Waste water treatment plant (WWTP)

PROJECT

Improve the energy efficiency of a waste water treatment plant

SECTOR

Water treatment

CLIENT

Catalan Water Agency (ACA)

INFORMATION OF INTEREST

Efficiency improved after an 8.5% reduction in the (EnPI) kWh/m³ ratio of treated water

FALL IN ENERGY CONSUMPTION

69,745 kWh/year (-8.6%)

SAVINGS

€27,029 a year

Objective achieved:

Efficiency improved after an 8.5% reduction in the (EnPI) kWh/m3 ratio of treated water

Results:

With the implementation of a measuring, control and telemanagement system for Martorell's WWTP, the installation's electric energy management was improved, with energy ratio (EnPI) kWh/m³ savings of 8.6% and annual cost savings of €28,029, allowing payback on the investment in under 12 months.

The punctual control of the energy consumption of the electromechanical units and the detection of deviations in the specific electrical parameters measured (mainly current and voltage) enabled the adoption of a predictive maintenance program based on the early detection of breakdowns, which reduced the number of potential breakdowns and lengthened the useful life of units.

Initial situation

The Catalan Water Agency, the water authority responsible for planning and executing the water policy of the Catalan government, has been implementing the Savings and Energy Efficiency Programme (PEEE in Spanish) in water treatment installations in Catalonia since the end of 2008.

As part of the actions of the PEEE, the Martorell Waste Water Treatment Plant (WWTP) in Barcelona, which is managed by the Catalan Water Agency through the operating company, Compañía General de Aguas de Cataluña S.A., implemented actions to improve energy efficiency via measurement units and an energy telemanagement system, to significantly reduce energy consumption in the installations and extend the useful life of the main electromechanical units. This action received financial support from the Catalan Energy Institute.

Before the improvement, the total energy consumption of the Martorell WWTP and Anoia Pumping Station, in the year between September 2010 and August 2011, was 1,123,716 kWh.

Objectives

The main objective was to optimise the centre's energy consumption to reduce costs. The energy consumption of a WWTP represents approximately 20-25% of the total operation and maintenance costs, which is why it is so important to reduce this cost.
This objective was subdivided as follows:

Improve energy management and its efficiency.
Achieve economic savings as a result of a correct electric energy management approach.
Reduce service outages in installations.
Obtain an electric supply quality diagnosis.
Make available preventive maintenance procedures in lines and electrical installations.
Allocate electricity costs to production processes.
Optimise the modification of contracted tariffs, shifting consumption loads to cheaper periods, etc.

Solution

The solution consisted of the installation of a series of CVMK2 power analyzers at strategic points to collect the installation's necessary electric data values. CBS4 multipoint earth leakage systems, a computer with SCADA management software and a fibre optic communications network were also installed to collect data and coordinate all the operations.

The main units and their implementation are detailed below:

CIRCUTOR CVMK2 power analyzers for the different areas of the plant, logging values for voltage, current, power and other electrical parameters.
CBS-4 multipoint earth leakage systems each with 4 channels, loggging the current and leakage values to anticipate possible service stoppages in:
- pre-treatment (dirty water pumps)
- activated sludge process (primary decanting, aeration, agitation, internal and external recirculation and secondary decanting)
- each of the aeration blowers for the biological reactors
- dehydration units (centrifuges and sludge transportation),
- capacitor bank
- leakage current of the four aeration blowers.
Roll-out of a fibre optic communications network with four devices to reliably collect all field data and control the units remotely.
Implementation of CIRCUTOR SCADA Powerstudio energy management sof tware to improve the electric energy management, efficiency and control of the installation.

The data can be integrated thanks to the installation of these units and telemanagement, improving the electric energy management and thus achieving the project objectives.

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