CURING SEWER ODOURS: A BIOLOGICAL SOLUTION FOR A BIOLOGICAL PROBLEM

摘要

The South Australian Water Corporation (SAWC) has taken a holistic approach to wastewater odour and corrosion management. Data analyses of odour complaints, sewer corrosion hot spots, field sampling and subsequent computer modelling of the wastewater networks are important in identifying the sources of hydrogen sulfide (H_2S) gas production and understanding the reasons for existing odour/corrosion areas. A holistic network approach has been taken to allow the corporation to develop cost-effective odour and corrosion mitigation strategies aimed at controlling the 'root cause' sources of H_2S gas generation.Numerous large gravity-fed concrete sewer mains, laid in thel 880s-1980s, transport sewage to new wastewater treatment assets and upgraded treatment plants. Many sewers were constructed specifically to serve industrial customers outside of the Adelaide metropolitan area and were built to ensure flow capacity for future housing developments. Several of these wastewater trunk mains had slight gradients and, therefore, low flow velocities. Design rules used during this period protected the sewer mains via continuous local ventilation to mitigate potential sulfide generation due to the slow flows.At the time, these areas were typically rural; consequently any odours were dissipated with no issue or complaints. New urban expansion has been encouraged by the state government, supporting development of vacant land for domestic housing, including new high-density housing adjacent to wastewater treatment infrastructure. This encroachment, coupled with society's reduced tolerance of odours, has exacerbated odour complaints. As a consequence, many sewer vents have been deliberately blocked to reducecustomer complaints. Unfortunately this action has caused high H_2S gas levels within the infrastructure, creating significant odour hot spots or, in some cases, resulting in costly sewer collapses.This paper discusses current sewer infrastructure corrosion, odour problems and a successful odour abatement project undertaken in the Adelaide Hills. The project incorporates biofiltration as a low-cost, efficient and environmentally friendly means of removing H_2S.