Environmental impacts of wastewater treatment plants

It's #TechnicalTuesday so Ayash Anwar, a #teamWRc Graduate Water Process Engineer, is talking about the environmental impacts of wastewater treatment plants and the tools available to assess them.

Wastewater treatment plants (WWTP) are mainly designed to reduce wastewater and environmental pollution, but the raw materials, energy consumption and emissions from the WWTP subsequently result in different environmental impacts. The process emissions from wastewater treatments account for two thirds of the total greenhouse gases generated by the water and sewage companies. The operation of a wastewater treatment plant involves a range of direct and indirect emissions, so it is crucial to develop new ways and techniques to treat wastewater that causes minimal damage to our environment.

To assess the environmental impacts associated with the WWTP, there are several environmental assessment tools present, such as Environmental Impact Assessment, Material Flow Assessment, and Life Cycle Assessment (LCA). LCA is a tool that assesses a product or an entire system’s environmental impact over the course of its full life cycle. An LCA can be conducted to calculate the intensity of the environmental damage caused by wastewater treatment plants.

LCA involves 4 steps: goal and scope definition, inventory analysis, impact assessment, and interpretation. The goal and scope will define the aim of the study and the reason to carry out the LCA study. Inventory analysis involves the collection of data and the quantification of inputs and outputs which include the raw materials used, energy consumption, products and by products from waste and emissions to air, land, or water by substance. The life cycle impact assessment is a step used to evaluate the type and extent of the environmental impacts that will arise based on the inventory data collected. Interpretation is the final step, where the results obtained from inventory analysis and the impact assessment are considered together and analysed based on the goal and scope of the LCA study.

Life cycle assessment (LCA) is a valuable assessment methodology which can be used for assessing the sustainability of wastewater treatment plants. It can be used to compare alternative wastewater treatment processes or to analyse the environmental impacts associated with a wastewater treatment plant and potentially identify the need for new techniques with lower emissions.