Dublin City University

Energy requirements for water treatment vary significantly according to target quality.

Life cycle cost models reflect the broader costs of system ownership.

Environmental impacts should be considered holistically.

Article: Water and electrical energy are essential inputs to most manufacturing and production processes. The two are interconnected: in the broader context, water is required to generate electricity, and, at the manufacturing plant level, energy is required to treat water to various quality levels for process use and/or for wastewater mitigation. Depending on the application, water quality levels can span a broad range, from the Ultra-Pure Water (UPW) used in the semiconductor manufacturing industry to the highly contaminated industrial wastewater generated and treated on site in many manufacturing facilities. Water may also need to be pumped, pressurised, throttled, heated, and cooled. The resource requirements to meet various water quality targets and to pump water around the plant can be considerable.

Reducing the energy and other resources required to treat water is key for operating cost efficiency, particularly as, if predicted, environmental regulations become more stringent and manufacturing processes more complex. However, taking a holistic view is crucial to capture neglected impacts, such as sludge treatment and other outputs, which are often overlooked, but which may in some cases be valorised.

The energy footprint of both process water and wastewater is a function of several parameters: influent water quality; treatment system technology; operational expertise; scale; and importantly end water quality requirements. Very often, these requirements are driven by policy and environmental regulations, as in the case of a wastewater treatment plant. At times, however, these requirements are based on rules of thumb or other less scientific methods. Understanding and modelling water quality requirements, the consequent energy and resource impacts, and producing water quality to match those requirements is key to ensuring operational efficiency.

DCU Water Institute and Advanced Processing Technology Centre researchers have significant expertise in developing life-cycle cost, life-cycle assessment and benchmarking models for water

management, including detailed energy, chemicals and environmental impact models for water treatment technology options, see Figure 1. We also have the in-house expertise to build water treatment systems to serve as a testbed for process development and optimisation. Current research projects include ALICE (http://www.alice-wastewater-project.eu/), ESIPP (https://esipp.ie/) and Saltgae (http://saltgae.eu/). Figure 1: Life cycle cost model for wastewater treatment technology