Proceedings

Odour nuisance has been attracting increasing public concern in Scotland in recent years. One of the outcomes of this has been the introduction of a statutory Code of Practice for the control of nuisance at wastewater treatment works in April 2006. In parallel, in setting their spending objectives for the investment period 2006-2010, the Scottish Ministers directed Scottish Water to minimise odour at a minimum of 14 works, and a ring-fenced budget was allocated to carry out this work.

Prioritisation of the works to be improved was carried out by a combination of assessing the level of nuisance as indicated by the number of complaints and evaluating the level of reduction in the number of properties affected that would be achieved by different interventions. To carry out the second part of this analysis, a model was created based on an assessment of the odour emission rates of the various sources on the site, and creating a complaints radius based on a predicted level of 5 OU/m3 . The interventions were costed, and used to define scopes of work for capital investment projects at each of the 14 wastewater treatment works. These interventions were presented to the Scottish Odour Steering Group, which is chaired by the Scottish Executive, for approval.

Project teams from Scottish Water Solutions (the delivery arm of Scottish Water) were given the remit to deliver the agreed scope of works. The teams drew on the skills and experience of specialist odour consultants and contractors to ensure the projects had every chance of delivering a significant reduction in odour.

Odour nuisance has been recognised as a significant risk to Scottish Water’s reputation and so regular communication was maintained with interested parties to update on progress and to manage expectations regarding the degree of improvement that could be achieved within the available budgets.

KEY WORDS Odour nuisance, odour control, wastewater treatment, odour modelling.