Author(s): K. Tota-Maharaj; Olz
Linked Author(s): Kiran Tota-Maharaj
Keywords: Pervious pavements; Permeable pavements; Urban runoff; Microbial pollutants; Ground-source heat pumps; Stormwater reuse
Abstract: The use of hydraulic structures such as tanked permeable pavement systems with integrated geothermal heat pumps for the treatment and recycling of urban runoff is novel and timely. This study assesses the efficiency of the combined technology for controlled indoor and uncontrolled outdoor experimental rigs. Water quality parameters such as biochemical oxygen demand, nutrients, total viable heterotrophic bacteria and total coliforms were tested before and after treatment in both rigs. The water borne bacterial community genomic DNA was analysed by polymerase chain reaction (PCR) amplification followed by denaturing gradient gel electrophoresis (DGGE) and was further confirmed by DNA sequencing techniques. Despite the relatively high temperatures in the indirectly heated sub-base of the pavement, potentially pathogenic organisms such as Salmonella spp., Escherichia coli, faecal Streptococci and Legionella were not detected. Moreover, mean removal rates of 99% for biochemical oxygen demand, 95% for ammonia-nitrogen and 96% for orthophosphate-phosphates were recorded. This research enables decision-makers to assess public health risks associated with the recycling of urban runoff treated within a low-cost hydraulic structure. Microbial count reductions were relatively high during the treatment process despite the simulation of a worst case pollution scenario involving the introduction of dog faeces to the simulated runoff. The effluent could be used for recycling (e. g. garden watering and toilet flushing), considering that it does not pose an elevated risk to human heath. The additional heat provided by the ground source heat pumps did not result in a deterioration of microbial pollution due to regrowth during various operational modes.
Year: 2010