Development of a confined water sensitive urban design (WSUD) system using engineered soils

Innovative Water Sensitive Urban Design (WSUD) systems are being investigated at three locations to the north and south of Sydney, Australia. These systems contain porous concrete pipes that are designed so that stormwater exfiltrates through the permeable walls of the pipes into the surrounding substrate media material. The porous pipes and media material treat the passing stormwater. The primary aim of the overall project is to develop a model to describe the treatment effectiveness of confined WSUD systems. This paper focuses on the system located at the Weathertex Industrial Site, Heatherbrae. Due to wood processing operations that occur at this site, it is recognised that the surface runoff will carry a heavy organics loading. Granulated Activated Carbon (GAC) is recognised for its ability to reduce the concentration of dissolved organics present in both wastewater and stormwater. GAC was therefore chosen as a filtration medium to be investigated at this site. To maximise the effectiveness of the GAC, extensive laboratory batch studies were undertaken prior to the field system being constructed to determine the optimum GAC/sand ratio. The purpose of the experimental work was to assess the dissolved organic removal potential through sorption of various concentrations of GAC. The aim of this paper is to describe these laboratory experiments and discuss how they related to the field system. Through these experiments it was determined that a sand/GAC ratio of 25:1 was ideal for the media material at the Heatherbrae site.

Influence of compost characteristics on heavy metal sorption from synthetic stormwater

This paper has the aim to assess the ability of garden derived compost to remove dissolved heavy metal contaminants typically found in stormwater. Compost was found to have excellent chemical and physical properties for the sorption of dissolved metal ions (Cu2+, Pb2+ and Zn2+). Batch sorption data were used to determine the sorption efficiency of Cu (93%), Zn (88%) and Pb (97%) by compost. The relative sorption affinity of these metals by compost is found to be in the order of Pb2+ > Cu2+ Zn2+. The effect of different particle size fractions of compost upon the sorption of Cu was also investigated. Sorption conformed to the linear form of the Freundlich isotherm and can be considered favourable because the sorption intensity values obtained in this study are between 0.1 and 1. Compost with a smaller particle size fraction has larger surface areas and greater sorption than the larger particle size fraction. Compost derived from garden waste is efficient for removal of heavy metals from wastewater or treating water for industries.

Pollutant removal efficiency of alternative filtration media in stormwater treatment

Sorption experiments were used to assess the ability of various materials (sand, compost, packing wood, ash, zeolite, recycled glass and Enviro-media) to remove heavy metal contaminants typically found in stormwater. Compost was found to have the best physicochemical properties for sorption of metal ions (Cu, Zn and Pb) compared with sand, packing wood, ash, zeolite and Enviro-media. The compost sorption of these metal ions conformed to the linear form of the Langmuir adsorption equation with the Langmuir constants (q,) for Zn(ll) being 11.2 mg/g at pH 5. However, compost was also found to leach a high concentration of dissolved organic carbon (DOC, 4.31 mg/g), compared with the other tested materials. Various combinations of sand, compost and other materials were observed to have excellent heavy metal removal (75-96% of Zn and 90-93% of Cu), with minimal DOC leaching (0.0013-2.43 mg/g). The sorption efficiency of the different Enviro-media mixes showed that a combination of traditional (sand) and alternative materials can be used as an effective medium for the treatment of dissolved metal contaminants commonly found in stormwater. The application of using recycled organic materials and other waste materials (such as recycled glass) also provides added value to the products life cycle.