is typically based on potential energy (available head) to produce electricity. Most treatment facilities have low head, but high flows, so for this option kinetic energy systems were looked at to offset the power consumption of the WWtF.

The option showed that kinetic microturbines at the outfall would provide energy savings, but the high construction costs for a new chamber, among other things, made them cost prohibitive.

This option was classed as a long-term option to be considered during proposed upgrades to the secondary treatment, where there may be potential when bypassing equipment using effluent channels suitable for the kinetic energy micro-turbines. Using the kinetic approach relies on velocity, which allows them to be installed in multiple locations.
 

Installation of a biosolids dewatering system

Dewatering the digested biosolids to produce a solids cake with 28% total solids would reduce the volume of hauled biosolids by up to 95%. This reduces the number of trucks required for hauling and their associated costs.

However, installing the dewatering system at the WWtF would increase chemical use and power consumption at the plant, and a reduction at the Oro-Medonte biosolids facility.

This option provided potential for high operational savings and will be looked at in more detail.
 

Installation of a biosolids thickening system

Similar to the dewatering system, this approach considered only thickening the biosolids. The number of trucks required for hauling to the Oro-Medonte biosolids facility was reduced by up to 69%.

This option provided potential for high operational savings and will be looked at in more detail.

img-Barrie Wastewater Treatment Facility  Energy Recovery and Generation Study

The Energy and Generation study has not only provided focus to the city of Barrie with options to pursue straight away, such as the optimization of the filter backwash, but it has also provided options that could be implemented in future design and implementation upgrades.