Maintenance of oil-degrading pervious pavements: microbes, nutrients and long-term water quality provision

Oil degrading pervious paving systems PPS (meant to mean permeable pavements within this context and used interchangeably) have been demonstrated to require little maintenance, despite functioning as a very effective trap and in-situ bioremediation device, for urban-derived
pollutants. Our work has shown that providing the micro-organisms with inorganic nutrients through the use of liquid fertilisers is not effective over extended periods. The slow release fertiliser used by our group has been shown to be effective but the need to replenish this and some problems with the release of pulses of nitrogen and phosphorus has indicated that in great
care needs to be taken with such nutrient sources. Using large scale outdoor experiments it has been shown that for Nitrogen and Potassium there is an adequate input from the structure itself and from external inputs. Recently it has been discovered that other nutrients such as phosphorus are present within waste oil. These resources have been shown to be available to pavement microbes and this, added to diffuse sources such as leaf litter or those dissolved in rainwater, may be enough to maintain long-term oil degrading activity without additional inputs. There is still, however demonstrable advantages in providing some additional phosphorus. The widespread acceptance of sustainable technology depends on low maintenance costs and a record
of reliability. In this paper we also report some of the efforts being made to address the long term phosphorus issue.