Energy Benchmarking in Wastewater Collection and Treatment

This study develops a system of energy benchmarking that could be used to improve energy performance in Ireland. Using information available at local authorities, Irish Water, published EPA wastewater discharge license... [ view full abstract ]

This study develops a system of energy benchmarking that could be used to improve energy performance in Ireland. Using information available at local authorities, Irish Water, published EPA wastewater discharge license documentation and Census 2011 small area population statistics, a data sample of sewerage schemes was collated. The data sample comprised actual energy usage values and associated operation variable values related to energy usage, for both wastewater collection and treatment, for 59 independent Irish sewerage schemes. Using this data, a multiple linear regression analysis was carried out to determine two equations of significant predictor variables that would predict mean energy usage for wastewater collection and treatment. A five-variable linear regression model equation was used to predict the mean energy usage for each WwTP sample data point (R2 = 86.8). This multi-variable equation was used to develop an energy benchmarking model that would provide an energy performance score between 0 (very poor) and 100 (excellent) based on the actual energy usage and the predicted mean energy usage. Using sensitivity analysis, the wastewater treatment benchmark model was found to be robust and logical. A three-variable regression model equation of wastewater collection system energy usage (R2 = 59.6) was not as robust. Single variable energy benchmark models were also developed based on; actual energy usage, load treated, flow treated and treatment capacity utilised. The Irish data sample value of 45.9kWh/P.e./annum for the 15,000-30,000P.e. WwTP range is 48% greater than the German target of 31kWh/P.e./annum for the 10,000 to 30,000P.e..